Apple Inc. v. WI-LAN Inc., et al
Filing
1
COMPLAINT against WI-LAN Inc. ( Filing fee $ 400, receipt number 0971-8709033.). Filed byApple Inc.. (Attachments: # 1 Exhibit 1, # 2 Exhibit 2, # 3 Exhibit 3, # 4 Exhibit 4, # 5 Exhibit 5, # 6 Civil Cover Sheet)(Scarsi, Mark) (Filed on 6/19/2014)
Exhibit 5
US008537757B2
(12) United States Patent
Arviv et al.
(54)
(58)
ADAPTIVE CALL ADMISSION CONTROL
FOR USE IN A WIRELESS
COMMUNICATION SYSTEM
Field of Classi?cation Search
See application ?le for complete search history.
(56)
References Cited
Poway, CA (US); Kenneth L.
Stanwood, Cardiff by the Sea, CA (US);
David Gazelle, La Jolla, CA (US); Ofer
U.S. PATENT DOCUMENTS
3,949,404 A
4/1976 Fletcher et a1.
4,495,619 A
Zimmerman, Modiin (IL); Penny
l/l985 Acampora
Efraim, Kfar Sava (IL); Yair Bourlas,
San Diego, CA (US); Sheldon L.
Gilbert, San Diego, CA (US)
(Continued)
FOREIGN PATENT DOCUMENTS
0507384 Bl
0845916 Bl
EP
(73) Assignee: Wi-Lan, Inc., Ottawa (CA)
Notice:
(Continued)
Jun. 1, 2012
(Under 37 CFR 1.47)
(65)
Primary Examiner * Kevin C Harper
(74) Attorney, Agent, orFirm * Procopio, Cory, Hargreaves
Prior Publication Data
& Savitch LLP
US 2013/0064097 A1
Mar. 14, 2013
(57)
Related US. Application Data
(60)
(60)
Continuation of application No. 12/414,363, ?led on
Mar. 30, 2009, now Pat. No. 8,213,359, which is a
continuation of application No. 11/693,546, ?led on
Mar. 29, 2007, now Pat. No. 7,529,204, which is a
continuation of application No. 11/350,464, ?led on
Feb. 8, 2006, now Pat. No. 7,289,467, which is a
division of application No. 10/032,044, ?led on Dec.
21, 2001, now Pat. No. 7,023,798.
Provisional application No. 60/258,428, ?led on Dec.
27, 2000.
(51) Int- ClH04 W 4/00
(52)
OTHER PUBLICATIONS
“Asynchronous Transfer Mode (ATM) Technical Overview”, 2nd
Edition, Prentice Hall, Oct. 1995, Chapter 3, pp. 21-25.
(21) App1.No.: 13/487,013
Filed:
l0/l992
6/1998
(Continued)
Subject to any disclaimer, the term of this
patent is extended or adjusted under 35
U.S.C. 154(b) by 0 days.
(22)
Sep. 17, 2013
None
(75) Inventors: Eli Arviv, Modiin (IL); Brian Spinar,
(*)
US 8,537,757 B2
(10) Patent N0.:
(45) Date of Patent:
(200901)
ABSTRACT
The invention relates to communication systems and to sys
tems and methods for implementing adaptive call admission
control (CAC) in such systems. Adaptive call admission con
trol can determine what CPE to base station calls (connec
tions) are allowed at any given time. CAC, coupled with
precedence, can further determine what connections are sus
pended if less bandwidth is available than is currently com
mitted. Multiple techniques are disclosed to select connec
tions for suspension. These techniques include suspending
enough connections through the affected CPE until there is
enough bandwidth to meet the remaining commitment, ran
domly (or in a round robin fashion) choosing connection to
suspend from the entire set of connection, and using prece
dence priority levels.
US. Cl.
USPC ......................................... .. 370/328; 370/465
24 Claims, 6 Drawing Sheets
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US 8,537,757 B2
Page 2
(56)
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works with Delay Guarantees”, Bell Labs, 2005.
* cited by examiner
US. Patent
Sep. 17, 2013
Sheet 1 of6
BSatseion
US 8,537,757 B2
US. Patent
Sep. 17, 2013
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Sep. 17, 2013
Sheet 4 of6
US 8,537,757 B2
400
402
Receiver module receives
uplink from CPE
4O4\1iRSQ module dclennines signal quality J
l
406
RSQ module and control module compare quality
of uplink with threshold values
408
ls uplmk using
Has quality
less robust PHY
decreased
DO
mnde than its
across a
planned PHY
lhreshold?
mode?
416
Select and apply more
robust PHY mode
Select and apply
a less robust
Has quality
PHY mode
yes
increased
across a
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bandwidth
4
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4] ,
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error threshold
no *
for signal
quality?
420
APPIY
Precedence
FIGURE 4
US. Patent
Sep. 17, 2013
US 8,537,757 B2
Sheet 5 0f 6
600
CPE/base station selects
more robust PHY mode
FIGURE 4
Block 402
I
Y
Control module determines air link line
602
rate based on a reference PHY mode
l
V
Control module calculates the hard bandwidth
603
commitments based on current PHY mode
606
604
Does the air link line
m:
hard
yes
CPE/base station
applies more
robust PHY mode
cornxrurments between
the CPE; and base
station?
A
608
Are air link
yes
resources
available?
610
HO
Suspend connection(s) between
CPE and base station based on
precedence
FIGURE 5
US. Patent
Sep. 17, 2013
Sheet 6 of6
US 8,537,757 B2
500
502\
Receiver module receives a
request for a new connection
504
l
V
CAC module sums the hard bandwidth commitments between
the CPI-Is and base station based on planned PHY modes
l
506
510
Control Module determines air link line
Allow the new
rate based on reference PHY mode
connection
Y
512
/
Control Module determines hard bandwidth
508
commitments based on current PHY mode
Does the air link
line rate exceed the
hard bandwidth
commitments?
Does the at! link lute rate
exceed the hard
bandwidth commitments
between the CPEs and
no
base station?
Deny the new
connection
522
Arc air link
resources
available?
Suspend connection(s)
S20
between CPE and base
station based on precedence
T
Allocate air link
FIGURE 6
resources to the
new connection
yes
US 8,537,757 B2
1
2
ADAPTIVE CALL ADMISSION CONTROL
FOR USE IN A WIRELESS
COMMUNICATION SYSTEM
premise equipments (CPEs), wherein the base station and the
CPEs are each con?gured to increase or decrease the robust
ness of their transmission modulation technique by adapting
their PHY mode. The system comprises a ?rst CPE having a
?rst modem con?gured to modulate data in a communication
link using a ?rst current PHY mode and a ?rst planned PHY
mode, a second CPE having a second modem con?gured to
RELATED APPLICATIONS
This application is a continuation of US. application Ser.
No. 12/414,363, ?led Mar. 30, 2009, which is a continuation
modulate data in a communication linkusing a second current
PHY mode and a second planned PHY mode, and a base
ofU.S. application Ser. No. 11/693,546, ?led Mar. 29, 2007,
station having a third modem con?gured to transmit and
receive data to and from the ?rst and second CPEs. The
now US. Pat. No. 7,529,204, which is a continuation ofU.S.
application Ser. No. 11/350,464, ?led Feb. 8, 2006, now US.
Pat. No. 7,289,467, which is a divisional of US. application
Ser. No. 10/032,044, ?led Dec. 21, 2001, now US. Pat. No.
7,023,798, which claims priority to US. provisional patent
application Ser. No. 60/258,428, ?led Dec. 27, 2000, all
system further comprises a call admission control (CAC)
module con?gured to determine whether to allow a new con
entitled ADAPTIVE CALL ADMISSION CONTROL FOR
USE IN A COMMUNICATION SYSTEM, all of which are
nection between the ?rst CPE and the base station or between
the second CPE and the base station based on a comparison of
a total air link line rate between the ?rst and second CPEs and
the base station, wherein the total air link line rate is based on
a reference PHY mode, with a bandwidth commitment value
incorporated herewith in their entirety by reference.
between the base station and the ?rst and second CPEs,
wherein the bandwidth commitment is based on the ?rst and
BACKGROUND OF THE INVENTION
20
second planned PHY modes.
Another aspect is a method for controlling the admission of
1. Field of the Invention
The present invention relates to communication systems
and to a system and method for implementing adaptive call
admission control in such systems.
2. Description of the Related Art
A wireless communication system facilitates two-way
communication between a plurality of subscriber units (?xed
and portable) and a ?xed network infrastructure. Exemplary
communication systems include mobile cellular telephone
connections in a wireless communication system between a
base station and associated CPEs, including a requesting
CPE. The method comprises receiving a request for a new
25
connection from a requesting CPE, summing the hard band
width commitments between a base station and associated
CPEs, including the new connection and existing connec
tions, based on a planned PHY mode for each connection, and
determining an air link line rate between the base station and
30
the associated CPEs based on a reference PHY mode. The
systems, personal communication systems (“PCS”), and
method further includes if the air link line rate exceeds the
cordless telephones. An objective of these wireless commu
hard bandwidth commitments, accepting the new connection
nication systems is to provide communication channels on
demand between the subscriber units and their respective
and determining a second hard bandwidth commitments for
the existing connections between the base station and the
base stations in order to connect a subscriber unit end user 35 associated CPEs based on a current PHY mode for each
with the ?xed network infrastructure (usually a wire-line
connection, else denying the new connection. The method
still further includes if the air link line rate exceeds the second
hard bandwidth commitments, allocating air link resources to
the new connection, else determining whether additional air
system). In the wireless systems having multiple access
schemes, a time “frame” is used as the basic information
transmission unit. Each frame is sub-divided into a plurality
of time slots. Subscriber units typically communicate with
40
their respective base station using a “duplexing” scheme thus
allowing for the exchange of information in both directions of
new connection, else suspending at least one of the existing
connections between the base station and the associated
CPEs.
the connection.
Transmissions from the base station to the subscriber units
are commonly referred to as “downlink” transmissions.
Transmissions from the subscriber units to the base station are
link resources are available, and if additional air link
resources are available, allocating the air link resources to the
45
BRIEF DESCRIPTION OF THE DRAWINGS
commonly referred to as “uplink” transmissions. Depending
upon the design criteria of a given system, wireless commu
FIG. 1 is a simpli?ed block diagram of a wireless commu
nication systems have typically used either time division
duplexing (“TDD”) or frequency division duplexing
nication system including a base station and one or more
(“FDD”) methods to facilitate the exchange of information
CPEs.
FIG. 2 is an illustration of the structure of a Time Division
between the base station and the subscriber units.
Duplex (“TDD”) frame.
50
SUMMARY OF THE INVENTION
55
The systems and methods have several features, no single
one of which is solely responsible for its desirable attributes.
Without limiting the scope as expressed by the claims which
base station and a CPE.
FIG. 5 is a ?owchart illustrating the process of precedence
being applied to existing connections between the CPE and
follow, its more prominent features will now be discussed
brie?y. After considering this discussion, and particularly
60
after reading the section entitled “Detailed Description” one
will understand how the features of the system and methods
provide several advantages over traditional communication
the base station.
FIG. 6 is a ?owchart illustrating the process of call admis
sion control to a new connection between a CPE and the base
station.
systems.
One aspect is a communication system that is con?gured to
control the admission of new connections and the suspension
of existing connections between a base station and customer
FIG. 3 is a block diagram ofa modem.
FIG. 4 is a ?owchart illustrating the process of adaptively
adjusting a PHY mode for an uplink connection between the
DETAILED DESCRIPTION
65
The following detailed description is directed to certain
speci?c embodiments of the invention. However, the inven
US 8,537,757 B2
3
4
tion can be embodied in a multitude of different systems and
limited to a particular transmission sector 106 of the base
methods. In this description, reference is made to the draw
ings wherein like parts are designated with like numerals
station 102. Within a given sector 106, CPEs 104(a), 104(1)),
104(0) receive the same transmission along their respective
throughout.
downlinks 110(a), 110(1)), 110(0). To distinguish between
In connection with the following description many of the
data intended for a speci?c CPE, the CPEs can monitor con
components of the various systems, some of which are
referred to as a “module,” can be implemented as software,
?rmware or a hardware component con?gured to perform one
trol information in their respective downlink 110(a), 110(1)),
110(0) and typically retain only the data intended for them. In
communication systems that have multiple sectors, the base
or more functions or processes. Hardware components can
station 102 can include a sectored active antenna array (not
include, for example, a Field Programmable Gate Array
shown) which is capable of simultaneously transmitting to
(FPGA) or Application-Speci?c Integrated Circuit (ASIC).
multiple sectors. In one embodiment of the system 100, the
active antenna array transmits to four independent sectors.
Such components or modules may reside on the addressable
storage medium and con?gured to execute on one or more
The communication links 112(a), 112(1)), 112(0) are
processors. Thus, a module may include, by way of example,
components, such as software components, object-oriented
software components, class components and task compo
referred to as an uplink (i.e., from the CPEs 104 to the base
station 102) and can operate on a point-to-point basis. Thus,
nents, processes, functions, attributes, procedures, subrou
tines, segments of program code, drivers, ?rmware, micro
code, circuitry, data, databases, data structures, tables, arrays,
uplink 112(a), 112(1)), 112(0). Communication with the base
and variables. The functionality provided for in the compo
in FIG. 1, each CPE 104(a), 104(1)), 104(0) originates its own
20
station 102 is bi-directional and can be multiplexed on the
basis of Time Division Duplexing (TDD). For a TDD trans
mission from, for example, CPE 104(a), CPE 104(a) would
nents and modules may be combined into fewer components
and modules or further separated into additional components
send its data along communication link 112(a) to the base
and modules.Additionally, the components and modules may
station 102 during a preassigned time slot in a transmission
advantageously be implemented to execute on one or more
frame. The speci?c frame structures of the uplink and down
link will be discussed further below.
computers.
25
FIG. 1 is a block diagram of an exemplary wireless com
munication system 100. Alternatively, the methods and sys
Alternatively, the system can employ Frequency Division
Duplexing (FDD). In such an FDD system, duplexing of
tems herein disclosed can be implemented in wired commu
transmissions between the base station and the CPEs is per
nication systems (not shown). One exemplary broadband
wireless communication system is described in US. Pat. No.
formed in the frequency domain. Different sets of frequencies
30
6,016,311, by Gilbert et al., issued Jan. 18, 2000, entitled
“Adaptive Time Division Duplexing Method and Apparatus
FDD system.
for Dynamic Bandwidth Allocation within a Wireless Com
munication System,” hereby incorporated by reference. The
system 100 includes a base station 102 and at least one cus
35
CPE and the base station. Consequently, each end user con
nection can have different and varying usage and bandwidth
shows three CPEs 104(a)-(c). More or fewer CPEs can be
used. The CPEs and the base station receive and transmit data
requirements. Each CPE 104(a)-(c) may service several hun
along wireless communication links 110(a)-(c), 112(a)-(c).
40 dred or more end users, but at least one end user will be
assigned to transmit and receive data via at least one connec
tion through each CPE 104.
The data transmitted along the communication links 110,
112 is in analog form, and thus a modem 108 is used to
modulate the digital data prior to transmission. FIG. 1 illus
trates the modem 108 being located at the base station 102,
cate by transmitting their data as radio frequency signals. The
term channel refers to a band or range of radio frequencies of
suf?cient width for communication. For example, the range
of frequencies from 26.500 GHZ to 26.525 GHZ would pro
vide a 25 MHZ wide channel. Although the following discus
sion uses the example of a system that transmits information
within the Local Multi-Point Distribution Services (LMDS)
however, a similar or identical modem 108 may be used at the
other end of the downlinks 110(a), 110(1)), 110(0) to demodu
late the received analog data. Thus, the modems 108 in the
50
base station and each CPE are used for uplinking data from
the CPEs to the base station and for downlinking data from
the base station to the CPEs.
The base station and CPEs can use adaptive modulation
and forward error correction (FEC) schemes to communicate.
55
Adaptive modulation, or adaptable modulation density,
band at frequencies of approximately 28 GHZ, the invention is
not so limited. Information can be transmitted at various
frequencies and ranges including, for example, 10 GHZ to 66
GHZ using Quadrature Amplitude Modulation (QAM) sym
bols. The systems and methods described herein can also be
used in a Multichannel Multi-point Distribution Service
includes varying the bit per symbol rate modulation scheme,
or modulation robustness, of downlinks and uplinks transmit
ted between CPEs and the base station. Examples of such
(MMDS) which operates below 10 GHZ. In the MMDS,
Orthogonal Frequency Division Multiplexing (OFDM) sym
bols may be transmitted between the base station and CPEs as
an alternative to single carrier QAM modulation. In such a
system, the methods and systems are applied to one or more
of the OFDM subchannels.
60
Referring again to FIG. 1, the communication links 110(a),
110(1)), 110(0) are referred to as downlinks (i.e., from the base
station 102 to the CPE’ s 104) and can operate on a point (base
station)-to-multi-point (CPE’s) basis. Transmissions to and
from the base station 1 02 can be directional in nature, and thus
Each CPE 104 is further coupled to a plurality of end users
that may include both residential and business customers.
Each customer can have one or more connections between the
tomer premise equipment. The system depicted in FIG. 1
FIG. 1 does not show buildings or other physical obstruc
tions (such as trees or hills, for example), that may cause
channel interference between data from communication links
110, 112. The CPEs 104 and the base station 102 communi
are allocated for uplink and downlink transmissions. The
systems and methods described herein can be used in such an
modulation schemes include quadrature amplitude modula
tion-4 (QAM-4), QAM-16, QAM-64, and QAM-256. If
QAM-4 is used, each resulting symbol represents two bits. If
QAM-64 is used, each resulting symbol represents six bits.
Adaptive FEC includes varying the amount of error correc
tion data that is transmitted in the downlink and/ or uplink.
65
Channel characteristics, for example the modulation and
FEC, for the downlink and/or uplink can be varied indepen
dently. For ease of explanation, the phrase “PHY mode” is
US 8,537,757 B2
5
6
used to indicate characteristics of a communication channel
or link, including for example, modulation scheme and/ or an
FEC.
308 includes information for the CPEs to synchronize With
The PHY mode(s) planned for use in the sector 106 is
normally determined as a function of the geographical rela
the base station 102. The frame control header 308 can
include control information indicating Where a PHY mode
change occurs in the doWnlink. The frame control header 308
can also include a map of a subsequent uplink subframe 304.
tionship betWeen the base station 102 and the CPEs, the rain
region, and the implementation or modern complexity of the
This map allocates the PSs 306 in the uplink subframe 304
betWeen the different CPEs. The frame control header 308
CPEs. Examples of rain regions include rain regions A-Q.
can further include a map of attributes of the doWnlink data
Recommendations for modeling the rain region’s effect on
signal propagation can be found in Rec. ITU-R PN.837.1.
Thus, a planned PHY mode may be different for the CPEs
depending on the capabilities and transmission quality of
each CPE 104 and base station 102 pair. For ease of explana
tion, the phrase “planned PHY mode” is used to indicate the
planned PHY mode for a CPE 104 and base station 102 pair
310. For example, attributes may include, but are not limited
to, the locations of the PSs 306 in the subframe 302 that are
intended for each individual CPE.
The doWnlink data 310 is transmitted using a pre-de?ned
PHY mode or a sequence of PHY modes With three PHY
modes A, B, and C depicted in FIG. 2 as an example. Indi
vidual or groups of PSs 306 in the doWnlink subframe 302 are
as described above.
assigned to data intended for speci?c CPEs 104. For example,
Better environmental conditions, e. g., less distance,
betWeen some CPEs (such as CPE 104(0) for example) and
the base station 102 may permit the use of a less robust PHY
mode by such CPEs as compared to a PHY mode used by
CPEs located farther from the base station. For example, if
the base station 102 could assign PSs in one, some, or all of
20
CPE 104(0) is capable of receiving QAM-64 data coupled
With achieving adequate transmission quality betWeen CPE
104(0) and the base station 102, all data transmitted betWeen
the CPE and the base station can be modulated using QAM
64. In the same system CPEs 104(a), 104(b), Which, for
25
Still referring to FIG. 2, the uplink subframe 304 comprises
uplink data 314(a)-(n). The uplink subframe 304 is used by
example, are only capable of receiving QAM-4 data, Will only
transmit and receive QAM-4 data. By using different or vari
able PHY modes for different CPEs associated With a single
base station, the communication system 100 as a Whole
increases its bandWidth utilization.
30
The transmission quality betWeen the base station 102 and
a CPE 104 may not only vary betWeen each CPE and base
station pair as described above, but may also vary over time,
or betWeen the uplink and doWnlink transmissions of a single
35
pair (i.e. asymmetrical transmissions). For example, in FIG.
1, the transmission quality may signi?cantly decrease during
a rain or snoW storm. When the link quality is decreased, there
the CPEs 104(a)-(0) to transmit information to the base sta
tion 102. The subframe 304 is subdivided into a plurality of
PSs 306. Each CPE 104(a)-(0) transmits its information dur
ing its allocated PS 306 or range of PSs 306. The PSs 306
allocated for each CPE can be grouped into a contiguous
block ofa plurality of data blocks 314(a)-(n). The CPEs use
data blocks 314(a)-(n) to transmit the uplink subframe 304.
The range of PSs 306 allocated to each block in the plurality
of data blocks 314(a)-(n) can be selected by the base station
102. The data transmitted in each data block 314(a)-(n) is
modulated by the transmitting CPE. For example, CPE 104
(a) modulates and transmits uplink data block 314(a). The
is an increased chance that transmitted data along communi
cation links 110(a), 110(1)), 110(0), 112(0), 112(1)), 112(0)
the PHY modes A, B, and C for transmitting data to CPE
104(a). In FIG. 2, the data is divided into three PHY modes,
Where PHY mode A (312(a)) is the most robust modulation
(i.e. least prone to transmission errors caused by signal inter
ference) and While PHY mode C (312(0)) is the least robust
(i.e. most prone to transmission errors caused by signal inter
ference). In betWeen these PHY modes is PHY mode B (312
(19)). Additional PHY modes can also be used.
40
same or different PHY modes can be used for each data block
may be unrecognizable or lost to the receiving base station or
314(a)-(n). The data blocks 314(a)-(n) can also be grouped by
CPE. To accommodate these time variations in link quality,
the communication system 100 can dynamically adjust or
“adapt” the PHY mode for each base station 102 and CPE
104. In such an adaptive system, the bandWidth utilization of
the communication system 100 further increases.
FIG. 2 represents a time division duplexing (“TDD”) frame
and multi-frame structure for use in communication system
PHY mode.
During its data block, the CPE transmits With a PHY mode
that is selected based on measured channel parameters from
45
measured channel parameters from its prior transmission(s).
The process for selecting a PHY mode Will be explained in
more detail beloW. The measured channel parameters can be
100. Frame 300 includes a doWnlink subframe 302 and an
uplink subframe 304. The doWnlink subframe 302 is used by
its prior transmission(s). Similarly, the base station can select
a doWnlink PHY mode for a communication link based on
50
the base station 102 to transmit information to the CPEs
included in the uplink subframe 304 for transmission by the
CPEs to the base station or can be included in the doWnlink
104(a)-(0). In any given doWnlink subframe 302, all, some, or
subframe 302 for transmission by the base station to the CPE.
none of the transmitted information is intended for a speci?c
CPE 104. The base station 102 may transmit the doWnlink
Once received, the base station or CPE can utilize the channel
parameters to determine if the PHY mode of the doWnlink
subframe 302 prior to receiving the uplink subframe 304. The
uplink subframe 304 is used by the CPEs 104(a)-(0) to trans
55
Each CPE 104 can receive all doWnlink transmissions that
are modulated using its current PHY mode or are modulated
using a more robust PHY mode than its current PHY mode.
mit information to the base station 102.
Subframes 302, 304 are subdivided into a plurality of
physical layer slots (PS) 306. Each PS 306 correlates With a
duration of time. In FIG. 2, each subframe 302, 304 can be
subframe 302 or the uplink subframe 304 should be changed.
The frame control header 308 is typically modulated using
one-half millisecond in duration and include 400 PS for a total
the most robust PHY mode to ensure that all CPEs 104(a)-(0)
may receive it. Because each CPE receives the frame control
of 800 PS per frame 300. Alternatively, subframes having
header, each CPE 104 is initially synchronized With the
longer or shorter durations and With more or feWer PSs can be
doWnlink subframe 302 at the beginning of the frame 300.
The doWnlink subframe can be sorted by robustness, Which
alloWs each CPE to maintain synchronization during the sub
sequent portion of the doWnlink that could include data for
that CPE.
60
used. Additionally, the size of the subframes can be asym
metrical and can be varied over time.
65
Each doWnlink subframe 302 can include a frame control
header 308 and doWnlink data 310. The frame control header
US 8,537,757 B2
7
8
FIG. 3 is a block diagram ofa modem 108 Which can be
used to modulate/demodulate data in the Wireless communi
cation system 100 described above. The modem 108 is used to
control the number and quality of existing and neW connec
tions betWeen the CPEs and base station. Modems 108 are
used by the base station 102 and CPEs 104 to modulate and
demodulate data. For ease of description, the modem 108 Will
noW be described With reference to the base station 102.
The modem 108 can include a control section 108(a) and a
a communication system that adapts PHY modes, the selec
tion of a PHY mode can be based on channel parameters
monitored/measured by the RSQ module 208. These channel
parameters can include the signal to noise ratio (SNR) of the
modulated data at the receiver module 202 at the base station
102. A bit error rate (BER), at the base station 102 or CPE
104, can also be used in selecting the PHY mode. For
example, When the received signal drops beloW a threshold
value for a SNR, a more robust PHY mode can be selected by
the modem 108 for the connection. Signal quality can be
measured over a period of time by the RSQ module 208, and,
in response to changes in the signal quality, the control mod
ule 212 determines if the PHY mode for the transmitting CPE
should be changed. The control module 212 at the base station
102 interfaces With the transmitter module 204 to control the
PHY mode for the modem 108. Further, the control module
212, via the transmitter module 204, can alert the transmitting
CPE to change its PHY mode. Measuring signal quality over
time helps avoid cyclic changes in the PHY mode due to
modem section 108(b). The modem section 108(b) includes a
receiver module 202 and a transmitter module 204. The con
trol section 108(a) includes a call admission control (CAC)
module 206, a Receive Signal Quality (RSQ) module 208, a
precedence module 210, and a control module 212. Alterna
tively, the functionality provided for by the control section
108(a) can be separate from the modem 108. Further, the
control section 108(a) components and modules may be com
bined into feWer components and modules or further sepa
rated into additional components and modules Within the base
station 102 and/or CPE 104.
At a base station 102, the transmitter module 204 converts
digital data to an appropriately modulated analog signal com
municated as a doWnlink 110, using for example, QAM
modulation and FEC. The analog signal may also be up con
verted to a carrier frequency prior to transmission. The
20
25
receiver module 202 at the base station 102 demodulates an
uplink 112(a), 112(1)), 112(0) and converts it back to digital
form. When con?gured as a CPE 104(a), the transmitter
module 204 converts digital data to an appropriately modu
lated analog signal communicated as an uplink 112, using for
example, QAM modulation and FEC. The analog signal may
30
sion. The receiver module 202 at the CPE 104 demodulates a
quality of service requested by the end users served by the
35
end users are variable and selectable. The amount of band
on intrinsic factors relating to the neW connection as Well as
communication system level factors. Examples of intrinsic
40
include the type and quality of service for the existing con
nections, Whether available bandWidth is allocated to the
45
50
information rate and the quality of service required by that
service (and also taking into account bandWidth availability
and other system parameters as Will be described beloW). For
bandWidth allocation for each doWnlink subframe 302 and
uplink subframe 304 in a frame 300 (see FIG. 2). In contrast,
certain types of data services such as Internet Protocol data
services (“TCP/IP”) are bursty, often idle (Which at any one
instant may require Zero bandWidth), and are relatively insen
sitive to delay variations When active.
55
ured to monitor signal quality of the received uplink signal. In
requesting CPE, the available bandWidth in the communica
tion link, and the portion of the frame that is allocated for the
uplink and doWnlink. An example of a type and quality of
service that can be evaluated by the CAC module 206 are hard
bandWidth commitments.
The CAC module 206 can be con?gured to determine
Whether there Will be enough bandWidth to support all of the
connections betWeen the CPEs 104 and the base station 102.
For example, the CAC module 206 can determine Whether
there Will be enough bandWidth for hard bandWidth commit
ments betWeen the base station and CPEs. These hard band
Width commitments can include, for example, constant bit
rate (CBR) connections, the minimum cell rate (MCR) por
tion of a guaranteed frame rate (GFR) connections, and some
function of sustainable cell rate (SCR) for variable bit rate
60
(VBR) and variable bit rate real-time (VBR-rt) connections.
Alternatively, hard bandWidth commitments could be the
bandWidth measured, rather than calculated, that is necessary
to provide the quality of service (QoS) desired for the con
nection. For ease of explanation, the folloWing description
65
uses hard bandWidth commitments as an exemplary type of
Referring again to FIG. 3, the Receive Signal Quality
(RSQ) module 208 interfaces With the receiver module 202
and the control module 212. The RSQ module 208 is con?g
factors are a quality of service and a type of service requested
by the end user for the neW connection. The extrinsic factors
are external to the neW connection. The extrinsic factors can
Width dedicated to a given service can be determined by the
example, Tl -type continuous data services typically require a
great deal of bandWidth having Well controlled delivery
latency. Until terminated, these services require constant
What CPE to base station connections are alloWed at any given
time. For example, the receiver module 202 can receive a
request for a neW connection betWeen the CPE and base
station in the uplink 112. The CAC module determines
Whether to grant that request. This determination can be based
CPE. A CPE or base station can continue an existing connec
tion or alloW a neW connection depending on, for example, a
user’ s de?ned quality of service, bandWidth needs, and trans
mission quality. Thus, each end user potentially uses a differ
ent broadband service having different bandWidth and latency
requirements. Moreover, each user can select a portion(s) of
their bandWidth to have variable priority levels, or prece
dence.
To this end, the type and quality of service available to the
The RSQ module at the CPE can measure signal quality for
a signal that is transmitted by the base station 102 and
received by the CPE. The CPE can alert the base station to
change the base station’s transmitting PHY mode. In one
embodiment, only the modem 108 at the base station 102
includes the control module 212. In this embodiment, each
CPE measures its oWn signal quality and transmits its value
Within its uplink 112 to the base station 102. The control
module 212 is then able to monitor the signal quality of the
signal received by the CPEs to determine if the doWnlink 110
PHY modes should be changed.
The call admission control (CAC) module 206 determines
also be up converted to a carrier frequency prior to transmis
doWnlink 110 and converts it back to digital form.
The Wireless communication system 100 can provide
“bandWidth-on-demand” to the CPEs. Thus, the uplink can
include bandWidth requests for neW and existing connections
from end users. The CPEs request bandWidth allocations
from their respective base station 102 based upon the type and
transient changes in the communication link’s quality.
connection. HoWever, the systems and methods disclosed
herein are not so limited and can be applied to any type of
US 8,537,757 B2
10
connection. Further, the systems and methods can be applied
freed up bandWidth When the decision to alloW neW connec
to one or more types of connections.
tions is based upon the minimum air link line rate.
In another embodiment of the communication system 100
The CAC module 206 determines Whether there is enough
that adapts PHY modes, the CAC module 206 alloWs the CPE
to take advantage of the freed up bandWidth. The CAC mod
bandwidth to allow the neW connection. This can be deter
mined by summing the hard bandWidth commitments for
each connection on each CPE 104(a), 104(1)), 104(0) (see
ule 206 limits neW connections based on a comparison of the
bandWidth required for the connection if it is modulated using
the CPE’s planned PHY mode With the available bandWidth.
The available bandWidth is determined by summing the
CPE’s hard bandWidth commitments that Would be used by
FIG. 1). Thus, each CPE Will have a hard bandWidth commit
ment for its existing connections. All of the hard bandWidth
commitments from the CPEs can then be summed to get the
total hard bandWidth commitments for all of the existing
connections through base station 102. The control module
212 can perform these calculations. The CAC module 206
the existing connections if those connections Were modulated
using the planned PHY mode of the CPE. If the available
bandWidth is equal to or exceeds the bandWidth required for
compares the total hard bandWidth commitments to an air link
line rate. The air link line rate is the amount of bandWidth
the neW connection, the CAC module 206 Will alloW the
connection. HoWever, if the CPE operates using a less robust
available betWeen the CPEs and base station. If the air link
line rate exceeds the total hard bandWidth commitments, the
neW connection is alloWed. If the total hard bandWidth com
mitments meet or exceed the air link line rate, the CAC
module 206 denies the neW connection.
In the communication system described above, each con
nection betWeen the CPE 104 and base station 102 Will have
20
PHY mode than its preferred PHY mode, there is the potential
that data through the CPE Will be lost.
In the presence of adaptive PHY modes and to take advan
tage of the CPE’s planned PHY mode, the bit rate associated
With each connection’ s PHY mode is compared. Connections
at different PHY modes (modulation and FEC) effectively
have different bit rates, or air link line rates, and thus are not
a planned PHY mode. The planned PHY mode is used by the
directly compared. One method for comparing these bit rates
CAC module 206 in determining Whether to alloW the neW
is to normaliZe the PHY modes associated With each connec
connection. As Will be explained beloW, the calculation of the
total hard bandWidth commitments for any given sector 106
25
(see FIG. 1) presents additional dif?culties for communica
tion systems 100 Which adapt PHY modes.
tion.
Equation 1, beloW, can be used to normalize the bandWidth
used for connections through an individual CPE.
In communication systems 100 that adapt, or vary, their
PHY modes, the available bandWidth necessary for existing
30
(a)-(c), 112(a)-(c) is adaptive, the robustness of each com
munication link can vary (see FIG. 1). As the robustness
varies, the bandWidth allocated for an existing connection or
Where WCPEZ- is a normaliZed value or Weight for the entire
35
40
45
to the equivalent bandWidth of its connections and the current
modulation associated With each connection. Er is the number
of bits per unit time that are transmitted by the CPE for a
connection. Each connection is modulated using an associ
ated PHY mode. The term mod is the inverse of the associated
PHY mode ef?ciency that is used to modulate the connection.
betWeen CPE 104(a) and the base station 102, 10,000 bits/ s
Were transmitted using QAM-4, and during a second connec
tion betWeen CPE 104(a) and the base station, 18,000 bits/ s
Were transmitted using QAM-64, Equation 1 Would be:
WCPEIO4(Q)I(IO,OOO bits/s*1/2 symbol/bit)+(l8,000
50
cient PHY mode regardless of Whether the least e?icient PHY
mode is actually used. The least ef?cient PHY mode can
bits/s*1/6 symbol/bit):8,000 bits/s.
The 8,000 bits/s for CPE 104(a) is then added to WCPE104
include, for example, QAM-4 modulation With a maximum
amount of FEC overhead bits. This method ensures that dur
ing adverse Weather conditions each CPE Will be able to
select its least e?icient PHY mode and transmit its data Within
bandWidth used by an individual CPE. WCPEZ. is proportional
The bit/symbol rate for QAM-64 is 6, for QAM-l6 is 4, and
for QAM-4 is 2. For example, if during a ?rst connection
Would be required if all of the existing connections betWeen
the CPEs and base station Were modulated using a least e?i
Equation 1
[:1
neW connection Will also vary.
In such communication systems, connections are alloWed
to be modulated With PHY modes that are more or less robust
than the planned PHY mode. Each end user connection can
dynamically select its current PHY mode. This current PHY
mode can be different than the planned PHY mode that Was
planned for the connection. If a connection is modulated
using a more robust PHY mode than the planned PHY mode,
the connection Will exceed its allocated bandWidth.
In an embodiment of a communication system 100 that
adapts PHY modes, the CAC module 206 alloWs neW con
nections With reference to a minimum air link line rate. The
minimum air link line rate is a measure of bandWidth that
"
WCPE; = 2 ER * mod
connections can vary. Since each PHY mode used by the base
station 102 and/or CPE 104 for its communication link 110
55
(b) and WCPEIO4(C) to determine a total normaliZed bandWidth
for the CPEs in sector 106.
Normalization is used to determine the effective hard band
Width commitment usage through the modem 108. The CAC
module 206 interfaces With the control module 212 to com
its assigned bandWidth Without losing its connection With the
pare the different PHY modes for the existing connections
base station. In this embodiment, the CAC module 206 Will
and the neW connection With the available bandWidth
betWeen the base station 102 and CPEs 104. In this embodi
ment, the control module 212 is con?gured to normaliZe each
CPE’s air link line rate. Once the control module 212 has
determined the normaliZed value for each CPE’s committed
bandWidth requirements, the CAC module 206 can sum and
deny a neW connection if the neW connection Will cause the
CPE to exceed its minimum air link line rate. The CAC
60
module 206 can determine Whether to alloW or deny a neW
connection in conjunction With the control module 212. Dur
ing spells of good Weather, the CPE can select a less robust
PHY mode for its current PHY mode. By selecting a less
robust PHY mode, additional bandWidth betWeen the CPE
and base station Would be freed up. HoWever, the communi
cation system 100 is constrained from taking advantage of the
compare them against a common air link line rate.
65
Equation 2, beloW, can be used by the CAC module 206 to
determine the total bandWidth used, i.e. WLMFW, by all of
the CPEs in the sector.
US 8,537,757 B2
11
12
able. Should additional bandwidth be needed when only a few
"
existing connections, between the base station 102 and CPEs
Equation 2
WLink = z WCPEi
104 in sector 106, select a more robust PHY mode, the base
station 102 may be able to reallocate the available bandwidth.
[:1
Thus, if the communication system is suf?ciently under sub
scribed, the CPE 104 can use the additional air link resources
Where WCPEZ- is a normalized value or weight for the entire
bandwidth used by an individual CPE in the sector.
it requires when using a more robust PHY mode than its
planned PHY mode during the 53 minutes. If many existing
For example, with PHY modes of QAM-4, QAM-16, and
QAM-64, each using the same FEC, QAM-4 requires 3 times
connections between the base station and CPEs are subject to
similar adverse environmental conditions, the base station
the air link resources, or bandwidth, of QAM-64 and QAM
16 requires 1.5 times the air link resources of QAM-64. In this
example, the control module 212 can normalize to QAM-64.
Thus, CPEs operating at QAM-64 would have their hard
bandwidth commitments multiplied by a weight of 1, CPE’s
operating at QAM-16 would have their hard bandwidth com
102 may be unable to accommodate the CPEs’ bandwidth
requests. When the air link resources aren’t available, the
precedence module 210 selects which of the existing connec
tions from the CPEs 104 (a)-(c) to suspend.
The precedence module 210 interfaces with the control
module 212 to compare the bit rates for the existing connec
tions through each CPE based on each CPE’s current PHY
mode. While the CAC module 206 compares the planned
mitments multiplied by a weight of 1.5, and CPE’s operating
at QAM-4 would have their hard bandwidth commitments
multiplied by a weight of 3. The CAC module 206 then sums
these hard bandwidth commitments and compares the total
against a line rate of a communication link operating entirely
at the selected normalized PHY mode, QAM-64 with the
single FEC. Alternatively, the control module 212 normalizes
to QAM-4 by applying weights of 1/3 to QAM-64, 1/2 to
QAM-16, and 1 to QAM-4. The selection of QAM-64 and
PHY modes of the CPEs to determine whether a new connec
20
current PHY modes to the selected reference air link line rate
to determine if a suspension should occur. The control mod
ule 212 is con?gured to compare the current PHY modes of
25
QAM-4, each with a single FEC, for use as a normalization
PHY mode are only examples. Any PHY mode could be used
to de?ne the air link line rate for normalizing the connections
between the CPEs and base station.
Still referring to FIG. 3, the precedence module 210 will
30
apply a priority, or precedence, to one or more connections
tional bandwidth until there is enough bandwidth to meet the
when less bandwidth is available than required to meet the
35
connections based on planned PHY modes of the CPEs but
ever, before connections are suspended, the base station 102
can re-allocate bandwidth, that is not intended for hard band
width commitments, among the CPEs to increase the avail
able bandwidth for hard bandwidth commitments. Alterna
tively or in addition to, in TDD systems, the base station 102
can adjust the portion of a downlink subframe 302 and of an
40
45
bandwidth connections with the base station 102 suspended.
These CPEs may receive the full brunt of the planned 53
minutes per year outage. In contrast, other CPEs (in particu
lar, those barely unable to meet the availability number at the
next less robust PHY mode) would have plenty of bandwidth
50
because connections through the geographically challenged
55
CPE’s would be suspended before they need to drop to a more
robust PHY mode and request additional bandwidth.
Alternatively, the precedence module 210 can also ran
domly select connections for suspension or select them in a
round robin fashion. The precedence module 210 chooses
connection to suspend from the entire set of connections that
have hard bandwidth commitments through the CPEs in the
sector 106. The CPEs subject to potential suspension include
CPEs that may still be operating at their planned PHY mode.
uplink subframe 304 in the frame 300 (see FIG. 2) to increase
not available, the precedence module 210 selects which con
nections from among the CPEs are suspended.
Bandwidth problems can arise when one or more CPEs are
using more robust PHY modes than their planned PHY modes
for their connections. For example, if communication system
100 was designed for 99.99% availability, a comparison
would be made between a CPE’s geographical proximity to
the base station and the communication system’s rain region.
Based on this comparison, a planned PHY mode is selected
for that CPE that allows it to operate at that planned PHY
60
ability numbers since the planned outage is evenly shared. For
mode than its planned PHY mode, it will require additional
during this 53 minutes depending on whether additional air
link resources in the communication system 100 are avail
In this embodiment, the communication system 100 as a
whole, and each individual connection still meets its avail
mode or a less robust PHY mode the entire year except for
approximately 53 minutes. If a CPE exceeds a SNR or BER
threshold and transmits its uplink using a more robust PHY
bandwidth for these 53 minutes. At least two things can occur
likely be subject to the application of precedence. In this
embodiment, CPE’s are penalized by their geographic prox
imity to the base station 102. For example, the same CPEs,
those that are barely able to meet their availability numbers at
their planned PHY modes, would be the ?rst to have their hard
the available bandwidth for a CPE that requires additional
bandwidth due to a change in the current PHY mode or the
addition of a connection. However, if additional bandwidth is
remaining demand. The amount of outage during the year for
the connections through the affected CPE 104 is planned
based on the availability and rain region as discussed above.
CPEs 104 located at greater distances from the base station
102 or having limited visibility of the base station wouldmore
some or all of the CPEs are operating at a more robust (less
e?icient) current PHY mode. The precedence module 210
determines which connection(s) are to be suspended. How
the CPEs. As explained above, one method for comparing the
PHY modes is normalization. Once normalized, the prece
dence module 210 determines if additional bandwidth
between the CPEs and base station is available. If additional
bandwidth is available, the precedence module 210 can deter
mine a margin value. If additional bandwidth is not available,
the precedence module 210 selects which connections are
going to be suspended.
The precedence module 210 can be con?gured to suspend
enough connections through the CPE that is requesting addi
now be described. The precedence module 210 interfaces
with the receiver module 202 and the control module 212 to
hard bandwidth commitments. This can occur when the CAC
module 206 is con?gured as described above to limit new
tion is allowed, the precedence module 210 compares the
65
example, if a rain fade caused the base station 102 and CPEs
to lose half of their bandwidth, each connection from among
all of the CPEs would, on average, see only 26 minutes outage
per year rather than 53 minutes. Thus, the precedence aspect
of adaptive CAC can allow you to increase system availability
US 8,537,757 B2
13
14
(26 minutes outage vs 53 minutes outage) or capacity. For
etc.) and the ability of both the transmitting and receiving
example, operating a CPE 104 at a less robust PHY mode than
components (eg CPE 104 and base station 102) to respec
Would typically be planned for the CPE increases the sys
tively transmit and receive data. The base station 102 can
tem’ s capacity. The communication system can rely on adap
determine the quality of each uplink 112(a)-(c). Alternatively,
tive CAC coupled With precedence to distribute the outage
among all of the CPEs. This achieves the planned 53 minutes
outage, but With increased modulation ef?ciency for the CPE
operating at the less robust PHY mode.
the base station 102 periodically transmits channel parameter
measurements, Which are indicative of the quality of a CPE’ s
uplink 112, to that CPE 104. The CPE 104 then uses these
channel parameter measurements to determine the quality of
its uplink. These channel parameter measurements can
include a SNR and/or a BER measurement of the uplink
112(a)-(c). For example, base station 102 can determine the
Further, the precedence module 210 can use levels in con
junction With the random selection method discussed above
When selecting Which connections to suspend. In this embodi
ment, each connection betWeen the CPEs 104(a)-(c) and base
station 102 is assigned a precedence level. Alternatively, each
CPE is assigned a precedence level for its connections. For
example, there are ?ve levels, one through ?ve, With prece
dence level one being assigned to the most important connec
tions and precedence level ?ve being assigned to the least
important connections. The random selection of connections
for suspension is applied as discussed above With reference to
the second embodiment. HoWever, instead of applying the
quality of uplink 112(c) based on a measurement by its RSQ
module 208 (see FIG. 3). A single SNR measurement or a
series of several SNR measurements taken during a frame 3 00
(see FIG. 2) or during multiple frames may be used to deter
mine the uplink quality. The control module 212 can analyZe
multiple measurements to determine an uplink’s quality.
Continuing to block 406, the base station 102 or CPE 104
compares the calculated uplink quality With a current PHY
20
method of the second embodiment to all connections simul
taneously, the precedence module 210 applies it based on
PHY mode is changed. For example, if CPE 104(a) is cur
rently uplinking data to base station 102 using PHY mode B,
the PHY mode Will change When the uplink quality exceeds
each connection’s assigned precedence level. Continuing
With the example above, the random selection Would be ini
tially applied to connections assigned to precedence level
25 an upper threshold or goes beloW a loWer threshold.
?ve. If and When the precedence level ?ve connections are
Next at decision block 408, the CPE determines Whether
the uplink quality has decreased and crossed a PHY mode
loWer threshold according to the comparison made in block
exhausted, the precedence module 210 applies the random
selection process to connections assigned to precedence level
406. Continuing With the example above, if the PHY mode
four and so on until there is adequate bandWidth available for
the remaining connections that have hard bandWidth commit
30
other connections.
Further, the precedence module 210 can alloW connections
35
second threshold is implemented to maintain the connection
at the same PHY mode. HoWever, the error rate associated
With the connection may increase.
FIG. 4 is a ?owchart illustrating the process of adaptively
adjusting a PHY mode for a connection betWeen the base
station 102 and a CPE. This process can be implemented by a
modem 108 at a base station. Alternatively, this process is
performed by a modem 108 at the CPE. A speci?c CPE 104
can change its uplink PHY mode independent of that CPE’s
loWer threshold associated With PHY mode B has not been
crossed, ?oW proceeds to decision block 410 Where the sys
tem determines Whether the uplink quality has crossed an
ments. Thus, individual connections can be selected to have
their uplink or doWnlink transmissions suspended in favor of
to continue to operate With their current PHY mode even
When a ?rst SNR or BER threshold is exceeded. Instead, a
mode threshold. The current PHY mode threshold can
include an upper threshold and a loWer threshold at Which the
upper PHY mode threshold associated With PHY mode B. If
the current modulation upper threshold has been exceeded,
?oW continues to block 412 Where the PHY mode is changed
to a less robust, denser modulation. For example, PHY mode
C is selected for CPE 104(a). The base station 102 can send a
request to the CPE 104 indicating a desired uplink PHY mode
change. Alternatively, the base station 102 transmits an uplink
40
map to all CPEs 104 in the doWnlink subframe 302 (see FIG.
2) indicating Which CPEs have been allotted uplink PS’ s and
the PS’s associated PHY modes. The base station 102 indi
cates to an individual CPE 104 that the PHY mode has been
changed by allotting uplink subframe 304 PSs to that CPE
doWnlink PHY mode. The speci?c CPE’s PHY mode can also
that use a less robust PHY mode. For example, if the uplink
PHY mode for CPE 104(a) is to be changed from PHY mode
be independent of the uplink PHY modes used by other CPEs
B to PHY mode C, the base station 102 assigns uplink sub
104 Within the same sector 106. Because the base station 102
frame PS’s Which are to be modulated using PHY mode C.
This uplink assignment serves as an indicator to the CPE that
must synchronize With each individual CPE 104 that uplinks
data, the uplink quality may be different than the doWnlink
45
50
quality With a speci?c CPE 104. The base station 102 can
perform the process of adaptively adjusting the uplink PHY
mode used by a speci?c CPE 104. As such, a similar process
may be completed for each CPE 104 Within the sector 106 in
order to adaptively adjust each CPEs 104 uplink modulation.
The folloWing description describes a process for adap
55
tively adjusting a PHY mode for an uplink from a CPE to a
base station. The same process is used for adaptively adjust
ing a PHY mode for a doWnlink from the base station to the
CPE.
In particular, ?oW begins in start block 400. How moves to
its uplink PHY mode has been change. FloW continues to a
block 413 Where the system can reallocate the neWly available
bandWidth. For example, the neWly available bandWidth can
be allocated for neW or existing hard bandWidth commit
ments, neW connections, or connections that had been previ
ously suspended. How then returns to block 402 as described
above.
Returning to decision block 410, if the current PHY mode
upper threshold has not been exceeded, ?oW continues to
block 402 as described above.
60
Returning to decision block 408, if the PHY mode loWer
threshold has been crossed, ?oW proceeds to a decision block
414 Where the system determines Whether the connections,
betWeen the CPE and base station that have a hard bandWidth
commitment, are using a less robust PHY mode than the
65
module 208. The quality may be a function of the state of the
planned PHY mode for the connections. If the connection(s)
is using a less robust PHY mode than its planned PHY mode,
transmission medium (e.g. air, foggy air, Wet air, smoky air,
the process proceeds to block 416 Where a more robust PHY
a block 402 Where a receiver module 202 at a base station 102
receives an uplink from a CPE 104. How proceeds to block
404, Where the quality of the channel parameters for the
uplink 112 is determined by a receive signal quality (RSQ)
US 8,537,757 B2
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16
mode is selected for the connection(s). If the base station
determines Whether the uplink quality has crossed a thresh
bandWidth in the doWnlink subframe 304 (see FIG. 2). If
104 in the doWnlink subframe 302 indicating Which CPEs
have been allotted uplink PS’s along With the PS’ s associated
additional air link resources are available, How proceeds to
block 606 Where the more robust PHY mode is applied for the
existing connection. How then returns to block 402 of FIG. 4
Where the base station 102 receives the next uplink from a
CPE 104.
Returning to decision block 608, if additional air link
PHY modes. This alloWs the base station 102 to indicate to an
resources are not available, How moves to a block 610 Where
individual CPE 104 that the PHY mode has been changed by
the precedence module 210 suspends existing connections
allotting uplink subframe 304 PSs to that CPE that uses a
more robust PHY mode. For example, if the uplink PHY
mode for CPE 104(a) is to be changed from PHY mode B to
betWeen the base station 102 and the CPEs 104. As described
PHY mode A, the base station 102 assigns uplink subframe
CPE, randomly suspend connections betWeen the base station
old, the base station 102 can send a request to the CPE 104
indicating a desired uplink PHY mode change. Alternatively,
the base station 102 can transmit an uplink map to all CPEs
PS’s Which are to be modulated using PHY mode A. This
uplink assignment serves as an indicator to CPE 104(a) that
above, the precedence module 210 can, for example, suspend
connections only betWeen the base station and the affected
5
its uplink PHY mode has been change. How then continues to
block 420 Where a precedence module 210 (see FIG. 3) deter
mines Whether connections betWeen the base station and the
CPEs are to be suspended. Precedence Will be explained With
reference to FIG. 5. How then continues to block 402 as
and all of the CPEs in a sector 106, or suspend connections
betWeen the base station and all of the CPEs in the sector in a
round-robin fashion. Further, the precedence module 210 can
randomly suspend connections betWeen the base station and
20
described above.
Returning to decision block 414, if the connection’s cur
rent PHY mode is at least as robust as its planned PHY mode,
the process continues to decision block 418 Where the control
module 212 can replace the loWer threshold associated With
the current PHY mode of the connection that has the hard
bandWidth commitment With a second loWer threshold. The
process continues to block 402 as described above except that
at block 406 the RSQ module 208 and the control module 212
25
use the second loWer threshold to compare With the measured
30
the CPEs that have a loWer precedence priority than other
connections. Alternatively, the precedence module 210 can
suspend the connections that have a loWer precedence priority
in a round-robin fashion. The process moves to block 606 as
described above Where the more robust PHY mode is applied
for the existing connection. The process then returns to block
402 of FIG. 4 Where the base station 102 receives the next
uplink from a CPE 104.
FIG. 6 is a ?owchart illustrating the process of call admis
sion control for a neW connection betWeen a CPE and the base
station. This process can be implemented at a base station.
Alternatively, this process is performed at the CPE. FloW
begins in start block 500. How proceeds to block 502 Where
signal quality of the connection.
Returning to decision block 418, if the control module does
the base station receiver module receives a request for a neW
not select the second loWer threshold, the process moves to a
CAC module 206 sums the hard bandWidth commitments
betWeen the CPEs and base station based on the planned
modulations of the CPEs. Next, at a block 506, the control
module 212 determines an air link line rate for the existing
connections betWeen the base station and CPEs based on the
reference PHY mode. FloW moves to a decision block 508
Where the CAC module 206 determines Whether the air link
line rate determined at block 506 exceeds the hard bandWidth
commitments determined at block 504. If the air link line rate
exceeds the hard bandWidth commitments, the process con
tinues to a block 510 Where the CAC module 206 alloWs the
neW connection. HoWever, air link resources are not initially
allocated to the connection since the connection has been
alloWed based on the planned PHY modes of the CPEs and
block 420, as described above, Where the precedence module
21 0 (see FIG. 3) determines Whether connections betWeen the
connection. The process continues to block 504 Where the
35
base station and the CPEs are to be suspended. Precedence
Will be explained With reference to FIG. 5. Once precedence
has been applied, the process returns to state 402 as described
above.
FIG. 5 is a ?oWchart illustrating the process of applying
precedence to existing connections betWeen the CPEs 104
and the base station that have hard bandWidth commitments.
40
This process can be implemented by a modem 108 at a base
station. Alternatively, this process is performed by a modem
108 at the CPE. FloW begins in start block 600. How moves to
block 601 Where a more robust PHY mode is selected for the
45
existing connection. FloW proceeds to block 602 Where the
base station. The CPEs and base station could be operated at
control module 212 determines an air link line rate based on
a reference PHY mode. FloW moves to block 603 Where the
a more robust PHY mode than their planned PHY mode.
control module calculates the hard bandWidth commitments
for the existing connections betWeen the base station 102 and
50
based on the current PHY mode for each connection. FloW
moves to a decision block 514 Where the precedence module
210 determines Whether the air link line rate determined at
CPEs 104 based on the current PHY mode for each connec
tion. FloW moves to a decision block 604 Where the prece
dence module 210 determines Whether the air link line rate
determined at block 602 exceeds the hard bandWidth com
55
mitments betWeen the CPEs and base station. If the air link
line rate exceeds the hard bandWidth commitments, the pro
cess continues to a block 606 Where the more robust PHY
mode selected in block 601 is applied for the existing con
nection. How then returns to block 402 of FIG. 4 Where the
base station 102 receives the next uplink from a CPE 104.
Returning to decision block 604, if the air link line rate
does not exceed the hard bandWidth commitments, ?oW pro
ceeds to a decision block 608 Where the precedence module
FloW proceeds to block 512 Where the control module 212
determines the hard bandWidth commitments for the existing
connections betWeen the base station 102 and CPEs 104
60
block 506 exceeds the hard bandWidth commitments betWeen
the CPEs and base station determined at block 512. If the air
link line rate exceeds the hard bandWidth commitments, the
process continues to a block 516 Where the base station allo
cates air link resources to the neW connection. How then
returns to block 502 Where the base station 102 receives a
request for a neW connection.
Returning to decision block 514, if the air link line rate
does not exceed the hard bandWidth commitments, ?oW pro
ceeds to a decision block 518 Where the precedence module
210 determines Whether additional air link resources are 65 210 determines Whether additional air link resources are
available. These additional air link resources can include
available. These additional air link resources can include
available bandWidth in the uplink subframe 302 and available
available bandWidth in the uplink subframe 302 and available
US 8,537,757 B2
17
18
bandwidth in the doWnlink subframe 304 (see FIG. 2). If
instruct the modem section to receive the doWnlink data
based on the current doWnlink PHY mode,
Wherein the doWnlink PHY mode speci?es a modulation
format and a forWard error correction technique used for
transmission of doWnlink data.
2. A subscriber station as claimed in claim 1, Wherein the
current doWnlink PHY mode is different from the preferred
doWnlink PHY mode.
3 . A subscriber station as in claim 1, Wherein the DL quality
additional air link resources are available, How proceeds to
block 516 Where the base station allocates air link resources to
the neW connection. How then returns to block 502 Where the
base station 102 receives a request for a neW connection.
Returning to decision block 518, if additional air link
resources are not available, How moves to a block 520 Where
the precedence module 210 suspends existing connections
betWeen the base station 102 and the CPEs 104. As described
above, the precedence module 210 can, for example, suspend
parameter is the signal to noise ratio (SNR).
connections only betWeen the base station and the affected
4. A subscriber station as in claim 3, Wherein a less robust
CPE, randomly suspend connections betWeen the base station
preferred doWnlink PHY mode is selected by the subscriber
and all of the CPEs in a sector 106, or suspend connections
betWeen the base station and all of the CPEs in the sector in a
round-robin fashion. Alternatively, the neW connection is
accepted into a suspended state since the precedence module
210 has already determined Which of the other connections
are to be suspended. Further, the precedence module 210 can
randomly suspend connections betWeen the base station and
the CPEs that have a loWer precedence priority than other
connections. Alternatively, the precedence module 210 can
suspend the connections that have a loWer precedence priority
in a round-robin fashion. The process moves to block 516
Where the base station allocates air link resources to the neW
connection. How then returns to block 502 Where the base
station 102 aWaits a request for a neW connection.
station if the SNR value is above the ?rst and the second
threshold.
5.A subscriber station as in claim 1, Wherein the DL quality
parameter is the bit error rate (BER).
6. A subscriber station as in claim 5, Wherein a less robust
preferred doWnlink PHY mode is selected by the subscriber
20
25
Returning to decision block 508, if the air link line rate
does not exceed the hard bandWidth commitments, ?oW pro
ceeds to a block 522 Where the CAC module 206 denies the
neW connection. The process then returns to block 502 to 30
aWait the next request for a neW connection.
The foregoing description details certain embodiments of
the invention. It Will be appreciated, hoWever, that no matter
hoW detailed the foregoing appears in text, the invention can
be practiced in many Ways. As is also stated above, it should
be noted that the use of particular terminology When describ
ing certain features or aspects of the embodiments should not
instruct the modem section to transmit the uplink data
using the uplink PHY mode.
9. A subscriber station as claimed in claim 1, further com
35
40
uplink connection based on the uplink bandWidth allocated to
the subscriber station and a planned uplink PHY mode.
45
11 . A subscriber station as claimed in claim 10, Wherein the
control module is con?gured to suspend an uplink connection
1. A subscriber station for a Wireless communication sys
tem comprising:
based on the bandWidth allocated to the subscriber station and
the priority of all uplink connections served by the subscriber
a modem section con?gured to receive doWnlink data from
a base station on a doWnlink link and to transmit uplink
data to the base station on an uplink link shared With
When less uplink bandWidth is available for the subscriber
station on the uplink link than required to serve all uplink
connections.
10. A subscriber station as claimed in claim 9, Wherein the
control module is con?gured to limit establishment of a neW
appended claims and any equivalents thereof.
What is claimed is:
prising a precedence module that interfaces With the modem
module and the control module to apply a priority to one or
more uplink connections established at the subscriber station
be taken to imply that the terminology is being re-de?ned
herein to be restricted to including any speci?c characteristics
of the features or aspects of the embodiment With Which that
terminology is associated. The scope of the embodiments
should therefore be construed in accordance With the
station if the BER value is under the second and the ?rst
threshold.
7. A subscriber station as claimed in claim 1, Wherein the
control section further selects the doWnlink PHY mode based
on the subscriber station capabilities.
8. A subscriber station as claimed in claim 1, Wherein the
control module is further con?gured to:
identify in an UL sub-frame map received from the base
station, a current uplink PHY mode selected for the
subscriber station based on a UL quality parameter for
the uplink data and the bandWidth available to the sub
scriber station on the uplink link; and
50
station.
12. A method of communication in a Wireless communi
cation system, comprising:
other subscribers stations;
a receive signal quality module con?gured to monitor a
receiving at a subscriber station doWnlink data from a base
station on a doWnlink link and transmitting uplink data
to the base station on an uplink link shared With other
doWnlink (DL) quality parameter for the doWnlink data
providing a parameter value; and
subscribers stations;
a control section con?gured to:
determine a preferred doWnlink physical (PHY) mode
for the doWnlink data among a plurality of PHY
monitoring a quality parameter for the doWnlink data and
providing a parameter value;
modes of different degrees of robustness, the pre
determining a preferred doWnlink physical (PHY) mode
ferred doWnlink PHY mode being de?ned betWeen a
?rst and a second threshold for the parameter value;
instruct the modem section to transmit to the base station
an indication of the preferred doWnlink PHY mode;
identify in a DL sub-frame map received from the base
station, a current doWnlink PHY mode selected for the
subscriber station based on the preferred doWnlink
PHY mode and the bandWidth available to the sub
scriber station on the doWnlink link; and
for the doWnlink data among a plurality of PHY modes
60
of different degrees of robustness, the preferred PHY
mode being de?ned betWeen a ?rst and a second thresh
old for the parameter value;
transmitting to the base station an indication of the pre
ferred PHY mode;
65
identifying in a DL sub-frame map received from the base
station, a current doWnlink PHY mode selected for the
subscriber station based on the preferred doWnlink PHY
US 8,537,757 B2
19
20
mode and the bandwidth available to the subscriber sta
tion on the doWnlink link; and
19. A method as claimed in claim 18, Wherein the current
uplink and doWnlink PHY modes can be adapted indepen
receiving the doWnlink data having the current doWnlink
PHY mode,
dently based on one or more parameters for the uplink and
respectively doWnlink data.
Wherein the doWnlink PHY mode speci?es a modulation
format and a forward error correction technique used for
transmission of doWnlink data.
13. A method as claimed in claim 12, Wherein the quality
parameter is the signal to noise ratio (SNR), and Wherein a
20. A method as claimed in claim 18, Wherein the step of
establishing a current uplink PHY mode comprises:
receiving from the base station an indication of the quality
of the uplink data and determining if the quality of
uplink data is betWeen a ?rst and a second thresholds;
selecting a less robust UL PHY mode than the current UL
more robust preferred doWnlink PHY mode is provided by the
subscriber station if the SNR value is under the ?rst and the
second threshold.
14. A method as claimed in claim 12, Wherein the quality
parameter is the bit error rate (BER).
PHY mode if the quality of uplink data increased over
the ?rst and second threshold; and
selecting a more robust UL PHY mode than the current UL
PHY mode if the quality of uplink data is decreased
15. A method as claimed in claim 14, Wherein a more
robust preferred doWnlink PHY mode is selected by the sub
scriber station if the BER value is above the second and the
?rst threshold.
16. A method of communication in a Wireless communi
cation system, comprising:
20
receiving at a subscriber station doWnlink data from a base
station on a doWnlink link and transmitting uplink data
to the base station on an uplink link shared With other
When a more robust UL PHY mode is selected:
determining the amount of UL bandWidth available to the
subscriber station using a reference PHY mode for the
subscribers stations;
monitoring a parameter for the doWnlink data and provid
ing a parameter value;
transmitting to the base station the parameter value for
enabling the base station to establish a current doWnlink
PHY mode for the subscriber station based on a ?rst and
a second threshold for the parameter value and the
doWnlink resources available to the subscriber station on
25
30
ment.
the amount of UL bandWidth available to the subscriber sta
35
40
eter value is one of a BER value and a SNR value.
18. A method as claimed in claim 16, further comprising
establishing a current uplink PHY mode for transmission of
for transmission of uplink data.
tion is less than the hard bandWidth commitment for the CPE,
re-select a less robust uplink PHY mode Whenever addi
tional bandWidth is allocated to the subscriber station
from the base station; and
suspend a connection established on the subscriber station
if additional bandWidth is not available to the subscriber
station.
24. A method as claimed in claim 20, further comprising,
Wherein the bandWidth resulting from using a more robust UL
PHY mode is reallocated to other CPEs or connection for UL
uplink data, Wherein the uplink PHY mode speci?es a modu
lation format and a forWard error correction technique used
mode if the amount of UL bandWidth available to the
subscriber station exceeds the hard bandWidth commit
23. A method as claimed in claim 22, further comprising, if
identifying in a DL sub-frame map received from the base
Wherein the doWnlink PHY mode speci?es a modulation
format and a forWard error correction technique used for
transmission of doWnlink data.
17. A method as claimed in claim 16, Wherein the param
subscriber station;
calculating a hard bandWidth commitment for all UL con
nections currently established on the CPE, based on the
current PHY mode; and
transmitting the uplink data using the more robust PHY
the down-link; and
station, the current doWnlink PHY mode; and
receiving the doWnlink data having the current doWnlink
PHY mode,
under the ?rst and second threshold.
21. A method as claimed in claim 18, Wherein the step of
establishing a current uplink PHY mode further comprises
maintaining the current UL PHY mode if the quality of the
uplink data betWeen the ?rst and second thresholds.
22. A method as claimed in claim 20, further comprising,
45
transmission.
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