Core Wireless Licensing S.a.r.l. v. Apple, Inc.

Filing 1

COMPLAINT against Apple, Inc. ( Filing fee $ 350 receipt number 0540-3468392.), filed by Core Wireless Licensing S.a.r.l.. (Attachments: # 1 Civil Cover Sheet, # 2 Exhibit 1 - United States Patent No. 6,792,277, # 3 Exhibit 2 - United States Patent No. 7,606,910, # 4 Exhibit 3 - United States Patent No. 6,697,347, # 5 Exhibit 4 - United States Patent No. 7,447,181, # 6 Exhibit 5 - United States Patent No. 6,788,959, # 7 Exhibit 6 - United States Patent No. 7,529,271, # 8 Exhibit 7 - United States Patent No. 6,266,321, # 9 Exhibit 8 - United States Patent No. 6,978,143, # 10 Exhibit 9 - Nokias June 14, 2011 press release)(Hill, Jack)

EXHIBIT 4

111111

1111111111111111111111111111111111111111111111111111111111111
US007447181Bl

(54)

United States Patent

(10)

Forssell

(12)

(45)

METHOD AND APPARATUS FOR
IMPROVING A MOBILE STATION CELL
CHANGE OPERATION IN THE GENERAL
PACKET RADIO SYSTEM (GPRS)
Mika Forssell, Espoo (FI)

(75)

Inventor:

(73)

Notice:

(21)

Appl. No.: 10/004,723

(22)

Filed:

(51)

Int. Cl.
H04J 3/00
(2006.01)
U.S. Cl. ........................ 370/336; 370/349; 455/442
Field of Classification Search . ... ... ... ....... 370/331;
455/436
See application file for complete search history.

WO
WO
WO

WO-98/59468
WO-99/66740
WO-02119739 A2

(52)
(58)

Subject to any disclaimer, the term of this
patent is extended or adjusted under 35
U.S.c. 154(b) by 1324 days.

EP

Dec. 5, 2001

A
911996 Sallberg et al. ............... 370/17
A * 1111998 Kauppi .................... 455/432.1
A * 9/2000 Stephenson et al. ...... 455/432.1
Bl * 10/2002 Lupien et al. ............... 370/353
B2 * 7/2003 Yegani et al. ............... 455/512
Bl * 2/2005 Sonti et al. .................. 370/252
Bl * 8/2005 Forslow ...................... 370/231
Al * 6/2002 Lohtia et al ................. 455/517
Al * 12/2002 Otting et al. ................ 370/337
Al * 5/2003 Bernhard et al ........ 370/395.21

1 257 096 A2

Primary Examiner-Edan Orgad
Assistant Examiner-lung Park
(74) Attorney, Agent, or Firm-Harrington & Smith, PC
ABSTRACT

(57)

FOREIGN PATENT DOCUMENTS

12/1998
12/1999
3/2002

(Continued)

U.S. PATENT DOCUMENTS
5,555,264
5,832,381
6,119,000
6,463,055
6,597,920
6,859,440
6,937,566
2002/0082033
2002/0186675
2003/0095552

Nov. 4, 2008

ETSI, Global System for Mobile Telecommunications, ETSI TS 101
343 V7.4.0 (2001).

References Cited

(56)

US 7,447,181 Bl

OTHER PUBLICATIONS

Assignee: Nokia Corporation, Espoo (FI)

( *)

Patent No.:
Date of Patent:

A mobile station executed method, wherein upon changing
from a current cell to a new cell in a wireless packet data
network the mobile station enters the new cell; generates a
cell change packet data unit (PDU) message for informing the
network of the location of the mobile station in the new cell;
buffers the cell change PDU message into a PDU transmit
queue before any buffered PDU s that were present before the
mobile station entered the new cell; and transmits the buffered
cell change PDU before any of the buffered PDUs that were
present before the mobile station entered the new cell. In
accordance with another method for informing the wireless
network of the MS cell change, the following steps are
executed: (i) in response to the MS making access in a new
cell, sending a Channel Request that indicates a Cell Update
operation; (ii) establishing an uplink (UL) Temporary Block
Flow (TBF) for transferring Logical Link Control (LLC)
Packet Data Units (PDU s) from the MS to the network; (iii) in
response to the network receiving an unknown Temporary
Logical Link Identifier (TLLI) from the MS, sending a message to a Serving GPRS Support Node (SGSN) and (iv) based
on the message, determining with the SGSN the new cell
location of the MS.

38 Claims, 3 Drawing Sheets

1112002

MS CHANGES CELLS
WITH BUFFERED
LLC PDU(s), REQ
LLC PDU

2A

29

2C

20

2E

2F

US 7,447,181 Bl
Page 2
OTHER PUBLICATIONS
"Digital cellular telecommunications system (Phase 2+); General
packet Radio Service (GPRS); Mobile Station (MS)-Base Station
System (BSS interface; Radio Link Control I Medium Access Control (RLC/MAC) protocol (3GPP TS 04.60 version 8.11.0 Release
1999)", ETSI TS 101 349 V8.11.0 (Sep. 2001), pp. 1-106,
XP002230365, Chapter 9.1.11.

Chew et ai., "Performance analysis for GPRS with prioritized and
non-prioritized mobility management procedures", IEEE Conference on 3G Mobile Communication Technologies 2002, May 8-10,
2002, pp. 1-5, XP002230366, London Chapters 1-3.

* cited by examiner

u.s. Patent

US 7,447,181 Bl

Sheet 1 of 3

Nov. 4, 2008

MESSAGES

WIRELESS
COMMUNICATIONS
SYSTEM,
60,
5

MC

~

NETWORK
OPERATOR
30

10 "

GGSN,32

40
SGSN

PDN

BSC

NEIGHBOR
CELL
(NEW CELL)
MOBILE
STATION,
100

\

XMIT BUFFER

130A
130

MEMORY

LLC
UNIT GMM
120
UNIT RLC/MAC
UNIT
120C
MCU
120B
120A
140

260,
SYNTH

180

DSP
TUNE
160

FIG.1

u.s. Patent

US 7,447,181 Bl

Sheet 2 of 3

Nov. 4, 2008

MS CHANGES CELLS
WITH BUFFERED
LLC PDU(s). REO
LLC PDU

t

V- 2A

V- 28

COMPOSE SHORT CELL
CHANGE LLC PDU.
SEND TO RLC/MAC

t

2C

~

STORE LLC PDU IN
FRONT OF QUEUED
LLC PDU(s)

V

20

~
INITIATE UL TBF
ESTABLISHMENT
PROCEDURE

1

V- 2E

TRANSMIT CELL CHANGE
LLC PDU BEFORE ANY
QUEUED LLC PDU

t
NETWORK REDIRECTS
DL PDUs TO MS
IN NEW CELL

FIG.2

V- 2F

u.s. Patent

Nov. 4, 2008

US 7,447,181 Bl

Sheet 3 of 3

VMS MAKES ACCESS
IN NEW CELL WITH
CELL UPDATE INDICATED

3A

r

ESTABLISH UL TBF
FOR TRANSFERRING
LLC PDUs

BASED ON TLLl,

NEnNORK DOES/DOES

NOT NOTIFY SGSN OF
MS's NEW CELL

FIG.3

V- 38

V-

3C

US 7,447,181 Bl
1

2

radio resources are pre-allocated in the new cell is not currently defined in the GPRS specification.
When the GPRS MS is operating in a GMM (GPRS Mobility Management) READY state, and when the MS enters the
new cell, the MS is expected to send an LLC PDU (Logical
TECHNICAL FIELD
Link Control Packet Data Unit) to the SGSN (Serving GPRS
Support Node). Based on the LLC PDU the SGSN is able to
These teachings relate generally to wireless connnunicadetermine in which cell the MS is located. As such, the SGSN
tions systems and methods and, more specifically, relate to
cellular wireless connnunications systems and to techniques 10 is not required to initiate a Paging procedure when sending
LLC PDUs to the MS.
for a mobile station to transition from one cell to another.
In the GPRS system, when a MS operating in the GMM
BACKGROUND
READY state changes to a new cell (either MS initiated or
network controlled) that is associated with the same routing
The following abbreviations are herewith defined.
15 area as the previous cell, the following process is executed:
BSC Base Station Controller
(i) the MS determines that it will change to the new cell;
BTS Base Transceiver Station
(ii) the MS terminates all TBFs (Temporary Block Flows)
CN Core Network
in the previous cell, meaning that an ongoing data transCRS Cell Re-Selection
fer is terminated abnormally (a TBF is a unidirectional
DL Down Link (to the MS)
20
radio connection between MS and the network, where
EDGE Enhanced Data rate for Global Evolution
there may be an UL (Uplink) and/or a DL (Downlink)
EGPRS Enhanced General Packet Radio Service
TBF established at any given time);
GERAN GSMIEDGE Radio Access Network
GGSN Gateway GPRS Support Node
(iii) the MS enters the new cell;
GPRS General Packet Radio Service
25
(iv) the GMM or LLC of the MS (depending on the impleGMM GPRS Mobility Management
mentation) requests the LLC to send a LLC PDU to the
GSM Global System for Mobile Connnunications
network;
GSN GPRS Support Node
(v) the LLC of the MS sends the LLC PDU to the RLCI
HO Handover
MAC of the MS;
30
LLC Logical Link Control
(vi) when the RLC/MAC of the MS has obtained the
MAC Medium Access Control
parameters related to packet access from a System InforMS Mobile Station
mation message being broadcast in the new cell, or has
MSC Mobile Switching Center
obtained these parameters via some other means (such
PDP Packet Data Protocol
35
as from the previous cell), the RLC/MAC of the MS
PDU Packet Data Unit
initiates an UL TBF establishment procedure;
RLC Radio Link Control
(vii) when the UL TBF is established, the RLC/MAC sends
RNC Radio Network Controller
the LLC PDU to the network; and
SAPI Service Access Point Indicator
SGSN Serving GPRS Support Node
(viii) the SGSN determines from the received LLC PDU
40
TBF Temporary Block Flow
the new location of the MS.
TLLI Temporary Logical Link Identity
A publication entitled Digital Cellular TelecommunicaUL Uplink (from the MS)
tions System (Phase 2+); General Packet Radio Service
UMTS Universal Mobile Teleconnnunications System
(GPRS); Mobile Station (MS)-Base Station System (BSS)
URA User (or UTRAN) Registration Area
45 interface; Radio Link Control/Medium Access Control
(RLC/MAC) protocol; (GSM 04.60 version 6.8.0 Release
UTRAN Universal Terrestrial Radio Access Network
1997) requires that the received (and segmented) LLC PDU s
Reference can also be made to 3GPP TR 21.905, V4.4.0
be put into RLC data blocks in the same order as they are
(2001-10), Third Generation Partnership Project; Technical
received from higher layers. This means that if there was an
Specification Group Services and System Aspects; Vocabulary for 3GPP Specifications (Release 4), as well as to ETSI 50 ongoing data transfer in the previous cell, the RLC of the MS
may have several untransmitted LLC PDUs in its transmit
TR 101 748, V8.0.0 (2000-05), Digital cellular teleconnnubuffer that are to be transmitted to the network in the new cell.
nications system (Phase 2+); Abbreviations and acronyms
The above-mentioned cell change LLC PDU that was initi(GSM 01.04 version 8.0.0 release 1999).
ated by the GMM is thus placed in the last available entry of
In general, when the MS (Mobile Station) changes from
one cell to another in the GPRS (General Packet Radio Ser- 55 the transmit queue (i.e., behind any untransmitted LLC
PDUs). Before the SGSN receives the first LLC PDU from
vice) system any ongoing TBFs in the old cell are terminated
the MS via the new cell, the SGSN sends all DL LLC PDUs
and the new cell is entered. The cell change decision can be
to the previous cell. If the LLC is operating in an unacknow1made by the MS or by the wireless network. In the case where
edged (UNACK) mode, the DL LLC PDUs destined to be
the network makes the cell change decision, the network
sends a Packet Cell Change Order message to the MS. The 60 transmitted to the previous cell are discarded because the
network can not contact the MS via the previous cell. If the
MS leaves the old cell and enters the new cell almost as if the
LLC is operating in an acknowledge (ACK) mode, those DL
MS had itself made the cell change decision.
LLC PDUs destined to be transmitted to the previous cell
In GPRS there is no handover as in the GSM system,
must be retransmitted to the new cell, which takes time and
meaning that the radio connections (TBFs) are not maintained during the cell change. When the MS enters the new 65 unnecessarily wastes network resources.
Two examples are now provided to further clarify the curcell any ongoing TBFs in the old cell are released and rerent state of the prior art.
established in the new cell. A handover procedure in which

METHOD AND APPARATUS FOR
IMPROVING A MOBILE STATION CELL
CHANGE OPERATION IN THE GENERAL
PACKET RADIO SYSTEM (GPRS)

US 7,447,181 Bl

3
EXAMPLE 1

4

In the presently preferred embodiment the generated cell
change PDU is transmitted only if a first PDU in the transmit
queue exceeds a predetermined length, otherwise the cell
ACK RLC Mode
change PDU is discarded and the first PDU in the transmit
Assume that the RLC of the MS has one 1500 octet LLC 5 queue is transmitted instead.
PDU in its transmit buffer when the MS changes from the
In the presently preferred embodiment the wireless packet
previous cell to the new cell. In GPRS the radio resources may
data network is a General Packet Radio Service (GPRS) network, the PDUs are Logical Link Control (LLC) PDUs, and
be shared between several MSs. If the MS is required to share
TSs (time slots) that are assigned to its UL TBF with other
the cell change LLC PDU has a length that fits within one
MSs, the MS may not receive permission to send in a timely 10 Radio Link Control (RLC) data block. In this case the step of
generating employs a LLC unit that uses a Service Access
manner, and it may require a significant amount of time to
transmit the LLC PDU. Furthermore, if some RLC data
Point Indicator (SAPI) of a GPRS Mobility Management
blocks are lost they must be retransmitted, which requires
(GMM) unit to form an empty GMM PDU, and a mobile
even more time. As a result, the SGSN may transmit a large
station location update procedure is then triggered by the
number of DL LLC PDUs to the previous cell before the 15 Serving GPRS Support Node (SGSN) when the GMM PDU
SGSN learns of the new cell location of the MS.
is received. Also in this case a Radio Link Control/Medium
Access Control (RLC/MAC) unit initiates an uplink TBF in
EXAMPLE 2
the new cell, and indicates to a RLC/MAC of the network if an
ACK or an UNACK RLC mode is to be used when transmitUNACK RLC Mode
20 ting the cell change PDU. The RLC/MAC unit of the mobile
station selects either the ACK or the UNACK RLC mode
Assume as in example 1 that the RLC of the MS has one
based on the RLC mode of a next queued LLC PDU in the
1500 octet LLC PDU in its transmit buffer when the MS
transmit queue.
changes from the previous cell to the new cell, and is also
The above-described mechanism is presently preferred,
required to share radio resources. In the UNACK case if some
25 since if the RLC mode changes during a TBF, the ongoing
RLC data blocks are lost, the RLC on the network side sets
TBF is released and another TBF is established with the new
zero octets into the LLC PDU to replace the missing data
RLC mode. If a cell change LLC PDU and the next LLC PDU
octets. If the LLC in the SGSN calculates a CRC for the LLC
in the RLC buffer use the same RLC mode, they can be
PDUs, one missing RLC data block means that the CRC
transmitted within the same TBF.
calculation fails. Since it takes some tens ofRLC data blocks
30
In accordance with the teachings of this invention, when
(depending on the channel coding scheme) to transmit one
the MS changes to the new cell the SGSN is enabled to more
1500 LLC PDU, the probability of one block going missing
rapidly determine the new cell location of the MS, and thus
for whatever reason is increased. If the LLC PDU CRC calDL LLC PDUs being sent to the MS can be directed more
culation fails in the SGSN, the LLC in the SGSN discards the
rapidly to the correct (new) cell. The result is fewer missing
LLC PDU and the SGSN does not update the new cellloca35 LLC PDUs, more efficient usage of network resources and
tion of the MS.
better service for the user.
The presence of missing user data packets can result in
In accordance with a further embodiment of this invention
detrimental side effects for the user, as MS applications that
a method is disclosed for informing the wireless network
rely on receiving the user data packets can malfunction, or
SGSN that the MS has made a cell change. This method
even cease to function.
40 includes changing from a first cell to a second cell with the
As can be appreciated, there are significant problems inherMS and, prior to the SGSN receiving a communication from
ent in the prior art approach to the MS changing cells in the
the MS, notifYing the SGSN of the MS cell change. The
GPRS.
communication may be at least one of a Packet Data Unit
(PDU) and a message.
SUMMARY OF THE PREFERRED
45
In one embodiment the step of notifYing includes steps of:
EMBODIMENTS
(a) in response to the MS making access in the second cell,
sending a Channel Request that indicates a Cell Update
The foregoing and other problems are overcome, and other
operation; (b) establishing an uplink (UL) Temporary Block
advantages are realized, in accordance with the presently
preferred embodiments of these teachings.
Flow (TBF) for transferring Logical Link Control (LLC)
Disclosed is a method for quickly notifying the SGSN of a 50 Packet Data Units (PDUs) from the MS to the network; (c) in
response to the network receiving an unknown Temporary
change from one cell to another by the MS. In accordance
with this mobile station executed method, upon changing
Logical Link Identifier (TLLI) from the MS, sending a mesfrom a current cell to a new cell in a wireless packet data
sage to the SGSN; and (d) based on the message, determining
network, the mobile station enters the new cell; generates a
with the SGSN the that the MS is located in the second cell.
cell change packet data unit (PDU) message for informing the 55 The TLLI may be received in a Packet Resource Request
network of the location of the mobile station in the new cell;
message, in the case of a two phase access, or in a first Radio
buffers the cell change PDU message into a PDU transmit
Link Control (RLC) data block, in the case of a one phase
queue before any buffered PDU s that were present before the
access.
In other embodiments the step of notifYing occurs in
mobile station entered the new cell; and transmits the buffered
cell change PDU before any of the buffered PDUs that were 60 response to the MS being assigned a TDMA frame number of
present before the mobile station entered the new cell. The
when to make the cell change, or occurs in response to the
step of transmitting includes a preliminary step of requesting
network receiving a Radio Link Control/Medium Access
Control (RLC/MAC) message from the MS, or occurs in
an uplink resource, preferably a Temporary Block Flow
(TBF), for transmitting the cell change PDU. The wireless
general in response to the network receiving a TLLI from the
packet data network, in response to receiving the cell change 65 MS.
PDU, transmits downlink PDUs for the mobile station into
These teachings also provide a method and an apparatus for
the new cell.
organizing PDUs into a transmit queue. In this embodiment

US 7,447,181 Bl

5

6

the method includes passing a PDU to a Radio Link Control
(RLC) unit, the PDU having a flag for indicating a priority of
the PDU relative to other PDUs; storing the PDU into the
transmit queue in accordance with the indicated priority; and
transmitting the stored PDU to a radio channel before any
stored PDUs having a lower priority. For the case where the
RLC unit is associated with the mobile station, the PDU is a
cell change PDU and the cell change PDU is assigned a
highest priority.

keypad 160. The mobile station 100 may be a handheld radiotelephone, such as a cellular telephone or a personal communicator. The mobile station 100 could also be contained
within a card or module that is connected during use to
another device. For example, the mobile station 10 could be
contained within a PCMCIA or similar type of card or module
that is installed during use within a portable data processor,
such as a laptop or notebook computer, or even a computer
that is wearable by the user.
The MCU 120 is assumed to include or be coupled to some
type of a memory 130, including a read-only memory (ROM)
for strong an operating program, as well as a random access
memory (RAM) for temporarily storing required data,
scratchpad memory, received packet data, packet data to be
transmitted, and the like. A transmit buffer (XMIT BUFFER)
BOA is assumed to be contained in the memory 130. A
separate, removable SIM (not shown) can be provided as
well, the SIM storing, for example, a preferred Public Land
Mobile Network (PLMN) list and other subscriber-related
information. The ROM is assumed, for the purposes of this
invention, to store a program enabling the MCU 120 to
execute the software routines, layers and protocols required
to implement the methods in accordance with these teachings.
As such, and for convenience, associated with the MCU 120
is shown a RLC/MAC unit 120A, a GMM unit 120B and a
LLC unit 120C. While shown as functional blocks, in practice
each of these is implemented by software instructions that are
executed by the MCU 120.
It should be noted that the wireless network 10, such as the
SGSN 30, has associated therewith a RLC/MAC unit 30C, a
GMM unit 30B and a LLC unit 30A. While shown as functional blocks, in practice each of these is also implemented by
software instructions that are executed a data processor that is
resident at the network operator 10. According to the current
specification, the network RLC/MAC may be located in the
BTS 50, the BSC 40, or in the SGSN 30.
The ROM of the MS 100 also typically stores a program
that provides a suitable user interface (VI), via display 140
and keypad 160.
Although not shown, a microphone and speaker are typically provided for enabling the user to conduct voice calls in
a conventional manner.
The mobile station 100 also contains a wireless section that
includes a digital signal processor (DSP) 180, or equivalent
high speed processor or logic, as well as a wireless transceiver
that includes a transmitter 200 and a receiver 220, both of
which are coupled to an antenna 240 for communication with
the network operator. At least one local oscillator (LO) 260,
such as a frequency synthesizer, is provided for tuning the
transceiver. Data, such as digitized voice and packet data, is
transmitted and received through the antenna 240.
Referring now as well to FIG. 2, the following method is
employed, in accordance with this invention, to improve the
cell change procedure when the MS 100 has data to transmit
to the network 10.
At Step 2A it is assumed that the RLC/MAC unit 120A of
MS 100 has one or more LLC PDU(s) in the transmit buffer
BOA when the change from the current cell to the new cell
takes place. The GMM unit 120B (or the LLC unit 120C)
requests the LLC unit 120C to transmit the LLC PDU in order
to notifY the SGSN 30 of the cell change.
At Step 2B the LLC unit 120C composes a short LLC PDU
and sends it to the RLC/MAC unit 120A. Preferably the LLC
PDU is short enough to fit within one RLC data block, as will
be discussed in further detail below.
At Step 2C the RLC/MAC unit 120A detects that the
received LLC PDU is a cell change LLC PDU (e.g., based on

5

10

BRIEF DESCRIPTION OF THE DRAWINGS
The foregoing and other aspects of these teachings are
made more evident in the following Detailed Description of
the Preferred Embodiments, when read in conjunction with
the attached Drawing Figures, wherein:
FIG. 1 is a simplified block diagram of an embodiment of
a wireless communications system that is suitable for practicing this invention;
FIG. 2 is a logic flow diagram that is descriptive of a first
method in accordance with this invention; and
FIG. 3 is a logic flow diagram that is descriptive of a second
method in accordance with this invention.
DETAILED DESCRIPTION OF THE PREFERRED
EMBODIMENTS
Referring first to FIG. 1, there is illustrated a simplified
block diagram of an embodiment of a wireless communications system 5 that is suitable for practicing this invention.
The wireless communications system 5 includes at least one
mobile station (MS) 100. FIG. 1 also shows an exemplary
network operator having, for example, a Serving GPRS Support Node (SGSN) 30 for connecting to a telecommunications network, such as a Public Packet Data Network or PDN,
via a Gateway GPRS Support Node (GGSN) 32, at least one
base station controller (BSC) 40, and a plurality of base
transceiver stations (BTS) 50 that transmit in a forward or
downlink direction both physical and logical channels to the
mobile station 100 in accordance with a predetermined air
interface standard. A reverse or uplink communication path
also exists from the mobile station 100 to the network operator, which conveys mobile originated access requests and
traffic. Each BTS 50 supports a cell, such as a serving cell that
is currently serving the MS 100, and at least one neighbor cell,
which can be a new cell that the MS 100 enters from the
servicing cell (which then becomes the previous cell).
The air interface standard can confonn to any suitable
standard or protocol, and may enable both voice and data
traffic, such as data traffic enabling Internet 70 access and
web page downloads. In the presently preferred embodiment
of this invention the air interface standard is a Time Division
Multiple Access (TDMA) air interface that supports a GSM
or an advanced GSM protocol and air interface, although
these teachings are not intended to be limited to TDMA or to
GSM or GSM-related wireless systems.
The network operator may also include a suitable type of
Message Center (MC) 60 that receives and forwards messages for the mobile stations 100. Other types of massaging
service may include Supplementary Data Services and possibly Multimedia Massaging Service (MMS), wherein image
messages, video messages, audio messages, text messages,
executables and the like, and combination thereof, can be
transferred between the network and the mobile station 100.
The mobile station 100 typically includes a microcontrol
unit (MCU) 120 having an output coupled to an input of a
display 140 and an input coupled to an output of a keyboard or

15

20

25

30

35

40

45

50

55

60

65

US 7,447,181 Bl
7

8

a flag or other infonnation received from the LLC unit 120C
with the LLC PDU). In response, the cell change LLC PDU is
placed at the head of the LLC PDU transmit queue (i.e.,
before any buffered LLC PDUs in the transmit buffer 130A).
As an option, if the first LLC PDU in the transmit buffer 130A
is short enough (e.g., less than about 50 octets), the RLCI
MAC 120A may discard the cell change LLC PDU sent by the
GMM unit 120B in order not to transfer unnecessary octets to
the network.
Further in this regard, it is noted that when the cell change
takes place, the MS 100 transmits the LLC PDU to the SGSN
30 and, based on the LLC PDU, the SGSN 30 detennines the
new location of the MS 100. The LLC PDU may be any valid
LLC PDU such as, but not limited to, user data, GMM signalling, or an LLCACK. In this case if the head of the MS 100
RLC/MAC transmit queue 130A happens to contain, for
example, a LLC ACK PDU (having a length of, for example,
six octets), this LLC PDU may be transmitted to the network.
It is also within the scope of these teachings to provide a
general mechanism to prioritize the contents of the transmit
queue 130A. For example, a PDU such as a LLC PDU (in
(E)GPRS) or a 3G PDP when passed to the RLC can contain
a flag that is used when buffering the PDU. In one embodiment, the flag can comprise just on bit that when set causes the
PDU to be buffered so that it becomes the next PDU to be
transmitted (i.e., it is put at the head of the transmit queue in
buffer memory 130A.) In this case the flag can be set for the
cell change PDU causing it to be transmitted before any other
buffered PDUs.
In another embodiment the flag can comprise more than
one bit, and thus specifies an internal priority (IP). For
example, a Data PDU can have a flag indicating an IP of four,
while a GMM Cell Update PDU may have an IP equal to one.
The RLC then organizes the PDUs in the transmit buffer
130A according to their respective priorities such that the
higher priority PDU s are transmitted before the lower priority
PDUs.

the RLC/MAC unit 120A. At Step 2F the SGSN 30 learns
from the received cell change LLC PDU the new location of
the MS 100, and DL PDUs are redirected accordingly.
It is noted that it is advantageous if the cell update LLC
PDU does not use the same LLC SAPI (Service Access Point
Indicator) as the normal data LLC PD U s so that the LLC PDU
numbering does not become confused. When the SGSN 30
receives LLC PDUs in the wrong order (as indicated by the
SAPI), and if the SGSN LLC 30A is operating in the ACK
mode, the LLC 30B in the SGSN 30 would send anACK or a
SACK PDU to the MS 100 and thus waste network resources.
It is preferred that the LLC unit 120C use SAPI of the GMM
unit 120B and fonn an empty GMM PDU. In this case the
LLC PDU triggers the MS 100 location update procedure
when it is received by the SGSN 30, and the receiving LLC is
not confused.
It is further noted that when the RLC/MAC unit 120A
initiates the UL TBF establishment in the new cell, the RLCI
MAC unit 120A indicates to the network's RLC/MAC 30C if
the ACK or the UNACK RLC mode is to be used. In this
invention the RLC/MAC unit 120A of the MS 100 may
always use the ACK RLC mode for the cell change LLC PDU
in order to ensure that the cell change PDU is received by the
network 10. However, in that the cell change LLC PDU is
preferably short enough (e.g., less than about 20 octets) so as
to fit into one RLC data block, the RLC/MAC 120A is
enabled to determine the RLC mode of the next queued LLC
PDU in the transmit buffer 130A, and may thus use the same
mode for the cell change RLC mode. This is advantageous, as
otherwise a new UL TBF would need to be established for the
next LLC PDU, as one UL TBF may carry RLC data blocks
only in one RLC mode (i.e., either ACK or UNACK). By
making the RLC mode of the UL cell change LLC PDU the
same as the RLC mode of next queued LLC PDU, the establishment of another UL TBF is avoided and time and network
resources are saved.
Further in accordance with these teachings, and referring to
FIG. 3, another technique for rapidly informing the SGSN 30
of the MS 100 cell change is as follows:
(Step 3A) The MS 100 makes access in the new cell with a
(Packet) Chaunel Request. In the access type field the
MS indicates a Cell Update operation.
(Step 3B) An UL TBF is established for transferring LLC
PDUs from the MS 100 to the network 10.
(Step 3C) When the network receives a temporary MS 100
identity (Temporary Logical Link Identifier (TLLI))
either in a Packet Resource Request message, in the case
of a two phase access, or in the first RLC data blocks, in
the case of a one phase access, the network 10 sends a
message to the SGSN 30. Based on the message the
SGSN 30 is enabled to determine the new cell location of
the MS 100.
The use of one phase and two phase accesses are well
known and basic procedures in (E)GPRS. For example, reference can be made to GSM 04.60 (e.g., versions 6.X'y or 8.
X.Y), Section 7. In the case where the MS 100 makes a one
phase access the MS 100 is not able to accurately detennine
what type of data it is about to transmit. (the RLC defaults to
the ACK mode). In the case of the two phase access, the
network allocates first only one (or two in the case ofEGPRS)
sending permissions for the MS 100. In the sending permission the MS 100 transmits a Packet Resource Request message, wherein the MS 100 can accurately define what kind of
data the MS 100 is about to transmit (e.g., RLC mode ack/
nack, throughput and so forth).
The foregoing technique shown in FIG. 3 is an alternative
method for quickly infonning the SGSN 30 of the MS 100

5

10

15

20

25

30

35

EXAMPLE
40

Current queue: [ipl packetl] [ipl packet2] [ip2 packet 3]
[ip4 packet 4]. In this case packetl is the first to be transmitted
to the network. The RLC next receives a new PDU (packetS)
from the upper layers containing an internal priority= I. This
results in Current queue: [ipl packetl] [ipl packet2] [ipl
packetS] [ip2 packet 3] [ip4 packet 4]. The RLC then receives
new PDU (packet6) from the upper layers containing an internal priority=3. This results in Current queue: [ipl packetl]
[ipl packet2] [ipl packetS] [ip2 packet 3] [ip3 packet 6] [ip4
packet 4]. It should be noted that this procedure is not limited
for execution by the controller 120 of the mobile station 100,
but could be executed as well at the network operator 10.
In accordance with this aspect of the invention, and having
now thus more advantageously staged the cell change LLC
PDU into the transmit buffer queue 130A, the following steps
may be similar to those executed in the prior art case discussed above. For example, at Step 2D, when the RLC/MAC
120A of the MS 100 has obtained the parameters related to
packet access from a System Infonnation message being
broadcast in the new cell, or has obtained these parameters via
some other means (such as from the previous cell), the RLCI
MAC 120Aofthe MS 100 initiates an UL TBF establishment
procedure. At Step 2E, when the UL TBF is established, the
RLC/MAC 120A sends the LLC PDU to the network 10.
However, in accordance with this invention the first LLC
PDU to be sent in the new cell is the cell change LLC PDU
that was inserted into the head of the transmit buffer queue by

45

50

55

60

65

US 7,447,181 Bl
9

10

cell change. The RLC/MAC 30C of the network may check
the TLLI type when deciding when to send the cell change
message to the SGSN 30. For example, the RLC data block
received with a local TLLI does not generate a cell change
message to the SGSN 30, but the RLC data block received
with a random or foreign or otherwise unknown TLLI generates the cell change message to the SGSN 30. A random!
foreign TLLI is considered herein to be one that has not (yet)
been allocated by the SGSN 30, and thus can not be used in a
nonnal data transfer.
Furthermore, the access type may also be considered. For
example, for a case where the MS 100 indicates a cell change
as a reason for establishing an UL TBF, the SGSN 30 may be
notified when receiving, for example, the TLLI from the MS
100.
In general, and in accordance with this aspect of the invention, the SGSN 30 is informed of the new location of the MS
100 before the SGSN 30 receives a PDU/message from the
MS 100. Furthermore, notifYing the SGSN 30 upon reception
of the TLLI, as described above, is but one embodiment for
performing the SGSN 30 notification function. For example,
in another embodiment the radio part of the network (e.g.
network elements containing the RLC/MAC 30C) synchronizes the MS cell change in the case of a network controlled
cell change. That is, the MS 100 is given, for example, a
TDMA frame number in the old cell of when to perfonn the
cell change, and the SGSN 30 may then be notified of when
the cell change takes place. In this case the SGSN 30 may be
notified of the new location of the MS 100 even before the MS
100 begins communicating to the network, or it may be notified after the network has received some type of confinnation
that the MS 100 is within the new cell.
For example, the SGSN 30 may be infonned of the MS cell
change either when the cell change takes place, or when the
network receives a RLC/MAC message from the MS 100, or
a TLLI from the MS 100. These various embodiments may be
especially useful for performing cell-to-cell MS 100 handovers.
While described in the context of various messages and
GPRS-specific functions, those having skill in the art should
appreciate that the teachings of this invention are not intended
to be limited to only the presently preferred embodiments.
The foregoing method is applicable to any packet based network that allows user mobility. The disclosed method clearly
improves the cell change procedure, as well as conserving
network resources and speeding up the user data transmission. While the disclosed method is especially applicable for
GPRS, EGPRS and GERAN, it is not limited for use in only
these network types.
What is claimed is:
1. A mobile station executed method comprising:
entering a new cell;
generating a cell change logical link control packet data
unit massage for infonning the network of the location
of the mobile station in the new cell;
buffering the cell change logical link control packet data
unit message into a logical link control packet data unit
message transmit queue such that it is selected for transmission prior to any buffered packet data units that were
present before the mobile station entered the new cell;
a radio link control/medium access control unit of a mobile
station initiating an uplink temporary block flow in the
new cell;
indicating to a radio link control/medium access control of
the network if an ACK or an UNACK radio link control
mode is to be used when transmitting the cell change
packet data unit message; and

transmitting the buffered cell change packet data unit
before any of the buffered packet data units that were
present before the mobile station entered the new cell.
2. A method as in claim 1, wherein the transmitting
includes requesting an uplink resource for transmitting the
cell change packet data unit.
3. A method as in claim 1, wherein the transmitting
includes requesting an uplink temporary block flow for transmitting the cell change packet data unit.
4. A method of claim 1, wherein, in response to receiving
the cell change packet data unit downlink packet data units for
the mobile station are transmitted into the new cell.
5. A method as in claim 1, wherein the generated cell
change packet data unit is transmitted only if a first packet
data unit in the transmit queue exceeds a predetermined
length, otherwise the cell change packet data unit is discarded
and the first packet data unit in the transmit queue is transmitted instead.
6. A method as in claim 1, where the cell change logical
link control packet data unit has a length that fits within one
radio link control data block.
7. A method as in claim 6, wherein the generating operates
a logical link control unit to use a service access point indicator of a general purpose radio service mobility management
unit to fonn an empty a general purpose radio service mobility management packet data unit, and where a mobile station
location update procedure is triggered by a serving general
packet radio service support node when the a general purpose
radio service mobility management packet data unit is
received.
8. A method as in claim 6, wherein the radio link control/
medium access control unit of the mobile station selects
either the ACK or the UNACK radio link control mode based
on the UNACK radio link control mode of a next queued
logical link control packet data unit in the transmit queue.
9. A method as in claim 1, wherein the generating includes
setting a priority level of the cell change packet data unit such
that the buffering the cell change packet data unit message
into the packet data unit transmit queue causes the cell change
packet data unit to be transmitted before any lower priority
packet data units.
10. An apparatus comprising: a packet data buffer and a
controller that is responsive to changing location from a previous cell to a new cell in a wireless packet data network for
generating a cell change logical link control packet data unit
message for infonning the wireless packet data network of the
presence of the apparatus in the new cell and for buffering the
cell change logical link control packet data unit message into
the packet data buffer such that it is selected for transmission
prior to any buffered packet data units that were present
before the apparatus entered the new cell, the controller being
arranged to operate a radio link control/medium access control unit to initiate an uplink temporary block flow in the new
cell, and to indicate to a radio link control/medium access
control of the network if an ACK or an UNACK radio link
control mode is to be used when transmitting the cell change
logical link control packet data unit, said apparatus comprising a transmitter for transmitting the buffered cell change
logical link control packet data unit message for infonning
the wireless packet data network of the cell in which the
apparatus is currently located so that packet data intended for
the apparatus is not transmitted into the previous cell by the
wireless packet data network.
11. An apparatus as in claim 10 wherein the controller,
prior to operating said transmitter for transmitting the buff-

10

15

20

25

30

35

40

45

50

55

60

65

US 7,447,181 Bl
11

12

ered cell change logical link control packet data unit, requests
21. A method as in claim 18, wherein the notifYing occurs
an uplink resource for transmitting the cell change logical
in response to the network receiving a radio link control/
link control packet data unit.
medium access control message from the mobile station.
12. An apparatus as in claim 10 wherein the controller,
22. A method as in claim 18, wherein the notifYing occurs
prior to operating said transmitter for transmitting the buffin response to the network receiving a temporary logical link
ered cell change packet data unit, request an uplink temporary
identifier from the mobile station.
block flow for transmitting the cell change packet data unit.
23. A method comprising:
13. An apparatus as in claim 10, wherein the generated cell
passing a cell change logical link control packet data unit
message to a radio link control unit for informing a
change packet data unit is transmitted only if a first packet
data unit in the transmit buffer exceeds a predetermined 10
network of the location of a mobile station in a new cell,
length, otherwise the cell change packet data unit is discarded
the cell change logical link control packet data unit
and the first packet data unit in the transmit queue is transmessage having a flag for indicating a priority of the
mitted instead.
packet data unit relative to other packet data units;
14. An apparatus as in claim 10, where the cell change
storing the cell change logical link control packet data unit
logical link control packet data unit has a length that fits 15
message into a logical link control packet data unit meswithin one radio link control data block.
sage transmit message queue in accordance with the
15. An apparatus as in claim 14, wherein the controller,
indicated priority;
when generating the cell change packet data unit, operates a
a radio link control/medium access control unit of a mobile
station initiating an uplink temporary block flow in the
logical link control unit to use a service access point indicator
new cell;
of a general purpose radio service mobility management unit 20
indicating to a radio link control/medium access control of
to form an empty general purpose radio service mobility
the network if an ACK or an UNACK radio link control
management packet data unit, and where a apparatus location
mode is to be used when transmitting the cell change
update procedure is triggered by a serving general purpose
packet data unit message; and
service support node when the general purpose radio service
25
transmitting the stored cell change logical link control
mobility management packet data unit is received.
16. An apparatus as in claim 14, wherein the radio link
packet data unit to a radio chamlel before any stored
control/medium access control unit of the apparatus selects
packet data units having a lower priority.
either the ACK or the UNACK radio link control mode based
24. A method as in claim 23, where the cell change packet
on the radio link control mode of a next queued logical link
data unit is assigned a highest priority.
30
control packet data unit in the transmit buffer.
25. A computer readable medium encoded with a computer
17. An apparatus as in claim 10, wherein controller sets a
program the execution of which in association with a device
priority level of the cell change packet data unit such when
cell change operation performs operations of:
buffering the cell change packet data unit message into the
responsive to entering a new cell, generating a cell change
packet data unit transmit queue the cell change packet data
logical link control packet data unit message for inforunit is caused to be transmitted before any lower priority 35
mation a wireless network of the location of the device;
and
packet data units.
buffering the cell change logical link control packet data
18. A method comprising:
unit message into a logical link control packet data unit
changing from a first cell to a second cell with a mobile
message transmit queue such that it is transmitted to the
station; and
network before any already buffered packet data units
prior to a serving general packet radio service support node 40
receiving at least one of a packet data unit and a message
that were present before the mobile station entered the
from the mobile station, notifying the serving general
new cell;
packet radio service support node of the mobile station
a radio link control/medium access control unit of a mobile
cell change, wherein notifying the serving general
station initiating an uplink temporary block flow in the
new cell;
packet radio service support node of the mobile station 45
cell change comprises
indicating to a radio link control/medium access control of
the network if an ACK or an UNACK radio link control
in response to the mobile station making access in the
mode is to be use when transmitting the cell change
second cell, sending a chaunel request that indicates a
packet data unit message; and
cell update operation;
transmitting the buffered cell change packet data unit
establishing an uplink temporary block flow for transfer- 50
ring logical link control packet data units from the
before any of the buffered packet data units that were
mobile station to the network;
present before the mobile station entered the new cell.
in response to the network receiving an unknown tempo26. A computer readable medium encoded with a computer
rary logical link identifier from the mobile station, sendprogram as in claim 25, further comprising requesting from
ing a message to the serving general packet radio service 55 the wireless network an uplink resource for transmitting the
support node; and
cell change packet data unit.
27. A computer readable medium encoded with a computer
based on the message, determining with the serving genprogram as in claim 25, further comprising requesting from
eral packet radio service support node that the mobile
the wireless network an uplink temporary block flow for
station is located in the second cell.
19. A method as in claim 18, wherein the temporary logical 60 transmitting the cell change packet data unit.
28. A computer readable medium encoded with a computer
link identifier is received in a packet resource request mesprogram as in claim 25, where the cell change logical link
sage, in the case of a two phase access, or in a first radio link
control packet data unit has a length that fits within one radio
control data block, in the case of a one phase access.
link control data block, and where the generating operation
20. A method as in claim 18, wherein the notifying occurs
in response to the mobile station being assigned a time divi- 65 operates a logical link control unit to use a service access
point indicator of a general packet radio service mobility
sion multiple access frame number of when to make the cell
change.
management unit to form an empty general packet radio

US 7,447,181 Bl
13

14

service mobility management packet data unit, and where a
device location update procedure is triggered by a serving
general packet radio service support node when the general
packet radio service mobility management packet data unit is
received.
29. A computer readable medium encoded with a computer
program as in claim 25, where the cell change link logical
control packet data unit has a length that fits within one radio
link control data block, and where a radio link control/medium access control unit initiates an uplink temporary block
flow in the new cell.
30. A computer readable medium encoded with a computer
program as in claim 29, where a device radio link control/
medium access control unit selects either the ACK or the
UNACK radio link control mode based on the radio link
control mode of a next queued logical link control packet data
unit in the transmit queue.
31. A computer readable medium encoded with a computer
program as in claim 25, where the generating operation comprises setting a priority level of the cell change packet data
unit such that buffering the cell change packet data unit message into the packet data unit transmit queue causes the cell
change packet data unit to be transmitted before any lower
priority packet data units.
32. A device, comprising:
means, responsive to entering a new cell, for generating a
cell change logical link control packet data unit message
for informing a wireless network of the location of the
device; and
means for buffering the cell change logical link control
packet data unit message into a logical link control
packet data unit message transmit queue such that it is
transmitted to the wireless network before any already
buffered packet data units that were present before the
mobile station entered the new cell;
means for initiating an uplink temporary block flow in the
new cell;
means for indicating to a radio link control/medium access
control of the network if an ACK or an UNACK radio

link control mode is to be used when transmitting the cell
change packet data unit message; and
means for transmitting the buffered cell change packet data
unit before any of the buffered packet data units that
were present before the mobile station entered the new
cell.
33. A device as in claim 32, further comprising means for
requesting from the wireless network an uplink resource for
transmitting the cell change packet data unit.
34. A device as in claim 32, further comprising means for
requesting from the wireless network as uplink temporary
block flow for transmitting the cell change packet data unit.
35. A device as in claim 32, where the cell change logical
link control packet data unit has a length that fits within one
radio link control data block, and where the generating means
operates a logical link control unit to use a service access
point indicator of a general packet radio service mobility
management unit to form an empty general packet radio
service mobility management packet data unit, and where a
device location update procedure is triggered by a serving
general purpose radio service support node when the general
packet radio service mobility management packet data unit is
received.
36. A device as in claim 32, where the cell change logical
link control packet data unit has a length that fits within one
radio link control data block, and where a radio link control/
medium access control unit initiates an uplink temporary
block flow in the new cell.
37. A device as in claim 36, where a device radio link
control/medium access control unit selects either the ACK or
the UNACK radio link control mode based on the radio link
control mode of a next queued logical link control packet data
unit in the transmit queue.
38. A device as in claim 32, where the generating means
sets a priority level of the cell change packet data unit such
that buffering the cell change packet data unit message into
the packet data unit transmit queue causes the cell change
packet data unit to be transmitted before any lower priority
packet data units.

10

15

20

25

30

35

* * * * *