GPRS—General packet radio service
`
`Hakan Granbohm and Joakim Wiklund
`
`By adding GPRS to the GSM network, operators can offer efficient wire(cid:173)
`less access to external IP-based networks, such as the Internet and cor(cid:173)
`porate intranets. What is more, operators can profit from the rapid pace of
`service development in the Internet world, offering their own IP-based
`services using the GPRS IP bearer, thereby moving up the Internet value
`chain and increasing profitability.
`End-users can remain connected indefinitely to the external network
`and enjoy instantaneous transfer rates of up to 115 kbit/s. Users who are
`not actually sending or receiving packets occupy only a negligible amount
`of the network's critical resources. Thus, new charging schemes are
`expected to reflect network usage instead of connection time.
`Ericsson's implementation of GPRS enables rapid deployment while
`keeping entry costs low—the two new nodes that are added to the net(cid:173)
`work can be combined and deployed at a central point in the network.
`The rest of the GSM network solely requires a software upgrade, apart
`from the BSC, which requires new hardware.
`The authors describe Ericsson's implementation of GPRS. In particular,
`they explain the role of the two new GPRS support nodes and needed
`changes to Ericsson products in the PLMN.
`
`TRADEMARKS
`
`Java™ is a trademark owned by Sun Microsys(cid:173)
`tems Inc. in the United States and other coun(cid:173)
`tries.
`
`Introduction
`General packet radio service (GPRS) is a
`standard from the European Telecommuni(cid:173)
`cations Standards Institute (ETSI) on pack(cid:173)
`et data in GSM systems. GPRS has also been
`accepted by the Telecommunications In(cid:173)
`dustry Association (TIA) as the packet-data
`
`Figure 1
`The GPRS reference model.
`
`node
`
`support
`
`node
`
`systems. By
`for TDMA/136
`standard
`adding GPRS functionality to the public
`land mobile network (PLMN), operators can
`give their subscribers resource-efficient ac(cid:173)
`cess to external Internet protocol-based (IP)
`networks.
`GPRS offers air-interface transfer rates up
`to 115 kbit/s—subject to mobile terminal
`capabilities and carrier interference. More(cid:173)
`over, GPRS allows several users to share the
`same air-interface resources and enables op(cid:173)
`erators to base charging on the amount of
`transferred data instead of on connection
`time. In the initial release, GPRS uses the
`same modulation as GSM (GMSK). The
`subsequent
`evolution
`of packet-based
`services
`in GSM
`introduces
`EDGE
`technology.1
`GPRS introduces two new nodes (Fig(cid:173)
`ure 1) for handling packet traffic:
`• the
`serving GPRS
`support
`(SGSN); and
`• the
`gateway GPRS
`(GGSN).
`These nodes interwork with the home loca(cid:173)
`tion register (HLR), the mobile switching
`center/visitor location register (MSC/VLR)
`and base station subsystems (BSS).
`The GGSN, which is the interconnection
`point for packet data networks, is connect(cid:173)
`ed to the SGSN via an IP backbone. User
`data—for example, from a GPRS terminal
`to the Internet—is sent encapsulated over
`the IP backbone.
`The SGSN, in turn, is connected to the
`BSS and resides at the same hierarchical level
`in the network as the MSC/VLR. It keeps
`track of the location of the GPRS user, per(cid:173)
`forms security functions and handles access
`control—that is, to a large extent, it does
`for
`the packet data service what
`the
`MSC/VLR does for circuit-switched service.
`In the GPRS standard, three new types of
`mobile terminal have been defined:
`• Class A terminal, which supports simul(cid:173)
`taneous circuit-switched and packet-
`switched traffic;
`• Class B terminal, which supports either
`circuit-switched or packet-switched traf(cid:173)
`fic (simultaneous network attachment)
`but does not support both kinds of traffic
`simultaneously; and
`• Class C terminal, which is attached either
`as a packet-switched or circuit-switched
`terminal.
`The terminal types are further differentiated
`by their ability to handle multi-slot operation.
`Since class A and class B terminals sup(cid:173)
`port both circuit-switched and packet-
`
`82
`
`Ericsson Review No. 2,1999
`
`Ex.1010
`APPLE INC. / Page 1 of 7
`
`

`

`BOX A, ABBREVIATIONS
`
`APN
`BCCH
`BGP
`BGW
`BSC
`BSS
`BTS
`CDR
`CHAP
`
`C/l
`CORBA
`
`DNS
`ETSI
`
`GGSN
`GPRS
`GSM
`
`GSN
`GTP
`
`Access point name
`Broadcast common control channel
`Border gateway protocol
`Billing gateway
`Base station controller
`Base station subsystem
`Base transceiver station
`Call data record
`Challenge handshake authentication
`protocol
`Carrier-to-interference ratio
`Common object request broker archi(cid:173)
`tecture
`Domain name server
`European Telecommunications Stan(cid:173)
`dards Institute
`Gateway GPRS support node
`General packet radio service
`Global system for mobile communi(cid:173)
`cation
`GPRS support node
`GPRS tunneling protocol
`
`GUI
`HLR
`HTML
`HTTP
`IETF
`IMEI
`
`IMSI
`
`IP
`IPSec
`ISP
`LA
`MAC
`MSC
`O&M
`OSPF
`OSS
`OTP
`PAP
`PCU
`PDCH
`
`Graphical user interface
`Home location register
`Hypertext markup language
`Hypertext transfer protocol
`Internet Engineering Task Force
`International mobile equipment iden(cid:173)
`tity
`International mobile subscriber iden(cid:173)
`tity
`Internet protocol
`IP security
`Internet service provider
`Location area
`Medium access control
`Mobile switching center
`Operation and maintenance
`Open shortest path first
`Operations support system
`Open telecom platform
`Password authentication protocol
`Packet control unit
`Packet data channel
`
`PDP
`PLMN
`PXM
`QoS
`RA
`RACH
`RADIUS
`
`RIP
`RLC
`SGSN
`SMS
`SNMP
`
`SOG
`TFI
`TIA
`
`TMOS
`
`TRX
`VLR
`
`Packet data protocol
`Public land mobile network
`Packet exchange Manager
`Quality of service
`Routing area
`Random access channel
`Remote authentication dial-in user
`service
`Routing internal protocol
`Radio link control
`Serving GPRS support node
`Short message service
`Simple network management proto(cid:173)
`col
`Service order gateway
`Temporary flow indicator
`Telecommunications Industry Associ(cid:173)
`ation
`Telecommunications management
`and operations support
`Transceiver
`Visitor location register
`
`switched traffic, the network may combine
`mobility management. For instance, loca(cid:173)
`tion updates can include information relat(cid:173)
`ing to both services.
`To support efficient multiplexing of
`packet traffic to and from mobile terminals,
`a new packet data channel (PDCH) has been
`defined for the air interface. One PDCH is
`mapped onto a single time slot, thereby uti(cid:173)
`lizing the same physical channel structure
`as ordinary circuit-switched GSM channels.
`Four different channel-coding schemes
`have been defined for GPRS to make opti(cid:173)
`mum use of varying radio conditions.
`All radio resources are managed from the
`BSC, where the pool of physical channels for
`a given cell can be used as either circuit-
`switched GSM channels or packet data chan(cid:173)
`nels. By means of packet multiplexing, the
`allocated PDCHs can be shared by every
`GPRS user in the cell. The number of
`PDCHs in a cell can be fixed or dynamical(cid:173)
`ly allocated to meet fluctuating traffic de(cid:173)
`mands. Thus, physical channels not cur(cid:173)
`rently in use by the circuit-switched service
`can be made available to GPRS traffic (Fig(cid:173)
`ure 2).
`More than one time slot can be allocated
`to a user during packet transfer. Uplink and
`downlink resources to connections are allo(cid:173)
`cated separately on a case-by-case basis,
`which reflects the asymmetric behavior of
`packet data communication.
`
`Ericsson Review No. 2,1999
`
`Figure 2
`In this example, one time slot is statically assigned to GPRS; all other time slots are
`defined as dynamic GPRS resources.
`
`83
`
`Ex.1010
`APPLE INC. / Page 2 of 7
`
`

`

`BOX B, PACKET-SWITCHED TRANSMISSION OVER THE AIR INTERFACE
`
`User data packets are segmented, coded and
`transformed into radio blocks. Each radio block
`is further interleaved over four standard GSM
`normal bursts—that is, over the same basic
`vehicle that carries coded, circuit-switched
`speech across the air interface.
`When errors occur, data packets can be
`retransmitted at the radio block level. The set of
`bursts that results from a single user data pack(cid:173)
`et is marked with a temporary flow identifier
`(TFI), which is used on the receiving side to
`reassemble the user data packet.
`A new set of logical channels has been defined
`for GPRS traffic. This set includes control chan(cid:173)
`nels and packet data traffic channels. A physi(cid:173)
`cal channel allocated for GPRS traffic is called
`a packet data channel (PDCH). One or more
`physical channels in a cell can be statically or
`dynamically assigned for PDCHs. Static PDCHs
`are always available, whereas dynamic PDCHs
`are provided on a case-by-case basis.
`The PDCH consists of a multiframe pattern
`that runs on time slots assigned to GPRS. This
`is basically a predefined pattern of GPRS con(cid:173)
`trol channels and data traffic channels that
`keeps repeating itself. In cells defined as hav(cid:173)
`ing only dynamic GPRS resources and which
`
`only run circuit-switched channels, the GPRS
`terminals use the circuit-switched control chan(cid:173)
`nels until one or more PDCH are assigned. Cer(cid:173)
`tain circuit-switched mobility-management pro(cid:173)
`cedures may also use GPRS control channels
`(for example, for location update).
`Several mobile terminals can dynamically
`share the pool of packet data channels in a cell,
`and several PDCHs can be used simultaneous(cid:173)
`ly for a single connection. Thus, a user data
`packet can be transmitted over multiple packet
`data channels and reassembled at the other end
`(Figure 4).
`The network side controls the allocation of
`resources. To start packet transmission on the
`uplink, the mobile terminal requests resources.
`The network tells the terminal which PDCHs to
`use. The network also sends a flag value which,
`when it occurs on the corresponding downlink,
`tells the mobile terminal to begin transmitting.
`To start packet transmission on the downlink,
`the network sends an assignment message to
`the mobile terminal, indicating which PDCHs will
`be used and the value of the TFI assigned to the
`transfer. The mobile terminal monitors
`the
`downlink PDCHs and identifies its packets via
`the TFI.
`
`Figure 3
`Impact of GPRS on an existing Ericsson PLMN.
`
`84
`
`Ericsson's implementation
`of GPRS
`Ericsson's
`implementation of GPRS for
`GSM complies with the ETSI standard and
`supports open interfaces. The implementa(cid:173)
`tion enables fast deployment while keeping
`entry costs low (Figure 3):
`• The two new support nodes—the SGSN
`and GGSN—can be combined into one
`physical node and deployed at a central
`point in the network.
`• Apart from the BSC, which requires a
`hardware upgrade, the existing GSM net(cid:173)
`work solely requires software upgrades to
`support GPRS.
`
`T wo new nodes
`
`GPRS support
`
`nodes
`
`The GPRS support nodes (GSN) are based
`on Ericsson's AXB 250 platform,
`a
`new, general-purpose, high-performance,
`packet-switching platform. The AXB 250
`combines features usually associated with
`data communication (compactness and high
`functionality) with features from telecom(cid:173)
`munications (robustness and scalability).
`Designed for nonstop operation, the plat(cid:173)
`form incorporates duplicated hardware and
`modular software. Thus, individual mod(cid:173)
`ules of the platform can be upgraded with(cid:173)
`out disturbing traffic. The AXB 250 plat(cid:173)
`form is robust and embodies advanced func(cid:173)
`tions for capturing software faults, isolating
`hardware faults, and protecting against
`overload. The platform is based on industry
`standards and standard software compo(cid:173)
`nents, including
`• a U N IX operating system;
`• C and Java programming languages;
`• the common object request broker archi(cid:173)
`tecture (CORBA) interface; and
`• the hypertext transfer protocol (HTTP)
`and the simple network management pro(cid:173)
`tocol (SNMP).
`Hardware redundancy and the open telecom
`platform (OTP)—which is specific Ericsson
`middleware—support carrier-class features,
`such as high reliability, system recovery, a
`real-time database, and minimum down(cid:173)
`time. The OTP, which is a generic system
`for fault-tolerant, real-time applications,
`provides a platform and a set of tools for eas(cid:173)
`ily and accurately generating datacom or
`telecom applications. It is entirely scalable,
`from low-end, PC-based testing and ad(cid:173)
`ministrative applications
`to very
`large,
`multiprocessor, n+m redundant systems.
`
`Ericsson Review No. 2,1999
`
`Ex.1010
`APPLE INC. / Page 3 of 7
`
`

`

`Applications can be designed on a small sys(cid:173)
`tem and ported to a variety of computer en(cid:173)
`vironments.2
`All operation and maintenance (O&M) ac(cid:173)
`tivities directed toward the GSNs are han(cid:173)
`dled through a Java-based graphical user in(cid:173)
`terface (GUI), called the Packet eXchange
`Manager (PXM), which is an element man(cid:173)
`ager based on the thin-client concept. This
`means that all GUI software, such as files
`written in the hypertext markup language
`(HTML) and Java applets, is stored on the
`GSN, and that a presentation layer (Java) is
`downloaded and run on the client. Conse(cid:173)
`quently, the GUI always conforms with the
`software of the node that handles traffic. The
`client can run on any computer with an In(cid:173)
`ternet browser that supports Java.
`Alarm and event management can be in(cid:173)
`tegrated
`into Ericsson's
`telecommunica(cid:173)
`tions management and operations support
`(TMOS) or into external management sys(cid:173)
`tems that use the SNMP.
`The GSN also supports traditional tele(cid:173)
`com performance-management
`features,
`such as performance measurements and
`event recordings.
`A router function has been integrated into
`the GSN. Intranetwork routing protocols
`and external gateway protocols include the
`routing information protocol (RIP), open
`shortest path first (OSPF), and the border
`gateway protocol (BGP). Several packet-
`filtering options are also available. IPSec
`functionality ensures secure
`transmission
`between the GSNs as well as between the
`PLMN and external networks.
`
`Serving GPRS support node
`
`The SGSN, which
`
`is based on
`
`the
`
`Ericsson Review No. 2,1999
`
`Figure 4
`GPRS users share the pool of resources in a cell.
`
`BOX C, GPRS ATTACH
`
`GPRS attach and PDP context activation must
`be executed in order for GPRS users to connect
`to external packet data networks.
`The mobile terminal makes itself known to the
`network by means of GPRS attach—GPRS
`attach corresponds to IMSI attach, which is
`used for circuit-switched traffic. Once the ter(cid:173)
`minal is attached to the network, the network
`knows its location and capabilities. If the unit is
`a class A or class B terminal, then circuit-
`switched IMSI attach can be performed at the
`same time (Figure 5)
`"I.The mobile terminal requests that
`
`it be
`
`attached to the network. The terminal's
`request, which is sent to the SGSN, indicates
`its multi-slot capabilities, the ciphering algo(cid:173)
`rithms it supports, and whether it wants to
`attach to a packet-switched service, a circuit-
`switched service, or to both.
`2. Authentication is made between the terminal
`and the HLR.
`3. Subscriber data from the HLR is inserted into
`the SGSN and the MSC/VLR.
`4. The SGSN informs the terminal that it is
`attached to the network.
`(See also Box D, PDP context activation).
`
`Figure 5
`GPRS attach.
`
`Ex.1010
`APPLE INC. / Page 4 of 7
`
`

`

`BOX D, PDP CONTEXT ACTIVATION
`
`Before the mobile terminal can communicate with
`an external packet data network, the packet data
`protocol (PDP) context must be activated.
`The PDP context describes the characteristics
`of the connection to the external packet data
`network—type of network, network address,
`access point name (APN), QoS, radio priority,
`and so on. (Figure 6).
`I.The mobile terminal requests PDP context
`activation.
`2. The SGSN validates the request based on
`subscription information received from the
`HLR during GPRS attach.
`3. The APN is sent to the domain name server
`(DNS) in the SGSN to find the IP address of
`the relevant GGSN.
`
`4. A logical connection is created between the
`SGSN and the GGSN (GTP tunnel).
`5. The GGSN assigns a dynamic IP address to
`the mobile terminal—from the range of IP
`addresses allocated to the PLMN or exter(cid:173)
`nally, from a remote authentication dial-in
`user service (RADIUS) server (a fixed IP
`address from the HLR could also be used). A
`RADIUS client is included in the GGSN to sup(cid:173)
`port password authentication protocol (PAP)
`and challenge handshake authentication pro(cid:173)
`tocol (CHAP) authentication to external net(cid:173)
`works with RADIUS servers.
`At this stage, communication between the user
`and the external packet data network can com(cid:173)
`mence.
`
`AXB 250 platform, serves every GPRS
`subscriber that is physically located with(cid:173)
`in the SGSN service area. In the PLMN, ir
`resides at the same hierarchical level as the
`MSC/VLR. The main functions of the
`SGSN are
`• to perform mobility management for
`GPRS Terminals (attach/detach, user au(cid:173)
`thentication, ciphering, location manage(cid:173)
`ment, and so on);
`• to support combined mobility manage(cid:173)
`
`ment for class A and class B mobile ter(cid:173)
`minals by
`interworking with
`the
`MSC/VLR;
`to manage the logical link to mobile ter(cid:173)
`minals (the logical link carries user pack(cid:173)
`et traffic, SMS traffic, and layer 3 sig(cid:173)
`naling between the network and the
`GPRS terminal);
`to route and transfer packets between mo(cid:173)
`bile terminals and the GGSN;
`to handle packet data protocol (PDP) con-
`
`Figure 6
`PDP context activation.
`
`86
`
`Ericsson Review No. 2,1999
`
`Ex.1010
`APPLE INC. / Page 5 of 7
`
`

`

`texts (the P DP context defines important
`parameters, such as the access point name,
`quality of service, the GGSN to be used,
`and so on, for connection to the external
`packet data network);
`• to interwork with the radio resource man(cid:173)
`agement in the BSS; and
`• to generate charging data.
`
`Gateway GPRS support node
`Like the SGSN, the GGSN is a new com(cid:173)
`ponent (also based on the AXB 250 plat(cid:173)
`form) in the PLMN. It accommodates the
`interface to external IP-based networks. The
`access-server functionality in the GGSN is
`defined according to standards from the In(cid:173)
`ternet Engineering Task Force (IETF). The
`main functions of the GGSN are
`• to function as a border gateway between
`the PLMN and external networks;
`• to set up communication with external
`packet data networks;
`• to authenticate users to external packet
`networks;
`• to route and tunnel packets to and from
`the SGSN; and
`• to generate charging data.
`
`Changes to a PLMN with Ericsson
`products
`Cell plan
`GPRS introduces a new set of logical chan(cid:173)
`nel types that have been optimized for pack(cid:173)
`et data. The physical radio resources in a cell
`may be dedicated to GPRS or shared with
`the circuit-switched service, in which case
`this service takes precedence. If dedicated
`resources have not been assigned in a cell,
`then GPRS broadcast and control signaling
`is handled via ordinary control channels
`(BCCH, RACH, and so on).
`GPRS does not use location areas (LA). In(cid:173)
`stead, a routing-area (RA) concept has been
`introduced.
`In the first GPRS release, and in cases
`where GPRS traffic does not constitute a sig(cid:173)
`nificant part of network traffic, operators are
`advised to use the same cell parameters and
`borders as for their circuit-switched sys(cid:173)
`tems. Later, as GPRS traffic grows, the
`GPRS service and the circuit-switched ser(cid:173)
`vice might need different cell parameters
`and borders.
`GPRS can be introduced by defining ei(cid:173)
`ther shared or dedicated resources on exist(cid:173)
`ing transceivers (TRX). New transceivers
`and frequencies can also be set aside specif(cid:173)
`ically for GPRS.
`
`Ericsson Review No. 2,1999
`
`Billing and customer administration
`systems
`W i th the introduction of GPRS, current
`customers' subscriptions will be enhanced
`and new customer categories will appear—
`possibly including those with GPRS-only
`subscriptions. These and other changes will
`have an impact on the operator billing and
`customer administration (BCA) systems.
`The call detail recotds (CDR) generated
`by the SGSN and the GGSN indicate to
`which external packet network the connec(cid:173)
`tion was set up, the volume of data that was
`transferred, the quality of service offered, the
`date and time of connection, and the dura(cid:173)
`tion of the session. This information, which
`differs from what CDRs of circuit-switched
`services currently provide, will affect exist(cid:173)
`ing billing systems. In all likelihood, oper(cid:173)
`ators will not base charges for GPRS services
`on the duration of a session, as is the case
`with circuit-switched
`services.
`Instead,
`charges will be based on a flat fee or on vol(cid:173)
`umes of data transferred. Operators may also
`want to offei subscribers of both circuit-
`switched and packet-switched services a
`single, consolidated invoice with itemized
`charges for each service.
`To moderate the impact on billing sys(cid:173)
`tems, Ericsson's billing gateway (BGW) can
`be connected between the SGSN and the
`GGSN (which generate CDRs) and
`the
`billing systems. The functionality of the
`billing gateway entails
`• storing CDRs during long GPRS sessions
`(sessions last for as long as the PDP con(cid:173)
`text is active);
`
`BOX E, SECURITY
`
`Several features have been included in
`Ericsson's implementation of GPRS to provide
`security, confidentiality and user integrity:
`• User authentication (GSM style) prevents
`illegitimate users from using the network.
`• Ciphering of the path between the mobile
`terminal and the SGSN protects the link
`against eavesdropping.
`• The GPRS tunneling protocol (GTP) encap(cid:173)
`sulates user packets in the IP backbone.
`• IPSec functionality provides secure connec(cid:173)
`tions between the SGSN and GGSN in the
`PLMN.
`• IPSec provides secure connections to exter(cid:173)
`nal packet data networks.
`• Packet filtering in the GGSN and SGSN pro(cid:173)
`vide firewall functionality, which protects
`against network intruders.
`
`Ex.1010
`APPLE INC. / Page 6 of 7
`
`

`

`infor(cid:173)
`• matching CDRs—to consolidate
`mation from several CDRs generated dur(cid:173)
`ing one session;
`• rating volume-based CDRs; and
`• translating new CDR types into fotmats
`that can be handled by existing billing
`systems.
`
`BSS
`
`To support GPRS, the base station controller
`(BSC) requires new hardware and software. In
`terms of hardware, the BSC requires a packet
`control unit (PCU) to handle GPRS packets.
`In particular, the PCU is responsible for the
`radio link control (RLC) and the medium ac(cid:173)
`cess control (MAC) layers over the air inter(cid:173)
`face. It also manages the transfer of user data
`packets between mobile terminals and the
`SGSN.
`Regarding the BTS, Ericsson's RBS2000
`and RBS200 product families solely require
`a software upgrade.
`
`HLR
`
`To support GPRS, the software in the home
`location register must be upgraded. The up(cid:173)
`grade adds functionality for
`• interconnecting to the SGSN—to func(cid:173)
`tion as an HLR for the GPRS service;
`• supporting
`the
`transfer of SMS over
`GPRS; and
`
`• supporting combined mobility manage(cid:173)
`ment.
`
`MSC/VLR
`
`As with the HLR, software in the MSC/VLR
`must be upgraded to support GPRS. The
`upgrade enables the MSC/VLR to be con(cid:173)
`nected to the SGSN, to support integrated
`mobility management for class A and class
`B terminals.
`
`Conclusion
`GPRS enables GSM operators to offer effi(cid:173)
`cient mobile access to external packet-
`switched networks, such as the Internet
`and corporate intranets. Several users can
`share the same network resources at the
`same time and enjoy transfer rates of up to
`L15 kbit/s.
`To support GPRS, two new nodes—the
`SGSN and the GGSN—must be added to
`the GSM network.
`Ericsson has developed a complete fami(cid:173)
`ly of products for GPRS:
`• TheSGSNandGGSNarebasedontheAXB
`250, a new packet-switching platform;
`• Apart from the BSC, existing nodes in the
`network solely require a softwate upgrade
`to support GPRS. The BSC requires new
`hardware and software.
`
`REFERENCES
`
`1 Furuskar, A., Naslund, J. and Olofsson H.:
`Edge—Enhanced data rates for GSM and
`TDMA/136 evolution. Ericsson Review
`Vol. 76(1999):1, pp. 28-37
`2 Torstendahl, S.: Open telecom platform.
`Ericsson Review Vol. 74(1997): 1, pp. 14-23
`
`Ericsson Review No. 2,1999
`
`Figure 7
`Idealized comparison of GPRS and
`circuit-switched data services.
`
`BOX F, GPRS EFFICIENCY
`
`Figure 7 shows an idealized comparison of
`GPRS and circuit-switched data services for
`typical
`Internet browsing. In this context,
`throughput is the average throughput that a
`user experiences as he or she downloads infor(cid:173)
`mation from the Internet. In the case of GPRS,
`fewer active users implies that each user has
`access to more bandwidth. As the number of
`active users grows, the bandwidth allocated to
`each user decreases. Compare this to circuit-
`switched service, where fixed bandwidth is
`allocated to a limited number of users.
`Compared with circuit-switched connec(cid:173)
`tions, GPRS offers superior performance to
`applications like Internet browsing. Due to
`bursty user behavior (users suddenly require
`lots of bandwidth, then nothing, then lots of
`bandwidth, and so forth), GPRS can serve
`more users than ordinary circuit-switched ser(cid:173)
`vices. On the other hand, GPRS offers non-
`bursty applications the same level of service—
`in terms of throughput—as circuit-switched
`data. Obviously, in evaluating efficiency, the
`user traffic model plays a central role.
`
`88
`
`Ex.1010
`APPLE INC. / Page 7 of 7
`
`