UMA/GAN the next wireless revolution?

Transcription

1 UMA/GAN the next wireless revolution? Sandy Fraser Mobile Broadband Division This paper includes the opinions of the author and should not be taken as fact All trademarks are the properties of their respective owners Apr 2007

2 Agenda Background to UMA/GAN Overview of operation Overview of specification and standards Challenges in protocol and functional test Summary References & Resources Page 2

3 Relevant Bodies UMA Technology Group initiated in January 2004, with participation from operators to suppliers. Published initial specifications before transitioning activities to 3GPP June GPP: Release 6 GERAN standards added UMA, called it Generic Access Network (GAN) ETSI Manage the standards on behalf of 3GPP. FMCA: Alliance of telecom operators, collaborating with standards bodies, to provide consistent services independent of underlying infrastructure. The word 3GPP is a Trade Mark of ETSI in France and other jurisdictions. Page 3

4 What is driving GAN Extended geographic coverage Better quality of service indoors in the home / office Higher bandwidth needed for triple-play services typically 1 to 2Mb/s limited by handset rather than Access Point compared with typical 100kb/s for EGPRS Increased network capacity without additional cellular infrastructure Fend off threat from VoIP operators gives users an alternative whilst retaining revenue for the operators Operators can bundle fixed line/internet in addition to cellular services Revenge (re-entry) of fixed-line operators Page 4

5 It s already happening. Fusion Norway's Hello AS Page 5

6 What enables GAN 1. Local area wireless networks using technologies such as Bluetooth (802.15) and WLAN (802.11) 2. Handsets which are dual-mode and GAN-enabled: They will need to run procedures that will detect when the user is roaming in and out of a Bluetooth, WLAN or other networks so that it can switch to and from GERAN/UTRAN cellular mode. 3. A new architectural component is required for the cellular network referred to as the Generic Access Network Controller (GANC): This is similar to a Base Station Controller; the backend connects to the operator s core mobile network while the front end connects to the local IP Access Network Page 6

7 Agenda Background to UMA/GAN Overview of operation Overview of specification and standards Challenges in protocol and functional test Summary References & Resources Page 7

8 GAN Concept (from 3GPP) Cellular Access Network GAN enabled dual mode handset Private Network IP Access Network BSC GANC Mobile Core Network Generic Access Network Page 8

9 GAN Functional Architecture (from TS ) Page 9

10 IP and GAN-Specific Protocols (TS sections 7.2,7.3) Standard IP based Protocols TCP for tunnelling IPsec ESP for secure tunnel used with GERAN bearer and signalling traffic IKEv2 and EAP-SIM for authentication and security association between MS and UNC UDP for IPsec NAT traversal UDP for GPRS data transfer RTP/UDP for GSM vocoder frames over IP transport GA-RC (Generic Access Resource Control) GANC discovery and Registration registration Update with GANC; application level keep-alive support for identification of the AP being used for GAN access. GA-CSR (Generic Access Circuit Switched Resources) equivalent to the GSM-RR GA-PSR (Generic Access Packet Switched Resources) equivalent to the GPRS-RLC Page 10

11 Agenda Background to UMA/GAN Overview of operation Overview of specification and standards Challenges in protocol and functional test Summary References & Resources Page 11

12 Key documents from 3GPP Release 6 TS Generic access to the A/Gb interface; Stage 2 Describes the overall architecture for Generic Access (GA) to the A/Gb interfaces. It describes the system concepts, documents the reference architecture, functional entities, network interfaces, and high-level procedures of GA service. TS Generic Access (GA) to the A/Gb interface; Mobile GA interface layer 3 specification Describes the procedures used over a generic access interface, namely the Up interface. It specifies the handling of secure connection, Discovery and Registration, CS domain and PS domain signalling and voice and data. These procedures are defined in terms of messages exchanged over a generic access interface. Page 12

13 Key documents from 3GPP Release 7 TS V7.5.0 ( ) Technical Specification GroupGSM/EDGE Radio Access Network Digital cellular telecommunications system (Phase 2+); Mobile Station (MS) conformance specification Part 1 GAN Relevant sections: 80 Generic Access default conditions, message contents and macros 81 GAN Discovery and Registration Procedures 82 GAN CS Domain Procedures 83 GAN PS Domain Procedures Page 13

14 GAN conformance summary Conformance category Number of tests Discovery/Registration 40 Handover related 6 Circuit Switched Resource 16 Packet Switched Resource 18 All tests 80 GAN related tests NOT currently included in today Application testing for the user experience data throughput, web browsing, gaming, PoC Voice quality GAN voice is essentially (but not exactly) VoIP. Simultaneous multiple services, eg SMS, MMS, Voice, Data, Voice+Data (Dual Transfer Mode), Video Page 14

15 Does GAN relate to both GERAN and UTRAN? briefly mentions UTRAN UE <> GANC interface for handovers HOWEVER.. UTRAN GANC to Core Network interfaces are still being debated Several options, no decisions yet HOCs/GAN_Enhancements/Docs/ lists the latest 3GPP documents Meeting notes/minutes from Sophia Antipolis (January 07) are the latest published documents on this page Meeting minutes from Seoul (February 07) or Montreal (March 07) have not been published yet. Next meeting is late May Shenzhen. Page 15

16 Agenda Background to UMA/GAN Overview of operation Overview of specification and standards Detailed operation and protocol/functional test challenges Summary References & Resources Page 16

17 Mode and PLMN Selection (TS sections 8.1, 8.2) Mode Selection Always powers up in GSM mode, after mode selected depends on user preferences and service provider configuration GERAN/UTRAN-only, remains in this mode, never switches to GAN mode GERAN/UTRAN-preferred, remains in this mode as long as there is a PLMN available GAN-preferred, as above but favouring to stay in GAN GAN-only, after initial power-up sequence in GERAN/UTRAN to obtain cellular network information, never switches back to cellular mode PLMN Selection A GANC can only be connected to one PLMN In cellular mode, only PLMNs available via GERAN/UTRAN can be selected In GAN mode, only the PLMN associated with the registered GAN is selected Manual PLMN selection as normal Page 17

18 GAN challenges - Voice GAN Voice is essentially, but not precisely VoIP. IP packets contain encapsulated GSM encoded voice information GAN AMR codec change hysteresis and threshold are controlled not by power level and interference, but by number of lost packets. There are no GAN Rx sensitivity tests mandated for AMR codec rate changes Delay and latency will be critical in determining voice quality. Existing GSM voice testing will not be sufficient to ensure suitable user experience Page 18

19 GAN Challenges Data The Load gets Greater UE performance demands increasing all the time. Simplistically, there are two major factors in processor loading number of things a UE has to do at once how quickly it has to do these things Strong pressure in both of these factors from current changes in handsets Peak processor usage can be the problem but can be hard to spot the peaks (and the effects of those peaks) GAN adds to this issue with WiFi throughput rates - theoretically much higher than HSPA, similar (perhaps) to WiMAX!!! Music/Video Gaming Voice Web Browsing MMS SMS Page 19

20 Re-selection between GERAN/UTRAN and GAN modes (TS sections 8.3, 8.14, ) Roving modes: Similar to the above, takes place when MS is in idle state and roams Rove-in (from GERAN/UTRAN mode to GAN mode) Rove-out (from GAN mode to GERAN/UTRAN) Handover modes: take place when MS is engaged in an active session and roams Handover in, where the MS moves from cellular network to GAN. Handover out, where the MS moves from GAN to cellular network. Handover GAN, where the MS moves within a GAN or across GANs In order to Handover to/from GAN, the MS must provide adjacent cell information... Page 20

21 GANC emulation of GERAN cell GANC is configured to EMULATE a GERAN Cell All GERAN Identifiers are replicated for each GAN, eg BCC, Cell ID GANC must indicate it s capabilities Many GERAN Cell capabilities must be settable/configurable for GAN test Page 21

22 GAN Handovers Protocol Logging 1 Protocol log of GERAN to GAN handover 2 UMA-GAN Protocol logs show the encapsulation of regular GSM voice handover information within UMA-GAN identified IP packets 3 Page 22

23 GAN Measurement Reports In GERAN, UE will measure adjacent cell power and report these to the currently camped BSC. The preferred cell is usually the one with highest power. When a UE discovers a GAN cell, it s cell power is reported as maximum, in order to make it appear as the preferred cell When a UE is GAN connected, it still measures adjacent GERAN/UTRAN cells for the situation when GAN signal strength dictate HO back to Cellular Page 23

24 GERAN <> GAN Handovers The Core network is still in charge of GERAN<>GAN Handovers The GANC is not quite a pass through entity, but it has minimal control in this process The most significant challenge for the UE is handling simultaneous radio access environments. MS (UE) reports are vital. The GAN MS cell quality reports are always maximised, ie the GAN is always notified to the CN as the best neighbour cell Page 24

25 GAN Challenges DTM Dual Transfer Mode (simultaneous voice and data) in GERAN Voice is still circuit switched a dedicated channel Dual Transfer Mode in GAN Voice and Data have separate IP streams Both subject to latency/delay GAN Cell loading will have a significant effect Non (E)DTM UE s will still require the suspend/resume procedures, when prioritised voice interrupts data services GAN cells will require to advertise DTM (and also (E)GPRS) availability Page 25

26 GAN Challenges Battery life GSM Typical battery standby life of 8-10 days, call time 5-6 hours Agilent 14565B battery drain analysis 66319B power supply W-CDMA Typical battery standby life of 4-5 days, call time 3 hours WLAN Typical battery standby life of 1-2 days, call time1-2 hours. The devices receiver(s) have to monitor GERAN networks, UTRAN networks and GAN networks. WLAN standards were not written to accommodate portable devices with limited battery capacity Testing and improving WLAN/GAN battery performance will be a significant step towards acceptability of devices by the domestic user Page 26

27 What is important to the customer? A user s perception of quality based around their end to end experience of the service. Comparisons between networks are drawn around easily observable facts such as: dropped calls a common satisfaction issue in GERAN/UTRAN number of successful connections registration/discovery Voice quality, latency/delay, speech clarity Data throughput rates, latency/delay Battery life Getting these basics right will allow customers to differentiate between networks, and therefore must be criteria which networks use to differentiate between the handsets they select for use on their network. Page 27

28 Agenda Background to UMA/GAN Overview of operation Overview of specification and standards Detailed operation and protocol/functional test challenges Summary References & Resources Page 28

29 Summary GAN/GAN requires the use of two bearers simultaneously in the UE, loading the processor and draining the battery The most basic requirement is the provision of seamless voice services when transitioning between GAN, GERAN, UTRAN Common services such as SMS, MMS, Web browsing, Video, etc will need to be tested, as well as supplementary services such as emergency calling. The higher data rates via GAN will create new possibilities, and will place even higher demands on the MS processor Developers will require to test MUCH MORE than is required by conformance specifications If you would like more information on Agilent GAN test solutions, contact your representative (ask for 8960 with E6701x) or Page 29

30 Agenda Background to UMA/GAN Overview of operation Overview of specification and standards Detailed operation and protocol/functional test challenges Summary References & Resources Page 30

31 UMA/GAN references and resources UMA web site: 3GPP TS Generic access to the A/Gb interface; Stage 2 Stage 2 TS Generic Access (GA) to the A/Gb interface; Mobile GA interface layer 3 specification TS Mobile Station (MS) conformance specification Part 1 Fixed-Mobile Convergence Alliance Wi-Fi GAN (UMA) PRD, Rel 2.0, May 2006 Wi-Fi Net News Your presenter - Sandy Fraser sandy_fraser@agilent.com Page 31

32 END Page 32