1 Wireless Networks Lecture 24 CDMA2000 Dr. Ghalib A. Shah

2 Outlines  Last lecture review  Cdma2000 introduction  New MAC and Physical layer features  Physical layer of cdma2000  Reverse Physical channels  New Network elements in cdma2000 ►Packet Control Function (PCF) ►Packet Data Serving Node (PDSN)  Mobility Management  Handoff ►Intra-PCF ►Inter-PCF/Intra-PDSN ►Inter-PDSN

3 Last Lecture review  Compressed mode measurements  Handover measurements ►Intra-mode ►Inter-mode ►Inter-system  WCDMA packet data access  Transport channels for packet data ►Common, dedicated, shared  Packet scheduling algorithms ►Time division scheduling ►Code division scheduling ►Transmission Power-based scheduling

4 CDMA2000 Introduction  Provides seamless and evolutionary upgrade path for 2G and 2.5G cdma technology.  Centers on original 1.25 MHz radio channel  CDMA operators may seamlessly and selectively upgrade without changing entire BS equipment  The first 3G cdma standard cdma2000 1xRTT using single channel (1x => multi-carrier)  Cdma2000 1x ►Supports data rate up to 307 kbps in packet mode ►Can support up to twice as many users as 2G cdma ►Cdma 1xEV-DO dedicates the channel strictly to data user and support 2.4 Mbps per channel.

5 cdma2000  Cdma2000 3xRTT ►The ultimate 3G solution relies upon multicarrier that gang adjacent channels together into 3.75 MHz. ►Three non-adjacent channels may be operated simultaneously and in parallel. ►Data rate in excess of 2 Mbps similar when compared to W-CDMA  Advocates of cdma2000 claim their standard much more seamless and less expensive upgrade path when compared to W-CDMA.

6 WCDMA vs. CDMA2000

7  The new physical and MAC layer features and techniques ►Link adaptation based on adaptive modulation, coding and spreading ►Physical layer fast hybrid ARQ ►Enhanced channel coding and turbo codes ►Space and antenna diversity ►Fast forward link power control and coherent uplink demodulation

8 Physical Layer  The cdma2000 air interface is designed to provide flexible framework for supporting voice and other circuit-switched data as well as bursty packet data bearer services with different QoS  cdma2000 supports RF channel band width of SRx1.25 MHz. currently SR 1 and 3 are supported and can be extended to 6, 9 and 12.  A number of fixed and variable rate physical channels are defined with new variable-length spreading codes and PN codes.  The data rate, channel encoding and modulation parameters are specified by radio configurations (RCs) ►For SR 1 and 3, there are 7 RCs for reverse link and 9 for forward link

9 SRForward RC Data Rate (Base, Peak) Reverse RC Data Rate (Base, Peak) SR 1 RC19.6RC19.6 RC214.4RC214.4 RC39.6, 153.6RC39.6, RC49.6, RC514.4, 230.4RC414.4, SR 3 RC69.6, 307.2RC59.6, RC79.6, RC814.4, 460.8RC614.4, RC914.4, RC1 and RC2 are similar to Rate Set 1 and 2 in IS-95 RCs are chosen such that base rate for a forward and a reverse link match. If RC3 is used on reverse link, either RC3 or RC4 can be used on forward

10 Reverse Physical Channel Channel TypeMax SR1 Max SR3 Common Channel Reverse Pilot channel 11 Un-modulated SS signal by each MS, BS detect corresponding Uplink channel Reverse Access Channel 1NA For backward compatibility, used for uplink common control signaling Reverse Enhanced Access Channel 11 New channel used by MS to initiate communicate or respond to BS when no dedicated channel is assigned to user Reverse Common Control Channel 11 Common channel used for short burst data and signaling messages when traffic channels are not in use Dedicated Channel Reverse Dedicated Control Channel 11 As before Reverse Fundamental Channel 11 Basic traffic channel that carries voice, low-rate data and associated signaling messages Reverse Supplemental Code Channel 7NA Fixed rate data only channel to provide higher transmission rate Reverse Supplemental Channel 22 Variable rate packet data channel carrying only high speed coded info

11 Legacy cdmaOne Network  Designed to support voice and low-rate circuit-switched traffic A Ref (A1, A2, A5) STM over T1/T3 or AAL1 over SONET BSC A-bis BTS A-bis BTS IS-95 MS IS-95 MS Ater Ref (A3, A7) VLREIRACHLR

12 New Network elements in CDMA2000 BSC A-bis BTS MS PCFPDSN/FA R-P IP Core Network BSC A-bis BTS MS A3 (UT) A7 (S) A3 (US) A1 (S) A5 (UT) A2 (UT) A9 (US) A8 (UT) HA AAA Legacy IS-95 A/B

13  MS: additional features to support data services and enhanced signaling messages to both circuit-switched and packet-switched  BS (BTS & BSC): enhanced radio interface (significant hardware and software changes) to provide voice, data and multimedia traffic support  Packet Control Function (PCF): ►an entity that manages the buffering and relay the packets between BS and PDSN ►Maintain radio resource status (e.g. active, dormant) ►Collects radio link related accounting info to be used by AAA.

14  Packet Data Serving Node (PDSN): new network entity ►Acting as a FA by providing routing services (maintaining routing tables and route discovery) according to Mobile IP ►Managing the radio-packet (R-P) interface and PPP sessions for MS ►Initiating authentication, authorization and accounting for mobile user to the AAA server ►When part of VPN, it can establish a tunnel through the public data network using layer 2 tunneling protocol (L2TP) to the VPN gateway. ►PDSN may optionally use IPSec protocol to further protect the tunnel

15  Home Agent ►Network element within mobile’s home network ►Two major functions: mobile IP registration and packet forwarding ►HA interacts with AAA to receive mobile IP registration requests that have been authenticated and return registration response ►HA also forwards IP packets to and from current point of attachment through FA

16  AAA ►Authentication: verification of devices and subscribers for network access as well as user-based QoS requests ►Authorization: whether a user or device is authorized for particular service with a specific QoS based on service profile. The requesting entity may cache the authorization info making further decision itself without going to AAA. ►Accounting: involves collecting and storing billing-related data concerning the offered services. It includes session details (requested and offered QoS, duration of usage etc) and mobility records (dates and times of attach and detach etc)

17 Mobility management for packet data services  When an MS originates a call ►Messages are exchanged to establish and close an R-P connection between PCF/BSC and PDSN ►Once serial connection established between MS and PDSN MS and PDSN negotiate authentication protocol according to a challenge handshake authentication protocol (CHAP) or a password authentication protocol (PAP) PDSN sends authentication response to AAA server, which decide to authenticate or not PDSN constructs a network access identifier (NAI) of the form (realm of the home network) The user is identified as a valid user and PDSN also knows which IP service template to apply to this subscriber

18 ►When PPP session is established, PDSN assigns the mobile an IP address from a pool of IP addresses ►The routers in the packet network must be able to route any packet with this IP to the PDSN that provides service to the mobile

19 Handoff  Intra-PCF ►Supported by A8/A9 interfaces carrying user traffic and signaling between BS and PCF  Inter-PCF and Intra-PDSN ►On location change, must occur when causes to divert the packet data session from one R-P interface to another ►New R-P connection between target PCF and serving PDSN is established and PPP session will be moved to this ►Previous R-P session tear down ►PCF-PCF handoff may occur while MS is in active or dormant state ►Dormant handoff is supported to maintain PPP session, where a MS is dormant to minimize the use of air-link resources. ►During active session, PDSN supports low-latency handoff by bi-casting data to the target and previous PCF

20  Inter-PDSN ►A network based on simple IP does not support mobility beyond a PDSN coverage area because New IP will be acquired from new PDSN and traffic on existing IP will be undeliverable. Needs to support fast handoff i.e. Mobile IP

21  Inter-PSDN Fast Handoff ►The target PDSN initiates establishment of a P-P session with the serving PDSN. ►P-P interface is used to keep PPP session anchored when PDSN to PDSN handoff is performed allowing existing PPP session to continue and reducing service interruption time and data loss

22 Summary  Cdma2000 introduction  New MAC and Physical layer features  Physical layer of cdma2000  Reverse Physical channels  New Network elements in cdma2000 ►Packet Control Function (PCF) ►Packet Data Serving Node (PDSN)  Mobility Management  Handoff ►Intera-PCF ►Inter-PCF/Intra-PDSN ►Inter-PDSN