Lucent Technologies Bell Labs Innovations 1 3GPP2 ALLIP By Chung Liu, Enrique Hernandez-Valencia, and Mike Dolan IP to BTS Performance Analysis for cdma2000 voice application

Lucent Technologies Bell Labs Innovations 2 3GPP2 ALLIP Network Engineering Issues in VoIP n Large protocol stack overhead and desire to keep voice packetization delay small makes straightforward transport of voice over IP very inefficient. n Efficiency can be improved in various ways: IP/UDP/RTP header compression (a la RFC 2508, ROCCO or tcRTP). Effective on point-to-point or virtual links but not applicable end-to-end. MPLS and/or ATM networks may be used to provide a virtual point-to-point link between IP edge nodes. Multiple voice packets from different voice connections between the same edge nodes can be multiplexed into one L2\L3 packet (e.g., GeRM, PPPMux and tcRTP) thus reducing the effective transport overhead per voice packet. GeRM: Generic RTP Multiplexing (draft-ietf-avt-germ-00.txt) PPP MUX: PPP Multiplexing (draft-ietf-pppext-pppmux-00.txt)

Lucent Technologies Bell Labs Innovations 3 3GPP2 ALLIP Implementation Issues in VoIP n VoIP assumes IP/UDP/RTP protocol stack n RTP/UDP header compression increases per packet processing complexity at end-points only n IP header compression increases per packet processing complexity at each hop where IP routing is required n Removing IP, UDP or RTP layer is viable for certain transport scenarios, but it also decreases OA&M functionally and makes it potentially less compatible with existing hardware/software

Lucent Technologies Bell Labs Innovations 4 3GPP2 ALLIP Packet Voice Transport Options n Voice over Frame Relay (VoFR) - without Packet Pipes IS-95 Frame HDLC/PPP UDP RTP IP IS-95 Frame HDLC/PPP C-UDP/RTP IP VoIP via RTP or compressed UDP/RTP headers (cRTP) IS-95 L2/L3 Voice Frame Frame Relay IS-95 Frame C-XXX notation signifies all headers in XXX layer are compressed An * signifies IP layer header is also compressed.

Lucent Technologies Bell Labs Innovations 5 3GPP2 ALLIP Packet Voice Transport Options (cont’d #1) n Raw voice over IP (no UDP/RTP) IP IS-95 Frame HDLC/PPP IS-95 Frame HDLC/PPP n Raw voice over MPLS (IP routing only but no IP transport) MPLS

Lucent Technologies Bell Labs Innovations 6 3GPP2 ALLIP Packet Voice Transport Options (cont’d #2) n Generic RTP Multiplexing: w/out header compression (GeRM): with compressed UDP/RTP headers (cGeRM) with compressed IP/UDP/RTP headers over MPLS (McGeRM) GeRM IS-95 Frame HDLC/PPP UDP RTP IP IS-95 Frame HDLC/PPP C-GeRM/RTP/UDP IP IS-95 Frame HDLC/PPP C-GeRM/RTP/UDP/IP MPLS

Lucent Technologies Bell Labs Innovations 7 3GPP2 ALLIP Packet Voice Transport Options (cont’d #3) n PPP multiplexing: w/out header compression (PPPMux) with compressed UDP/RTP headers (cPPMux) raw voice over IP * Short sample PPP Mux IS-95 Frame HDLC/PPP UDP RTP IP IS-95 Frame HDLC/PPP C-RTP/UDP PPP Mux IS-95 Frame HDLC/PPP IP PPP Mux IP

Lucent Technologies Bell Labs Innovations 8 3GPP2 ALLIP Transport Capacity on a DS-1 Facility using HDLC

Lucent Technologies Bell Labs Innovations 9 3GPP2 ALLIP Transport Capacity on a DS-3 Facility using HDLC OC-3c capacity roughly 3xDS-3 capacity

Lucent Technologies Bell Labs Innovations 10 3GPP2 ALLIP Comparative Transport Efficiency #1 IP headers required for routing  Uncompressed IP header

Lucent Technologies Bell Labs Innovations 11 3GPP2 ALLIP IP Header Compression - Remarks n Transport efficiency for PPP/HDLC can be further improved with IP-header compression Requires physical or virtual point-to-point link RFC2508 or ROCCO style header compression over MPLS or ATM/AAL2 –Limited deployment (so far) –Larger implementation complexity VJ header compression –already standardized in IETF –slightly larger overhead –widely deployed

Lucent Technologies Bell Labs Innovations 12 3GPP2 ALLIP Comparative Transport Efficiency #2 * Compressed IP Header (cIP)

Lucent Technologies Bell Labs Innovations 13 3GPP2 ALLIP CDMA2000 Capacity Summary

Lucent Technologies Bell Labs Innovations 14 3GPP2 ALLIP Brief Comparison of IP & ATM Backhaul Proposals

Lucent Technologies Bell Labs Innovations 15 3GPP2 ALLIP Comparison of IP & ATM Backhaul Proposals (Cont’d)

Lucent Technologies Bell Labs Innovations 16 3GPP2 ALLIP Summary for ATM vs. IP Backhaul n ATM has the similar capacity as IP GeRM and higher than PPP MUX. n IP needs MUX (like AAL2) and compression in order to reach same capacity as ATM Applicable MUX: GeRM (RTP mux) or PPP MUX Existing IETF compression (e.g. RFC2508) is used for backhaul. Not require ROCCO like enhancement for radio link. n Why ATM first, then IP ? ATM has proven and standardized technology & products with similar capacity ATM does not need additional processing (MUX & compression) in BTS, SDU & intervening routers if needed ATM introduce less delay without processing additional headers IP needs to be standardized in IETF and proven for delay, soft handoff, QoS & reliability n GeRM (RTP MUX) is other IP to BTS alternative (compared to PPP MUX) Higher capacity Compression and MUX are at end points without additional processing in each hops –Use MPLS as routing label will reduce the processing & delay of intervening hops Shorter delay (critical for cdma2000 soft handoff)