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PON Architecture for Wireless Backhaul Paul Wilford October 28, 2009 - 1 The mobile backhaul problem 2 | PON Architecture for Wireless Backhaul All Rights Reserved © Alcatel-Lucent 2009 The mobile backhaul problem Current Wireless Carrier Environment Increased bandwidth demands Due to more advanced users and handsets Mobile broadband (killer app) TDM Backhaul is not efficient for packet data Doesn’t fit well in traditional T1 Architecture 3 | PON Architecture for Wireless Backhaul All Rights Reserved © Alcatel-Lucent 2009 The mobile backhaul problem Data is becoming the primary use of the network 4 | PON Architecture for Wireless Backhaul All Rights Reserved © Alcatel-Lucent 2009 The mobile backhaul problem New mobile data services require exponentially increasing bandwidth but generate less revenue per bit transported than voice services. 100 Kb/s for GSM GPRS (downlink) ≥100 Mb/s for LTE (downlink) This will break the traditional voice-optimized TDM Mobile Backhaul (MBH) network Legacy leased line capex and opex scale linearly with bandwidth Traffic ARPU 2000-2005 5 | PON Architecture for Wireless Backhaul 2005-2010 All Rights Reserved © Alcatel-Lucent 2009 2010-2020 2 Landscape of today 6 | PON Architecture for Wireless Backhaul All Rights Reserved © Alcatel-Lucent 2009 Landscape of today Voice Channels GSM UMTS IP Channel Base Station NodeB •SGSN – Serving GPRS Support Node •GGSN – Gateway GPRS Support Node •PDSN – Packet Data Support Node •HSGW – HRPD Serving Gateway Separate Core Networks for different Radio Access Networks •RNC – Radio Network Controller •DoRNC – Data Optimized RNC •BSC – Base Station Controller •MSC – Mobile Switching Center •HRPD – High Rate Packet Data (1xEV-DO) DoRNC Voice Channels 3G1X HRPD 7 | PON Architecture for Wireless Backhaul PDSN/HSGW BTS IP Channel BTS All Rights Reserved © Alcatel-Lucent 2009 Landscape of today Examples of customer deployments – Customer ‘X’ Customer ‘X’ primarily uses ATM for backhaul. The overall strategy is to seek higher-capacity, lower-cost solutions as the more data-centric technologies such as HSDPA drive capacity requirements. The target state architecture is one that is flexible and can scale as capacity demand increases. Some solutions being considered include fiber to the cell site and bonded copper. Customer ‘X’ has a combination of GSM/UMTS networks and will need to integrate backhaul for all networks as it migrates from GSM to UMTS to LTE. 8 | PON Architecture for Wireless Backhaul All Rights Reserved © Alcatel-Lucent 2009 Landscape of today Examples of customer deployments – Customer ‘Y’ Customer ‘Y’s backhaul strategy consists of delivering Ethernet over the existing copper infrastructure with a migration to fiber-based Ethernet backhaul services. Customer ‘Y’ plans to leverage its Fiber to the Premise (FTTP) network with pseudowire to provide backhaul services. 9 | PON Architecture for Wireless Backhaul All Rights Reserved © Alcatel-Lucent 2009 3 Landscape of Tomorrow 10 | PON Architecture for Wireless Backhaul All Rights Reserved © Alcatel-Lucent 2009 Landscape of tomorrow – Evolution to a common core GSM and CDMA voice and data networks converge into an IP-based evolved packet core (EPC) For LTE, IP data from the eNodeB connects directly to the EPC Voice Channels GSM UMTS IP Channel Base Station RNC NodeB MME LTE PCRF SGW PDN GW HSGW DoRNC Voice Channels 3G1X HRPD BTS IP Channel 11 | PON Architecture for Wireless Backhaul BTS All Rights Reserved © Alcatel-Lucent 2009 Landscape of tomorrow - 4G/LTE Mission High Peak Data Rates 100 Mbps DL (20 MHz, 2x2 MIMO) 50 Mbps UL (20 MHz, 1x2) Improved Spectrum Efficiency 3-4x HSPA Rel’6 in DL* 2-3x HSPA Rel’6 in UL 1 bps/Hz broadcast Full Broadband Coverage Network Co-existence UMTS, GSM, HRPD, CDMA Core Network 12 | PON Architecture for Wireless Backhaul for DL in LTE, but 1x2 for HSPA Rel’ 6 Improved Cell Edge Rates 3-4x HSPA Rel’6 in DL* 2-3x HSPA Rel’6 in UL Scalable Bandwidth 1.4, 3, 5, 10, 15, 20 MHz Radio Access Network *Assumes 2x2 Packet Domain Only Simplified Network Architecture Low Latency < 5ms User Plane (UE to RAN edge) < 100ms camped to active < 50ms dormant to active All Rights Reserved © Alcatel-Lucent 2009 Landscape of tomorrow – Technology Innovation With increased spectral efficiency, reduced latency and increased bandwidth, LTE enables innovations to improve performance at the handset. An example of this is CoMP. 13 | PON Architecture for Wireless Backhaul All Rights Reserved © Alcatel-Lucent 2009 4 What is CoMP? 14 | PON Architecture for Wireless Backhaul All Rights Reserved © Alcatel-Lucent 2009 What is CoMP? – Cooperative Multi-Point Overcome inter-cell interference by coordinating Tx/Rx at several base stations, thereby greatly increasing user rates and system capacity. Controller Today’s network High-speed backhaul Interference Desired signal Desired signal Each user is connected to a single base Each user is connected to several bases Data rates limited by interference All signals are potentially useful – no interference! 15 | PON Architecture for Wireless Backhaul All Rights Reserved © Alcatel-Lucent 2009 What is CoMP? - System Outline Backhaul that conveys both uplink and downlink baseband signal. Handset Base Station Base Station CoMP Processor Base Station Performs downlink and uplink CoMP beamforming. Base Station Handset Handset Handset Base stations communicate with a centralized CoMP processor. The backhaul network conveys both uplink and downlink signals. 16 | PON Architecture for Wireless Backhaul All Rights Reserved © Alcatel-Lucent 2009 What is CoMP? – Coherent vs. Non-Coherent Coherent Uses I/Q samples for CoMP processing in time or frequency domain Requires the highest bandwidth from the backhaul network Potential for greatest gain at the handset Non-coherent Uses soft bits for CoMP processing Requires less backhaul bandwidth than coherent scheme 17 | PON Architecture for Wireless Backhaul All Rights Reserved © Alcatel-Lucent 2009 What is CoMP? – Uplink and Downlink Uplink To perform uplink CoMP, I/Q samples or soft bits must be transmitted to the CoMP processor Downlink To perform downlink CoMP there are two options: Data and beam forming coefficients sent to each base station I/Q samples or soft bits sent to each base station After CoMP processing performed at CoMP processor The backhaul network must support the required data distribution to all nodes Channel State Information is required for beam forming Different base stations adjust the amplitude and phase of the transmission of the signals to the handsets to achieve improved handset performance 18 | PON Architecture for Wireless Backhaul All Rights Reserved © Alcatel-Lucent 2009 What is CoMP? - Requirements CoMP schemes demand for High bandwidth multiple Gbit/s (DL &UL coherent, time domain) <1 Gbit/s (DL & UL coherent, frequency domain) about 100 Mbit/s (non-coherent) Low latency about 1 ms (all schemes, optimal case) high backhaul latency may become a show stopper for CoMP – Need for a backhaul solution that is low latency The Technical challenge is to meet the latency requirement under fully loaded conditions. This requires sophisticated scheduling and MAC Layer processing. 19 | PON Architecture for Wireless Backhaul All Rights Reserved © Alcatel-Lucent 2009 5 Different PON technologies 20 | PON Architecture for Wireless Backhaul All Rights Reserved © Alcatel-Lucent 2009 Different PON technologies PON technologies: APON – ATM PON First PON standard – used primarily for business applications 622 Mbps/155 Mbps BPON – Broadband PON Extension of APON – added OMCI (OAM Management Control Interface) and WDM capability 622 Mbps/155 Mbps GEPON/EPON – Ethernet PON IEEE 802.3ah Standard 1Gbps/1Gbps GPON – Gigabit PON ITU-T G.984 Standard Evolution of BPON 2.5Gbps/1.25Gbps 21 | PON Architecture for Wireless Backhaul All Rights Reserved © Alcatel-Lucent 2009 Different PON technologies PON technologies: 10G EPON – 10G Ethernet PON Extension of GE/EPON 10 Gbps/1 Gbps XGPON – 10G GPON Extension of GPON XGPON1 – 10 Gbps/2.5 Gbps XGPON2 – 10 Gbps/10 Gbps GPON is a suitable backhaul technology for packet-based services For increased capacity and to support applications like CoMP, XGPON2 is the best backhaul solution 22 | PON Architecture for Wireless Backhaul All Rights Reserved © Alcatel-Lucent 2009 6 Synchronization 23 | PON Architecture for Wireless Backhaul All Rights Reserved © Alcatel-Lucent 2009 Synchronization: Problems with synchronization Base station radio interface typically requires some level of synchronization Frequency accuracy Time/phase accuracy Base station backhaul interface (typically legacy base stations) may be synchronous (T1/E1) Synchronization considerations Relative phase stability Mobile hand-off between base stations Coherent CoMP Core network may or may not be synchronous (Traditional) Ethernet, Synchronous Ethernet, SONET, etc. Separate timing distribution network may or may not exist GPS, NTR, etc. 24 | PON Architecture for Wireless Backhaul All Rights Reserved © Alcatel-Lucent 2009 Synchronization: GPON Mobile Backhaul End-to-End Synchronization E1/Sync E GPON PHY 8 kHz clock IEEE 1588v2 (when PRC not avail. at OLT) PRC PRC E1, GPON-fed cell site Eth gateway (ONU) GPON IP/ Ethernet Network Cell site OLT E1, Eth RNC/BSC Gateway RNC BSC The GPON Transmission Convergence (GTC) layer supports the transport of an 8 kHz clock via 125 microsecond framing Therefore GPON provides deterministic synchronization like TDM However, CoMP requires something better To achieve more precise timing synchronization, provisions must be made to compensate for the OLT-ONU delay variations GPON frame ONU t OLT ONU ONU GPON frame 25 | PON Architecture for Wireless Backhaul GPON frame GPON frame t t All Rights Reserved © Alcatel-Lucent 2009 t 7 The MAC Layer 26 | PON Architecture for Wireless Backhaul All Rights Reserved © Alcatel-Lucent 2009 The MAC Layer: GPON GPON QoS is maintained through transmission containers (T-CONTs) T-CONT classes Type 1 – fixed bandwidth Type 2 – assured bandwidth Type 3 – allocated bandwidth + non-assured bandwidth Type 4 – best effort Type 5 – superset of all of the above Scheduling algorithm at the GEM Layer guarantees that transmission container bandwidth and latency guarantees are satisfied under fully loaded conditions Dynamic Bandwidth Allocation Maximum fiber bandwidth utilization Based on queue status from ONUs Security (via AES) FEC 27 | PON Architecture for Wireless Backhaul All Rights Reserved © Alcatel-Lucent 2009 The MAC Layer: Backhaul challenges CoMP data processed and sent to downstream path for scheduling/reflection to ONUs Very low latency requirement of 1 ms Handoff between eNodeBs requires tighter synchronization at base stations OLT must send additional information to ONUs so they know neighboring ONU timing for handoffs FEC at 10 Gbps Completing R-S computations for 10 Gbps within 125 us is challenging 28 | PON Architecture for Wireless Backhaul All Rights Reserved © Alcatel-Lucent 2009 The MAC Layer: CoMP timing messages I/O Macro Scheduling for QoS and CoMP reflection North Bound I/F GEM Layer Downstream (encapsulation) AES Encryption I/O Macro TC Layer Downstream I/O Macro PHY Layer Downstream PLOAM Downstream BWMap (Dual Port) 10G FEC encode FEC Encode Processor I/F Regs I/O Macro S1/X2 translation South Bound I/F DBR Upstream GEM Layer Upstream PLS Upstream PLOAM Upstream TC Layer Upstream FEC Decode PHY Layer Upstream MAC CORE I/O CoMP processing. Data fed to downstream GEM Layer for reflection to ONUs 29 | PON Architecture for Wireless Backhaul S1/X2 translation All Rights Reserved © Alcatel-Lucent 2009 I/O Macro I/O 10G FEC decode 8 Conclusions 30 | PON Architecture for Wireless Backhaul All Rights Reserved © Alcatel-Lucent 2009 Conclusions XGPON2: Is a backhaul solution that can accommodate growth in bandwidth demand Is a backhaul solution that connects to the simplified network architecture Is a backhaul solution that can integrate data from 2G,3G and LTE networks Is a backhaul solution that can handle the uplink and downlink data distribution requirements for applications like CoMP Is a backhaul solution that is synchronous and is compatible with IEEE 1588v2 synchronization through packet networks Is a backhaul solution that contains efficient scheduling in the MAC layer for maintaining QoS under fully loaded conditions 31 | PON Architecture for Wireless Backhaul All Rights Reserved © Alcatel-Lucent 2009 Thank You! 32 | PON Architecture for Wireless Backhaul All Rights Reserved © Alcatel-Lucent 2009 Backup Slides 33 | PON Architecture for Wireless Backhaul All Rights Reserved © Alcatel-Lucent 2009 The MAC Layer: ONU block diagram I/O Macro 10G PHY Layer Downstream FEC Decode TC Layer Downstream PLOAM FIFO DS GEM Layer Downstream BWMap (Dual Port) USER I/F Translation I/O Macro(s) AES Decryption I/O Macro FEC Encode I/O Macro PHY Layer Upstream I/O 34 | PON Architecture for Wireless Backhaul Processor I/F PLOAM FIFO US TC Layer Upstream GEM Layer Upstream MAC CORE All Rights Reserved © Alcatel-Lucent 2009 Regs USER I/F Translation I/O Macro I/O Conclusions: Broadband Access Networks can support 3G/LTE Bandwidth Requirements GPON satisfies LTE bandwidth needs XGPON2 satisfies LTE bandwidth needs • 2.5G DS/1.25G US shared • Optical split adjusted as required. DL Speed [Mbps] > 1000 500 100 • Future evolution to 10G PON (λ overlay on same PON) GPON Wireline 10 ADSL2+ ADSL2 8 4 • 10G DS/10G US shared Bonded VDSL2 supports HSPA+ and early LTE LTE VDSL2 24 10G PON SHDSL.bis ADSL 1 0,512 HSPA GPRS 2000 35 | PON Architecture for Wireless Backhaul HSPA+ 2002 UMTS 2004 2006 2008 All Rights Reserved © Alcatel-Lucent 2009 Wireless 2010 2012 ADSL2+ and SHDSL.bis are tactical solutions for 2G 3G