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Power Matters.TM Achieving Phase Accuracy for LTE-A Synchronization Field Measurement Results © 2014 Microsemi Corporation. COMPANY PROPRIETARY 1 Agenda Overview • Frequency, Time, and Phase Synchronization • IEEE 1588 Precision Time Protocol Profiles • ITU Standards and Deployment Models Achieving Phase Accuracy in the Field • Field Testing Overview • Specific test cases • Field Test Results Conclusions © 2014 Microsemi Corporation. COMPANY PROPRIETARY Power Matters.TM 2 Frequency, Time and Phase Synchronization E1/T1, SyncE, PTP, GNSS, NTP, 10Mhz, 1PPS Frequency Synchronization TA=1/fA A t TB=1/fB B t fA=fB Phase Synchronization PTP, GNSS, NTP, 1PPS TA=1/fA A t TB=1/fB B t fA=fB Time Synchronization 01:00:00 PTP, GNSS, NTP 01:00:10 TA=1/fA A t TB=1/fB B t fA=fB © 2014 Microsemi Corporation. COMPANY PROPRIETARY 01:00:00 01:00:10 Power Matters.TM 3 Mobile Wireless Synchronization Requirements Mobile Technology Frequency Input into Base Station Inter Cell Phase Alignment FDD 16 ppb N/A LTE-TDD ± 1.5µs eICIC ± 1.5µs CoMP ± 0.5 to ± 1.5µs LTE-A MBSFN ± 1.5µs MBMS ± 1 to ± 32µs © 2014 Microsemi Corporation. COMPANY PROPRIETARY Power Matters.TM 4 IEEE 1588-2008 Profiles IEEE 1588-2008 … • -2008 defined for all applications … barrier to interoperability • profiles define application related features from the full specification, enabling interoperability Power Profile Defined by IEEE PSRC (C37.238) Substation LAN Applications Telecom Profile Defined by ITU-T (G.8265.1, G.8275) Telecom WAN Applications Default Profile Defined in Annex J. of 1588 specification LAN/Industrial Automation Application (v1) © 2014 Microsemi Corporation. COMPANY PROPRIETARY Power Matters.TM 5 PTP (IEEE 1588) Routing Options Multicast Grandmaster broadcasts PTP packets to a Multicast IP address Switches/Routers… • With IGMP snooping, forwards multicast packets to subscribers • Else traffic broadcast to all ports Multicast Sync Interval: Unicast Grandmaster sends PTP packets directly to PTP slaves Switches/Routers forward PTP packets directly to slaves Unicast Sync Interval; Telecom Profile: • User defined Sync interval up to 128Hz • Many subscribers supported Fixed rate, example 16Hz Multicast (1:group) Unicast (1:1) © 2014 Microsemi Corporation. COMPANY PROPRIETARY Power Matters.TM 7 How Time Offsets are Corrected in Time Transfer Client Server 1. Originate Time Stamp 2. Receive Time Stamp 3. Transmit Time Stamp 4. Client Time Received 1. Originate Time Stamp 2. Receive Time Stamp 3. Transmit Time Stamp Client Time = (Receive Time – Originate Time) + (Transmit Time – Client Time Received) Offset 2 Assumes symmetric path latency (delay) for outbound and return paths © 2014 Microsemi Corporation. COMPANY PROPRIETARY Power Matters.TM 10 Automatic Path Asymmetry Correction • Automatic Path Asymmetry Correction algorithm supplies external correction factor as defined in IEEE 1588 standard. • Algorithm learns path asymmetries to the north-bound master … even while system may using GNSS as the primary clock source. Customer network test environment Path Re-arrangement (Ring Topology • In the event of a GNSS failure, the system will operate revert to using Asymmetry corrected PTP. • Feature available with the TimeProvider 2700 • Will be added to G.8273.4 APTS BLUE: PPS performance without asymmetry correction. © 2014 Microsemi Corporation. COMPANY PROPRIETARY RED: PPS performance with asymmetry correction. Power Matters.TM 11 Structure of ITU-T Sync Requirements G.8260: Definitions and Terminology for Synchronization in Packet Networks Definitions / Terminology Basic Aspects Network Requirements Clocks Frequency Time/Phase G.8261: Timing and Synchronization Aspects in Packet Networks (Frequency) G.8271: Time and Phase Synchronization Aspects in Packet Networks G.8271.1: Network Requirements for Time/Phase Full on Path Support G.8261.1: PDV Network Limits Applicable to PacketBased Methods (Frequency) G.8261.2: Reserved for future use G.8271.2: Network Requirements for Time/Phase Partial On Path Support G.8262: Timing Characteristics of a Synchronous Ethernet Equipment Slave Clock (EEC) G.8272: PRTC (Primary Reference Time Clock) Performance G.8263: Timing Characteristics of Packet-Based Equipment Clocks (PEC) G.8273: Packet-Based Equipment Clocks for Time/Phase: Framework G.8273.1: Telecom Grandmaster (T-GM) G.8273.2: Telecom Boundary Clock (T-BC) G.8273.3: Telecom Transparent Clock (T-TC) G.8273.4: Telecom Time Slave Clock (T-TSC) Methods Profiles G.8264: Distribution of Timing Information through Packet Networks G.8274: Reserved for future use G.8265: Architecture and Requirements for PacketBased Frequency Delivery G.8275: Architecture and Requirements for PacketBased Time and Phase Delivery G.8275.1: PTP Telecom Profile for Time/Phase Synchronization, Full OPS G.8265.1: Precision Time Protocol Telecom Profile for Frequency Synchronization G.8275.2: PTP Telecom Profile for Time/Phase Synchronization, Partial OPS G.8265.2 PTP Telecom Profile for Frequency #2 agreed ongoing options © 2014 Microsemi Corporation. COMPANY PROPRIETARY Power Matters.TM 12 LTE FDD Frequency, Managed Ethernet Backhaul G.8265.1 Architecture Managed Ethernet Backhaul consistent, known performance CORE AGGREGATION ACCESS PTP GM Macro eNodeB PTP slave/client device CES/PWE IWF PTP GM GPON Base Station • Set frequency with PTP (GNSS/GPS primary source) • 10 hops with QoS on PTP flow • No on path support (BC/TC) required © 2014 Microsemi Corporation. COMPANY PROPRIETARY Media Gateway Power Matters.TM 13 LTE-A, TDD Phase, Retrofitted or New Ethernet Backhaul - G.8275.1 Architecture Retrofit Existing Backhaul or New Build Managed Ethernet, Synchronous Ethernet, Boundary Clocks CORE ACCESS AGGREGATION PTP GM SyncE BC BC SyncE BC SyncE SyncE BC BC SyncE SyncE PTP GM SyncE BC SyncE BC SyncE Rb Macro eNodeB BC SyncE BC BC SyncE SyncE BC BC BC BC SyncE Small Cell Agg. Metro Small Cells • Set time/phase with PTP (GNSS at primary source) • SyncE and Boundary Clock in every node for asymmetry mitigation © 2014 Microsemi Corporation. COMPANY PROPRIETARY Power Matters.TM 14 LTE-A, TDD Phase, Overlay Existing Backhaul G.8275.2 Architecture Existing Backhaul Edgemaster Overlay with Asymmetry Correction CORE AGGREGATION ACCESS Ethernet PTP GM PTP GM Macro eNodeB Microwave Macro eNodeB PON OLT ONU Small Cell Aggregation DSL PTP GM modem DSLAM • Set time/phase in macro/small cells with GMC at edge (asymmetry not an issue) • Hold time/phase with GMC from MSC using asymmetry compensation PTP GM Metro Small Cells • Once time/phase is set asymmetry is not an issue © 2014 Microsemi Corporation. COMPANY PROPRIETARY Power Matters.TM 15 Achieving Phase Accuracy in the Field © 2014 Microsemi Corporation. COMPANY PROPRIETARY Power Matters.TM 16 Field Test – Overview Objective: Confirm that PTP can be used to synchronize eNodeBs • Test Case 1: • Test Case 2: Partial On-Path Support without GNSS support Partial On-Path Support with GNSS reference on the Edge (as per ITU G.8275.2) • Test Case 3: • Test Case 4: Partial On-Path Support with loss of GPS at the Edge (with Asymmetry Correction). Partial On-Path Support 3rd party embedded PTP in CSR Satisfy LTE-A Phase Requirements ±1.5µs (3µs total) Measure PTP Phase Performance to the eNodeB. Measure Packet Delay Variation (PDV) Backhaul Path © 2014 Microsemi Corporation. COMPANY PROPRIETARY Power Matters.TM 17 Path PDV Characteristics Direction PD Min PD Max PD Range PD Mean Forward 647us 14,500us 13,900us 709us Reverse 629us 989us 360us 663us © 2014 Microsemi Corporation. COMPANY PROPRIETARY Power Matters.TM 19 Path PDV Characteristics (Zoom) Direction PD Min PD Max PD Range PD Mean Forward 647us 14,500us 13,900us 709us Reverse 629us 989us 360us 663us © 2014 Microsemi Corporation. COMPANY PROPRIETARY Power Matters.TM 20 Path PDV Characteristics ( FW floor Zoom) Mean FPP ( 200sec window) : 10us – 5.88% 100us – 81.94% © 2014 Microsemi Corporation. COMPANY PROPRIETARY Power Matters.TM 21 Path PDV Characteristics ( RV floor Zoom) Mean FPP ( 200sec window) : 10us – 2.53% 100us – 99.86% © 2014 Microsemi Corporation. COMPANY PROPRIETARY Power Matters.TM 22 Phase Performance Comparison TC 1: Partial On-Path TP2700 with PTP input only (BC) TC 2: Partial On-Path TP2700 with GNSS input TC 3: Partial On-Path (Loss of GPS) TP2700 with Asymmetry compensation TC 4: Partial On-Path Embedded in 3rd party CSR © 2014 Microsemi Corporation. COMPANY PROPRIETARY Power Matters.TM 23 Test Case 1: Partial On-Path Support without GNSS support eNB Site MSO GPS TP-5000 PDV Probe 1PPS & 10MHz Reference GPS CSR PTP Slave TP-5000 GM 1PPS Out 1PPS Ref 10MHz Counter Ref Ethernet Backhaul Network TP-2700 w/o GPS PTP – Forward direction PTP – Reverse direction Counter TimeMonitor Data collection and analysis Router or Switch © 2014 Microsemi Corporation. COMPANY PROPRIETARY Power Matters.TM 24 TC1 Phase Performance 7.86usp-p © 2014 Microsemi Corporation. COMPANY PROPRIETARY Power Matters.TM 25 Test Case 2: Partial On-Path Support As per ITU G.8275.2 eNB Site MSO GPS TP-5000 PDV Probe 1PPS & 10MHz Reference GPS CSR PTP Slave TP-5000 GM 1PPS Out Wireless Ethernet Backhaul Network TP-2700 w/ GPS PTP – Forward direction PTP – Reverse direction 1PPS Ref 10MHz Counter Ref Counter TimeMonitor Data collection and analysis Router or Switch © 2014 Microsemi Corporation. COMPANY PROPRIETARY Power Matters.TM 26 TC2 Phase Performance 567nsp-p © 2014 Microsemi Corporation. COMPANY PROPRIETARY Power Matters.TM 27 Test Case 3: Partial On-Path Support Loss of GPS at the Edge (Asymmetry Compensation) eNB Site MSO GPS TP-5000 PDV Probe 1PPS & 10MHz Reference GPS CSR eNB with PTP Slave TP-5000 GM 1PPS Out Wireless Ethernet Backhaul Network 1PPS Ref 10MHz Counter Ref X TP-2700 w/ GPS PTP – Forward direction PTP – Reverse direction Counter TimeMonitor Data collection and analysis Router or Switch © 2014 Microsemi Corporation. COMPANY PROPRIETARY Power Matters.TM 28 TC2 to TC3 – GNSS to PTP fallback © 2014 Microsemi Corporation. COMPANY PROPRIETARY Power Matters.TM 29 TC3 Phase Performance 1.74usp-p © 2014 Microsemi Corporation. COMPANY PROPRIETARY Power Matters.TM 30 Test Case 4: Partial On-Path Support 3rd party embedded PTP in CSR eNB Site MSO GPS TP-5000 PDV Probe 1PPS & 10MHz Reference GPS CSR eNB with PTP Slave TP-5000 GM 1PPS Out 1PPS Ref 10MHz Counter Ref Wireless Ethernet Backhaul Network Counter PTP – Forward direction PTP – Reverse direction TimeMonitor Data collection and analysis Router or Switch © 2014 Microsemi Corporation. COMPANY PROPRIETARY Power Matters.TM 31 TC4 Phase Performance 1.25usp-p © 2014 Microsemi Corporation. COMPANY PROPRIETARY Power Matters.TM 32 Field Test – Summary All TP2700 Test Cases met and exceeded ±1.5µs (3µs total) for LTE-A phase performance. Combining GNSS and PTP with Asymmetry correction give fastest reference switchover and good performance. Many embedded PTP clients fail to compensate the network asymmetry. Phase accuracy isn’t the only important parameter! © 2014 Microsemi Corporation. COMPANY PROPRIETARY Power Matters.TM 33 Thank You Eran Gilat EMEA, System Sales Engineer [email protected] +972.52.342.4718 © 2014 Microsemi Corporation. COMPANY PROPRIETARY Power Matters.TM 35