Delivering Time and Phase for LTE Networks

Transcription

1 Delivering Time and Phase for LTE Networks Simon Butcher 2016 Microsemi Corporation. Company Proprietary.

2 Small Cell Deployments - And LTE-Advanced (LTE-A) at the Mobile Edge LTE-FDD requires frequency sync LTE-TDD requires phase sync to UTC LTE-A Can be deployed on LTE-FDD or TDD networks LTE-A services are designed to enhance network RF performance, Improve spectrum availability and reach, Avoid interference between the enb, Enable more users onto the network, Dynamically allocate bandwidth etc Most LTE-A services such as eicic, CoMP, embms, MBSFN require inter cell phase sync

3 Mobile Wireless Synchronization Requirements Mobile RF GSM, WCDMA LTE-FDD Input into Base Station 16 ppb Inter Cell Alignment 50ppb LTE-TDD LTE-A e.g. CoMP, eicic, embms, MBSFN ± 1.1µs ± 1.5µs (phase) Not all LTE-A functions require phase, Carrier Aggregation for example does not

4 ITU-T Synchronization Standards Frequency Time/Phase Basic aspects Network Limits Clocks Methods Profiles G.8261 Timing & Sync: Frequency G.8271 Timing & Sync: Time & Phase G Network Limits: Frequency G Network Limits: Full On Path Support G Network Limits : Partial On Path Support G.8262 SyncE clock EEC G.8272 Primary Time Reference Clock - G.8263 PTP Clocks: Frequency (PEC) G.8273 G PTP Clocks: Time & Phase (T-BC, T-TC, T-SC) Assisted Partial Time Support G.8265 Architecture: Frequency G.8275 Architecture: Time & Phase G Telecom Profile G Time Profile : Full On path support G, Time Profile : Partial On Path Support consented consented not yet consented

5 PTP Delivery Packet Network Timing System PRC PTP GM PTP GM PTP Timing Flows AG1 Aggregation router PTP Slave Base Station PTP Slave GPON OLT AG1 PTP Slave Edge Router Asymmetric Data Path PTP Slave Microwave End Equipment

6 Time/Phase : The Time Error Budget PRC GPS ±100 ns ± 1000 nsec ± 400 nsec Transport, Noise, & Network Asymmetry enb SOURCE OF TIME TRANSPORT OF TIME USE OF TIME & Holdover Network Error Budget +/- 1 µsec Total enb Inter Cell Time Error +/- 1.5 µsec from UTC

7 G Time Profile: Full On Path Support GNSS Packet Network with Embedded Boundary Clocks Time Slave Clock GM T-BC T-BC T-BC T-BC T-SC PRC End Equipment Attributes PTP Multicast over Layer 2 network Time Boundary Clock (T-BC) on every network element Physical layer frequency support from synce (needs a PRC) Max Hops: 10 (20 is currently theoretical) Provides hop by hop engineering guideline for time/phase as per SEC/EEC

8 G Time Profile: Partial On Path Support Unicast Segment 1 Unicast Segment 2 GNSS Time Slave Clock GM BC T-SC PRC Asynchronous Packet Network End Equipment In G we place a Boundary Clock at the most effective point on the transport path Boundary Clocks cannot remove Asymmetry.. They can only reduce it.

9 Removing Asymmetry G Assisted Partial Timing Support (APTS) Unicast Segment 1 Unicast Segment 2 GNSS APTS Node T-SC PRC Frequency ref Asynchronous Packet Network Time Slave Clock End Equipment GPS to calibrate out PTP asymmetry, and to measure its performance Provides Holdover in the event of Local GPS failure.

10 The Time Error Budget with APTS and Asymmetry Compensation Transport Network Base Station budget ±100 ns ±200 ns ±350 ns ±50ns ±800 ns Constant time error network asymmetry is calibrated out of the system using GPS dynamic time error Slave Clock Holdover etc Network Equipment End systems Total Time Error Budget +/- 1.5 µsec

11 G APTS with Asymmetry Compensation with Unicast or Multicast at Edge unicast mode unicast or multicast mode Grandmaster ASYMMETRY CALIBRATION APTS T-SC Packet Network PTP FLOWS Mobile Edge T-SC End Equipment (Base stations)

12 Challenges for Small Cell Deployment Key Synchronization Requirements Small Cells require accurate timing Timing is dependent on GNSS GPS Antenna Critical Problems High Cost of GPS antenna cabling Roof access/rental fees Installation Costs through several floors Operators requesting less devices to deploy and manage combining functions into single device Switch NID 2014 Microsemi Corporation. COMPANY PROPRIETARY. 12

13 MSCC igm Indoor Use Device Features Integrated GPS receiver + Antenna + PTP Grand Master GPS Features Enhanced Indoor GNSS Assist Optimized for urban canyon / indoor use APTS Support SyncE / PTP Features 2014 Microsemi Corporation. COMPANY PROPRIETARY. 13

14 Thank You Simon Butcher Solutions Architect EMEA Microsemi