delivering time and phase for lte networks...2016/04/27 · delivering time and phase for lte...
TRANSCRIPT
Power Matters
Delivering Time and Phase for LTE Networks
Simon Butcher
©2016 Microsemi Corporation. Company Proprietary.
Power Matters
Small Cell Deployments - AndLTE-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
Power Matters
Mobile Wireless Synchronization Requirements
Mobile RFInput into Base
StationInter Cell Alignment
50ppb16 ppbGSM, WCDMA
LTE-FDD
LTE-TDD
LTE-Ae.g. CoMP, eICIC, eMBMS, MBSFN
± 1.1µs
50ppb
± 1.5µs (phase)
Not all LTE-A functions require phase,
Carrier Aggregation for example does not
Power Matters
ITU-T Synchronization Standards
G.8261 Timing & Sync: Frequency G.8271 Timing & Sync: Time & Phase
G.8261.1 Network Limits: Frequency G.8271.1 Network Limits: Full On Path Support
G.8271.2Network Limits : Partial On Path
Support
G.8262 SyncE clock – EEC G.8272 Primary Time Reference Clock -PRTC
G.8263PTP Clocks: Frequency
(PEC)G.8273
PTP Clocks: Time & Phase
(T-BC, T-TC, T-SC)
G.8273.4 Assisted Partial Time Support
G.8265 Architecture: Frequency G.8275 Architecture: Time & Phase
G.8265.1 Telecom Profile G.8275.1 Time Profile : Full On path support
G,8275.2 Time Profile : Partial On Path Support
Basic
aspects
Network
Limits
Clocks
Methods
Profiles
Frequency Time/Phase
not yet consentedconsented consented
Power Matters
PTP Delivery
AG1
PRC
PTP GM
PTP GM
End Equipment
PTP Timing Flows
AG1Aggregation
router
Packet Network Timing System
PTP Slave
GPON OLT
Edge Router
Microwave
PTP Slave
PTP Slave
PTP Slave
Base Station
Asymmetric Data Path
Power Matters
Time/Phase : The Time Error Budget
±100 ns
Transport, Noise, & Network Asymmetry eNB
PRTC
± 400 nsec± 1000 nsec
SOURCE
OF TIME
USE OF TIME
& Holdover
Total eNB Inter Cell Time Error +/- 1.5 µsec from UTC
Network Error Budget +/- 1 µsec
GPS
TRANSPORT OF TIME
PRC
Power Matters
G.8275.1 Time Profile: Full On Path Support
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
PRC
GM
End Equipment
Time Slave
Clock
T-SCPRTC
GNSS
Packet Network with
Embedded Boundary Clocks
T-BC T-BC T-BC T-BC
Power Matters
G.8275.2 Time Profile: Partial On Path Support
• In G.8275.2 we place a Boundary Clock at the most effective point on the
transport path
• Boundary Clocks cannot remove Asymmetry .. They can only reduce it.
PRC
GM
End Equipment
Time Slave
Clock
T-SCPRTC
GNSS
BC
Unicast Segment 1 Unicast Segment 2
Asynchronous Packet Network
Power Matters
Removing Asymmetry G.8273.4 Assisted Partial Timing Support (APTS)
GPS to calibrate out PTP asymmetry, and to measure its performance
Provides Holdover in the event of Local GPS failure.
PRC
Frequency ref
End Equipment
Time Slave
Clock
T-SCPRTC
GNSS
Asynchronous Packet Network
Unicast Segment 1 Unicast Segment 2
PRTC
APTS Node
Power Matters
The Time Error Budget with APTS and Asymmetry Compensation
±100 nsPRTC
dynamictime error
Holdover etc
±50ns
Total Time Error Budget +/- 1.5 µsec
Network Equipment End systems
Slave Clock
±800 ns Constant time error
Transport Network Base Station budget
network asymmetry is calibrated out of the system using GPS
±200 ns ±350 ns
Power Matters
G.8275.2 + APTS with Asymmetry Compensation with Unicast or Multicast at Edge
Packet Network
PRTCGrandmaster
PTP FLOWS
End Equipment (Base stations)
unicast or multicast mode
ASYMMETRY
CALIBRATION
T-SC
APTS PRTC
T-SC
unicast mode
Mobile Edge
PRTC
PRTC
Power Matters.™ 12© 2014 Microsemi Corporation. COMPANY PROPRIETARY
Key Synchronization Requirements
Small Cells require accurate timing
Timing is dependent on GNSS
Critical Problems
Challenges for Small Cell Deployment
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 NIDSwitch
GPS Antenna
Power Matters.™ 13© 2014 Microsemi Corporation. COMPANY PROPRIETARY
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
SyncE / PTP Features
APTS Support
