ANGA COM 2020 Online Event 17-November-2020 Trimble - Time & Frequency Division Synchronization Concepts
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ANGA COM 2020
Online Event
17-November-2020
Trimble
Time & Frequency
Division
Synchronization Concepts
transforming
THE WAY THE WORLD WORKS
A world leader in transforming how work is done, across multiple
industries and professions
Our customers gain significant economic breakthroughs at the same
time improving quality, regulatory, specification compliance and reducing
costs
Our technological capabilities in GNSS are unsurpassed in the
industry, with a 40-year history in GNSS systems, positioning and
timing… THE GNSS Experts!
2019 Revenue $3.2+ Billion USD; 11,000+ employees worldwide
Deep knowledge of communication systems synchronization and
mission critical requirements
Technology supplier to:
NEMs for 20+ years (GSM, TETRA, UMTS & LTE)
Automotive industry for 25+ years
Headquartered in Sunnyvale, California with facilities in 40 countries,
partners in 125 countries and customers in 150 countries
Trimble confidential, ©2020 Page 2
transforming
THE WAY THE WORLD WORKS – ACROSS MULTIPLE INDUSTRIES & PROFESSIONS
Agriculture Heavy Civil Building Geospatial Transportation &
Construction Construction Logistics
Rail Environmental & Water Utilities Electric Utilities Mining
Waste
Forestry Field Service Oil, Gas & Time & Government
Trimble confidential, ©2020 Chemical Frequency Page 3
Business Organization
The businesses are now organized into five major groups:
Autonomy
Organized in Q4 2019
Autonomy Business Unit includes the following divisions:
Advanced Positioning
Applanix
InTech (Precision GNSS)
Embedded Technologies
Autonomous Solutions
Time & Frequency
Trimble confidential, ©2020 Page 4
3 Types of Timing
Absolute Timing / Synchronization
– What time is it at your place, in your timezone?
Timestamps
Time of Day (ToD)
Coordinated Universal Time (abbreviated to UTC) is the primary time
standard by which the world regulates clocks and time
Frequency Timing / Synchronization
o The number of cycles per unit time,
clocks running at the same rate and the
ability to distribute precision frequency
around a network
o Used to “synchronize” transmitters and
receivers in communications systems
Phase Timing
o Alignment of rising and trailing pulse
edges in time
o Will be key to 5G, LTE-Advanced and TDD
Trimble confidential, ©2020 Page 5
Clock Types
There are "Master" clocks and "Slave" clocks
– Masters (servers) provide timing; slaves (client) receive timing
Ordinary Clock (OC)
– End device on network; there are 3 flavors:
1. Slave-only clock (receiving timing from a master)
2. Grandmaster: only acts as a master, never as a slave
o GM has a good oscillator and the ability to obtain standard time (UTC), often GNSS receiver
3. Master clock or slave clock
o This type of OC can act as either a master or slave; usually acting as a slave, unless there is no
better master available in the network, in which case it takes over that function to become the GM
(Best Master Clock Algorithm)
Boundary Clock (BC)
– A BC has one port which acts as a slave (getting time from an upstream master),
and all other ports act as masters to downstream clocks to disseminate time to
downstream slaves
Transparent Clock (TC)
– A TC provides hardware timestamps whenever a sync message arrives or
departs to adjust for packet delay
1-Step Clock versus 2-Step Clock
– 1-Step clock: the timestamp from the master clock is included in the first “sync"
message sent master slave
– 2-Step clock: the timestamp from the master clock is sent in a separate
message after the "sync" message has been sent
Trimble confidential, ©2020 Page 6
"Anyhaul" Defined
First it was Backhaul:
– 2G, 3G
– Connecting cell site, base station radios to the network
switching elements
o 2G (GSM): BTS BSC "Core"
o 3G (UMTS): NB RNC “Core”
Then came Fronthaul
– 4G (LTE-A): RRH (eNB) BBU
– Connecting cell site radios to a geographically
distanced baseband unit
– BBU "Core" = backhaul
Now there is also Midhaul
– 5G NR: RU (gNB) DU = fronthaul
– DU CU = midhaul
– CU "Core“ = backhaul
Trimble confidential, ©2020 Page 7
DOCSIS Sync Architecture
The DOCSIS 3.1 architecture introduced the need for an industry
standard PTP Grandmaster clock (IEEE-1588v2) to providing timing to
the CMTS and RPDs
– The GM can be used to synchronize both the CMTS and RPDs, whereby the timing is
decoupled from the CMTS itself to simplify its design and offload timing performance to a
high-quality timing source (GM) for better accuracy and reliability.
– DOCSIS Timing Protocol (DTP) introduced for more accurate timing and a mechanism to
measure/model the asymmetries in the HFC network, as well as provide an adjustment
factor to the DOCSIS timestamps
– 2021 will introduce the requirement to support phase sync over DOCSIS with partial
network (G.8275.2 PTP profile)
Trimble confidential, ©2020 Page 8
IEEE-1588v2 Time Transfer Technique
Master Clock Slave Clock Data At Round Trip Delay
Slave Clock RTD = (t2 - t1) + (t4 - t3)
Switch/Router Layer Offset:
(slave clock error and one-way path delay)
OffsetSYNC = t2 – t1
t1 Leap second offset OffsetDELAY_REQ = t4 – t3
t2 t2 (& t1 for 1-step) We assume path symmetry, therefore
One-Way Path Delay = RTD ÷ 2
t1,t2
Slave Clock Error = (t2 - t1) - (RTD ÷ 2)
t3 t1, t2, t3
Notes:
1. One-way delay cannot be calculated
t4
exactly, but there is a bounded error.
2. The protocol transfers TAI (Atomic Time).
UTC time is TAI + leap second offset from
the announce message.
t1, t2, t3, t4
Time
Time
The process is repeated up to 128 times per second.
Trimble confidential, ©2020 (Announce rate is lower than Sync rate) Page 9
PTP Profile Comparison
G.8265.1 PTP Telecom Profile enables the
deployment of PTP-based frequency
synchronization by telecoms operator
G.8275.1 is aimed at new build networks
– Furnishes both frequency and phase synchronization
– Requires boundary clocks at every node in the network
G.8275.2 is aimed at operation over existing
networks
– Furnishes both frequency and phase synchronization
– Permits Boundary Clocks (BCs) or Transparent Clocks
(TCs), but are not required
– BCs placed at strategic locations to reduce noise (e.g.,
PDV)
Trimble confidential, ©2020 Page 10PTP (IEEE-1588v2) Network Example Trimble confidential, ©2020 Page 11
Mobile Network Timing Requirements
The PTP Time Alignment Error (TAE) that was introduced for LTE-A macro and
small cells was +/- 1.5 microseconds of phase accuracy (per the 3GPP standard)
Time Error Budget:
5G will have more stringent phase sync requirements (e.g., massive 5G NR, Massive
MIMO, O-RAN); for example:
o DU AU/RU = ±130 ns
o PTRC-B = ±40 ns
Trimble confidential, ©2020 Page 12The Mobile Backhaul (MBH) Opportunity
The Opportunity: provide MBH for 5G small cells over the
DOCSIS network
But why transport Mobile telephone traffic over DOCSIS?
The CATV Operator HFC infrastructure provides the
following (competitive) advantages:
o Ubiquity – HFC networks run down every street and to
every building in the cities, giving wireless planners
significant flexibility to design optimal small cell
deployments
o Power – HFC’s ability to provide (transport) power to
small cells; i.e., power can’t be transported over fiber or
microwave backhaul radios
o Deployment Speed & Simplicity – HFC architectures can
facilitate fast small cell deployments
Trimble confidential, ©2020 Page 13LTE RAN / Backhaul Evolution
C-RAN introduced the concept
of Fronthaul
(CPRI), a TDM fiber
connection between
Baseband units and Remote
Radio Heads
eCPRI introduced Ethernet fiber
into Fronthaul, along with
functional Baseband split:
Distributed Unit (DU) & Central Unit
(CU); RRH = Antenna Unit (AU)
Trimble confidential, ©2020 Page 14From: 5GPPP Architecture Working Group
5G Architecture White Paper
A separation of the upper and
lower parts of the RAN was
standardized in 3GPP R15, where
a higher-layer split was specified
with a well-defined interface (F1)
between two logical units: the
Centralized Unit (CU) and the
Distributed Unit (DU). The CU—
with less stringent processing
requirements—has been more
amenable to virtualization than
the DU and its functions that are
closer to the radio.
For full-stack RAN virtualization,
the DU is connected to the radio
via a packet interface known as
enhanced Common Public Radio
Interface (eCPRI). There are
multiple ways to divide functions
between the DU and the radio; in
standards discussions these are
referred to as lower-layer split
(LLS) options. One possible
alternative specified by the O-
Synchronization is required at the DU for distribution to the Radio Units (RUs) RAN Alliance is referred to as the
7-2x split, but other functional
splits are also being considered.
Trimble confidential, ©2020 Page 15The Basic MBH Evolution Trimble confidential, ©2020 Page 16
The New Mobile Backhaul
Backhaul will change with 5G & O-RAN
1. Fronthaul (DU to RU)
2. Midhaul (CU to DU)
3. Backhaul (Aggregation/Core to CU)
Trimble confidential, ©2020 Page 17O-RAN Synchronization
Per ORAN-WG4.CUS.0-v02.00, § 9.2 Synchronization Baseline:
• Time and frequency synchronization can be distributed to the O-DU and
O-RU in different manners
• Synchronization accuracy is mostly impacted by implementation (e.g.,
timestamping near the interfaces, number of hops)
Trimble confidential, ©2020 Page 18O-RAN Synchronization Trimble GM200 Trimble confidential, ©2020 Page 19
O-RAN Synchronization
Trimble
Acutime 360
Trimble confidential, ©2020 Page 20ThunderBolt™ PTP Grandmaster GM200
Features:
– IEEE 1588v2 PTP Grandmaster Clock and NTP v4 Time Server
Supports 64 Simultaneous PTP clients in PTP-only mode at 32 transactions per second (tps)
Supports 2,500 NTP tps in NTP mode
A PTP-only model also exists
– 15 ns time accuracy (one sigma) of GNSS / UTC
– GNSS (GPS, Galileo, GLONASS & BeiDou)
– Extended temperature operation (hardened)
-40° to +85° C (no fan or heater element)
– Superior holdover performance
±1.5µsec 4+ hours (live tests have consistently seen as much as 20 hours after GNSS lock for 7
days)
– Multiple profiles supported
IEEE-1588v2, G.8265.1, G.8275.1, G.8275.2, Telecom-2008, Power (IEEE C37.238-2011), Enterprise, Broadcast
(ST 2059-2:2015 SMPTE), IEEE 802.1AS
− Assisted Partial Timing Support (APTS)
− Boundary Clock (BC) operation supported
– Two Gigabit Ethernet Interfaces: 1x RJ45, 1x SFP
– One dedicated Management Port: 1x RJ45 (10 / 100 Mbps)
– IPv4 and IPv6 Support
– SNMPv3 Management
– Web User Interface and CLI
Roadmap GM310 board with PTP
– Security: RADIUS, TACACS Migrating GM200 features
– Dual Power Input (-48VDC) provides power redundancy
– Power Dissipation: 5 Watts typical; 10 Watts Max
– Multiple installation options, including redundancy in 1 RU
½ RU unit; install two unit in a 19-inch, 1 RU space
– Lowest price on market for feature set offered
Trimble confidential, ©2020 Page 21GM200 Edge Grandmaster (a closer look)
GM200 Front Panel
RJ45 port
PPS or 10MHz (PTP and SyncE)
RS‐232 Serial Management Port (10/100 Base‐T) SFP port (PTP and SyncE)
Trimble confidential, ©2020 Page 22GM200 Edge Grandmaster (a closer look)
GM200 Back Panel
Frame GND
GNSS input (SMA, Female) Alarm Relay Power Input x 2 (‐48VDC)
Trimble confidential, ©2020 Page 23Acutime 360 is “Smart” antenna
for outdoor installation
GNSS: GPS, GLONASS, Galileo & BeiDou
“Smart” antenna because:
A GNSS antenna, receiver, LNA & power supply are
contained in a IP67-compliant radome, roof-top
enclosure
Outputs two (2) RS-422 downlinks, supporting:
– 1 PPS, 15 ns (1σ)
– NMEA or Trimble TSIP
RS-422 can reach 1000 m @ 9.6 kbps
T-RAIM
Self-Survey
Trimble confidential, ©2020 Page 24Trimble GNSS Antennas increase reliability
Meet all common standards
Support multi constellation
Low cost
Examples of standard products:
Active LNA
Any Form Factor available
– Magnetic Mount
– Bulkhead
– Unpackaged
– Rooftop (Bullet)
Connector options
– TNC or F for Bullet
3V or 5V supply
Trimble confidential, ©2020 Page 25Thank You
Robert Pagano
Sales & Business Development
EMEA
robert_pagano@trimble.com
Mobile: +39 346 654 0987
www.trimble.com
Trimble confidential, ©2020 Page 26You can also read
