<May 2017>
doc.: IEEE 802. 15-17-0286-00-hrrc
Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs)
Submission Title: [Random access and mobility procedure for high-speed train communication systems]
Date Submitted: [10 May, 2017]
Source: [Bing Hui, Junhyeong Kim, Gosan Noh, Hee-Sang Chung, and IlGyu Kim] Company [ETRI]
Address [218 Gajeong-ro, Yuseong-gu, Daejeon, 34129, KOREA]
Voice:[+82-42-860-5324], FAX: [+82-42-860-6732], E-Mail:[[email protected]]
Abstract: []
Purpose: [For discussion]
Notice: This document has been prepared to assist the IEEE P802.15. It is offered as a basis for
discussion and is not binding on the contributing individual(s) or organization(s). The material in this
document is subject to change in form and content after further study. The contributor(s) reserve(s) the right
to add, amend or withdraw material contained herein.
Release: The contributor acknowledges and accepts that this contribution becomes the property of IEEE
and may be made publicly available by P802.15.
Submission
Slide 1
<Bing Hui>, <ETRI>
<May 2017>
doc.: IEEE 802. 15-17-0286-00-hrrc
Random Access and Mobility Procedure for HighSpeed Train Communication Systems
Submission
Slide 2
<Bing Hui>, <ETRI>
<May 2017>
doc.: IEEE 802. 15-17-0286-00-hrrc
Outline
• HST Network Deployment & Observations
• Random Access Procedure for HST Communications
• Mobility Measurement for HST Communications
• Handover Strategies
• Discussions
Submission
Slide 3
<Bing Hui>, <ETRI>
<May 2017>
doc.: IEEE 802. 15-17-0286-00-hrrc
HST Network Deployment & Observations
•
HST Network Deployment
–
–
–
Up to 500 km/h mobility is included in eMBB use case for 5G.
NR employs both below 6 GHz and above 6 GHz frequency band
Directional network deployment with onboard relay has been approved.
Fig. Cell layout for High Speed Train (4GHz)
Fig. Cell layout for High Speed Train (30GHz)
Submission
Slide 4
<Bing Hui>, <ETRI>
<May 2017>
doc.: IEEE 802. 15-17-0286-00-hrrc
HST Network Deployment & Observations
• Observations
– Severe radio link failure (RLF) rate in directional network deployment
•
•
Submission
UE (onboard relay) is always attempting to handover from a source cell with strong received
power to a target cell with weak received power
UE (onboard relay) cannot report the target cell to the source cell or receive a handover
command
Slide 5
<Bing Hui>, <ETRI>
<May 2017>
doc.: IEEE 802. 15-17-0286-00-hrrc
HST Network Deployment & Observations
• Handover Zone by Huawei
C1 RRH #N-2
C1 RRH #N-1
C1 RRH #N
TRAIN A
TRAIN B
C2 RRH #1
C2 RRH #2
C2 RRH #3
Figure A.1-1: Handover zone created by overlapping coverage between SFN cell group C1 and SFN cell group C2. Note that
the RRHs can be co-located although illustrated as separate sites.1
Submission
Slide 6
<Bing Hui>, <ETRI>
<May 2017>
doc.: IEEE 802. 15-17-0286-00-hrrc
HST Network Deployment & Observations
• Handover Zone by ETRI
– Without artificially created handover zone (overlapped area), the nature of
antenna pattern can be used as handover zone.
•
Directional antenna & free space path loss model [ITU-R]
 4d 
Ls  20 log 
  92.45  20 log f GHz  20 log d km [ dB]
  
Beam Pattern
25
20
15
Amplitude (dB)
10
5
0
-5
-10
-15
-20
-25
-200
-150
Submission
-100
-50
0
Degree
50
100
150
200
Slide 7
<Bing Hui>, <ETRI>
<May 2017>
doc.: IEEE 802. 15-17-0286-00-hrrc
RA Procedure for HST Communications
• Observations
Onboard Relay
– Contention-free RA in most of the
cases
– Conventional HO cannot work
efficiently
– 1 active onboard relay mostly during
communication
•
Terrestrial BS
Msg. 1: RTS + Temporary onboard relay ID etc.
No need of timing advance (TA)
• Proposal
Msg. 2: RAR
– 2-step RA procedure for both IDLE
& CONNECTED Modes
•
•
•
Submission
Msg 1: request to send + relay ID
Msg 2: RA response
Msg. 3 & 4: Omitted since no need for
contention resolution
Slide 8
<Bing Hui>, <ETRI>
<May 2017>
doc.: IEEE 802. 15-17-0286-00-hrrc
Mobility Measurement for HST Communications
• IDLE Mode Measurement
– Synchronization signal (SS)
– Demodulation reference signal (DMRS) for physical broadcast
channel (PBCH)
• CONNECTED Mode Measurement
– Wideband channel state information reference signal (CSI-RS)
Submission
Slide 9
<Bing Hui>, <ETRI>
<May 2017>
doc.: IEEE 802. 15-17-0286-00-hrrc
Handover Strategies
Relay
• Handover Triggers
– Option 1: Network makes
handover decision (conventional
hard handover)
– Option 2: Onboard relay makes
network access decision based on
DL measurement (instead of
handover)
BS
1. DL measurement
2. NW access decision
3. RTS + ID
4. Admission control
5. RAR
Submission
Slide 10
<Bing Hui>, <ETRI>
<May 2017>
doc.: IEEE 802. 15-17-0286-00-hrrc
Handover Strategies
• Handover Strategies
Start
– Strategy 1: conventional hard
handover
•
•
CONNECTED mode mobility measurement
Information exchange within handover
zone
– Strategy 2: network re-access
instead of handover
•
Obtain onboard relay ID from 1st UL data
reception
Install ID & compare with the previous
decoded onboard relay ID
Is the received ID same as the previous ID?
Yes
No
It is a re-access,
continue the previous DL transmission.
It is a new access,
Request PDCP sequence number from
neighbor BSs.
IDLE mode mobility measurement
Yes
Get PDCP sequence number from neighbor?
Perform handover (RRC connected state)
related higher layer operation.
No
Perform initial access (RRC idle state)
related higher layer operation.
End
Submission
Slide 11
<Bing Hui>, <ETRI>
<May 2017>
doc.: IEEE 802. 15-17-0286-00-hrrc
Discussions
• Current discussions within the scope of single-beam system
• How about multi-beam system?
Submission
Slide 12
<Bing Hui>, <ETRI>