Transcript IEEE C802.16n-11/0021r2

HR-MS Neighbor Discovery in 802.16n
Document Number:
IEEE C802.16n-11/0021r2
Date Submitted:
2011-03-14.
Source:
Haiguang Wang, Hoang Anh Tuan, Jaya Shankar,
Zhongding Lei, Shoukang Zheng, Yeow Wai Leong,
Teo Joseph Chee Ming, Mar Choon Hock
Voice:
+65 6408 2256
Institution for Infocomm Research (I2R)
E-mail:
[email protected]
1 Fusionopolis Way, #21-01, Connexis (South Tower)
Re:
Call for contributions for 802.16n AWD
Base Contribution:
IEEE C802.16n-10/0021
Purpose:
To discuss and adopt the proposed text in the 802.16n draft Text
Notice:
This document does not represent the agreed views of the IEEE 802.16 Working Group or any of its subgroups. It represents only the views of the participants listed in
the “Source(s)” field above. It is offered as a basis for discussion. It is not binding on the contributor(s), who reserve(s) the right to add, amend or withdraw material
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Introduction
• Section 6.1.3.3 of 802.16n SRD:
– “HR-Network shall support neighbor and path discovery between HRMSs as well as between HR-MS and HR-Network infrastructure
stations”
• Neighbor discovery is one of the key enabling mechanisms for:
– HR-MS direct communications (DCm)
– HR-MS forwarding to network (FTN)
– Path discovery & management
Usage Scenarios
• Registered HR-MSs
discover each other
• Outside-of-coverage
HR-MSs discover
network infrastructure
HR-BS
HR-BS
HR-MS
HR-MS
HR-MS
HR-MS
HR-MS
HR-MS
Neighbor Discovery for Registered HR-MSs (1/2)
• Basic design principles:
– Centralized control: serving HR-BS/HR-RS schedules HR-MSs to
broadcast predefined self-advertizing (PSA) signals so that other HRMSs can try to detect and verify their neighbor relationship
– Design reuse: PSA signal is ranging sequences defined in 802.162009/802.16m
– Low cost: serving HR-BS/HR-RS schedules neighbor discovery as and
when needed, and for selected stations
Neighbor Discovery for Registered HR-MSs (2/2)
•
Step 1: HR-BS schedules one or multiple HR-MSs to broadcast dedicated ranging sequences
in dedicated ranging channels. Two HR-MSs may share the same ranging sequence or the
same ranging channel, but not both. HR-BS also schedules some other HR-MSs to listen on
those ranging channels for scheduled PSA signals.
•
Step 2: Each HR-MS that is scheduled to listen for PSA signals shall determine what ranging
sequences it can decode, together with estimations of time/freq offsets and signal strength.
•
Step 3: Receiving HR-MSs report measurements to HR-BS.
•
Step 4: HR-BS constructs neighbor topology and may request HR-MSs to carry out extra
measurements.
Proposed Text
17.2.7.1 Neighbor Discovery for Registered HR-MSs
For registered HR-MSs to discover each other, the serving HR-BS/HR-RS shall schedule some HR-MSs to
broadcast predefined self-advertizing (PSA) signals so that other HR-MSs can attempt to receive and verify their
neighbor relationship. The receiving HR-MSs shall report their measurements of PSA signals to the serving HRBS/HR-RS. Based on the reported information, HR-BS/HR-RS may request the HR-MSs to carry out extra
measurements so that HR-MS direct communications (DCm) and HR-MS forwarding to network (FTN) can be
initiated.
Ranging sequences shall be used as PSA signals. The process of ranging-based neighbor discovery for
registered HR-MSs shall be carried out as follows:
-The serving HR-BS/HR-RS schedules one or multiple registered HR-MSs to broadcast dedicated ranging
sequences in dedicated ranging channels. Two HR-MSs may share the same ranging sequence or the same
ranging channel, but not both. The ranging preambles and/or channels shall not overlap with those allocated for
normal initial and periodic ranging. At the same time, the serving HR-BS/HR-RS also schedules some other HRMSs to listen on those ranging channels scheduled for PSA signals.
-Each HR-MS that is scheduled to receive PSA signals shall determine what ranging sequences it can properly
decode, together with related information such as estimations of time/frequency offsets and signal strength.
-The receiving HR-MSs then report their measurements to the serving HR-BS/HR-RS.
Neighbor Discovery during Coverage Extension
• Basic design principles:
– Centralized control: serving HR-BS/HR-RS schedules a registered HRMS to broadcast preamble so that out-of-coverage HR-MSs can scan,
detect, and start network entry
– Design reuse: using existing DL preambles and following similar
network entry procedure of 16e/16m
Coverage Extension for 16e
RTG
frame: n-1
frame: n
frame: n+1
...
frame: n+1
...
downlink
uplink
downlink
uplink
TTG (optional)
•
Preamble transmitted by BS/RS
Network configuration information
transmitted by forwarding HR-MS
Preamble transmitted by HR-MS
for forwarding purpose
Subchannel reserved for HR-MS outside
coverage to send in ranging signals to
forwarding HR-MS
Procedure:
– Serving HR-BS schedules a registered HR-MS to broadcast preamble, followed by
network configuration information (NCI)
– An outside-of-coverage HR-MS detects the preamble, reads NCI, and subsequently sends
in ranging signal
– The inside-of-coverage HR-MS assist the outside-of-coverage HR-MS to carry out
network entry with HR-BS
Coverage Extension for 16m
•
Procedure:
– Similar to 16e, except that both PA & SA preambles are broadcasted at 2nd and 3rd frames
by cell-edge HR-MSs
Proposed Text
17.2.7.2 HR-MS Discover Network Infrastructure (802.16-2009)
To enable coverage extension, a serving HR-BS/HR-RS shall schedule some of its registered HRMSs to transmit frame preamble, together with FCH and network configuration information
(NCI), so that an outside-of-coverage HR-MS can detect and start network entry.
The transmission of frame preamble, FCH, NCI, shall be scheduled at the end of uplink subframes
and can be for two or three OFDMA symbol durations. In case two symbols are scheduled, one is
used for preamble and another is used for FCH and network configuration information (NCI). In
case three symbols are scheduled, the first symbol is used for TTG for other HR-MSs to switch
their transceiver to receiving mode for neighbor discovery purpose. The HR-BS shall also
schedule ranging opportunities in the following subframes so that the outside-of-coverage HRMS can transmit ranging signals at the reserved location and start network entry. The transmission
opportunity is dynamic and may not appear in every frame. The content of FCH and NCI is
[TBD].
Proposed Text
17.3.7.2 HR-MS Discover Network Infrastructure (802.16m)
To enable coverage extension, a serving HR-BS/HR-RS shall schedule some of its registered HRMSs to transmit PA/SA preamble signals, together with network configuration information (NCI),
so that an outside-of-coverage HR-MS can detect and start network entry.
The registered HR-MS shall transmit PA preamble at the beginning of the 2nd frame and SA
preamble at the beginning of the 3rd frame (of a super-frame). Any non-registered HR-MS
scanning for DL preambles for possible network entry shall be able to differentiate between
preambles transmitted by normal infrastructure stations (HR-BS/HR-RS) and those transmitted by
a coverage-extending HR-MS. This is based on the [TBD] mechanism.
After receiving the SA-preamble transmitted by a potential forwarding HR-MS, the out-ofcoverage HR-MS shall also be able to determine where to look for the NCI. The mechanism to
enable this is [TBD]. NCI message contains essential PHY/MAC configurations that are required
for the out-of-coverage HR-MS to configure its transceiver and subsequently send a ranging
signal toward the coverage-extending HR-MS.
Upon receiving the ranging signal from the out-of-coverage HR-MS, the coverage-extending HRMS shall assist this HR-MS to carry out subsequent adjustments and handshaking with the serving
HR-BS/HR-RS. The process finishes when the out-of-coverage HR-MS becomes registered with
the serving HR-BS/HR-RS.