1. Clarification of Burst-based Forwarding in RS Group
Document Number:
IEEE S802.16j-08/049
Date Submitted:
Source:
Kanchei (Ken) Loa, Hua-Chiang Yin, Yung-Ting Lee, Voice:
Yi-Hsueh Tsai, Shiann-Tsong Sheu, Youn-Tai Lee
Institute for Information Industry (III)
7F, No. 133, Sec. 4, Minsheng E. Rd., Taipei City 105, Taiwan
Re:
IEEE j-07/059: “IEEE Working Group Letter Ballot Recirc #28a: Announcement”
Abstract:
This contribution modifies the relaying support for combined ranging and initial topology discovery in order to consistent with the network entry procedure.
Purpose:
Text proposal for j Baseline Document.
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2. PDU Forwarding
Whenever a new path is established between MR-BS and MS, CID to Path binding is required to update the routing table at the RSs along the relay path

3. In an RS Group The access RS of an MS may change very often
Every time MS sends a CDMA code, the access station of the MS may be re-selected by the MR-BS
The MR-BS has to update the routing table before PDU could be forwarded

4. Flow Chart of PDU Forwarding In an RS Group (1/2)
The MR-BS re-selects RS2 as the access station of MS after BR
MR-BS
RS1
(access RS)
RS2 MS
RS1 is the access station
BR Code
MR_Code-REP
MR_Code-REP
MR-BS
selects RS2
to forward the BR header
UL_Burst_Receive IE
CDMA Alloc IE
BR Header
MR-BS
re-selects RS2
as the access station of MS
BR Header

5. Flow Chart of PDU Forwarding In an RS Group (2/2)
MR-BS
RS1
RS2
(Access RS) MS
DSD-REQ
CID to path
binding removal
DSD-RSP
CID to path binding
(MS  RS2)
DSA-REQ
DSA-RSP
BW allocation
PDU
PDU

6. Flow Chart of Burst-based Forwarding in an RS Group (1/2)
The MR-BS re-selects RS2 as the access station of MS after BR
MR-BS
RS1
(access RS)
RS2 MS
RS1 is the access station
BR Code
MR_Code-REP
MR_Code-REP
MR-BS
selects RS2
to forward the BR header
UL_Burst_Receive IE
CDMA Alloc IE
BR Header
MR-BS
re-selects RS2
as the access station of MS
BR Header

7. Flow Chart of Burst-based Forwarding In an RS Group (2/2)
No CID to path binding updates are required whenever the access station is changed since the forwarding rules are encoded in Burst IE sent from MR-BS to RS
MR-BS
RS1
RS2
(Access RS) MS
DSD-REQ
CID to path
binding removal
DSD-RSP
CID to path binding
(MS  RS2)
DSA-REQ
DSA-RSP
Burst IE (RS2 forwarding MS PDU)
BW allocation
PDU
PDU

8. Enhance PDU Forwarding with Burst-based Forwarding In an RS Group
In an RS group with non-transparent RSs, the burst-based forwarding + the MPDU-based forwarding + RS member list update messages provide the most efficient and complete solution
When the RS group routing table is converged, MPDU-based forwarding is used to minimize the overhead
Using the unicast/multicast RS member list update and the acknowledgement, the convergence of the routing table update could be time-consuming
Burst-based forwarding are used to minimize the outage

9. Enhance PDU Forwarding with Burst-based Forwarding In an RS Group – MS Movement (1/2)
The MS moves from RS1 to RS2, where RS1 and RS2 broadcast same preamble/FCH/MAP
MR-BS
RS1
(access RS)
RS2 MS
RS1 is the access station
………..
MSID  MS
MAP IE (RS1)
PDU (MSID)
MAP IE (MS)
PDU (MSID)
MS move into the proximity of RS2. But MS is unaware
RS_MOB_MEAS-REP
Mode 1 or 2
Event trigger or periodic
RS_MOB_MEAS-REP
Mode 1 or 2
Event trigger or periodic
MR-BS
recognize MS attachment to RS2

10. Burst-based forwarding via RS2
Enhance PDU Forwarding with Burst-based Forwarding In an RS Group – MS Movement (2/2)
MR_Member_List_Update message is used to update the forwarding rules of specific MSs in an unicast fashion as defined in D2.
However, the period to complete the member list update could be long due to ACK failure
Then burst-based forwarding can be used for data forwarding before the member list update is complete
MR-BS
RS1
RS2
(Access RS) MS
RNG-RSP (Adjustments to sync with RS2)
Burst-based forwarding via RS2
MR_Member_List_Update
CID to path
binding update
………..
MSID  MS
ACK
MR_Member_List_Update
CID to path binding
(MS  RS2)
………..
MSID  MS
ACK
MAP IE (RS2)
PDU (MSID)
MAP IE (MS)
PDU (MSID)

11. Summary
The burst-based forwarding scheme is the most efficient forwarding scheme for the RS group (transparent RS or non-transparent RS in a RS group)
Burst-based forwarding scheme for the transparent RS has been accepted in D2.
Burst-based forwarding scheme for an RS group with non-transparent RS is provided by comment #2216