Clarification of Burst-based Forwarding in RS Group
Document Number:
IEEE S802.16j-08/049
Date Submitted:
2008-01-21
Source:
Kanchei (Ken) Loa, Hua-Chiang Yin, Yung-Ting Lee,
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
Voice:
E-mail:
+886-2-6600-0100
loa@iii.org.tw
Re:
IEEE 802.16j-07/059: “IEEE 802.16 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 802.16j Baseline Document.
Notice:
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contained herein.
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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
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
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 is the
access station
MR-BS
selects RS2
to forward the
BR header
MR-BS
re-selects RS2
as the access
station of MS
RS1
(access RS)
RS2
MS
BR Code
MR_Code-REP
MR_Code-REP
UL_Burst_Receive IE
CDMA Alloc IE
BR Header
BR Header
Flow Chart of PDU Forwarding In
an RS Group (2/2)
MR-BS
CID to path
binding removal
CID to path
binding
(MS  RS2)
RS2
RS1
MS
(Access RS)
DSD-REQ
DSD-RSP
DSA-REQ
DSA-RSP
BW allocation
PDU
PDU
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 is the
access station
MR-BS
selects RS2
to forward the
BR header
MR-BS
re-selects RS2
as the access
station of MS
RS1
(access RS)
RS2
MS
BR Code
MR_Code-REP
MR_Code-REP
UL_Burst_Receive IE
CDMA Alloc IE
BR Header
BR Header
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
CID to path
binding removal
CID to path
binding
(MS  RS2)
RS2
RS1
MS
(Access RS)
DSD-REQ
DSD-RSP
DSA-REQ
DSA-RSP
Burst IE (RS2 forwarding MS PDU)
BW allocation
PDU
PDU
Enhance PDU Forwarding with Burstbased 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
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 is the
access station
RS1
RS2
(access RS)
MAP IE (RS1)
PDU (MSID)
MS
………..
MSID  MS
………..
MAP IE (MS)
PDU (MSID)
RS_MOB_MEAS-REP
RS_MOB_MEAS-REP
MR-BS
recognize MS
attachment to
RS2
Mode 1 or 2
Event trigger
or periodic
Mode 1 or 2
Event trigger
or periodic
MS move into
the proximity
of RS2. But
MS is unaware
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
MS
(Access RS)
RNG-RSP (Adjustments to sync with RS2)
CID to path
binding update
MR_Member_List_Update
ACK
CID to path binding
(MS  RS2)
………..
MSID  MS
………..
Burst-based forwarding via RS2
MR_Member_List_Update
ACK
………..
MSID  MS
………..
MAP IE (RS2)
PDU (MSID)
MAP IE (MS)
PDU (MSID)
Summary
• The burst-based forwarding scheme is the
most efficient forwarding scheme for the
RS group (transparent RS or nontransparent 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