IEEE C802.16m-09/1742
Project
IEEE 802.16 Broadband Wireless Access Working Group <http://ieee802.org/16>
Title
Proposed AWD Text for Coverage and Capacity Optimization (SON)
Date
Submitted
2009-09-14
Source(s)
Jung-Mao Lin, Chie Ming Chou, Frank
Ren
ITRI
Wern Ho Sheen
Chaoyang University of Technology /
ITRI
E-mail: moumou3@itri.org.tw
whsheen@itri.org.tw
Re:
P802.16m/D1 topic (SON), IEEE 802.16m-09/0037: Support for Self Organizing Networks
(SON), Call for Contributions for P802.16m Amendment Proposals for Features
Abstract
The contribution proposes the text of coverage and capacity optimization procedure in the SON
section of the 802.16m amendment.
Purpose
To be discussed and adopted by TGm for the 802.16m Amendment.
Notice
Release
Patent
Policy
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
contained herein.
The contributor grants a free, irrevocable license to the IEEE to incorporate material contained in this contribution,
and any modifications thereof, in the creation of an IEEE Standards publication; to copyright in the IEEE’s name
any IEEE Standards publication even though it may include portions of this contribution; and at the IEEE’s sole
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contributor also acknowledges and accepts that this contribution may be made public by IEEE 802.16.
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<http://standards.ieee.org/guides/bylaws/sect6-7.html#6> and
<http://standards.ieee.org/guides/opman/sect6.html#6.3>.
Further information is located at <http://standards.ieee.org/board/pat/pat-material.html> and
<http://standards.ieee.org/board/pat>.
Proposed AWD Text for Coverage and Capacity Optimization in SON section
Jung-Mao Lin, Chie Ming Chou, Frank Ren
ITRI
Wern Ho Sheen
Chaoyang University of Technology / ITRI
1.
Introduction
Base on current SDD, the SON functions need a coverage extension method to resolve the blind
areas and achieve the coverage and capacity optimization. In this contribution, we propose an inter-ABS
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IEEE C802.16m-09/1742
coordination based power configuration method to extend the cell coverage.
2.
Discussion and proposal
In most cases, an ABS can’t use the unlimited power to transmit data. This is because it may cause
serious interference to neighbor ABS and inaccessible subscribers. An ABS, especial a Femto ABS may be
requested to reduce its power when an AMS suffers serious interference from it. Once ABS reduces its
transmission power, its cell coverage and capacity will be reduced and some blind areas may be appeared.
Besides, when Femto ABSs are introduced into the network, Femto ABSs may shut down or temporarily stop
services (e.g., Femto ABS goes into low duty mode). In this case, some operating ABSs may have chance to
reconfigure its transmission power without the risk to raise interference. To reconfigure the transmission power
of ABS, an inter-ABS coordination-based mechanism is proposed. This mechanism can be event-triggered or
periodic triggered:

Event-triggered scenario:
When there are some blind areas discovered by the services AMS in the ABS, the AMS could request
to trigger power reconfiguration by notifying its serving ABS. When network receives this request from
one ABS, the core network will negotiate with the neighbor ABSs whose geological locations are close
to the requested ABS with operating at the same FA. During negotiation, the network will coordinate a
common time interval and resources for involved ABSs. Network will further inform those neighbor
ABSs a dedicated sounding signal would be transmitted at coordinated resources. The sounding signal
can be PA/SA-preamble or other dedicated signaling. After that, the network will request the ABS
which triggers the inter-ABS coordination based power configuration to transmit corresponding
sounding signal at this coordinated resources with recommended transmitting power. To continue
supporting the services, the involved other ABSs will reconfigure their frame structures to provide
transmission for serving AMSs and to measure the signal quality (e.g. RSSI) of this signal at one frame.
After measurements, ABS will report the results to the network. The network will then calculate an
acceptable transmission power and inform the results to the requested ABS The whole process is
described in figure 1. The detail of reconfigure frame structure is introduced at the following section.
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IEEE C802.16m-09/1742
Requested
ABS
Neighbor ABSs
Network
inter-ABS coordination power reconfiguration request
Coordinate a common time interval, resources and a dedicated signal
Reconfigure frame structure
Sounding signal
Make measurements
Report measurement result
Decide a suitable
transmission power
Power configuration results
Operate
Figure 1, Inter-ABS coordination based power configuration (event-triggered)

Periodic triggered scenario:
In event-triggered, only the requested ABS can be reconfigured its power to improve the blind area.
Alternatively; in periodic triggered scenario, every involved ABSs can configure its power to improve
network performance. The network will coordinate the involved ABSs to reconfigure power by turns.
Those involved target ABSs may include Macro and Femto ABS with same FA. During configuration,
each ABSs will in-turn transmits a specific sounding signaling at a coordinated channel. The sounding
signal can be PA/SA-preamble or other dedicated signaling. Except transmitted ABS, other involved
ABSs will reconfigure their frame structures and prepare to receive and measure the signal quality (e.g.
RSSI) of sounding signal and report to the network. The network can calculate the suitable
transmission power for every involved ABSs and give commend to reconfigure the power. The whole
process is described in Figure 2.
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IEEE C802.16m-09/1742
ABS
Neighbor
ABS
Network
Coordinate a common time interval, resources and a dedicated signal
Reconfigure frame structure
Reconfigure frame structure
Sounding signal 1
Make measurements
Reconfigure frame structure
Report measurement result
Reconfigure frame structure
Sounding signal 2
Make measurements
Report measurement result
Decide suitable
transmission power
Power configuration results
Power configuration results
Operation
Operation
Figure 2, Inter-ABS coordination based power configuration (periodic triggered)

Frame structure to support inter-ABS coordination power reconfiguration:
When proposed process is triggered, the ABS which is recommended to transmit a sounding signal will
configure its last DL subframe as a sounding region. In this region, ABS will not schedule any data
transmission and give any associated A-MAP for its serving AMSs and will place a sounding signal in
this region. Figure 3 is an example of reconfigured frame (Tx side) when DL to UL ratio is 4:4.
TTG
A-MAP
DL
SF1
DL
SF2
DL
SF3
Dedicated resource for ABS to
transmit the sounding signal
DL
SF0
A-MAP
Advanced Air Interface DL Zone
UL
SF4
UL
SF5
UL
SF6
Uplink
4
UL
SF7
IEEE C802.16m-09/1742
Figure 3, an example of the reconfigured frame structure (Tx side)
Once the ABS want to transmit the sounding signal at the dedicated resource in TDD frame, the
Nsubframe,A-MAP parameter should be 2 and the Allocation Relevance parameter in A-MAP IE need to be
configured based on the DL subframe to UL subframe ratio to prevent A-MAP be appeared in the last
DL subframe and conflict with sounding signal. Table 1 is the required parameters for different channel
bandwidth.
Table 1, an example of Nsubframe,A-MAP and Allocation Relevance parameters configuration
Channel bandwidth is 5, 10, or 20MHz
D:U
Nsubframe,A-MAP
(the DL subframe to UL subframe ratio in the frame)
8:0
2
6:2
5:3
4:4
3:5
Allocation
Relevance
0
0
1
0
1
On the other side, other involved ABSs also need to configure their frame structure to be able to
receive and measure the sounding signal. The original last DL subframe will be reconfigured as a
special UL subframe which be allowed to receive the sounding signal from one ABS instead of make
transmission with serving AMSs. Figure 4 is an example of reconfigured frame (Rx side) when DL to
UL ratio is 4:4.
TTG
S-TTG
A-MAP
DL
SF2
DL
SF3
Advanced Air Interface DL Zone
Idle
DL
SF1
Receive sounding signal
DL
SF0
A-MAP
UL
SF4
UL
SF5
UL
SF6
UL
SF7
Uplink
Figure 4, an example of the reconfigured frame structure (Rx side)
To receive the sounding signal at the last DL subframe, an S-TTG is required to make DL/UL
translation. The length of S-TTG is equal to the TTG. The S-TTG is used for ABSs to switch DL to UL
in order to receive the sounding signal. Once the S-TTG appears in the frame structure, the ABS does
not need to switch Tx to Rx again at original TTG but reserve this gap and keep idle to make align with
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IEEE C802.16m-09/1742
original start timing of UL for AMSs. Once the ABS wants to receive the sounding signal at the last DL
subframe, the Nsubframe,A-MAP parameter should be 2 and the Allocation Relevance parameter in A-MAP
IE need to be configured based on the DL subframe to UL subframe ratio in a frame to prevent A-MAP
at the last DL subframe of the advanced air interface DL zone. The recommended parameters for this
configuration are same as shown in table 1. When re-configuring the frame structure, there will be two
timing for appearing A-preamble: one for synchronization and one for inter-ABS sounding. New
incoming AMSs may be confused and synchronize with the sounding signal. Once AMS doesn’t detect
SFH followed by an A-preamble during one super-frame, it will try to perform synchronization again.
With this mechanism, one or multiple ABSs could be able to configure its transmitting power by themselves.
Based on the sounding action performed by involved ABSs, the power configuration results expected to be able
to ensure the satisfied interference level and optimize the coverage and capacity of a network.
3.
Proposed AWD Text
 Proposed Text for 16.2.1 
---------------------------------------------------- Start of Proposed Text----------------------------------------------------
16.2.1 Coverage and Capacity Optimization
[Insert the new sub-section with following text]
16.2.1.1 Inter-ABS coordination for coverage and capacity optimization
When detecting a blind area or needing to configure transmission power of ABSs, the inter-ABS coordination
could be initiated to start a power sounding process for involved ABSs. An ABS may request core network for
triggering the process. After receiving the request, the core network will coordinate ABSs those locations are
close to requested ABS and operate at the same FA. The core network can also periodically trigger the power
sounding process.
After inter-ABS coordination, involved ABSs will be recommended to reconfigure their frame structure as
specified in section 15.3.3.7 to support power sounding process. One selected ABS will transmit a dedicated
sounding signal at reconfigured subframe with a pre-defined transmission power. Other involved ABSs will
receive the sounding signal at the same subframe and report the measurement results to the core network. The
core network will then calculate an acceptable transmission power for the ABS.
15.3.3 Frame structure
[Insert the new sub-section with following text]
15.3.3.7 Power sounding support in frame structure
When power sounding is triggered, the ABS which is recommended to transmit a sounding signal will configure
its last DL subframe as a sounding region. In this region, ABS will not schedule any data transmission and give
any associated A-MAP for its serving AMSs. Instead, it will place a sounding signal in this region. The basic
principle is shown in Figure xxx.
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IEEE C802.16m-09/1742
TTG
A-MAP
DL
SF1
DL
SF2
Dedicated resource for ABS to
transmit the sounding signal
DL
SF0
A-MAP
DL
SF3
UL
SF4
UL
SF5
Advanced Air Interface DL Zone
UL
SF6
UL
SF7
Uplink
Figure xxx, power sounding support frame structure (Tx side)
On the other side, other involved ABSs also need to configure their frame structure to be able to receive and
measure the sounding signal. The original last DL subframe will be reconfigured as a special UL subframe
where is allowed to receive the sounding signal from one ABS instead of make transmission with serving AMSs.
To receive the sounding signal at the last DL subframe, an S-TTG is required for ABS to make DL/UL
translation. The length of S-TTG is equal to the TTG. Once the S-TTG is used in the frame structure, the
original TTG shall be reserved to make align with original start timing of UL subframe for AMSs. Figure yyy is
a principle structure.
TTG
S-TTG
A-MAP
DL
SF2
DL
SF3
Idle
DL
SF1
Receive sounding signal
DL
SF0
A-MAP
Advanced Air Interface DL Zone
UL
SF4
UL
SF5
UL
SF6
UL
SF7
Uplink
Figure yyy, power sounding support frame structure (Rx side)
During this frame structure, the Nsubframe,A-MAP parameter should be 2 and the Allocation Relevance parameter in
A-MAP IE need to be configured based on the DL subframe to UL subframe ratio to prevent A-MAP be
appeared in the last DL subframe. Table zzz is the required parameters for different channel bandwidth.
Table zzz, Nsubframe,A-MAP and Allocation Relevance parameters configuration
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Channel bandwidth is 5, 10, or 20MHz
D:U
Nsubframe,A-MAP
(the DL subframe to UL subframe ratio in the frame)
8:0
2
6:2
5:3
4:4
3:5
Allocation
Relevance
0
0
1
0
1
---------------------------------------------------- End of Proposed Text ------------------------------------------------
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