Dynamic Subcarrier/Subchannel Allocation for Interference Mitigation in IEEE802.16m Networks
IEEE 802.16 Presentation Submission Template (Rev. 9)
Document Number:
IEEE C802.16m-08/781r2
Date Submitted:
2008-07-07
Source:
Honghai Zhang, Narayan Prasad, Sampath Rangarajan
Voice:
+01-609-951-2454
Yuefeng Zhou
NEC
E-mail:
honghai@nec-labs.com
*<http://standards.ieee.org/faqs/affiliationFAQ.html>
Venue:
IEEE 802.16 Session #56, Denver, CO, USA
IEEE 802.16m-08/024 “Call for Comments and Contributions on Project 802.16m System Description Document (SDD)”
In response to the topic: Interference Mitigation
Base Contribution:
IEEE C802.16m-08/781r2
Purpose:
To discuss and adopt the subcarrier/subchannel allocation schemes to mitigate interference among multiple 802.16m base-stations
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Dynamic Subcarrier/Subchannel Allocation for
Interference Mitigation in IEEE802.16m Networks
Authors:
Honghai Zhang, Narayan Prasad, Sampath Rangarajan
NEC US Labs
Yuefeng Zhou
NEC Europe
Dynamic Subcarrier/Subchannel Allocation for
Interference Mitigation in IEEE802.16m Networks
• Traditional static subchannel allocation has many limitations
– 1/1 frequency reuse leads to high interference and small coverage
– 1/3 frequency reuse reduces interference, and improves coverage, but is at the cost
of low average spectrum efficiency.
• The need of dynamic subchannel/subcarrier allocation
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IEEE802.16m needs to improve both coverage and spectrum efficiency
New cells are installed, and switched on and off
Relay stations may be mobile
Traffic load in each cell may be varying
Basic Ideas
•
Each BS/Sector is initially allowed to have full frequency
reuse but base stations can communicate with each other or
through network controllers (e.g., ASN-GW) to dynamically
turn on and off some subcarriers/subchannels in order to
mitigate interference.
There are two possible underlying approaches to support
interference mitigation:
•
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Using PUSC subchannels. Channel measurement is performed based on
preambles. Each BS/Sector is allowed to turn on or off a subset of physical
subcarriers.
Using Band AMC subchannels. Channel measurement is performed based
on pilots. Each BS/Sector is allowed to turn on or off a subset of
subchannels.
Interference Mitigation Using Band AMC
Subchannels
•
To enable interference mitigation using Band AMC subchannels,
mobiles should report the CQI (Channel Quality Information) as follows.
Mobiles select M subchannels with the best SINR and report for each
selected subchannel:
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•
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the SINR value,
the ratio of the signal from the interfering BS to the signal from the serving
BS and the preamble index of the interfering BS (used to identify the
neighbor BS), for each of up to K most significant interfering neighbor
stations on the selected subchannel.
Base stations should convey the above information and the weight of the
selected mobile on each subchannel representing the fairness and QoS
information to high-layer network controllers (i.e., ASN-GW).
High-layer network controllers (i.e., ASN-GW) will dynamically
determine the allocation of subchannels to each cell to mitigate
interference and ensure fairness.
High-layer network controllers can be distributed and co-located with
base stations (in which case the base-stations will coordinate among
themselves to determine the allocation of subchannels)
Interference Mitigation Using PUSC
Subchannels
•
To enable interference mitigation using PUSC subchannels, mobiles
should report the following information based on preambles:
–
–
•
•
•
the SINR value,
the ratio of the signal from the interfering BS to the signal from the serving
BS, and the preamble index of the interfering BS (used to identify the
neighbor BS), for each of up to K most significant interfering neighbor
stations.
Base stations should convey the above information and the weight of
each mobile representing the fairness and QoS information to high-layer
controllers (i.e., ASN-GW).
High layer controllers (i.e., ASN-GW) will dynamically determine the
allocation of sets of subcarriers to each cell in order to reduce
interference and ensure fairness.
High layer controllers can be distributed and co-located with base
stations (in which case the base-stations will coordinate among
themselves to determine the allocation of sets of subcarriers)
Proposed Text
-- IEEE802.16m base stations shall support periodic neighbor station
measurement. The measurement should include the SINR of the
current serving BS, the ratio of the signal strength of neighbor stations
to the signal strength of the current serving BS, and preamble index of
neighbor stations. For PUSC-zones, the signal strength is based on the
preambles and the measurement is for each user. For Band-AMC
zones, the signal strength is based on the pilots and is measured for M
best subchannels for each user.
The base stations shall periodically report these measurements and the
weights of all users that represent the fairness and QoS information to a
network controller (eg. ASN-GW) to facilitate the scheduling
algorithms in the network controller to allocate subchannels/subcarriers
to each base station. The network controller can be distributed among
the base-stations in which the base-stations will coordinate among
themselves to allocate subchannels/subcarriers to each base-station.