Transcript IEEE C802.16m-08/588r2

Flexible Frequency Reuse for 16m
IEEE 802.16 Presentation Submission Template (Rev. 9)
Document Number: IEEE C802.16m-08/588r2
Date Submitted:
2008-07-07
Source:
Kwanhee Roh, Jeongho Park, Jaehee Cho
Voice:
+82-31-279-4863
Samsung Electronics
E-mail:
[email protected]
416 Maetan-dong, Yeongtong-gu
Suwon-si, Gyeonggi-do, Korea
*<http://standards.ieee.org/faqs/affiliationFAQ.html>
Venue:
IEEE 802.16m-08/024 “Call for Comments and Contributions on Project 802.16m System Description Document (SDD)” in response to the
following topic: “Interference Mitigation”
Base Contribution:
None
Purpose:
To be discussed and adopted by TGm for use in 802.16m SDD
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Introduction
• Flexible Frequency Reuse
– Each reuse set(F1, F2, F3 and F4)
experiences different interferences
• Higher interference in FRF=1
region
• Lower interference in FRF=3
region
– Trade-off between throughput and
cell edge performance can be
controlled by adjusting the amount
of reserved resources (un-used
resource in FRF 3 region)
High inter-cell interference
Low inter-cell interference
Issues of FFR
• Reduced BW efficiency
– Available subchannels are decreased when FFR is employed
– SNR gain with FFR is not enough to compensate the loss caused by
bandwidth reduction
– Spectral efficiency in cell boundary can be increased but overall
throughput may decrease!
 Need to enhance/optimize FFR
Enhanced FFR
• Compensate BW reduction by re-using reserved resource
allocating to those MSs with good channel condition
– MSs located close to BS can be serviced with low transmit power
• Low transmit power can prohibit severe interference to edge MSs in neighbor
cells
• Transmit power in reserved resource region should be carefully
controlled
– Upper limit of transmit power can be controlled by coordination between
adjacent cells
Simulation Result
• Enhanced FFR
– Use subchannels in reserved region with low TX power (mostly allocated
to MSs located within cell center area)
• FFR evaluation result
FFR (Partial Loading = 26.7%)
N/A
Static
Aggressive
Avg throughput (kbps)
4804
4449
4675
Ratio (%)
100%
92.6%
97.3%
Lower 5% SE (bps/Hz)
0.344
0.483
0.473
Ratio (%)
100.00%
140.48%
137.56%
– Enhanced FFR outperforms static FFR in avg throughput but slight
degradation of edge spectral efficiency
Conclusion
• FFR can enhance spectral efficiency in the cell edge area
• But total average throughput may be degraded due to the
reduction of usable subcarriers in each cell
• If subcarriers in reserved zone can be re-used for MSs located in
cell center area with only small TX power, the degradation due to
FFR can be compensated
Proposed Text
• 11.x Inter-cell interference mitigation
11.x.1 Flexible Frequency Reuse
Flexible Frequency Reuse may be used to help users suffering from severe
inter-cell interference. FFR can limit the usage of frequency resources in each
cell such that part of frequency resources can be restricted to use according to
the coordination between cells. Restriction can be achieved by leaving the
resources unused or by lowering down the transmission power in those
resources.
11.x.2 Control signals for inter-cell interference mitigation
BS shall transmit signaling channel or message to MS to support Flexible
Frequency Reuse
MS shall transmit signaling channel or message to BS to support Flexible
Frequency Reuse
BS can coordinate with neighbor BSs to support Flexible Frequency Reuse
through the backbone network