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Interference Aware Medium Access for
Dynamic Spectrum Sharing
Advisor ：Wei-Yeh Chen
Student ：楊
于
世
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Reference
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G. Auer , H. Haas and P. Omiyi , “Interference Aware Medium
Access for Dynamic Spectrum Sharing,” in DySPAN Ireland
Dublin, pp. 399 - 402 , April 2007.
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Outline
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Introduction
DSA principle
Dynamic channel assignment
Busy-tone concept
Dynamic spectrum assignment using busy bursts
Delay-throughput performance
Simulation
Conclusion
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Introduction
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Dynamic spectrum sharing for future mobile communication
systems where multiple operators share license exempt(免除)
spectrum.
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We propose dynamic spectrum assignment (DSA) based on
busy burst (BB) signaling.
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DSA principle
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Its basic principle is that receivers upon data reception transmit
a busy signal in an adjacent(鄰近的) time multiplexed minislot.
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Through exploitation(利用) of channel reciprocity(相互作用),
other potential(潛在的) transmitters are prevented(阻止) from
interfering by first listening to the busy signal.
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Dynamic channel assignment
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The implementation of an efficient medium access in
distributed self-organized networks is inevitably(不可避免的)
tied(出租) with the ability to deal with the hidden and exposed
node problems.
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The exposed node problem occurs(發生) when a transmitter,
refrain(抑制) from access due to strong interference from a
nearby transmissions.
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Example of inter-cellular interference scenario.
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Protocol
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All potential(潛在的;可能的) transmitters must sense the
minislot prior to transmission.
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Transmitters that sense a strong busy burst are prohibited(禁止)
to use this slot.
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Busy-tone concept
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Busy-tone concept: The key principle of the busy-tone
concept is that the receiver sends out a busy-signal on a timemultiplexed(多路傳輸) channel when it has successfully
received a data packet.
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A busy-tone is detected as “strong” by an intending transmitter
when the condition
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Dynamic spectrum assignment using
busy bursts
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Orthogonal(矩形) frequency division multiplexing (OFDM)
is considered a strong candidate as a wireless data
transmission technology in broadband(多頻的) cellular
networks.
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In the considered busy-tone concept, a number of
time/frequency resource units (slots) are grouped into
fixed-duration frames, and associated with each slot is a
minislot.
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MAC frame structure including in-band minislots for busy signaling.
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Delay-throughput performance(1)
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The performance of BB-DSA is analyzed by evaluation(估計)
of the throughput-delay performance of a certain user.
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For BB-DSA, only the first packet of a burst is transmitted in
contention (i.e., without busy burst protection) ,which may
cause outage(中斷) due to high interference in contention
mode.
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Delay-throughput performance(2)
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When this occurs, repeated transmission attempts(企圖) of the
packet are made in contention mode until the packet is
successfully received.
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Once a packet burst has been granted access to the channel, it
is protected by the receiver busy burst, effectively reserving
the slot for subsequent(後來的) packets, and so every packet
in the burst can be received without error.
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Simulation
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System Model: An OFDM system with 256 subcarriers
and 10 OFDM symbols per frame is used for a numerical
(數值的) example.
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Results: The BB-DSA is compared with a fixed spectrum
assignment (FSA) algorithm, without any interference
protection mechanism.
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Delay-throughput results for cell size Rcell = 1 km.
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Conclusion
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(1)了解DSA principle
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(2)了解Busy-tone concept
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(3)了解minislot的運用
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