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UWB, 802.11,Coding for Cross-Layer Design: Research Sampling Predrag Spasojevic WINLAB, Rutgers University IAB Spring, 2004
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UWB, 802.11,Coding for Cross-Layer Design: Research Sampling · UWB, 802.11,Coding for Cross-Layer Design: Research Sampling Predrag Spasojevic WINLAB, Rutgers University IAB Spring,

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Page 1: UWB, 802.11,Coding for Cross-Layer Design: Research Sampling · UWB, 802.11,Coding for Cross-Layer Design: Research Sampling Predrag Spasojevic WINLAB, Rutgers University IAB Spring,

UWB, 802.11,Coding for Cross-Layer Design:Research Sampling

Predrag Spasojevic

WINLAB, Rutgers University

IAB Spring, 2004

Page 2: UWB, 802.11,Coding for Cross-Layer Design: Research Sampling · UWB, 802.11,Coding for Cross-Layer Design: Research Sampling Predrag Spasojevic WINLAB, Rutgers University IAB Spring,

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Page 3: UWB, 802.11,Coding for Cross-Layer Design: Research Sampling · UWB, 802.11,Coding for Cross-Layer Design: Research Sampling Predrag Spasojevic WINLAB, Rutgers University IAB Spring,

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Page 4: UWB, 802.11,Coding for Cross-Layer Design: Research Sampling · UWB, 802.11,Coding for Cross-Layer Design: Research Sampling Predrag Spasojevic WINLAB, Rutgers University IAB Spring,

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Page 5: UWB, 802.11,Coding for Cross-Layer Design: Research Sampling · UWB, 802.11,Coding for Cross-Layer Design: Research Sampling Predrag Spasojevic WINLAB, Rutgers University IAB Spring,

Ultra-Wideband AntennasGuofeng Lu

Stefan von der Mark, Ilya Korisch (Lucent Tech.), Larry J. Greenstein

• Diamond and rounded diamond antennas for UWB communications

• Radiation pattern variations with frequency• Modeling, simulation and measurements• Good match between model prediction, simulation and

measurements• Good insights from a model to further improve

performance

Page 6: UWB, 802.11,Coding for Cross-Layer Design: Research Sampling · UWB, 802.11,Coding for Cross-Layer Design: Research Sampling Predrag Spasojevic WINLAB, Rutgers University IAB Spring,

Modeling and simulation of diamond and rounded diamond

2/λ

4/λ

FeedPoi nt

FeedPoi nt

Diamond and rounded diamond antennas

Simplified models based on current concentration at the

edges

Page 7: UWB, 802.11,Coding for Cross-Layer Design: Research Sampling · UWB, 802.11,Coding for Cross-Layer Design: Research Sampling Predrag Spasojevic WINLAB, Rutgers University IAB Spring,

Radiation patterns, model predicted (left) and simulated (right)

At 3 GHz

At 6 GHz

At 8 GHz

Page 8: UWB, 802.11,Coding for Cross-Layer Design: Research Sampling · UWB, 802.11,Coding for Cross-Layer Design: Research Sampling Predrag Spasojevic WINLAB, Rutgers University IAB Spring,

WLAN throughput prediction

Praveen Gopalakrishnan

Larry Greenstein, Ivan Seskar

Page 9: UWB, 802.11,Coding for Cross-Layer Design: Research Sampling · UWB, 802.11,Coding for Cross-Layer Design: Research Sampling Predrag Spasojevic WINLAB, Rutgers University IAB Spring,

Aim & Approach

• Develop a simple and accurate method to predict the throughput characteristics of rate-adaptive WLANs.

• Use of a limited set of measurements, PHY layer simulation results and MAC layer analysis

Page 10: UWB, 802.11,Coding for Cross-Layer Design: Research Sampling · UWB, 802.11,Coding for Cross-Layer Design: Research Sampling Predrag Spasojevic WINLAB, Rutgers University IAB Spring,

Results

• Throughput predictor for 802.11a modems

• Predicted throughput statistics are close to the measurements.

Page 11: UWB, 802.11,Coding for Cross-Layer Design: Research Sampling · UWB, 802.11,Coding for Cross-Layer Design: Research Sampling Predrag Spasojevic WINLAB, Rutgers University IAB Spring,

Strategies To Improve Performance of Ad-Hoc 802.11 Networks

• Motivation:– Improving network performance should be joint effort

of all participating nodes – Network complexity should be transparent to the

users

• Approach:– Gain insight in uncontrolled 802.11b network

behavior– Test different strategies on set of typical scenarios– Determine optimal strategy for each scenario

Haris Kremo, Richard Howard, Ivan SeskarWinlab, Rutgers University

Eitan FensonPnP Networks

Page 12: UWB, 802.11,Coding for Cross-Layer Design: Research Sampling · UWB, 802.11,Coding for Cross-Layer Design: Research Sampling Predrag Spasojevic WINLAB, Rutgers University IAB Spring,

Baseline Experiment

• Actions:– Change packet lengths– Change period by which

the packets are sent– Gradually increase

separation of links in frequency

• Observable parameters:– Amount of data sent and

received on both links– Signal strength and noise

measurements reported by wireless interfaces

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Page 13: UWB, 802.11,Coding for Cross-Layer Design: Research Sampling · UWB, 802.11,Coding for Cross-Layer Design: Research Sampling Predrag Spasojevic WINLAB, Rutgers University IAB Spring,

Future Work

• Introduce limited number of typical scenarios involving more nodes and more complex topologies

• Expand set of actions:– Use different routing schemes– Change channel assignment and network id assignment– Adjust transmit powers– Switch between the medium reservation schemes

• Relate observable parameters and actions

Page 14: UWB, 802.11,Coding for Cross-Layer Design: Research Sampling · UWB, 802.11,Coding for Cross-Layer Design: Research Sampling Predrag Spasojevic WINLAB, Rutgers University IAB Spring,

“Good” Codes- Cross-Layer Analysis

� Good codes: Turbo, LDPC, repeat accumulate (RA) codes

� Threshold behavior

� Scalable error exponents for parallel channels

� Cross-layer topics

� User Cooperation with Punctured Turbo Codes

– A Throughput Analysis of Incremental Redundancy Hybrid ARQ Schemes

– Incremental Multi-Hop based on “Good” Punctured Codes

Ruoheng Liu,

Emina Soljanin (Bell Labs, Lucent)

Page 15: UWB, 802.11,Coding for Cross-Layer Design: Research Sampling · UWB, 802.11,Coding for Cross-Layer Design: Research Sampling Predrag Spasojevic WINLAB, Rutgers University IAB Spring,

User Cooperation with Punctured Turbo Codes

� users share their antennas and other resources to create a virtual array

� distributed transmission, encoding, and joint decoding

� Result:� design and analyze a cooperative coding scheme with punctured turbo codes

� using cooperative coding one can achieve the full diversity gain.

Page 16: UWB, 802.11,Coding for Cross-Layer Design: Research Sampling · UWB, 802.11,Coding for Cross-Layer Design: Research Sampling Predrag Spasojevic WINLAB, Rutgers University IAB Spring,

A Throughput Analysis of IR HARQSchemes

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• derived a close-form achievable throughput bound for an IR HARQ scheme

Page 17: UWB, 802.11,Coding for Cross-Layer Design: Research Sampling · UWB, 802.11,Coding for Cross-Layer Design: Research Sampling Predrag Spasojevic WINLAB, Rutgers University IAB Spring,

Analysis of multilevel coding schemes using low-density parity check codes

Ahmed Turk

Page 18: UWB, 802.11,Coding for Cross-Layer Design: Research Sampling · UWB, 802.11,Coding for Cross-Layer Design: Research Sampling Predrag Spasojevic WINLAB, Rutgers University IAB Spring,

Why MLC using LDPCC?

• MLC has shown very good bandwidth efficiency performance• MLC is very flexible in terms of the type of error correcting codes in each level.• LDPCC has shown close to Shannon limit error performance• LDPC have low decoder complexity using factor graphs.• MLC using LDPCC as component codes can achieve very good coding gain

without any bandwidth expansion which makes it suitable for band-limited applications.

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Page 19: UWB, 802.11,Coding for Cross-Layer Design: Research Sampling · UWB, 802.11,Coding for Cross-Layer Design: Research Sampling Predrag Spasojevic WINLAB, Rutgers University IAB Spring,

Applications

• Unequal error protection• Video transmission • Transmission of successively refineable

information

Page 20: UWB, 802.11,Coding for Cross-Layer Design: Research Sampling · UWB, 802.11,Coding for Cross-Layer Design: Research Sampling Predrag Spasojevic WINLAB, Rutgers University IAB Spring,

Distributed source codingPavan Kaivaram

• Multiple sources, Central receiver• Highly correlated data• Distributed compression algorithms

– Need good encoding algorithms• Without source communication• Fast and simple

– Possibly fast decoding algorithm• Results and directions:

– Correlation representation with hyper graphs

– Extensions for jointly distributed binary sources

• Coset Codes• Polynomial time encoding algorithms

– Results with hyper graphs• Applications

– Spectrum imaging• Sources sensing spectral intensity• Receiver requires the entire image of an

area. Multiple sources and Correlation map

Central Receiver

Page 21: UWB, 802.11,Coding for Cross-Layer Design: Research Sampling · UWB, 802.11,Coding for Cross-Layer Design: Research Sampling Predrag Spasojevic WINLAB, Rutgers University IAB Spring,

Results• Considered correlation structure specified by joint probability distribution.

– Every subset of sources has a equally likely joint alphabet– Represented by regular hyper graph for every induced graph on a subset of

sources

• Coset codes– Special case of above correlation– Extends two source joint binary distribution to multiple sources– Have a polynomial time encoding algorithm– Decoding algorithm, still exponential

• General Case– If DSC algorithm exists for every induced 2-graph, so does for N-graph– Simple extension from 2-source case to N-source case– Lot of results for two source case

• Research on graphs where DSC achieves maximum compression• Where compression is polynomial time encoding

• Future Work– Complete characterization of N-graphs where DSC is feasible in polynomial time– Extension from discrete alphabet to continuous with distortion criterion– Multiple source information theory.

Page 22: UWB, 802.11,Coding for Cross-Layer Design: Research Sampling · UWB, 802.11,Coding for Cross-Layer Design: Research Sampling Predrag Spasojevic WINLAB, Rutgers University IAB Spring,

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Page 23: UWB, 802.11,Coding for Cross-Layer Design: Research Sampling · UWB, 802.11,Coding for Cross-Layer Design: Research Sampling Predrag Spasojevic WINLAB, Rutgers University IAB Spring,

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Page 24: UWB, 802.11,Coding for Cross-Layer Design: Research Sampling · UWB, 802.11,Coding for Cross-Layer Design: Research Sampling Predrag Spasojevic WINLAB, Rutgers University IAB Spring,

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Page 25: UWB, 802.11,Coding for Cross-Layer Design: Research Sampling · UWB, 802.11,Coding for Cross-Layer Design: Research Sampling Predrag Spasojevic WINLAB, Rutgers University IAB Spring,

Topics considered

• LDPC codes (LDPCC)• Multilevel coding techniques (MLC)• Unequal error protection (UEP)

Page 26: UWB, 802.11,Coding for Cross-Layer Design: Research Sampling · UWB, 802.11,Coding for Cross-Layer Design: Research Sampling Predrag Spasojevic WINLAB, Rutgers University IAB Spring,

A Throughput Analysis of IR HARQ Schemes

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Page 27: UWB, 802.11,Coding for Cross-Layer Design: Research Sampling · UWB, 802.11,Coding for Cross-Layer Design: Research Sampling Predrag Spasojevic WINLAB, Rutgers University IAB Spring,

IR Multi Hop based on Good Punctured Codes

Traditional multi-hop transmission

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Page 28: UWB, 802.11,Coding for Cross-Layer Design: Research Sampling · UWB, 802.11,Coding for Cross-Layer Design: Research Sampling Predrag Spasojevic WINLAB, Rutgers University IAB Spring,

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Page 29: UWB, 802.11,Coding for Cross-Layer Design: Research Sampling · UWB, 802.11,Coding for Cross-Layer Design: Research Sampling Predrag Spasojevic WINLAB, Rutgers University IAB Spring,

Simple model using linear superposition

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Page 30: UWB, 802.11,Coding for Cross-Layer Design: Research Sampling · UWB, 802.11,Coding for Cross-Layer Design: Research Sampling Predrag Spasojevic WINLAB, Rutgers University IAB Spring,

Radiation patterns, simulated and measured

Page 31: UWB, 802.11,Coding for Cross-Layer Design: Research Sampling · UWB, 802.11,Coding for Cross-Layer Design: Research Sampling Predrag Spasojevic WINLAB, Rutgers University IAB Spring,

Gain vs. Frequency

Page 32: UWB, 802.11,Coding for Cross-Layer Design: Research Sampling · UWB, 802.11,Coding for Cross-Layer Design: Research Sampling Predrag Spasojevic WINLAB, Rutgers University IAB Spring,

Impedances,diamond and rounded diamond

Page 33: UWB, 802.11,Coding for Cross-Layer Design: Research Sampling · UWB, 802.11,Coding for Cross-Layer Design: Research Sampling Predrag Spasojevic WINLAB, Rutgers University IAB Spring,

Flow chart