bandwidth-efficient, energy-constrained short range wireless communications

Bandwidth-Efficient, Energy-Constrained Short Range

Wireless Communications

Thursday, February 26 2004 Bandwidth-Efficient, Energy-Constrained Short Range Wireless Communications 2

CUBAN Scenario

Copied from: “In-depth description of the Research Proposal Co-Optimized Ubiquitous Broadband Access Networks” (CUBAN)


Key Points

• Cross-layer optimization

• Uplink and downlink


Cross-Layer Optimization

6

1versus

24

7packets per time slot

Copied from: “Cross-Layer Design for Wireless Networks”, S. Shakkottai and T. Rappaport


Energy-constrained Modulation Optimization

• Assumption: Both the transmitter and the receiver operate on batteries

• Goal: Find the best modulation strategy to minimize the total energy consumption required to send a given number of bits

Based on: “Modulation Optimization under Energy Constraints”, S. Cui, A. Goldsmith and A. Bahai“Energy-constrained Modulation Optimization for Coded Systems”, S. Cui, A. Goldsmith and A. Bahai



• Analysis for:

– MQAM, MFSK

– AWGN and Rayleigh fading channels

– Coded / uncoded case




• In short range applications, the circuit energy consumption is non negligible compared with the transmission energy




Copied from: “Energy-constrained Modulation Optimization”, S. Cui, A. Goldsmith and A. Bahai



• bits have to be transmitted in a deadline

• The transceiver spends a time to transmit those bits

• Trade off: the transmission energy decreases with , but the circuit energy consumption increases with




• Example: Uncoded MQAM for AWGN channels

Copied from: “Modulation Optimization under Energy Constraints”, S. Cui, A. Goldsmith and A. Bahai


Adaptive Transmission Schemes

Use transmitter – receiver pair n when

Copied from: “Adaptive Coding and Modulation: A Key to Bandwidth-Efficient Multimedia Communications in Future Wireless Systems”, K. Hole and G. Øien


Adaptive Transmission Schemes

The channel model specifies apdf for the amplitude of

Copied from: “Adaptive Coding and Modulation: A Key to Bandwidth-Efficient Multimedia Communications in Future Wireless Systems”, K. Hole and G. Øien


Energy Optimal Scheduling under Average Throughput Constraint

• Goal: Adapt radio settings (e.g. modulation, error code, …) in response to changes in the wireless channel in order to minimize the energy consumption under an average throughput constraint

Based on: “Energy Optimal Scheduling under Average Throughput Constraint”, C. Schurgers and M. Srivastava



• System model:




• Assumptions:

– The channel (Rayleigh fading) varies slowly enough to be estimated efficiently

– Infinite number of samples Only knowledge of the channel statistics is required, instead of that of the exact future behaviour




• Problem: Find the values of the thresholds

• Assumption: The incremental power for adding one extra bit is monotonically

increasingBased on: “Energy Optimal Scheduling under Average Throughput Constraint”, C. Schurgers and M. Srivastava




10/ SEC


Results


190/ SEC


Results



Results

Based on: “Energy Efficient Wireless Scheduling: Adaptive Loading in Time”, C. Schurgers and M. Srivastava


Remarks – Ideas – Discussion

• Conclusions from p2:

– Minimize energy consumption instead of maximizing spectral efficiency when determining the thresholds

– The analysis has been done for situations where the electronics power is negligible compared to the transmission power



Research Objective 1

Design an adaptive transmission scheme (i.e. determine the thresholds, ,… ) for short range wireless channels in order to minimize energy consumption under an average throughput constraint


Research Objective 1• Remarks:

– The electronics (circuit) power is not considered negligible when compared to the transmit power. A model comparable to the one in p1 will be used

– In a first stage, MQAM modulation (no coding) and Rayleigh fading

– The throughput constraint should be set by the application layer


Research Objective 1

• It would be interesting to find out how far the transceiver designed using the above scheme is from the from the actual channel capacity

Based on: “Adaptive Coding and Modulation: A Key to Bandwidth-Efficient Multimedia Communications in Future Wireless Systems”, K. Hole and G. Øien


Other Ideas

• Nakagami-m channels– See what happens with p1

– Research objective 1

• OFDM based schemes, with adaptive transmission on subchannels

• Coding: Trellis codes / Turbo codes


Other Ideas

• Antenna diversity – SC / MRC

• Try to find more accurate / complete models for the electronics power consumption, try to find the best possible transceiver structure in terms of power consumption

• Network and data link layers joint optimization

bandwidth-efficient, energy-constrained short range wireless communications

Documents

energy constraints

transmission energy

circuit energy consumption

total energy consumption

bahai slide

short range applications

wireless networks

best modulation strategy