Initial Proposal for Low-Power and High-Performance MAC design for 802.11b- (used in wireless sensor network)

Zhibin Wu

Requirement:
Sensor Network with large number of nodes, low traffic load and low-energy consumption


Basic Suggestions:
1. Sleep/Wake-up Switch, saving operation power
 
2. No RTS/CTS,  saving transmission power

3. Memoryless Back-off procedure, saving transmit delay (contention window length).
    Study show that the channel throughput with 10,50,100 nodes improves when contention window is not doubled  every time when contention failures. Thus, each time when transmit needed, resetting the contention window length. Thus we set MaxLength of the window as a fixed valus, such as 8 timeslots.

4. PLCP (physical layer convergence procedure) is a factor to affect channel throughput , because each MPDU is transmitted, 24 octets of PLCP preamble + header is  attached no matter how long the packet is. Thus,  HR/DSSS/short is proposed. e.g, Long PLCP formats will cost 192us for each MPDU, but short PLCP formats will only cost 96us, only half of the long one.


Advanced Suggestions:

1. Data-compression module included in the chip to reduce the data load to be transmitted in the sensor node.
2. MAC-address on-demand assignment in an distributed environment.