Channel Estimation Performance for Zero-Overhead Channel Access in Mobile Sensor Networks
Abstract
In this work we study the effects of channel estimation/ equalization on the BER performance of RF carrier frequency hopped OFDM (FH-OFDM) when using synchronization information that is embedded directly into the OFDM baseband symbol stream. In sensor networks using CSMA, the acquisition preambles can require a large overhead percentage of the overall message. Embedding synchronization information into the data information stream eliminates this channel access overhead, thus providing potential for zero-time overhead channel access. Superposition (embedding) of the sync information, however, causes interference onto the data information, which must be removed for satisfactory BER performance. Consequently, embedded synchronization interference cancellation (EIC) is utilized, which requires accurate channel state estimation. Using coherent 4QAM- and 16QAM-OFDM modulation, channel estimation and BER performance is evaluated using the COST207 multipath fading channel model. Less than a 1 dB performance difference is found between a preamble and embedded system for short message bursts (< 1msec) and a burst data rate of greater than 1.6 Mbit/sec. The channel estimation mean square error (MSE) versus pilot symbol overhead is also determined as a function of urban and rural channel environments.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 01, 2004
- Accession Number
- ADA431596
Entities
People
- Brian M. Sadler
- Ghassan Maa1ou1i
- John E. Kleider
- Scott Chuprun
- Steve Gifford
Organizations
- General Dynamics