Design of a Low-Latency and Low-Power Short Frame OFDM System for Sensor Networks

摘要

In this paper, we consider a low-latency and low-power short frame OFDM system where devices send only one OFDM symbol per frame, using only a reduced number of sub-carriers. We study the design of the OFDM transmitter and receiver in terms of modulation, error correction, time synchronization and channel estimation. In order to respond favourably to the requirements of a low-latency, low-power sensor network, we adapt conventional OFDM techniques to the case of short-frame transmissions. Therefore, we analyse the performance of these proposed solutions and we show that our novel design allows the system to operate close to theoretical limits. We study the impact of the number of pilots on time synchronization performance, and we show also the advantage of adding memory to the channel estimation block. Moreover, we discuss our interest in using error correcting codes with a trade-off to make by using the lowest alphabet size of the modulation and/or adding redundancy for error correction in order to maintain a low Bit Error Rate (BER).