Clustered-OFDM transmitter implementation

An elegant means by which high-speed burst wireless transmission can be accomplished with small amounts of overhead is through a novel technique referred to as clustered-OFDM. By using OFDM modulation with a long symbol interval, this scheme overcomes the complex and costly equalization requirements associated with single carrier systems. Moreover, the need for highly linear power amplifiers typically required in OFDM systems is alleviated through the use of multiple transmit antennas combined with nonlinear coding. The clustering technique also leads to a natural implementation of transmit diversity. This paper reports on the implementation of a clustered-OFDM transmitter which was constructed using off-the-shelf components in a relatively short period of time. Despite the limitations associated with the prototyped system, it can deliver 7.5 Mbps and it is expected that this data rate could be easily tripled with existing technology. In addition to providing an introduction to clustered-OFDM, we describe the various architectural trade-offs which were made in order to reduce the hardware complexity of the boards as well as some experimental results showing the operation of the transmitter.