Use of a pre-FFT Equaliser (PFE) has been previously proposed as a method for either improving the efficiency of OFDM radio modems or increasing the excess delay spread that they are capable of operating under. In this
paper, application of the PFE to the Hiperlad/2 standard is considered. Key features of the physical layer specification of the Hiperlad/2 standard are summarised and those aspects that are particularly relevant when considering the use of the PFE are highlighted. A Hiperlad/2 compatible OFDM
receiver incorporating the PFE, known as a combined OFDM-equalisation receiver, is then described. In order to evaluate the relative performance of the conventional OFDM and combined OFDM-equalisation receivers, a Hiperlad/2 compliant software simulation of
the two receivers is undertaken. The results are used to compare the two systems in terms of Bit Error Rate (BER)and Packet Error Rate (PER) versus Signal to Noise Ratio (SNR) and also in terms of transmission eficiency.
It is shown that the combined FDM-equalisation receiver is capable of achieving near identical performance to the conventional OFDW receiver in terms
of bit error rates, but is further capable of achieving a 9% efficiency improvement. This equates to a potential increase of up to 6Mbits/s in the supported data rate. The
application of the PFE to improve BER and PER
performance under severe delay spread conditions is also discussed.
Sponsorship: The authors wish to acknowledge the support of the UK government’s Electronics and Physical Sciences Research Council (EPSRC).
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Name of Conference: 52nd IEEE Vehicular Technology Conference, 2000 (VTC Fall-2000)
Venue of Conference: Boston, Mass.