An evaluation of traffic throughput in the asynchronous UPCS bands

The US Federal Communications Commission (FCC) has to date allocated 30 MHz of spectrum intended for unlicensed use. These bands have been designated as either asynchronous or isochronous and are aimed at offering data and connection-oriented services respectively. Both types are subject to rules which are intended to allow fair access to the radio resource for all users in the uncoordinated unlicensed environment. Due to the availability of 'free' asynchronous spectrum (that is, without significant numbers of incumbents requiring relocation) at 2390-2400 MHz, this paper concentrates on the spectrum access etiquette and its implications on the use of the asynchronous band. The Listen Before Transmit (LBT) protocol has been implemented in a computer simulation. This allows the impact of multiple users in the band all competing for the same time-spectrum windows to be studied. An assessment of the suitability of the asynchronous band for supporting voice traffic is given, in conjunction with an analysis of likely data traffic throughputs attainable in a variety of multi-user scenarios.