Transmission of speech and data using packet reservation multiple access

The authors investigate the performance of PRMA (packet reservation multiple access) when speech and data terminals are sharing a common channel. Computer simulations show that a channel considered in an earlier study can carry 33 speech signals simultaneously with 33 random data signals, each with an average rate of 1200 b/s, and an average delay of less than 250 ms. If the data rate is 2400 b/s, the system supports 31 speech signals and 31 data signals. With random data only, PRMA is identical to slotted ALOHA. Within the constraint of a 250 ms delay, the maximum number of 1200 b/s sources is 190, which corresponds to a throughput of 0.358, very close to the maximum for slotted ALOHA with an infinite number of terminals. At the other extreme, PRMA with speech only supports 37 simultaneous conversations, equivalent to a throughput of 0.79