Cristian Demetrescu

Capacity of a packet switched cellular network with link adaptation

The purpose of this paper is the calculation of the teletraffic capacity of a cellular radio network that uses packet switching for voice transmission. In addition the network can support two types of voice connections: full rate and half rate, depending on the channel conditions. Switching between the two types is achieved by using link adaptation. We formulate a two-dimensional birth-death model in order to describe the channel occupancy distribution and calculate the average radio utilisation. We consider five different frequency reuse patterns and in each case we calculate the maximum traffic load per cell that the network can serve, provided that certain quality criteria are met. We finally compare the capacity results obtained with the capacity of a packet switched system without link adaptation and a circuit switched system with and without link adaptation, under the same operating requirements.

Transmission of voice in an EDGE network

A method to transmit the voice over an EDGE system is proposed. New radio link control (RLC)/medium access control (MAC) headers are proposed. To increase the reliability of RLC/MAC headers, an error detection and correction scheme is proposed. The simulation results show that between 12/spl sim/30% RLC/MAC can be saved due to our new method. The system capacity is increased significantly for voice transmission over a packet switched EDGE network compared to traditional circuit switched network such as GSM. To avoid the extra delay introduced by normal packet switch networks, a fast access mechanism for uplink transmission is introduced to guarantee the quality of service for voice.

Capacity calculation of a packet switched voice cellular network

A semi-analytical method for the calculation of the teletraffic capacity of a packet switched voice cellular network is provided. The capacity is defined as the maximum traffic load that can be accommodated subject to certain service quality criteria and can be limited either by co-channel interference levels or by the number of available traffic channels. Focusing on GSM-type systems it is demonstrated that there is a potential for a significant capacity improvement when packet switching is used instead of circuit switching over the air interface, due to the inherent statistical multiplexing gain associated with packet switching.