INTERFERENCE ANALYSIS AND PLANNING REQUIREMENTS FOR DATA OVER VOICE IN CELLULAR-SYSTEMS

The paper deals with the evaluation of performance of current cellular systems which are required to accommodate in an already operating sys tem a wide range of new services, with different quality requirements (on delays, retransmission rates, etc.), and often characterised by a high burstiness (i.e. with relatively short traffic bursts, interleave d by comparatively long silence periods). To this end, and extension o f packet communications is appealing for its inherent flexibility: sta ndardisation of packet protocols for data transmission over idle GSM c hannels is in progress, and a similar service exploiting AMPS radio an d network resources is already specified as Cellular Digital Packet Da ta. In both cases voice traffic retains a higher priority. The paper f ocuses on the evaluation of the effect of this additional traffic on e xisting voice traffic in a GSM Phase 2+ system. Although voice calls e xperience the same channel availability, their performance are worsene d by the higher co-channel interference due to the higher average chan nel occupancy. This impairment cannot be tackled, as a matter of cours e, by increasing the re-use distance as this would affect the overall system capacity. The paper suggests the use of smart planning strategi es capable to ease control of interference levels with a negligible im pact on system complexity and signalling load.