decorrelation between each burst increases, thereby increasing the efficiency of the coding signal. The assignment of the frequency can be done by two ways: sequentially or randomly. In the former, the system follows a strict pattern of frequency assignment to each burst; in the latter, it assigns frequencies randomly. Interference diversity: If each mobile has one constant frequency, some mobiles may be affected by interference more than others. With the use of frequency hopping, the interference spreads within the system because the interfering signal's effect gets reduced. As the interference becomes less, the frequency spectrum can be utilised better, and hence the capacity of the system increases. Frequency hopping is of two types: base-band FH and RF FH. In base-band FH, the calls are hopped between different TRXs. The number of frequencies used for hopping is correlated to the number of TRXs and is thus constant. In RF FH, the call stays on one TRX but a frequency change takes place with every frame. These frequencies are not included in the hopping sequence, thus effectively creating two layers in each cell, one FH and one non-FH. As RF FH is not correlated to the number of TRXs, it is considered to be more robust and hence used in network deployment frequency planning. 2.4.11 Parameter Planning The parameters used in a radio network are of two types: fixed and measured. These param- eters include those related to signalling, radio resource management (RRM), power control, neighbour cells, etc. Signalling Any flow of data in a network requires some additional information that helps the data to reach the destination in the desired fashion. This additional information is known as signalling. Signalling in GSM is required at all the interfaces, but radio network planners deal mostly with the signalling between the mobile station and base station (shown in Table 2.1). Signalling on all the interfaces except for the air-interface is done at 64 kbps. On the air- interface the signalling can be done either by us