The capacity gain achieved is directly proportional to the number of times a cluster is repeated, as as well as, for a fixed cell size, small N decreases the size of the cluster with in turn results in the increase of the number of clusters and hence the capacity. For small N, co-channel cells are located much closer and hence more interference. The value of N is determined by calculating the amount of interference that can be tolerated for a sufficient quality communication. Hence the smallest N having interference below the tolerated limit is used. But the cluster size N cannot take on any value and is given only by the following equation N= i2 + ij + j2 where i and j are integer numbers. LECTURE 14 To find the nearest co-channel neighbors of a particular cell, one must do the following: (1) move cells along any chain of hexagons and then (2) turn 60 i degrees counter-clockwise and move cells. This is illustrated in Figure 3.2 j for = 3 and =2 i j (example, = 19). N Method of locating co-channel cells in a cellular system. Example If a total of 33 MHz of bandwidth is allocated to a particular FDD cellular telephone system which uses two 25 kHz simplex channels to provide full duplex voice and control channels, compute the number of channels available per cell if a system uses (a) four-cell reuse, (b) seven-cell reuse, and (c) reuse. If 1 MHz of the allocated spectrum is dedicated to control
The capacity gain achieved is directly proportional to the number of times a cluster is repeated, as as well as, for a fixed cell size, small N decreases the size of the cluster with in turn results in the increase of the number of clusters and hence the capacity. For small N, co-channel cells are located much closer and hence more interference. The value of N is determined by calculating the amount of interference that can be tolerated for a sufficient quality communication. Hence the smallest N having interference below the tolerated limit is used. But the cluster size N cannot take on any value and is given only by the following equation N= i2 + ij + j2 where i and j are integer numbers. LECTURE 14 To find the nearest co-channel neighbors of a particular cell, one must do the following: (1) move i cells along any chain of hexagons and then (2) turn 60 degrees counter-clockwise and move j cells. This is illustrated in Figure 3.2 for i = 3 and j =2 (example, N = 19). Method of locating co-channel cells in a cellular system. Example If a total of 33 MHz of bandwidth is allocated to a particular FDD cellular telephone system which uses two 25 kHz simplex channels to provide full duplex voice and control channels, compute the number of channels available per cell if a system uses (a) four-cell reuse, (b) seven-cell reuse, and (c) reuse. If 1 MHz of the allocated spectrum is dedicated to control
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