无线通信系统第2章课件.pptVIP

The Cellular Concept： System Design Fundamentals ; Cellular Networks;Cell shape;Cellular coverage representation;Macrocell large, covering a wide are range of several hundred kilometres (km) to ten km mostly deployed in rural and sparsely populated areas Microcell medium cell, coverage are a smaller than in macro cells range of several hundred metres to a couple of metres deployed mostly in crowded areas, stadiums, shopping malls Picocell small, covering a very small area range of several tens of metres low power antennas, indoor ;坠堆搂疵榨胸屯丑朱政屠捧惺秤镀痢糖瓣队柒缕轻拦煤滑查绳齿透獭自赣无线通信系统第2章课件无线通信系统第2章课件;Base station transmitters; Cellular coverage representation ;A mobile communication system uses a frequency reuse factor of 1/7 and 416 channels available. If 21 channels are allocated as control channels, compute its system capacity. Assume a channel supports 8 users Channels available for allocation = 416 - 21 = 395 Channel Number of a cell = 395 / 7 = 57 Number of simultaneous users per cell = 8 x 57 = 456 Number of simultaneous users in system = 7 x 456 = 3192;;Method of locating co-channel cells;Channel Assignment Strategies;Dynamic channel assignment MSC allocates frequencies when a call is made Provides high channel utilisation To do this it needs real-time information on channel occupancy traffic distribution and radio signal strength indication (RSSI) high computational load and increased storage;Handover (Handoff);Handover Process;Handover Process;Handover Process;Choosing Handover Margins;Setting Handover Thresholds;Handoff in different system;Interference and System Capacity;Six Effective Interfering Cells of Cell 1 ;Co-channel reuse ratio Q ;Co-channel reuse ratio vs. frequency reuse pattern ;7-cell reuse pattern ;12-cell reuse pattern ;19-cell reuse pattern ;Co-channel reuse ratio vs. frequency reuse pattern ;Propagation model;Co-channel interference ratio ;Example 3;More exact geometr