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Lecture Wireless and mobile computing – Capter 28: Cellular wireless networks

The following will be discussed in this chapter: Principles of cellular networks, cellular geometries, frequency reuse, increasing capacity, macrocell and microcell, operation of cellular system, call stages, design factors, impairments, ist generation cellular networks, 2nd generation cellular networks. | Cellular Wireless Networks Lecture 28 Ovierview Principles of Cellular Networks Cellular Geometries Frequency Reuse Increasing Capacity Macrocell and Microcell Operation of Cellular System Call Stages Design Factors Impairments Ist Generation Cellular Networks 2nd Generation Cellular Networks 3rd and 4th Generation 2 Principles of Cellular Networks Developed to increase capacity for mobile radio telephone service Prior to cellular radio: mobile service was only provided by one high powered transmitter/receiver typically supported about 25 channels had a radius of about 80km 3 3 Cellular Network Organization key for mobile technologies based on multiple low power transmitters area divided into cells in a tiling pattern to provide full coverage each with own antenna each with own range of frequencies served by base station consisting of transmitter, receiver, and control unit adjacent cells use different frequencies to avoid crosstalk cells sufficiently distant can use same frequency band 4 4 Cellular Geometries 5 5 The first design decision to make is the shape of cells to cover an area. A matrix of square cells would be the simplest layout to define (Stallings DCC9e Figure 14.1a). However, this geometry is not ideal. If the width of a square cell is d, then a cell has four neighbors at a distance d and four neighbors at a distance d. As a mobile user within a cell moves toward the cell's boundaries, it is best if all of the adjacent antennas are equidistant. This simplifies the task of determining when to switch the user to an adjacent antenna and which antenna to choose. A hexagonal pattern provides for equidistant antennas (Stallings DCC9e Figure 14.1b). The radius of a hexagon is defined to be the radius of the circle that circumscribes it (equivalently, the distance from the center to each vertex; also equal to the length of a side of a hexagon). For a cell radius R, the distance between the cell center and each adjacent cell center is d = R. In practice, a . | Cellular Wireless Networks Lecture 28 Ovierview Principles of Cellular Networks Cellular Geometries Frequency Reuse Increasing Capacity Macrocell and Microcell Operation of Cellular System Call Stages Design Factors Impairments Ist Generation Cellular Networks 2nd Generation Cellular Networks 3rd and 4th Generation 2 Principles of Cellular Networks Developed to increase capacity for mobile radio telephone service Prior to cellular radio: mobile service was only provided by one high powered transmitter/receiver typically supported about 25 channels had a radius of about 80km 3 3 Cellular Network Organization key for mobile technologies based on multiple low power transmitters area divided into cells in a tiling pattern to provide full coverage each with own antenna each with own range of frequencies served by base station consisting of transmitter, receiver, and control unit adjacent cells use different frequencies to avoid crosstalk cells sufficiently distant can use same frequency .