why shape of cell is hexagonal in cellular network
Ans. The geographic area or cellular service area is divided into small hexagonal region called cells. It is the basic unit of a cellular system. These cells collectively provide coverage over larger geographical areas. Hexagonal cell shape is perfect over square or triangular cell shapes in cellular architecture because it cover an entire area without overlapping i. e. they can cover the entire geographical region without any gaps. Frequency reuse and cell splitting are two main concepts in cellular networks. Cell splitting is the process of dividing a larger congested cell into smaller cells. Each cell has its own base station with transmitter power and antenna height. When the traffic in an area increases, larger cells are split into smaller cells so that frequency can be reused. By splitting the cell, the capacity of the system will be increased because availability of additional number of channels per unit service area is also increased.
There are two types of cell splitting. In permanent cell splitting everything is planned before it is actually implemented for new split cell. The assigned frequencies, the transmitter power, traffic load etc. are considered before. The implementation of dynamic cell splitting is difficult job. Dynamic cell splitting is done according to the utilization of dedicated spectrum and traffic load.
ABSTRACT: Channel coding is a vital but complex component of cellular communication systems, which is used for correcting the communication errors that are caused by noise, interference and poor signal strength. The turbo code was selected as the main channel code in 3G and 4G cellular systems, but the 3GPP standardization group is currently debating whether it should be replaced by the Low Density Parity Check (LDPC) code in 5G. This debate is being driven by the requirements for 5G, which include throughputs of up to 20 Gbps in the downlink to user devices, ultra-low latencies, as well as much greater flexibility to support diverse use-cases, including broadband data, Internet of Things (IoT), vehicular communications and cloud computing.
In our previous white paper, we demonstrated that flexible turbo codes can achieve these requirements with superior hardware- and energy-efficiencies than flexible LDPC decoders. However, the proponents of LDPC codes have highlighted that inflexible LDPC decoders can achieve throughputs of 20 Gbps with particularly attractive hardware- and energy- efficiencies.
This white paper outlines a vision for 5G, in which channel coding is provided by a flexible turbo code for most use-cases, but which is supported by an inflexible LDPC code for 20 Gbps downlink use-cases, such as fixed wireless broadband. We demonstrate that this approach can meet all of the 5G requirements, while offering hardware- and energy-efficiencies that are significantly better than those of an LDPC-only solution. Furthermore, the proposed approach benefits from synergy with the 3G and 4G turbo code, as well as a significantly faster time-to-market for 5G. These benefits translate to a 5G that is significantly more capable, significantly easier to deploy and significantly lower cost.
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