It seems that the only solution for the first problem is to explore the space resource. The cellular system is a successful example. With a cellular structure, the frequency can be reused as many times as needed. Also, the cellular structure reduces the maximum distance from the terminal to the nearest base station, which is also a clue to solve the second problem.
However, in a traditional cellular system, when the cell size gets smaller, capacity can be increased linearly with cell density. But this is based on the assumption of a large path loss exponent. Pathloss is the amount of loss introduced by the propagation environment between transmitter and receiver. When the cell size is small enough, the exponent gets small, which may be approximately 2; thus, the interference may be so large that the system may not work, as seen in Fig. 2.The above phenomenon indicates that the system capacity cannot be increased anymore when the density of cells reaches a certain level.
However, in a traditional cellular system, when the cell size gets smaller, capacity can be increased linearly with cell density. But this is based on the assumption of a large path loss exponent. Pathloss is the amount of loss introduced by the propagation environment between transmitter and receiver. When the cell size is small enough, the exponent gets small, which may be approximately 2; thus, the interference may be so large that the system may not work, as seen in Fig. 2.The above phenomenon indicates that the system capacity cannot be increased anymore when the density of cells reaches a certain level.
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