Cellular respiration (cellular network)

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As cellular respiration , in the mostly English literature cell breathing , called the load-dependent increase and decrease is the coverage area of a radio cell in which the, code division multiple access is used, respectively. Cell respiration occurs, for example, in UMTS cellular networks, but not in GSM networks.

With an increasing number of users, the mutual interference in a radio cell, which only occurs in quasi-orthogonal scrambling codes of the code division multiplexing method, increases. These are compensated for by increasing the transmission power of the individual terminals in order to restore the required ratio of useful signal to interference signals, also known as the signal-to-interference ratio (SIR). Inevitably, all end devices within a radio cell have to increase their transmission power, whereby this has to be increased anyway with increasing distance to the base station (NodeB) in order to compensate for the signal attenuation.

However, the maximum permissible or possible transmission power is limited (in the case of UMTS terminals to 250 mW), so that terminals transmitting at maximum power cannot increase the transmission power further in the event of increasing inferences. This means that the required ratio of useful signal to interference signals can no longer be achieved and communication with the base station comes to a standstill.

The range of the base station is thus shortened, since only those terminals can further increase the transmission power that have not yet reached the transmission power maximum due to the shorter distance to the base station, and the coverage area of ​​the radio cell shrinks. As the number of users decreases, the range of the base station increases again.

Because of its analogy to the change in lung volume when breathing in and out , this process is known as cellular breathing.

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  1. ↑ 3GPP TS 25.101: User Equipment (UE) radio transmission and reception (FDD) , chap. 6.2.1 UE maximum output power, Release 8.7.0 from June 18, 2009

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