Radio-resource management

Radio resource management (RRM) is the system level management of co-channel interference, radio resources, and other radio transmission characteristics in wireless communication systems, for example cellular networks, wireless local area networks and wireless sensor systems. RRM involves strategies and algorithms for controlling parameters such as transmit power, user allocation, beamforming, data rates, handover criteria, modulation scheme, error coding scheme, etc. The objective is to utilize the limited radio-frequency spectrum resources and radio network infrastructure as efficiently as possible.

RRM concerns multi-user and multi-cell network capacity issues, rather than the point-to-point channel capacity. Traditional telecommunications research and education often dwell upon channel coding and source coding with a single user in mind, although it may not be possible to achieve the maximum channel capacity when several users and adjacent base stations share the same frequency channel. Efficient dynamic RRM schemes may increase the system spectral efficiency by an order of magnitude, which often is considerably more than what is possible by introducing advanced channel coding and source coding schemes. RRM is especially important in systems limited by co-channel interference rather than by noise, for example cellular systems and broadcast networks homogeneously covering large areas, and wireless networks consisting of many adjacent access points that may reuse the same channel frequencies.

The cost for deploying a wireless network is normally dominated by base station sites (real estate costs, planning, maintenance, distribution network, energy, etc.) and sometimes also by frequency license fees. The objective of radio resource management is therefore typically to maximize the system spectral efficiency in bit/s/Hz/area unit or Erlang/MHz/site, under some kind of user fairness constraint, for example, that the grade of service should be above a certain level. The latter involves covering a certain area and avoiding outage due to co-channel interference, noise, attenuation caused by path losses, fading caused by shadowing and multipath, Doppler shift and other forms of distortion. The grade of service is also affected by blocking due to admission control, scheduling starvation or inability to guarantee quality of service that is requested by the users.

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