What is 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. The main objective of RRM is to utilize the limited RF spectrum resources and radio network infrastructure as efficiently as possible. Several strategies and algorithms are used to control parameters such as transmit power, user allocation, beamforming, data rates, handover criteria, modulation scheme, error coding scheme, etc.

RRM addresses multi-user and multi-cell network capacity issues, rather than the point-to-point channel capacity. This means that it involves resource management of a large network consisting of several communication towers, several repeaters, routers and connected devices as a whole rather than individual connections of wireless devices to the towers. Traditional telecommunications research and education involve programming the communication channels and source codes with a single user in mind, but when several users and adjacent base stations share the same frequency channel it may not be possible to achieve the maximum channel capacity. RRM is particularly important in systems restricted by co-channel (within the same channel) interference rather than by external noise. For instance, cellular systems and broadcast networks simultaneously covering large areas and wireless networks consisting of many adjacent access points reuse the same channel frequencies and may produce interferences for each other in the same channel.

RRM also helps to maintain the spectral efficiency of the network within a budget. The cost for deploying a wireless network normally consists of base station site costs (real estate costs, planning, maintenance, distribution network, energy, etc.) and sometimes also by frequency license fees. RRM also maximizes the system spectral efficiency under some kind of user fairness constraint or grade of network quality so that the network quality doesn't drop below a certain level for the users in pursuit of achieving maximum efficiency.

While classical radio resource management primarily considered the allocation of time and frequency resources (with fixed spatial reuse patterns), recent multi-user MIMO techniques enable adaptive resource management in the spatial domain also.

Various Types of RRM:

Static radio resource management

Static RRM involves manual as well as computer-aided fixed cell planning or radio network planning. Static RRM schemes are used in many traditional wireless systems, for example - 1G and 2G cellular systems and also in today's wireless local area networks and non-cellular systems, for example - broadcasting systems.

Dynamic radio resource management

Dynamic RRM schemes adaptively adjust the radio network parameters to the traffic load, user positions, user mobility, quality of service requirements, base station density, etc. Dynamic RRM schemes are designed mainly to minimize expensive manual cell planning and implement stricter frequency reuse patterns to improve system spectral efficiency. 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.

Inter-cell radio resource management

Future networks, like the LTE and 5G standards, are designed in a way such that they reuse frequencies. In such networks, neighboring cells use the same frequency spectrum. Such standards use Space Division Multiple Access (SDMA) modulation and can thus be highly efficient in terms of spectrum but require close coordination between cells to avoid excessive inter-cell interference. In most cellular system deployments, the overall system spectral efficiency is not limited by range or noise but by interference. Inter-cell RRM coordinates resource allocation between different cell sites by using multi-user MIMO techniques. There are other various inter-cell interference coordination (ICIC) techniques also defined in the standards of these dynamic single-frequency networks like coordinated scheduling, multi-site MIMO or joint multi-cell precoding which are used in inter-cell RRM.