Load Balancing Algorithm in Multi-Channel Group Cells in Radio Networks
Original Publication Date: 2003-Apr-25
Included in the Prior Art Database: 2003-Apr-25
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The target of load balancing is the distribution of services on different processing units until the optimum balance is achieved. It is a powerful means for low and medium traffic situation, while in high traffic situations the load is automatically balanced due to high number of channels used. Load balancing algorithms are applied in many of today’s electronic systems but are not yet used between different channel groups of a cell in mobile radio networks. In cellular networks the essential impact on quality and capacity is the interference. It is generated e.g. in reference cells and perceived in cells that use the same frequency-time slot combination at a certain reuse distance. This is called co-channel interference. There is also the adjacent channel interference, which is related to the filter characteristics of transmitter and receiver. Each cell uses a subset of the available frequencies of the complete network. With increasing demand for capacity the frequency reuse distance has been reduced and in consequence the interference level has increased. The currently applied algorithms for resource allocation offer the preferred allocation on distinct channel groups taking into account the number of resources available on different channel groups and the affected running services. They do not offer load balancing mechanisms between the different channel groups of a cell. As an example the following algorithm is applied for the allocation of a new GPRS (General Packet Radio System) service in horizontal allocation. It is executed step by step and stops if a certain criterion is fulfilled by one option, but not by the other: 1. Maximum number of empty channels 2. Maximum number of reserved Packet Data Traffic Channels (PDTCH) / reuse of time slots already in packet mode 3. Minimum number of affected TBFs (Temporary Block Flow) already running / minimum number of forced hand-over on CS calls 4. Maximum number of adjacent time slots to the ones already in packet transfer mode 5. Preference expressed by callPolicy This invention describes a simple but effective algorithm for load balancing that can be applied within multi-channel group radio networks (e.g. Global System for Mobile Communications GSM, Universal Mobile Telecommunications System UTMS) and between different network technologies. Therefore only the last criterion shall be considered and combined with load thresholds. The callPolicy expresses the preferred allocation of a service on a certain channel group. The channel group is a subset of the channels available in the cell. The number of channels assigned to this channel group, which is now referred to as “layer”, can vary dynamically.