A novel load balancing scheme for the tele-traffic hot spot problem in cellular networks

We propose a dynamic load balancing scheme for the tele-traac hot spot problem in cellular networks. A tele-traac hot spot is a region of adjacent hot cells where the channel demand has exceeded a certain threshold. A hot spot is depicted as a stack of hexagonaìRings' of cells and is classiied as complete if all cells within it are hot. Otherwise it is termed incomplete. The rings containing all cold cells outside the hot spot are called`Peripheral Rings'. Our load balancing scheme migrates channels through a structured borrowing mechanism from the cold cells within thèRings' or`Peripheral Rings' to the hot cells constituting the hot spot. A hot cell in`Ring i' can only borrow a certain xed number of channels from adjacent cells in`Ring i+1'. We rst propose a load balancing algorithm for a complete hot spot, which is then extended to the more general case of an incomplete hot spot. In the latter case, by further classifying a cell as cold safe, cold semi-safe or cold unsafe, a demand graph is constructed which describes the channel demand of each cell within the hot spot or its`Peripheral Rings', from its adjacent cells in the next outer ring. The channel borrowing algorithm works on the demand graph in a bottom up fashion, satisfying the demands of the cells in each subsequent inner ring untiìRing 0' is reached. A Markov chain model is also developed for a cell within a hot spot and using these results a similar model is developed to capture the evolution of the entire hot spot region. Detailed simulation experiments are conducted to evaluate the performance of our load balancing scheme. Comparison with another well known load balancing strategy known as CBWL shows that under moderate and heavy tele-traac conditions, a performance improvement as high as 12% in terms of call blockade is acheived by our load balancing scheme.