Directional share and ranking based neighboring cell list optimization algorithm in UMTS cellular network

Handover is the main technique that is responsible for the mobility management in the cellular network. The decisions of handover from each cell is only limited to a certain number of cells called neighbors and the list that contains these neighbors is called the neighboring cell list (NCL). Improper construction of NCL may result in either missing some important neighbors or choosing unnecessary neighbors that increase the number of drop calls, the blocking rate and the suboptimal handover decisions while decreases the signal quality. As a solution, NCL optimization is done to remove the effect of improper NCL construction where the missing neighbors to be added and the unnecessary neighbors to be removed are detected using the handover statistics and a new UMTS feature called the detected set reporting (DSR). In this paper, a novel formulation for the NCL optimization problem is introduced that contains new criteria for evaluating the reported DSR cells. The new criteria evaluates the cells according to their directional share (D), distance from the cell under optimization and drop calls in addition to the share (S) which already exist in literature. The criteria and the constraints in formulation ensure the connectivity of users as they move away from the serving cell towards any direction in addition to add the missing neighbors that cause call drops and prohibit the addition of the far neighbors to the NCL since they will suffer from downlink interference. Finally, a complete NCL optimization algorithm is introduced that removes the drawback of the previous optimizations and solves the constrained formulation by ranking the reported cells. The results showed a decreased drop call rate with a decreased DSR signaling traffic compared to the previous introduced algorithms.