Hybrid channel borrowing and directed retry in highway cellular communications

Channel borrowing without locking (CBWL) is a new family of channel assignment and sharing methods for cellular communications. It uses an easily managed channel layout along with reduced transmitted power on borrowed channels to limit co-channel interference. In CBWL, mobiles which are close to a base site can use channels of neighboring cells through the closest base sites. Directed retry, on the other hand, allows users who are near the boundaries of cells to access channels of neighboring cells through the neighboring base sites. The two schemes are complementary in the sense that they benefit users in different areas. The hybrid scheme presented has the advantages of CBWL and directed retry such as high channel capacity and simple channel management. It also overcomes their disadvantages such as high system processing loads and intracell hand-off. We model and simulate a highway cellular system that uses the hybrid scheme. The blocking probabilities, hand-off failure probabilities and hand-off activity factors are collected from simulation. The results show that in comparison with FCA, the scheme can significantly improve system performance