Since the distance between the Base station and the border area of hexagon shape of the cell varies certain dead zones exist in the coverage at the border of cell, which leads to communication blockage in these areas. In this thesis a theoretical and simulation analysis of communication performance in these areas is discussed. Different enhancement techniques also are analyzed. Relay station is proposed to enhance coverage in gaps, it radiates with frequency which depends on channels distribution technique. Relays also are used to improve capacity of networks by means of Load Balance. Each relay is supposed to have three links one with base station within the same cell and two with other neighboring cells from other two close relays, in order to share traffic between closest relays. Global System for Mobile Communication (GSM) is simulated by using different base station antenna radiation patterns to reduce dead zone area. Relays placed on gaps are also simulated to enhance coverage and improve signal power level at mobile station. Two positions of relay are discussed depending on radiation pattern type of antenna (Omni directional antenna or 120º directional sector antennas) at it. The proposed Cellular system is simulated by using MATLAB software (Version R2010a). Simulation results demonstrate that with a good frequency plan for assign channels to relays, relaying can have a significant improvement on the coverage by enhancing the signal to interference ratio at mobile station, they also show that relay with 120º directional sector antenna has a better Signal toInterference Ratio (SIR) values by about 30 dB near relays position. Results show the outage probability can reduced by 23 % when using sector antenna at relays. Furthermore, these relays can also be used to enhance the capacity of network by using Load Balance technique by decreasing blocking probability that lead to improve spectral efficiency of network and increase the number of user accessed to the network. From results in case of each user generating 25 mE traffic and blocking probability 2% with scenario of using relay and Load Balance it is observed that the number of user increased by 10.5 % for N=4and 20% for N=7.