Other-cell interference in CDMA systems

Abstract

Using simulation and modelling, the other-cells interference factor for CDMA systems is obtained. Situations with tiers of neighbouring cells are investigated under various propagation parameters and for two scenarios, when the mobile chooses the nearest base station, and when it chooses the base station with the strongest signal as home cell. The results presented indicate that in most situations the other-cells interference factor can be significantly less than the upper bounds result published previously. It is concluded that it is enough to compare the link attenuation of three neighbouring cells to find the home cell.

Simulation Model, Warm-up Period, and Simulation Length of Cellular Systems

“…The first model developed was a M/M/1 queue with Poisson arrivals with exponential call holding times, single queue, single server, and no limit on the size of the queue. The average number of uses in the system is given by the formula [17,18]      N (11) Using both the analytical and simulation method, for arrival rate (λ) of 0.8 and call holding time (1/μ) of 1, the average number of calls in the system was found to be four. As the system has infinite size, there will be no call losses and probability of blockage is always zero.…”

“…SYSTEM MODEL A cellular CDMA system (a home cell and three tiers of neighbouring cells as discussed in [10]) is considered with a base station located at the centre of each cell. The signal strengths of three neighbouring cells are compared to find the home cell as found in [11]. Calls are considered to suffer log-normal shadowing (but not Rayleigh fading [12]).…”

“…Assuming a CDMA system with M outer cells and N users per cell, then the total other user interferences-to-signal ratio The system model is further explained in [11,16] …”

Analysis of Results in Simulation and Modeling of CDMA Systems

“…The signal strengths of three neighboring cells are compared to find the home cell as found in [6]. Calls are considered to suffer log-normal shadowing (but not Rayleigh fading [7]).…”

“…The reverse link (mobile to base station) is investigated as it is the limiting link due to its inferior performance compared to the forward link [8,9]. The simulation model and blocking probability calculations are further explained in [6,10,11] …”