# Game Theory-Based Load-Balancing Algorithms for Small Cells Wireless Backhaul Connections +
## 3 Results
### The Architecture of the Simulation Platform Used for the Evaluation of the LB Algorithms
#### 3.1.2 The Wireless Channel Simulator Module  
The cellular network scenario considered in the design of the wireless channel simulator is presented in Figure 1. The scenario is a realistic one that supposes the overlapping of the coverage area of several base stations using the same or different wireless access technologies. A device, i.e., a mobile router or a mobile AP, equipped with \(N\) cellular network interfaces is moving in an area covered by \(N\) independent wireless networks. The device follows a random walk motion pattern, and when the device arrives at the border of the cell, the position of the new serving base station is generated randomly so that the radius of the cells follows a Gaussian distribution with predefined parameters. In this case, we obtain a realistic network topology where the position of the base stations differs from one operator to another as well as the size of the cells the user passes through while moving on his route. It is also assumed that all networks serving the device have approximately the same load, which is less than their capacity, and each network uses a proportional fair radio resource management algorithm. In this case, the average transfer rate obtained by the device is highly related to the radio channel characteristics experienced by that device. In this simulator, it is considered that the instantaneous transfer rate is proportional with the effective instantaneous Signal to Noise Ratio (SNR) observed at the input of the considered receiver. The considered effective SNR-transfer rate mapping model is depicted in Figure 7. A modified ITU Vehicular B [46] channel model was considered, with mean mutual information per coded bit (MMIB)-based link to the system mapping technique. As an example, a particular situation regarding the capacity variation of the virtual tunnels established between the AP and the four base stations depicted in Figure 1 is presented in Figure 8. In Table 1 are presented the max./min. values and the mean, median, and standard deviation values of the transfer rates of the 4 considered tunnels. Can be noticed that some of the tunnels provide relatively constant transfer rates (tunnels 2 and 4), while on other tunnels the transfer rates varies significantly in time (tunnels 1 and 3). Figure 8: Variation in time of the capacity of the tunnels established over the macro cell wireless links. Figure 7: Effective SNR–bitrate mapping. The Architecture of the Simulation Platform Used for the Evaluation of the User Clustering Algorithms  
To test the proposed user clustering algorithms another simulation platform, depicted in Figure 9, was developed. The integration of the users' clustering algorithms in the complex simulation platform used for the evaluation of the presented LB algorithms is relatively difficult to perform. The developed platform includes the data flows generation module (User Cluster Traffic Generator), based on the considered traffic models (see Tables A1-A5) and traffic mixture specified in Table 2. To simplify the simulation a single output tunnel is considered, and this could be an aggregated tunnel. This aggregated tunnel is simulated by the Wireless Channel Simulator module. An AP Controller module is integrated into the simulation platform. This module receives the aggregated tunnel queues' status information and the data flows' characteristics and controls the transmission power of the APs according to the used clustering algorithm. Based on the selected transmission power the user clusters connected to different APs are generated, more users connecting to the APs with larger power. This approach has the target to simplify the users' access to the APs, only the power of the APs being manipulated. The APs with more available resources increase their transmission power on the AP-user links, while the APs with fewer available resources maintain or reduce their transmission power.