Description: Abstract: In this paper we present an algorithm, based on power management of Access Points (AP), to reduce congestion in Wireless Local Area Networks (WLANs). The algorithm finds the Most Congested Access Point (MCAP) and adjusts its transmitted power in discrete steps and determines the optimal users' assignment such that an optimal load distribution is achieved. Results show that the algorithm is capable of significantly reducing the overall congestion in the WLAN.

Description: This paper discusses non-uniform grid-based routing in sensor networks. Abstract: A non-uniform grid-based coordinated routing design in wireless sensor networks is presented. The conditions leading to network partition and analysis of energy consumption that prolongs the network lifetime are studied. We implement routing in heavily populated sensor networks. By maintaining constant values for parameters such as path loss exponent, receiver sensitivity and transmit power, and varying between uniform and non-uniform grids, we observe energy consumption patters for each of the grid structures, and infer from the network lifetime the better suited grids for uniformly and randomly deployed sensor nodes.

Description: In this article, an enhanced channel-assignment algorithm at the Access Points (APs) of a Wireless Local Area Network (WLAN) is validated. The algorithm aims to maximize the Signal-to-Interference Ratio (SIR) at the user level in order to determine the appropriate channel at the APs. The initial channel assignment step at the APs is based on minimizing the total interference between APs. Based on this initial assignment, the SIR for each user is calculated. Then, another channel assignment is performed based on maximizing the SIR at the users. The algorithm can be applied to any WLAN, irrespective of the user distribution and user load. Results show that the algorithm is capable of significantly increasing the SIR over the WLAN, which in turn should improve throughput. Therefore, the authors use OPNET simulation tool to construct several realistic scenarios in order to validate our results.

Description: This paper discusses parity assisted decision making for QAM modulation. A simple technique which involves the transmission of a Quadrature Amplitude Modulation (QAM) symbol and two parity bits in separate channels to improve the performance of communication systems is devised. When a symbol is received, a decision is made not solely by its Euclidean distances to the constellation points. Rather, the two parity bits are used to assist in making the decision. Unlike standard error correcting codes (ECC), the proposed method operates on the received symbols at the detector level and before the ECC. The parity bits and the information symbols can be sent in different channels (frequency division) or at different times on the same channel (time division). The available energy for transmission can be distributed unevenly among the information bits and the parity bits to improve the performance. Simulation results show large gains in required signal to noise ratios over uncoded system to achieve the same performance. The scheme is simple and is well suited for systems with low computational power.

Description: This paper discusses subscriber maximization in CDMA cellular networks. The author calculates the maximum number of subscribers in a CDMA cellular network for a given GoS requirement, QoS requirement, network topology, and user distribution profile. The author formulates a constrained optimization problem that maximizes the call arrival rates subject to upper bounds on the blocking probabilities and lower bounds on the bit energy to interference ratios. This paper presents examples for traditional and optimized network topologies with uniform and non-uniform user distribution profiles and different mobility scenarios.