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Reducing the energy consumption in wireless networks while maintaining the promised Long Term Evolution (LTE) high data rate has become a significant problem for network providers. To tackle these two conflicting objectives, this paper proposes to use Pico-eNBs in conjunction with a centralized switch on/off algorithm to create an adaptive radio coverage to match the radio resources to the user demand. The proposed approach relies on developing advanced centralized Self Organizing Network (SON) techniques to deploy, monitor and manage radio resources. The simulation results show that the proposed algorithm for adaptive coverage has improved the average throughput from 5.9 Mbps using Macro-eNBs to 47.9 Mbps, and the power consumption was reduced.

Traditional cellular network infrastructure provide fixed radio coverage. The temporal changes in user distribution throughout the day and from day to day leads to inefficient use of radio resources. Our position is to create an adaptive radio coverage to match the radio resources and user demand. The main approach for creating flexible radio coverage (in our view) is to replace large cells with many small cells that can be switched ON and OFF as needed. The small cells have the added crucial advantage of supporting the very high data rates expected in future networks. The proposed approach will rely on developing advanced Self Organizing Network (SON) techniques to deploy, monitor and manage radio resources in the small cells. This paper discusses requirements for this approach and how it can be implemented within the SON.

This paper presents a study of the Dedicated Short Range Communication (DSRC) Physical Layer in order to determine its reliability for Vehicle-2-Vehicle (V2V) communication under varying Signal-to-Noise Ratio (SNR), vehicle speed, delay spread, and packet lengths. In particular, we focus on computing the expected delay when packets with errors are retransmitted until received correctly. IEEE 802.11a MatLab model was used to simulate the DSRC Physical Layer.

Mobile users scattered in a microcell and communicating with co-located base station antennas, may cause a severe near-far problem for an uplink space division multiple access (SDMA) system. Also correlations within the multi-input multi-output (MIMO) channel matrix, in such uplink SDMA propagation scenario, can cause significant degradation in system performance. In this paper, we investigate the above problems. We propose to distribute the base station antennas, as multi- antenna arrays, at different sites in the microcell and deploy a correlation reduction algorithm. A significant improvement in the performance of the SDMA system is evident.

The ability of the base station to separate several users spatially depends on the pair-wise cross-correlations between the channel vectors of the users. In this paper we propose an improved uplink multi-user MIMO-OFDM system that reduces the intra-user correlations resulting in significant enhancement in the SDMA system performance. In this system, several base station multi-antenna arrays are distributed in a given area. Each array is communicating with the base station via optical fiber links. All signal processing is performed at the base station. Users are spatially separated such that in each tone of the OFDM symbol only a certain number of users (out of the total number of users) are selected. The selection is based on an algorithm that reduces the pair-wise intra-user correlations. Such a reduction in channel matrix correlations decreases the convergence time of iterative adaptive algorithms such as the LMS algorithm. The channel vector of each user is assumed correlated and Ricean distributed

The near-far problem and the correlations in a MIMO channel are two major obstacles in the way of widely implementing Space Division Multiple Access (SDMA) systems. In this paper we investigate the effect of distributing the basestation antennas and the reduction of intra-user correlations on the performance of a MIMO-OFDM system in which a basestation, composed of distributed antenna arrays, is communicating (downlink transmission) with several single antenna mobile users. The arrays are located at different sites in a Ricean-Lognormal channel environment. Very significant improvement in system performance is achieved due to the improved spatial properties of the MIMO channel and due to the reduction of channel matrix correlations.