Outage Capacity of Bursty Amplify-and-Forward with Incremental Relaying

We derive the outage capacity of a bursty version of the amplify-and-forward (BAF) protocol for small signal-to-noise ratios when incremental relaying is used. We show that the ratio between the outage capacities of BAF and the cut-set bound is independent of the relay position and that BAF is outage optimal for certain conditions on the target rate R. This is in contrast to decode-and-forward with incremental relaying, where the relay location strongly determines the performance of the cooperative protocol. We further derive the outage capacity for a network consisting of an arbitrary number of relay nodes. In this case the relays transmit in subsequent partitions of the overall transmission block and the destination accumulates signal-to-noise ratio until it is able to decode.Comment: 5 pages, 3 figures, submitted to IEEE International Symposium on Information Theory, Austin, TX, June 13-18, 201

Influence of Intra-cell Traffic on the Output Power of Base Station in GSM

In this paper we analyze the influence of intracell traffic in a GSM cell on the base station output power. It is proved that intracell traffic increases this power. If offered traffic is small, the increase of output power is equal to the part of intracell traffic. When the offered traffic and, as the result, call loss increase, the increase of output power becomes less. The results of calculation are verified by the computer simulation of traffic process in the GSM cell. The calculation and the simulation consider the uniform distribution of mobile users in the cell, but the conclusions are of a general nature

Error performance analysis of n-ary Alamouti scheme with signal space diversity.

Masters Degree. University of KwaZulu-Natal, Durban.In this dissertation, a high-rate Alamouti scheme with Signal Space Diversity is developed to improve both the spectral efficiency and overall error performance in wireless communication links. This scheme uses high modulation techniques (M-ary quadrature amplitude modulation (M-QAM) and N-ary phase shift keying modulation (N-PSK)). Hence, this dissertation presents the mathematical models, design methodology and theoretical analysis of this high-rate Alamouti scheme with Signal Space Diversity.To improve spectral efficiency in multiple-input multiple-output (MIMO) wireless communications an N-ary Alamouti M-ary quadrature amplitude modulation (M-QAM) scheme is proposed in this thesis. The proposed N-ary Alamouti M-QAM Scheme uses N-ary phase shift keying modulation (NPSK) and M-QAM. The proposed scheme is investigated in Rayleigh fading channels with additive white Gaussian noise (AWGN). Based on union bound a theoretical average bit error probability (ABEP) of the system is formulated. The simulation results validate the theoretical ABEP. Both theoretical results and simulation results show that the proposed scheme improves spectral efficiency by 0.5 bit/sec/Hz in 2 × 4 16-PSK Alamouti 16-QAM system compared to the conventional Alamouti scheme (16-QAM). To further improve the error performance of the proposed N-ary Alamouti M-QAM Scheme an × N-ary Alamouti coded M-QAM scheme with signal space diversity (SSD) is also proposed in this thesis. In this thesis, based on the nearest neighbour (NN) approach a theoretical closed-form expression of the ABEP is further derived in Rayleigh fading channels. Simulation results also validate the theoretical ABEP for N-ary Alamouti M-QAM scheme with SSD. Both theoretical and simulation results further show that the 2 × 4 4-PSK Alamouti 256-QAM scheme with SSD can achieve 0.8 dB gain compared to the 2 × 4 4-PSK Alamouti 256-QAM scheme without SSD

Resource Allocation for Vertical Sectorization in LTE-Advanced Systems

Massive multiple input multiple output (MIMO) technology has been discussed widely in the past few years. Three-dimensional MIMO (3D MIMO) can be seen as a promising technique to realize massive MIMO to enhance the performance of LTE-Advanced systems. Vertical sectorization can be introduced by means of adjusting the downtilt of transmitting antennas. Thus, the radiowave from a base station (BS) to a group of user equipments (UE) can be divided into two beams which point at two different areas within a cell. Intrasector interference is inevitable since the resources are overlapped. In this paper, the influence of intrasector interference is analyzed and an enhanced resource allocation scheme for vertical sectorization is proposed as a method of interference cancellation. Compared with the conventional 2D MIMO scenarios, cell average throughput of the whole system can be improved by vertical sectorization. System level simulation is performed to evaluate the performance of the proposed scheme. In addition, the impacts of downtilt parameters and intersite distance (ISD) on spectral efficiency and cell coverage are presented

Efficient channel allocation and medium access organization algorithms for vehicular networking

Due to the limited bandwidth available for Vehicular Ad-hoc Networks (VANETs), organizing the wireless channel access to efficiently use the bandwidth is one of the main challenges in VANET. In this dissertation, we focus on channel allocation and media access organization for Vehicle-to-Roadside Units (V2R) and Vehicle-to-Vehicle (V2V) communications. An efficient channel allocation algorithm for Roadside Unit (RSU) access is proposed. The goal of the algorithm is to increase system throughput by admitting more tasks (vehicles) and at the same time reduce the risk of the admitted tasks. The algorithm admits the new requests only when their requirements can be fulfilled and all in-session tasks\u27 requirements are also guaranteed. The algorithm calculates the expected task finish time for the tasks, but allocates a virtual transmission plan for the tasks as they progress toward the edges of the RSU range. For V2V mode, we propose an efficient medium access organization method based on VANETs\u27 clustering schemes. In order to make this method efficient in rapid topology change environment like VANET, it\u27s important to make the network topology less dynamic by forming local strongly connected clustering structure, which leads to a stable network topology on the global scale. We propose an efficient cluster formation algorithm that takes vehicles\u27 mobility into account for cluster formation. The results of the proposed methods show that the wireless channel utilization and the network stability are significantly improved compared to the existing methods

Resource Management for Device-to-Device Communications in Heterogeneous Networks Using Stackelberg Game

Device-to-device (D2D) communications and femtocell systems can bring significant benefits to users’ throughput. However, the complicated three-tier interference among macrocell, femtocell, and D2D systems is a challenging issue in heterogeneous networks. As D2D user equipment (UE) can cause interference to cellular UE, scheduling and allocation of channel resources and power of D2D communication need elaborate coordination. In this paper, we propose a joint scheduling and resource allocation scheme to improve the performance of D2D communication. We take UE rate and UE fairness into account by performing interference management. First, we construct a Stackelberg game framework in which we group a macrocellular UE, a femtocellular UE, and a D2D UE to form a two-leader one-follower pair. The cellular UE are leaders, and D2D UE is the follower who buys channel resources from the leaders. We analyze the equilibrium of the game and obtain solutions to the equilibrium. Second, we propose an algorithm for joint scheduling of D2D pairs based on their utility. Finally, we perform computer simulations to study the performance of the proposed scheme