Abstract: Adaptive resource allocation can drastically increase the throughput of an Orthogonal Frequency Division Multiple Access (OFDMA) system when the Channel State Information (CSI) is accurately known. Unfortunately, in practice, perfect CSI is rarely possible. In this paper, we study

Orthogonal Frequency Division Multiplexing (OFDM) has become the de facto standard for fourth generation wireless networks[5]. In such a network, the frequency band is divided into numerous orthogonal sub-carriers. In each time-slot, disjoint sets of sub-carriers can be assigned to users based

Efficient radio resource management is essential in Quality-of-Service (QoS) provisioning for wireless communication networks. In this paper, we propose a novel priority-based packet scheduling algorithm for downlink OFDMA systems. The proposed algorithm is designed to support heterogeneous applications consisting of both real-time (RT) and non-real-time (NRT) traffics with the objective to increase the spectrum efficiency while satisfying diverse QoS requirements. It tightly couples the subchannel allocation and packet scheduling together through an integrated cross-layer approach in which each packet is assigned a priority value based on both the instantaneous channel conditions as well as the QoS constraints. An efficient suboptimal heuristic algorithm is proposed to reduce the computational complexity with marginal performance degradation compared to the optimal solution. Simulation results show that the proposed algorithm can significantly improve the system performance in terms of high spectral efficiency and low outage probability compared to conventional packet scheduling algorithms, thus is very suitable for the downlink of current OFDMA systems.

patterns of the access terminals, integrating MIMO techniques in a wireless WAN system has been a difficult design problem. This paper overviews the multi-antenna techniques used in evolved 3G wireless communications systems, such as 3GPP2 Ultra-Mobile Broadband (UMB), IEEE Mobile Broadband Wireless Access

Abstract—The number of Machine-to-Machine (M2M) appli-cations is rapidly increasing in cellular communication systems. In order to ensure a maximum system capacity, the impact of this special kind of traffic on common Human-to-Human (H2H) communication needs to be analyzed. In this paper, a system model for performance evaluation of cellular networks like Long Term Evolution (LTE) in the presence of M2M communication and under different Quality of Service (QoS) constraints is presented. By means of a Markovian model, which is parameterized by laboratory measurements and ray tracing simulations, an estimation of the behavior of LTE for different traffic characteristics is shown. We present blocking probabilities for an LTE network with heterogeneous M2M and H2H traffic and compare different transmission strategies for M2M communication to minimize the impact on human users. The results show that particularly a large number of devices with a low data rate influences the utilization of an LTE cell very negatively.

Abstract—This paper studies various cooperative diversity

Abstract-Orthogonal frequency division multiple access (OFDMA) has been adopted by all the proposals which have been considered for the fourth generation (4G) wireless technologies. Specifically, the two main contenders in the 4G marketplace are likely to be evolutions of WiMAX and LTE

In this paper we propose a non-data aided synchronization algorithm for orthogonal frequency division multiple access systems. The method is applied to both quasisynchronous and asynchronous systems. The proposed algorithm does not require the transmission of training sequences or of repeated

two approaches to reduce this overhead by exploiting the correlation in frequency. These two schemes are shown to provide a significant reduction of the signaling overhead. 1

We develop synchronization algorithms for both the downlink and the uplink of quasi-synchronous and asynchronous orthogonal frequency division multiple access systems. Unlike existing alternatives, the proposed time- and carrier-offset estimators do not require the transmission of known sequences