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The prevalent assumption in the current utility maximisation-based rate control and scheduling solutions for multihop wireless networks has been that bounded packet end-to-end delay can be attained by guaranteeing a pre-specified bandwidth. However, in addition to the inherent complexities in determining the exact bandwidth, this approach requires an admission control strategy. In this paper we present...
Small cells are popular deployment options for coverage holes and capacity hotspot areas. Due to the poor outdoor-to-indoor propagation property of in-building environment, a dedicated wireless system installed inside the building is often preferred for providing indoor users high-data-rate services. Distributed antenna systems and Femto cells are cost-efficient techniques for this application. In...
In this paper, we consider the precoding problem in the nonregenerative dual hop multi-input multi-output (MIMO) relay system. We propose a joint beamforming and power allocation method for a limited feedback system where a codebook-based beamformer is considered for each hop. The destination node selects the optimal beamforming codeword by relying on full channel knowledge of both source-relay and...
In this paper, a group-wise joint detection (JD) algorithm is proposed for dual rate time division-synchronization code division multiple access (TD-SCDMA) systems. The proposed algorithm first groups users based on their data rates and then deals with them group by group starting from the group of high data rate users (HRUs). Simulation results illustrate that compared to conventional JD algorithms,...
In this paper we present a novel joint network-channel coding scheme for the time-division Multiple Access Relay Channel (MARC), which combines Bit-Interleaved Coded Modulation with iterative decoding (BICM-ID) based on nonbinary Low-Density Parity Check (LDPC) codes, along with the linear combination of blocks of data at the relay. The common receiver iteratively exchanges soft information between...
Low complexity, iterative MIMO detection algorithms are derived based on pair-wise Markov random fields (MRF). We consider two types, namely, the fully-connected and the ring-type MRF and, for the edge potentials, we use the bivariate Gaussian function obtained by marginalizing the posterior joint probability density under Gaussian-input assumption. Since the corresponding factor graphs has only 2...
Exploiting base station cooperation in wireless mobile access networks leads to benefits in wireless transmission capacity, inter-cell interference management, and cell edge user experience. The clustering of cooperative Base Station (BS) sets, necessary for achieving the desired wireless performance, poses several challenges in the backhaul architecture design. This paper addresses the problem of...
Per-cell codebook based limited feedback strategy is desirable for coordinated multi-point (CoMP) transmission system due to its scalability. In this paper, we study phase ambiguity quantization for centralized CoMP system with per-cell codebook based global channel quantization. We first analyze the performance degradation led by the phase ambiguity when codeword is selected for each cell separately,...
We consider joint scheduling and diversity to enhance the benefits of multiuser diversity in a multiuser OFDMA scheduling system. The OFDMA spectrum is assumed to consist of resource blocks and the reduced feedback scheme consists of each user feeding back only the best- signal to noise ratios. Assuming maximum SNR scheduling, we develop a framework to analyze the performance of both...
It is well known that coordinated multi-cell transmission in downlink (DL) is a promising technique to significantly increase the system throughput and cell-edge user throughput. In this paper, we propose a scalable two-stage channel feedback mechanism not only to support downlink single-cell multi-user MIMO (MU-MIMO), but also to efficiently support multi-cell coordination. This scheme yields remarkable...
We study and propose joint power control and cell-site selection schemes for cognitive cellular radios in fading channels. New analytical result on the cognitive radio cell coverage is presented in terms of the outage probability requirement of the primary cellular radio user. A new interference model for the secondary user (SU) is proposed, which includes the transmit powers from all the primary...
Uplink multi-user direct sequence-code division multi-access (DS-CDMA) suffers from strong multi-user interference (MUI) and self inter-chip interference (ICI) caused by severe frequency-selective fading. In this paper, we propose a joint Tx/iterative Rx frequency-domain equalization (FDE) based on minimum mean square error (MMSE) criterion and successive MUI cancellation (MUIC) for DS-CDMA uplink...
Coherent multi-cell cooperative transmission, also referred to as coordinated multi-point transmission (CoMP), is a promising way to provide high spectral efficiency for universal frequency reuse cellular systems. To report the required channel information to the transmitter in frequency division duplexing systems, limited feedback techniques are often applied. Considering that the large scale fading...
In this paper we propose the use of QAM constellations, specifically 4, 16, and 64-QAM, in severely time-dispersive channels and with moderate CFOs (Carrier Frequency Offsets). We consider an SC-FDE (Single Carrier Frequency-Domain Equalization) and assume that previously to the equalization procedure a coarse CFO estimation and compensation is performed. Since the coarse CFO estimate can have a significant...
We consider a time division multiple access (TDMA) based cognitive wireless mesh network (CWMN), where pairs of mesh nodes communicate with each other by sharing a spectrum that is licensed to a primary network with multiple primary users (PUs) who have exclusive right to occupy the spectrum. All the mesh nodes are equipped with multiple antennas capable of beamforming. For such a system, we investigate...
Antenna subset selection is a cost-effective way of exploiting the spatial dimension by only using a subset of the available antennas and thereby reducing the number of RF chains. A simple but effective way of precoding signals in multiantenna OFDM systems using antenna subset selection is per-tone antenna selection, which can be applied to the chosen subset. In a TDD system, estimates of the strength...
We provide an analytical formula to evaluate the performance of the uplink of planar cellular networks when joint processing is enabled among limited number of base stations in a generalised fading environment. Focusing on user transmission power allocation techniques to mitigate inter-cluster interference we investigate the system's spectral-energy efficiency trade-off. The paper addresses the gains...
This paper proposes low-complexity joint timing synchronization and channel estimation for multiple-input multiple-output orthogonal frequency-division multiplexing systems based on maximal length sequences. Under a Rayleigh channel assumption, an optimal threshold for the proposed joint scheme is derived, and a practical suboptimal threshold that requires neither pre-simulation nor prior information...
One of the primary aims of radio network planning is to place and configure the transmit antennas of the base stations such that the deployment achieves the required quality of service. Long term evolution (LTE) systems are operated with frequency reuse one and, therefore, a proper configuration of the antenna azimuth orientations and tilts is essential to mitigate the inter-cell interference. Various...
We propose and analyze a class of distributed algorithms performing the joint optimization of radio resources in heterogeneous cellular networks made of a juxtaposition of macro and small cells. We show that within this context, it is essential to use algorithms able to simultaneously solve the problems of channel selection, user association and power control. In such networks, the unpredictability...
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