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Fine timing estimation in timing synchronization scheme of orthogonal frequency division multiplexing systems gives an estimate of symbol starting time index corresponding to the path with maximal power within an interval suggested by coarse timing stage. The actual starting index fed to the following stages is brought forward by an amount that should be adaptive to the estimated index to optimize...
In single-stream multiple-input multiple-output (MIMO) schemes, such as spatial modulation (SM) and space shift keying (SSK), a single transmit antenna is activated at any given time. Therefore, unlike multi-stream MIMO transmitters, simultaneous pilot transmissions are prohibitive because of a single radio-frequency (RF) chain. In state-of-the-art literature, the channels of different transmit antennas...
We propose an adaptive scheme of a differential codebook for temporally correlated channels. The codeword entries of the proposed codebook are selected among the set of M-PSK constellations and the values of M proposed in this paper are 8, 16, or 32. Firstly, we analyze mathematically how the optimal spherical cap radius of the proposed codebook is tracked. Then, we explain how to implement the proposed...
In this paper we address the design of MIMO double codebook structure for cross-polarized antenna arrays. Double codebooks consist of two codebook components, a wide-band long-term component and a short-term sub-band component. Herein we study particularly the two layer short-term sub-band component and provide the complete set of structure types leading to orthogonal constant modulus codewords and...
This paper proposes a new codebook structure called Kronecker-product based codebook (KPC), where each codeword is the Kronecker product of two oversampled DFT codewords in both the horizontal and vertical domains. The KPC is especially suitable for the three-dimensional (3D) multiuser multi-input multi-output (MU-MIMO) systems. Besides, channel state information feedback based on the best companion...
Spatial Modulation is a newly developed concept for multi-antenna systems, which could greatly reduce the signal processing complexity and hardware implementation burden faced by these systems today. To improve the spectral efficiency of spatial modulation system, a novel precoding scheme for downlink multi-user system is proposed in this paper. The precoding scheme not only cancels the inter-user...
In wireless resource allocation, improving system throughput and simultaneously enhancing user fairness are two fundamental but contradictory objectives. As for fairness, both short-term and long-term fairness are of significant importance. However, less effort has been dedicated to explore the optimal tradeoff between system throughput and the two mentioned fairness in terms of widely used Jain's...
Machine-to-machine (M2M) communications exhibit quite different characteristics, compared with human-to-human (H2H) communications. Since the number of M2M devices is much larger than that of users for H2H communications, it may cause a shortage problem of radio resources if we do not consider an efficient radio resource management scheme. In this paper, we propose an efficient resource allocation...
In this paper, we propose a strategy for resource allocation for different traffic classes at the Medium Access Control (MAC) layer of wireless systems based on Orthogonal Frequency Division Multiple Access (OFDMA), such as the recent Long-Term Evolution (LTE) wireless standard. In order to achieve inter-class fairness, we propose a modification of the Virtual Token Modified Largest Weighted Delay...
Enhancing system throughput and improving user fairness are two basic but contradictory objectives for resource allocation in wireless cellular networks. To obtain an efficient tradeoff between these two goals, Network Utility Maximization (NUM) framework has been adopted with log-utility to obtain proportional fairness among all the users in the network. However, such tradeoff can not control the...
More and more Coordinated Multi-Point (CoMP) systems are attracting interest as a means to improve the performance of conventional cellular networks, particularly thanks to the joint processing approach. However, the large amount of signaling and computer operations required deserves special attention regarding both backhaul and radio resources constraints. Partitioning the set of transmission points...
Coordinated wireless point-to-point networks constitute a reliable and cost-efficient technology for providing backhaul connectivity for access networks in remote or topologically challenging environments, e.g. mountainous regions. Their flexibility allows for joint operation with any kind of access networks (including cellular), temporary or mobile deployment (e.g., for sport or entertainment events),...
In traditional cellular networks, User Equipments (UEs) always connect to the strongest Base Station (BS), which offers either the maximum Signal to Interference Plus Noise Ratio (SINR) or the best Reference Signal Received Power (RSRP). However, in heterogeneous networks, due to a large difference of transmit power between macrocells and low power nodes, the user association methods mentioned above...
Small-cell deployment within a wireless Heterogeneous Network (HetNet) presents backhauling challenges that differ from those of conventional macro-cells. Due to the lack of availability of fixed-lined backhaul at desired locations and due to cost saving reasons, operators may deploy a variety of backhaul technologies in a given network, combining available technologies such as fiber, xDSL, wireless...
Due to the changing network topology and the time and location varying spectrum availability in Cognitive Radio Networks (CRNs), there is a need of on-demand searching for a control traffic channel by CR users in order to be able to initiate a communication. This neighborhood discovery phase, also referred to as a rendezvous (RDV) phase, is challenging due to the dynamics of CRNs. There are a number...
A resource allocation scheme involving several Device-to-Device (D2D) multicast groups underlaying OFDMA-based systems is proposed in this paper. In order to guarantee Quality of service (QoS) of cellular users (CeUEs), we define the signal-to-interference-pulse noise ratio (SINR) threshold value for CeUEs. Meanwhile, the minimum throughput of a single D2D multicast group is predetermined to maintain...
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