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Terahertz (THz) band communication has abundant spectral resources to accommodate multiple broadband carriers. However, the strong path loss attenuation and the limited transmission power affect the maximum number of carriers that can be activated. A simple way to address this limitation consists in transmitting the same message from multiple transmission points, using Joint-Transmission (JT) Coordinated...
Maintaining both reliable and secret communication involves different objectives: ensuring sufficient throughput for reliable communication and ensuring the secrecy of the associated communication. The optimal solution for one of these objectives might not be optimal or even suitable for another objective and thus a question arises as to what is the appropriate criteria for fairly balancing these...
Time-domain enhanced inter-cell interference coordination (eICIC) scheme using almost blank sub-frames (ABS) is one of the key technologies in Heterogeneous networks (Het-net). Static configuration of ABS has been proven to increase performance but the optimal ABS ratio is yet to be examined. Moreover, combing Coordinated Multi-Point transmission (CoMP), ABS could be more efficiency. This paper proposes...
This paper investigates the resource allocation schemes for Voice over Internet Protocol (VoIP) traffic under high speed train scenario, in which 2-state VoIP traffic model based on Markov chain is considered. Unlike the full-buffer traffic, in which the transmitter buffer is always full of data to be transmitted, VoIP traffic can be characterized by small packets in regular intervals with tight delay...
Abstract-Energy efficiency (EE) has become an increasingly important issue in Device-to-Device (D2D) communications since wireless terminals are hand-held equipments with limited battery life. In this paper, an energy-efficient channel reusing scheme for multi-D2D links is proposed. We first analyze the EE of a single D2D link in both non-cooperative mode (NCM) and cooperative mode (CM), and prove...
It has been shown that, with the instantaneous power constraint and joint power allocation, two-way relaying (TWR) outperforms one-way relaying (OWR) in terms of system throughput. However, the conclusion is not clear for the case with the average power constraint and the case with the instantaneous power constraint but separate power allocation. In this paper, we shall first investigate the optimality...
Two-way relaying is an efficient way to improve the network capacity significantly. Subcarrier mapping (SCM) has been shown to evidently improve the average end-to-end capacity in OFDM relay networks. However perfect channel knowledge is required, which leads to large feedback amount of channel state information (CSI). In this paper, the multi-relay scenario of two-way relaying over OFDM based on...
This correspondence demonstrates the significant gains that multiple-access users can achieve from sharing a single amplify-forward relay in slow-fading environments. The proposed protocol, namely, multiple-access amplify-forward (MAF), allows for a low-complexity relay and achieves the optimal diversity-multiplexing tradeoff (DMT) at high multiplexing gains. Analysis of the protocol further reveals...
In this paper, we propose a robust STBC transmission scheme to combat the timing synchronization errors over frequency-selective multiple-access channels. First, the equivalent channel model in the presence of timing synchronization errors is derived and we find that the synchronization errors result in an equivalent channel model with larger number of correlated channel taps. Based on this correlated...
Some communication applications, like multimedia, deliver data of different importance classes allowing unequal error protection (UEP) levels. In this paper, a multiple-input multiple-output (MIMO) system using orthogonal frequency division multiplexing (OFDM) is considered with a new UEP bit-loading algorithm based on the non-UEP algorithm by Chow, Cioffi, and Bingham. In the proposed bit-loading...
In this paper we present an algorithm, based on power management of access points (AP), to reduce congestion in wireless local area networks (WLANs). The algorithm finds the most congested access point (MCAP) and adjusts its transmitted power in discrete steps and determines the optimal userspsila assignment such that an optimal load distribution is achieved. Results show that the algorithm is capable...
This paper explores the attributes, layering models and objective functions in cross layer designs for mobile ad hoc wireless networks by taking all the statistical characteristics and constraints from the physical (PHY) layer, media access control (MAC) layer and network (NET) layer into consideration. This paper reviews the entire network optimization across all the PHY/MAC/NET layers. At the PHY...
The next generation of wireless networks (4G) will use OFDMA (Orthogonal Frequency Division Multiple Access) in the reverse link. In OFDMA, the reverse link resources assigned to a user are called tiles each of which consists of a subset of consecutive subcarriers. Since at most one user is assigned to each of these tiles then reverse link transmissions within a sector are orthogonal. However, the...
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