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In this paper, an effective joint allocation of power and subcarriers is proposed under the total power constraint, aiming to maximize the capacity of OFDMA relaying network. In DF (decode and forward) scheme, an equivalent transmit rate formulation is developed, optimal power allocation is obtained by linear optimization and Lagrange multiplier method. By using this optimal power allocation, an efficient...
In this paper we evaluate the coded and uncoded performance of a 2-antenna terminal relaying scheme, for downlink OFDM based systems, using efficient space-frequency block coding protocols. We consider that the relay and the base station are equipped with 2 antennas and the user terminal has a single antenna. Two types of relay protocols are accounted for: equalize-and-forward and decode-and-forward...
In a multiple-input multiple-output (MIMO) multi-band orthogonal frequency division multiplexing (MB-OFDM) ultra-wideband (UWB) system, coherent detection where the channel state information (CSI) is assumed to be exactly known at the receiver requires the transmission of a large number of symbols for channel estimation, thus reducing the bandwidth efficiency. This paper examines the use of unitary...
Abstract-Non-orthogonal Spectrally Efficient Frequency Division Multiplexing (SEFDM) signals of a small dimensionality can be optimally detected using the Sphere Decoder (SD) algorithm. However, the employment of such detectors is restricted by two factors; the ill-conditioning of the SEFDM projections matrix in the system linear statistical model and the sensitivity of the SD complexity to noise...
In this paper, with the purpose to exploit the space and the frequency diversity, we propose an amplify-and-forward (AAF) cooperative system using orthogonal frequency division multiplexing (OFDM) with space-frequency codes (SFC). The signal processing algorithm of this presented system is introduced in detail and we also provide the system optimal power allocation strategy. Simulation results prove...
This paper describes a hardware demonstrator for wireless communication applications which is integrated into a single FPGA. The physical layer (PHY) is based on the Orthogonal Frequency Division Multiplexing (OFDM) transmission technique and is implemented with dedicated logic. The data link layer is defined by program code which is executed on the LEON3, a RISC processor module which is based on...
In this paper, a new distributed LDPC coder is developed in the cooperative relay networks. Although the proposed scheme requires to use the same bandwidth as the conventional approach over OFDM based transmission, the use of the hybrid ARQ can be reduced. In addition, the overall performance can be improved using the proposed approach.
In this paper, performance of double binary turbo coded orthogonal frequency division multiplexing (OFDM) system is analyzed and simulated in power line communications (PLC) channel. In order to make power line channel environments, Bernoulli-Gaussian noise is considered. The performance is evaluated in terms of bit error probability. From the simulation results, it is demonstrated that the double...
The aim of this paper is to propose and assess the performance of multiple antenna half-duplex relay-assisted cooperative schemes designed for the uplink OFDM based systems. We consider the use of an antenna array at the relay and base station and a single antenna at the mobile terminals. Two types of relay protocols are considered: equalize-and-forward and decode-and-forward. The performance of the...
Tailbiting convolutional codes will be used for several applications in new cellular mobile radio systems. This encoding method does not reset the encoder memory at the end of each data block, avoiding the overhead of the zero tail and improving the efficiency, especially when encoding short data blocks. Nevertheless, the absence of a known tail highly increases the complexity of the decoding process...
An OFDM transmission system for aerial photography is provided in this paper. The system can process and transmit the SDTV data stream in real-time with a bandwidth of 2 MHz. The structures of the OFDM transmission system are described and the design and implementation of a PC-based receiver is discussed in detail and simulation and test results are also included in this paper.
Cooperative communication has been intensively considered for general wireless and sensor networks. However, it has been almost untouched in space-time-frequency coded multi-band OFDM ultra-wideband (STFC MB-OFDM UWB) systems. This paper thus proposes two cross-layer designs for cooperative communication, namely simple cooperative communication scheme (SCCS) and advanced cooperative communication...
Low power consumption is one of the key elements to make UWB technology be the solution for future short-range and high-speed indoor wireless communications. To face the power limitation drawback, while still maintaining significant error correction capabilities, employing cooperation into UWB communications can bring a great performance. In this paper, symbol-error-rate (SER) performance is analyzed...
In this paper we present reduced-complexity high-performance iterative receivers for single-user MIMO systems that employ OFDM with bit-interleaved coded modulation. The proposed inner-outer decoder structures exploit the Soft-Output M algorithm (SOMA) to calculate bit-likelihood estimates via a limited search on a tree. A key element of the proposed designs is the way the SOMA front-end adapts at...
The long-term evolution (LTE), which was specified as the release 8 specification in the 3rd generation partnership project (3GPP), will achieve broadband services with the peak data rate of 100 Mbps in the downlink. This paper presents the measured throughput performance and power consumption performance of the implemented demodulation and decoding LSI for 2-by-2 MIMO-OFDM in the Rel-8 LTE downlink...
For orthogonal frequency-division multiplexing (OFDM) systems, the length of cyclic prefix (CP) is selected on the basis of the maximum delay spread of channel. However, the use of a CP reduces both the spectral efficiency and the power efficiency. In this paper, we proposed an iterative receiver for the space frequency block code (SFBC) OFDM system without CP. After tail cancellation, our proposed...
In this paper, we propose a feedback based cooperative transmission (FBCT) scheme for multiuser multichannel communication systems. We focus on uplink channels and consider a user, say user 1, who has a weak uplink channel. Another user (who is possibly located somewhere between the base station and user 1), say user 2, can be a relay for cooperative transmission. Using the feedback information of...
This paper proposes an uplink Multi-User (MU) Multiple-Input Multiple-Output (MIMO) protocol in IEEE 802.11 WLANs. In order to realize the uplink MU-MIMO transmission in 802.11 WLANs, there are several problems to be solved. Synchronized transmission among the stations (STAs) is one of the problems and the spatial compatibility between the transmitting STAs is another problem. Therefore, it is considered...
In the orthogonal frequency division multiplexing (OFDM) the multipath exceeding a guard interval (GI) is one of obstacles for high data rate transmission. For the purpose of the interference suppression the authors have proposed the canceller algorithm naming DWCC, where the canceller operation is based on decision feedback equalization (DFE), but the performance of the canceller is still subject...
This paper presents a novel WLAN-based system configuration employing Coded Multi-Carrier Code-Division- Multiplexing technology (CMC-CDM), as a potentially superior alternative to the currently standardized Coded OFDM (COFDM) technology. To further improve the performance of the system and reduce its complexity, a new concept of Chase detection is applied at the receiver. A comprehensive investigation...
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