The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
Both channel coding over a finite field and linear precoding over a complex field can improve the system performance in wireless fading channels. In this paper, we investigate the potential benefit of linear precoding in a nonbinary LDPC coded underwater acoustic OFDM system. Real precoders of small sizes are selected in different setups, in order to avoid any complexity increase at the receiver....
In conventional multicast scheme (CMS), the total throughput of multicast group is constrained by the user with the worst channel quality. In order to overcome this problem of limited throughput, we consider a resource allocation algorithm based on layered coding, when a limited feedback scheme is considered. A novel subcarrier and power algorithm is exploited for targeting the maximum throughput...
This paper describes the exploitation of physical layer confidence in bits (SoftPHY) in order to improve the rate selection in a bit-interleaved coded orthogonal frequency division multiplexing (BIC-OFDM) system. Instead of relying on a measured instantaneous bit error rate (I-BER) from received packets, we built a closed-form I-BER expression that gives accurate and simple functional mapping between...
The investigation of MIMO technology with OFDM has recently been the focus of extensive research. The main objectives of this technology are to improve bandwidth efficiency and bit error rates. In this paper, we propose an approach for high data rate communication systems. Our approach incorporates the turbo and space-time-frequency coding approaches. The proposed space-time-frequency turbo code (STF-TC)...
Dual polarization coherent systems are considered to be an attractive solution for optical fiber transmissions beyond 100Gb/s. Polarization multiplexing (PolMux) doubles the channel capacity and the spectral efficiency by transmitting two signals on the orthogonal polarization states. However optical polarization-dependent impairments, such as polarization mode dispersion (PMD) or polarization dependent...
This paper presents the implementation of a single FPGA intellectual property (IP) core for channel coding and interleaving used in Digital Video Broadcasting, second generation (DVB-T2). DVB-T2 is the extension of the television standard DVB-T, issued by the consortium DVB, and is devised for the broadcast transmission of digital terrestrial television. The higher offered bit rate, with respect to...
In this paper, we present the performance of the generalized type II hybrid selective repeat (SR) ARQ scheme using punctured convolutional coding and the code combining technique in Multi-Carrier Code Division Multiple Access (MC-CDMA) systems by computer simulations with different parameters. Multi-Carrier Code Division Multiple Access (MC-CDMA) allows high data rate transmission in a severe noisy...
In this paper, we investigate the error correction performance of Permutation Trellis Codes (PTC) combined with M-ary Frequency Shift Keying (M-FSK) modulation in Cognitive Radio Networks (CRNs). Using this modulation technique, a secondary user (SU) can improve its data rate by increasing its transmission bandwidth while operating at low power and without creating destructive interference to the...
This paper presents a performance evaluation of OFDM LTE downlink physical layer according to the latest 3GPP specifications. Particularly, adaptive modulation and coding (AMC) is described and analyzed. This is in conjunction with the turbo decoding algorithm Max-Log-Maximum A Posteriori (Max-Log-MAP) used in soft input soft output (SISO) decoders. The performance analysis is carried out in terms...
Abstract-For wireless network, spatial diversity similar to multiple-input and multiple-output (MIMO) scheme can be obtained by the use of cooperative relaying technique such as distributed space-time coding (DSTC), which can improve bandwidth utilization, power efficiency and reliability of the wireless terminal. On the other hand, the subcarrier pairing strategy of the first hop and the second hop...
The reduction of spurious emission is an important issue in future OFDM-based systems, especially in the context of cognitive radio, when the primary users must be protected from the interference. In this paper, flexible quasi-systematic precoder is presented for non-contiguous OFDM transmitter, which has the effect of relatively small distortion of the data symbols modulating the subcarriers. We...
In this paper, a transmission of JPEG2000 images using an Unequal Power Allocation (UPA) scheme and Orthogonal Frequency Division Multiplexing (OFDM) technique over a block fading — frequency selective channel is presented. Using instantaneous and average channel state information, power is assigned to each bit in the JPEG2000 bitstream based on its contribution to the decoded image quality. Moreover,...
This paper presents a machine learning approach for link adaptation in orthogonal frequency-division multiplexing systems through adaptive modulation and coding. Although machine learning techniques have attracted attention for link adaptation, most of the the schemes proposed so far are based on off-line training algorithms, which make them not well suited for real time operation. The proposed solution,...
In this paper, an adaptive scheme is developed for an Unequal Power Allocation (UPA) algorithm in a way to allow variable size grouping of the coding passes to enhance the optimization process at different Signal to Noise Ratio (SNR) values. The optimization algorithm exploits the hierarchical structure of the JPEG2000 images and uses a distortion model along with the channel state information (CSI)...
OFDM with Quadrature amplitude modulation (QAM) technique can be used for high speed optical applications. As the order of modulation increases, the bit error rate (BER) increases. Forward Error correction (FEC) coding like LDPC coding is generally used to Improve BER performance. LDPC provides large minimum distance and also the power efficiency of the LDPC code increases significantly with the code...
To achieve high data rate Multi-Carrier Code Division Multiple Access (MC-CDMA) is one suitable choice for next generation wireless communication system. MC-CDMA is the combination of CDMA and OFDM schemes, resulting into getting the advantages of both the schemes. Capacity planning is one of the major issues in designing of wireless communication system. In wireless communication system capacity...
Wimax has commercial networks in 149 countriesand subscriptions have reached 10 million globally today andare projected to grow to 130 million subscribers by 2014.This Paper is covering the development of Wimax Physical Layer Building Blocks using MATLAB and Simulink, based on the ETSI TS 102 177 V1.5.1 "Broadband Radio Access Networks (BRAN) HiperMan Physical Layer Standard", the scope...
In mobile communication systems, such as LTE and LTE-Advanced, the adaptive modulation and coding (AMC) scheme is employed to achieve higher peak- and cell-throughputs. The scheme improves the throughputs by selecting an optimum Modulation and Coding rate Set (MCS), according to a radio channel condition. The scheme usually employs channel quality indicator (CQI) to feedback an index of MCS, with...
WiMAX is an IEEE802.16 standard that provides a high speed transmission with wide coverage range. In IEEE 802.16j, the multiple Relay Stations (RS) are added to employ multihop links for WiMAX systems to extend coverage range and capacity. Many works in literature concern the RS locations based on the effective cost and the optimum user capacity. Most of them assumed the lossless transmission between...
This paper provides analytical derivation for the average pairwise error probability (PEP) of un-coded multiband orthogonal frequency division multiplexing (MB-OFDM) system for Ultra wideband (UWB) communications. To capture the behaviour of UWB channels in terms of cluster arrival rate, ray arrival rate, cluster and ray decay factors, the Saleh and Valenzuela model is employed. It is shown clearly...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.