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Cooperative relay has been an interesting research area for the past years as it promotes higher data rates and robust to wireless environment. IEEE Work Group initiated the use of relay stations in the IEEE 802.16e standard and it is called IEEE 802.16j. This paper proposed a multi-hop cooperative relay system with space-time codes (STC), with the integration of relay selection. In changing environment,...
The Long-Term Evolution (LTE) is the next generation of current mobile telecommunication networks. LTE has a new flat radio-network architecture and a significant increase in spectrum efficiency. In this paper a link level implementation in a system-level LTE simulator is proposed. There are two important functions at link level to increase the network capacity: Link Adaptation and Dynamic Scheduling...
The emerging technology of cooperative communication has been intensively examined in the recent years. However, few investigate its combination with the Multi-band (MB) OFDM physical layer. In the paper, we propose a cooperative MB-ODFM communication with efficiently grouped relays under multipath channel. Taking advantage of the multiple bands together with the grouped relays, the proposed zero-padding...
In this paper, we present a new robust scheme for use in asynchronous cooperative networks over frequency-selective channels through using three and four relay nodes. Based on extended orthogonal space-time block coding (EO-STBC), we have presented a direct quantized feedback approach that can achieve full cooperative diversity and array gain with unity code rate over each hop. In this scheme, we...
Orthogonal frequency division multiplexing (OFDM) and interleave-division multiple-access (IDMA) are both attractive technique in modern wireless communication. In this paper, we study a multi-user system, which combines OFDM and IDMA, and fortunately, inherits many advantages. In order to improve system performance, low-density parity-check (LDPC) coding is further applied. And moreover, a turbo-type...
For terrestrial television two television standards exist: The DVB-T standard is currently widely deployed and used in more than 35 countries worldwide. The second one is the emerging standard DVB-T2. It is a revised standard which offers a higher spectral efficiency and requires multiple transmit antennas. DVB-T2 promises performance gains because of improved coding, modulation and multiple antenna...
Orthogonal frequency division multiplexing (OFDM)is an excellent technique to reduce the effect of frequency selective in time varying multipath channels by dividing the transmission bandwidth into many narrow-band subcarriers, each of which exhibits an approximately flat fading. Cyclic extensions are added to OFDM symbols to allow time for mutipath signals from the previous symbol to die away before...
We investigate performance limits of a coded asymmetric OFDM (A-OFDM) system in multipath fading channels when maximum-likelihood (ML) detection is deployed. Our A-OFDM formulation is general and the analysis extends to coded OFDM (COFDM), precoded COFDM and single carrier systems. At first, an exact pairwise error probability is evaluated based on Craig's alternative form of the Q-function. Then...
In this paper, a new distributed space-frequency coding (DSFC) scheme, for broadband fading relay channels is presented. This scheme exhibits a spatial and a multipath diversity in a distributed fashion. An upper-bound on the pairwise error probability (PEP) is derived. From this PEP bound, it is shown that the proposed coding scheme achieves a diversity of order NL , where N is the number of relay...
The multipath diversity and coding gain metrics for cyclic-prefixed single-carrier (SC-CP) systems, which characterize the bit error rate (BER) at high SNR, have not been carefully studied in the literature. We first show that, unlike OFDM, the diversity and coding gains for SC-CP are data-realization-dependent. Then, we show that there is a signal-to-noise ratio (SNR) threshold beyond which the dominant...
The modern telecommunication industry demands higher capacity networks with high data rate. Orthogonal frequency division multiplexing (OFDM) is a promising technique for high data rate wireless communications at reasonable complexity in wireless channels. OFDM has been adopted for many types of wireless systems like wireless local area networks such as IEEE 802.11a, and digital audio/video broadcasting...
In OFDM, the orthogonal subcarriers can be assumed to undergo flat fading in a frequency selective channel permitting operation without an equalizer especially when differential data encoding is used. However, in CE-OFDM, the data symbols are no longer confined to orthogonal subcarriers and, therefore, an equalizer is required for operation in frequency selective channels. A frequency domain equalizer...
When spectral nulls are present in a channel, they can severely degrade or cancel out OFDM tones, resulting in an irreducible error rate. In Code Spread OFDM, each sinewave carries a weighted sum of all the information symbols being transmitted in an OFDM block interval. This creates a more robust modulation scheme which provides substantial performance improvement relative to standard OFDM. In this...
The decision-directed space-alternating generalized expectation-maximization (SAGE) algorithm is introduced in [1] to estimate the channel and track the channel varying for OFDM systems with transmitter diversity. However, this method is based upon a discrete Fourier transform (DFT), which will cause power leakage and result in an error floor in a multipath channel with non-sample-spaced time delays...
OFDM is the digital modulation scheme that multiplexes multiple orthogonal sub-carriers that are digitally modulated. One of the schemes that improve the performance of OFDM transmission is the sub-carrier adaptive modulation scheme. In order to perform sub-carrier adaptive modulation, it is necessary to transmit the allocation information of modulation schemes for each sub-carrier and this degrades...
Orthogonal frequency division multiplexing (OFDM) is the modulation scheme of choice for digital video broadcasting-handheld (DVB-H), which is required to operate under high mobility conditions resulting in significant Inter-carrier Interference (ICI). To mitigate ICI, several cancellation schemes have been proposed but they require reliable channel information at the receiver which is quite challenging...
Correlative minimum shift keying (MSK), a second order polynomial modulation scheme known as tamed frequency modulation (TFM), is a constant envelope type of modulation with a perfect peak to average power ratio (PAPR), besides the property of low out of band power. We apply the linearized TFM to the single carrier transmission with frequency domain equalization (SC/FDE) concept. We then obtain a...
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