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In this paper, a novel setpoint-based design approach for Irregular Repeat Accumulate (IRA) codes in iterative detection and decoding structures is presented. In contrast to conventional IRA code design in which the convolutional decoder is combined with the detector, the goal behind this approach is to keep the IRA decoding structure consisting of convolutional decoder and repetition decoder intact,...
In this paper, the design of Irregular Repeat Accumulate (IRA) Codes for Interleave-Division Multiple-Access (IDMA)-based multi-pair bidirectional relaying systems is presented. Bidirectional relaying allows to efficiently cope with the loss in spectral efficiency that is inherent to relaying systems due to the half-duplex constraint. However, as soon as multiple communication pairs use one common...
In this paper, distributed Interleave-Division- Multiplexing Space Time Codes (dIDM-STC) in Multi- User Decode-and-Forward Relay Systems are considered. Due to decoding errors at the relays, which are unavoidable in practical systems, error propagation to the destination occurs. In order to cope with this error propagation, recently a Reliability-Aware Iterative Detection Scheme (RAID) at the destination...
This paper is concerned with the application of distributed Interleave-Division-Multiplexing Space- Time Codes (dIDM-STCs) in relaying systems with error-prone relays applying Decode-and-Forward (DF). In case of erroneous decoding at the relays, error propagation occurs which is not considered by the original detection scheme for IDM-STCs. Hence, a new Reliability Aware Iterative Detection Scheme...
In this paper, the combination of distributed Interleave-Division-Multiplexing-Space-Time Codes (IDM-STCs) with Orthogonal Frequency Division Multiplexing (OFDM) in two-hop relay systems applying Decode-and-Forward (DF) is investigated. In order to cope with erroneous decoding at the relays, a model to capture the decoding reliabilities of the relays is formulated and a method to incorporate these...
Currently evolving communication standards, especially those using multi-antenna (MIMO) multicarrier modulation techniques, are based on the exploitation of channel state information (CSI) at the transmitter. The utilization of adaptive transmission schemes comes with a more sensitive behavior with respect to front-end imperfections. Direct-conversion architectures in turn allow for low-cost transceiver...
In this paper the application of the recently proposed interleave-division multiplexing space-time codes (IDM-STC) in coded relay networks is investigated. IDM-STC are a very flexible scheme to exploit space diversity with the benefits of IDM such as robustness against asynchronism and efficient iterative detection. While IDM-STC have been investigated for MIMO systems, relay networks induce additional...
One major drawback of Orthogonal Frequency Division Multiplexing (OFDM) is the large peak-to-average power-ratio (PAPR), which significantly degrades the power efficiency. In order to prevent nonlinear distortions the PAPR needs to be minimized to guarantee a linear dynamic range of the high power amplifier. Therefore, various reduction algorithms have been proposed. However, they do not include link...
Adaptive communication is an important topic to enhance the capabilities of future communication systems. Especially in combination with Orthogonal Frequency Division Multiplexing (ODFM) bit and power loading schemes have been devised to enhance the transmit rate of communication systems. The consideration of channel coding in the optimization is an obvious requirement. In the past, though, mainly...
Distributed MIMO multi-hop relaying is one of the most promising technologies that permits cost-effective improvement of coverage, data rate and end-to-end (e2e) user experience by utilizing distributed low-complexity space-time codes to overcome path losses and deep fades of wireless channels. However, an efficient transmission scheme and resource management are required to exploit these advantages...
In this paper a soft relaying scheme for coded relay networks combining the benefits of classical Decode-Forward (DF) and Amplify-Forward (AF) is extended to higher order modulation schemes. In order to minimize the mean-squared- error at the destination, the conditional expectation value of the symbol after soft-output channel decoding at the relay is transmitted. The main idea of this scheme called...
Distributed MIMO multi-hop relaying can provide cooperative diversity and overcome path losses, hence, boost the end-to-end (e2e) performance. By using a low-complexity adaptive scheme, where one relay stops sending the message if it is in outage and other nodes adapt to a new space-time code, robust communication links can be further achieved. The contribution of this paper is the derivation of near-optimal...
Adaptive coding and modulation is an important topic considering future communication systems. Orthogonal frequency division multiplexing (ODFM) has been identified as a promising technique, which offers the possibility for further enhancements by bit and power loading schemes. Commonly, channel coding has not been considered in the optimization of such algorithms. It is, however, an important component...
In this article, an adaptive distributed MIMO multihop network was presented, and the e2e outage probability was derived as the QoS parameter. The task of assigning the physical resources transmit power and the time to reduce the total transmit power while meeting a given QoS constraint was introduced and solved by means of common convex optimization tools. As shown by numerical investigations, the...
The throughput of multi-hop communication systems can significantly be increased by the application of MIMO concepts. To utilize the physical resources in an efficient way while meeting the quality-of-service (QoS) constraints, appropriate power allocation strategies are desired. In this paper the total transmit power of a MIMO multi-hop system is minimized under the constraint of a given end-to-end...
In this paper, a new combination of a multiple access scheme and spatial diversity offered by relays is proposed. In order to support several users in a system, interleave division multiple access (IDMA) is suggested here due to the capability to deal with asynchronous transmission by the users. The relays apply amplify-and-forward combined with delay-diversity in order to exploit the spatial diversity...
Distributed MIMO multi-hop schemes can provide high data rates through spatially distributed relaying nodes. The relaying nodes allow the deployment of MIMO techniques to enhance the throughput by utilizing uncorrelated sub-channels. However, the spatial farness of geometrically separated relaying nodes results in different path losses from the nodes of one virtual antenna array (VAA) to the nodes...
The concept of virtual antenna array (VAA) is a promising approach to apply MIMO concepts in relaying systems. In order to fulfill a given quality-of-service (QoS) requirement while reducing the power consumption of the entire system, efficient resource allocation strategies have to be developed. The optimum power allocation solution corresponds to a convex optimization problem. To achieve an analytical...
Power consumption and Quality-of-Service are the critical factors when developing resource allocation strategies for wireless networks. In order to minimize total transmission power while meeting the end-to-end outage probability requirement in a distributed MIMO multi-hop network, we will formulate the power allocation task as a convex optimization problem. By using some approximations to the optimization...
In this paper, we present a near-optimum resource allocation strategy for distributed multiple-input-multiple-output multiple hops multiple commodities OFDMA wireless networks. The novel per-hop-optimization strategy aims to reduce the total transmission power of the network while meeting the individual end-to-end outage probability constraint of each commodity, i.e. for each link of the network....
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