Accurate Bit-Error-Rate Analysis of Bandlimited Cooperative OSTBC Networks Under Timing Synchronization Errors

2010 IEEE International Conference on Communications

Chen

Hanzo

2010

Abstract-In this paper, we propose a differential Space-Time Coding (STC) scheme designed for asynchronous cooperative networks, where neither channel estimation nor symbol-level synchronization is required at the cooperating nodes. More specifically, our system employs differential encoding during the broadcast phase and a Space-Time Spreading (STS)-based amplify-and-forward scheme during the cooperative phase in conjunction with interference rejection Direct Sequence (DS) spreading codes, namely Loosely Synchronized (LS) codes. The LS codes exhibit a so-called Interference Free Window (IFW), where both the autocorrelation and cross-correlation values of the codes become zero. The IFW allows us to eliminate both the Multi-User Interference (MUI) as well as the potential dispersion-induced orthogonality degradation of the cooperative space-time codeword and the interference imposed by the asynchronous transmissions of the relay nodes. Furthermore, the destination node can beneficially combine both the directly transmitted and the relayed symbols using low-complexity correlation operations combined with a hard-decision detector. Our simulation results demonstrate that the proposed Cooperative Differential STS (CDSTS) scheme is capable of combating the effects of asynchronous uplink transmissions without any Channel State Information (CSI), provided that the maximum synchronization delay of the relay nodes is within the width of IFW. It will be demonstrated that in the frequency-selective environment considered our CDSTS arrangement is capable of exploiting both spacetime diversity and multi-path diversity with the aid of a RAKE combiner.

Section: Performance and Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Distributed Differential Space-Time Spreading for the Asynchronous Relay Aided Interference-Free Cooperative CDMA Uplink

2010 IEEE International Conference on Communications

Chen

Hanzo

2010

“…Similarly, due to the above-mentioned constraint of imposing a sparse structure on the dispersion matrices of our cooperative Asynchronous STSK (ASTSK) scheme, only a single RN is activated within each symbol duration, hence exhibiting robustness against IRS errors provided that they are limited to a fraction of the symbolduration. We note that the potential IRS error may severely degrade the performance of conventional cooperative STCs, which require symbol-level IRS, as investigated in [3]. On the other hand, when the IRS error exceeds the symbol duration, a severe impairment may be imposed also on our cooperative ASTSK scheme, since the structure of the STSK codeword is destroyed.…”

Section: B Relay Modelmentioning

confidence: 94%

“…Most of the previously-proposed cooperative STCs assumed perfect Inter-Relay Synchronization (IRS), although it is a challenging task to acquire symbol-level timing synchronization between the distributed Relay Nodes (RNs). However, as noted in [3], the asynchronous transmissions of the RNs may destroy the STC's orthogonality, leading to a severe performance degradation. For the sake of effectively combating this IRS problem, a number of asynchronous cooperative STCs were proposed in [4], [5].…”

Section: Introductionmentioning

confidence: 99%

Packet-Reliability-Based Decode-and-Forward Distributed Space-Time Shift Keying

2010 IEEE Global Telecommunications Conference GLOBECOM 2010

Chen

Hanzo

2010

Abstract-Motivated by the recent concept of Space-Time Shift Keying (STSK), we propose a novel cooperative STSK scheme, which is capable of achieving a flexible rate-diversity tradeoff, in the context of cooperative space-time transmissions. More specifically, in our cooperative STSK scheme each Relay Node (RN) activates Decode-and-Forward (DF) transmissions, depending on the success or failure of Cyclic Redundancy Checking (CRC). We propose a novel bit-to STSK mapping rule, where according to the input bits, one of the Q pre-assigned dispersion vectors is activated to implicitly convey log 2 Q bits, which are transmitted in combination with the classic log 2 L-bit modulated symbol. Additionally, we introduce a beneficial dispersion vector design, which enables us to dispense with symbol-level Inter-Relay Synchronization (IRS). Furthermore, the Destination Node (DN) is capable of jointly detecting the signals received from the source-destination and relay-destination links, using a low-complexity single-stream-based Maximum Likelihood (ML) detector, which is an explicit benefit of our Inter-Element Interference (IEI)-free system model. More importantly, as a benefit of its design flexibility, our cooperative STSK arrangement enables us to adapt the number of the RNs, the transmission rate as well as the achievable diversity order.

“…Since the resultant time synchronization errors impose a significant performance degradation as noted in [4], asynchronous cooperation schemes were investigated in [5], [6], under the assumption of having perfect CSI and/or delay information at the destination node. More recently, a CDSTC scheme was proposed for realistic asynchronous relay networks in [7] with the aid of interference rejection spreading codes, namely…”

Section: Introductionmentioning

confidence: 99%

Multiple-Relay Aided Distributed Turbo Coding Assisted Differential Unitary Space-Time Spreading for Asynchronous Cooperative Networks

2010 IEEE 71st Vehicular Technology Conference

Kong

et al. 2010

Abstract-This paper proposes a cooperative space-time coding (STC) protocol, amalgamating the concepts of asynchronous cooperation, non-coherent detection as well as Distributed Turbo Coding (DTC), where neither symbol-level time synchronization nor CSI estimation is required at any of the cooperating nodes, while attaining a high performance even at low SNRs. More specifically, a practical cooperative differential space-time spreading (CDSTS) scheme is designed with the aid of interference rejection spreading codes, in order to eliminate the effect of synchronization errors between the relay nodes without the assistance of channel estimation or equalization. Furthermore, a set of space-time codewords are constructed based on Differential Linear Dispersion Codes (DLDC), which allows our CDSTS system to support an arbitrary number of relay nodes operating at a high transmission rate due to its flexible design. Rather than using conventional single-relay-assisted DTCs, novel multi-relay-assisted DTCs and a three-stage iteratively-decoded destination receiver structure are developed. In our simulations the system parameters are designed with the aid of EXIT chart analysis, followed by the characterization of the achievable BER performance for various synchronization delay values as well as for various diversity-multiplexing relationships in frequencyselective fast and/or quasi-static Rayleigh fading environments.