Convergence Property of Transmit Time Pre-Synchronization for Concurrent Cooperative Communication

On cooperative transmission range extension in multi-hop wireless ad-hoc and sensor networks: A review

“…As a result, 90% of RTTSs are less than 300 ns in the experiments in [6], which implies that CCT can support up to 300 kbps data rate in narrow band waveforms without inter-symbol interference (ISI) degradation. Moreover, in [83,87], we show that the transmit time error statistics of the proposed TTS scheme are convergent over consecutive CCT hops through measurement and theoretical analysis. Synchronization for distributed MIMO-OFDM is also shown in [17].…”

“…We demonstrate concurrent CT (CCT)-based algorithms with a real testbed using 20 software-defined radios (SDRs) in [57,6,[82][83][84], because off-the-shelf radios do not support the physical-layer signal combining capability, which is required in CCT. One node of the testbed, shown in Fig.…”

Diversity in synchronization for scheduled OFDM time-division cooperative transmission

“…In this work, we focus on the synchronization at the destination receiver during the second phase, assuming presynchronization was done within the relay cluster before retransmission.With timing pre-synchronization [12], the kth relay is scheduled to transmit in the kth time slot as T k = T 0 +kt proc +e k , where T 0 is the transmitting time of the source node, and also the time that the source packet arrives at the antennas of the relay nodes; t proc is a period of time designed so that the transmit first-in-first-out buffer will be full when the transmission starts. The timing pre-sychronization error, e k , is modeled as a zero mean Gaussian random variable with variance δ 2 e , denoted as e k ∼ N (0, δ 2 e ).…”

“…For TDCT, when SNR is very low, the pre-synchronization error, which is a function of the SNRs at the relays, is assumed in this paper to be small enough to be ignored [12].…”

“…(12), the combined fractional CFO estimation metric is weighted by the sum of magnitude squared channel gains, h k 2 , which offers the diversity gain similar to maximum ratio combing (MRC).…”