In this paper, we propose an efficient channel estimation scheme in bi-directional wireless orthogonal frequency division multiplexing (OFDM) relay systems applying analog network coding (ANC). In the relay systems ap...
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In this paper, we propose an efficient channel estimation scheme in bi-directional wireless orthogonal frequency division multiplexing (OFDM) relay systems applying analog network coding (ANC). In the relay systems applying ANC, channel separation is needed to estimate each of the bi-directional channels simultaneously from the combined received signal. In the conventional channel estimation schemes, relatively higher-ratio pilots are needed to obtain accurate channels. In contrast, we propose a channel estimation scheme with sparse pilots, while maintaining high accuracy for channel estimation. In the proposed scheme, Walsh codes are inserted as the pilot symbols at both end nodes, and the individual channels are obtained by correlation processing from the combined signals. The improved bit error rate (BER) and throughput performances of the proposed scheme are shown through computer simulations.
In this letter, we evaluate the outage performance of analog network coding (ANC) protocol for a two-way half-duplex relaying system with asymmetric traffic requirements at end terminals. We derive a simple and genera...
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In this letter, we evaluate the outage performance of analog network coding (ANC) protocol for a two-way half-duplex relaying system with asymmetric traffic requirements at end terminals. We derive a simple and generalized expression for overall system outage probability in a Rayleigh flat-fading environment. We also deduce the optimal relay location and power allocation in order to minimize the overall system outage. Numerical and simulation results highlight the effect of optimal relay positioning and power allocation under various traffic requirements.
We propose a new random access protocol based on reservation ALOHA (R-ALOHA), called ANC-ALOHA, for applying analog network coding (ANC) to the slotted ALOHA channel of satellite networks (SATNETs). Although ANC promi...
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We propose a new random access protocol based on reservation ALOHA (R-ALOHA), called ANC-ALOHA, for applying analog network coding (ANC) to the slotted ALOHA channel of satellite networks (SATNETs). Although ANC promises excellent performance in SATNETs, ANC is not guaranteed in slotted ALOHA owing to the inherent randomness. R-ALOHA can be used to acquire a slot for ANC, but there are still two remaining problems to be overcome. First, the reservation maintenance of R-ALOHA does not work for ANC owing to the superposed signals. Second, a channel estimation scheme for ANC is needed in a slotted ALOHA channel. ANC-ALOHA exploits a keep-on sequence as the preamble and postamble of a burst for ANC to solve the above issues. The reduced payload size and delayed transmission are also proposed to assure the reception of the keep-on sequence. We derived an analytic model to verify the throughput of ANC-ALOHA, and validated it based on the simulation results. The results indicate that ANC-ALOHA significantly improves the channel throughput compared to R-ALOHA.
We investigate the performance of analog network coding (ANC) for multi-hop networks in this letter. With the amplify-and-forward (AF) protocol, relays broadcast the sum of two colliding signals to neighboring nodes, ...
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We investigate the performance of analog network coding (ANC) for multi-hop networks in this letter. With the amplify-and-forward (AF) protocol, relays broadcast the sum of two colliding signals to neighboring nodes, while the source node can subtract its own signal from the colliding signals to obtain the received information. We first give the transmission scheme expressions for the n-node m-frame two-way multi-hop network. For this scheme, we derive the end-to-end signal-to-noise ratio (SNR) expression. The closed-form expression of the outage probability for the generalized multi-hop network is evaluated. Numerical results demonstrate that the outage performance with ANC is better than that of the traditional AF scheme.
networkcoding (NC), which works in the network layer, is an effective technology to improve the network throughput, by allowing the relay to encode the information from different users and ensuring the destination to...
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networkcoding (NC), which works in the network layer, is an effective technology to improve the network throughput, by allowing the relay to encode the information from different users and ensuring the destination to retrieve the desired information. Employing networkcoding technique in a cooperative network can improve the network performance further. In this paper, we introduce analog network coding (ANC) to a simple two-user cooperative diversity network, which adopts amplify-and-forward (AF) mode and all nodes use multiple antennas. The impact of the number of antenna on the system achievable rate is investigated. And the bit error rate (BER) performances of the traditional relay cooperative network and the cooperative network based on analog network coding under different propagation conditions are discussed. The simulation results show that the performance of the traditional cooperative network has improved significantly due to the employ of networkcoding.
Radio channel is characterized by a mutlipath propagation that is suitable for application of networkcoding (NC) to improve the network capacity. In particular, physical layer networking coding (PNC) scheme is known ...
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ISBN:
(纸本)9781424451234
Radio channel is characterized by a mutlipath propagation that is suitable for application of networkcoding (NC) to improve the network capacity. In particular, physical layer networking coding (PNC) scheme is known to double the network capacity of bi-directional communication between pairs of end users assisted by a relay terminal in a Gaussian channel. Recently, analog network coding (ANC) has been proposed with a simpler implementation complexity in comparison with PNC scheme, but the same achievable network capacity. On the other hand, an important question is how much the channel capacity is improved over a conventional point-to-point communication in a frequency-selective fading channel. In this paper, we present the ergodic channel capacity analysis of bi-directional transmission with analog network coding in a frequency-selective fading channel. The channel capacity expression for transmission with frequency domain equalization (FDE) is derived based on the Gaussian approximation of the inter-symbol interference (ISI) after FDE.
In this paper, we investigate the possibility, from an energy efficiency point of view, of employing analog network coding in the Multiple Access Relay Channel (MARC) instead of the conventional Time-Division Multiple...
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ISBN:
(纸本)9781479957255
In this paper, we investigate the possibility, from an energy efficiency point of view, of employing analog network coding in the Multiple Access Relay Channel (MARC) instead of the conventional Time-Division Multiple Access (TDMA) protocol when time and not bandwidth is the available resource in the network. Towards this end, we derive a closed-form upper bound of the Bit Error Rate (BER) per source of analog network coding when the optimal maximum-likelihood (ML) detector is employed. Based on this framework, we mathematically prove that as either the number of sources or the number of relays or the modulation order increases, the possibility of analog network coding being more energy efficient than TDMA increases as well. These findings are substantiated by means of Monte Carlo simulations.
A novel generalized iterative approach (GIA) is proposed for jointly designing the MMSE MIMO processors (precoders, relay processors and decoders) for the analog network coding scheme. The MMSE performance can be achi...
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ISBN:
(纸本)9781424479078
A novel generalized iterative approach (GIA) is proposed for jointly designing the MMSE MIMO processors (precoders, relay processors and decoders) for the analog network coding scheme. The MMSE performance can be achieved for MIMO communication links with two end nodes and multiple relay nodes subject to either the per-node power constraint or the practical per-antenna power constraint. Numerical results show that the analog network coding scheme is more spectral and energy efficient than the conventional Direct Transmission (DT) scheme.
This paper evaluates the performance of an opportunistic scheduling scheme for a multiuser two-way relay network, wherein an analog network coding (ANC)-based relay assists the communication between multiple pairs of ...
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ISBN:
(纸本)9781612842547
This paper evaluates the performance of an opportunistic scheduling scheme for a multiuser two-way relay network, wherein an analog network coding (ANC)-based relay assists the communication between multiple pairs of users. To ensure fairness for each user pair, we consider a scheduler based on maximizing the normalized minimum of the instantaneous signal-to-noise ratios (SNRs) at each user of the pair. Under a high SNR assumption, we derive upper and lower bound expressions for the outage probability and the average sum-rate in a Rayleigh fading environment and establish that a multiuser diversity of order equal to the number of user pairs is harnessed by the scheme. Numerical and simulation results are presented to confirm the performance gain of the proposed scheme.
In this paper, we consider a general bi-directional relay network with two sources and N relays when neither the source nodes nor the relays know the channel state information (CSI). A bi-directional relay selection s...
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ISBN:
(纸本)9781424463985
In this paper, we consider a general bi-directional relay network with two sources and N relays when neither the source nodes nor the relays know the channel state information (CSI). A bi-directional relay selection scheme is proposed using differential analog network coding (BRS-DANC), and a simple linear detector is given to recover the received signals. In the proposed scheme, we provide an optimal and a sub-optimal methods to select the relay node from a single source by minimizing the average symbol error rate (SER). The performance of the proposed BRS-DANC scheme is analyzed, and a simple asymptotic SER expression is derived. It is shown that the SER performance of the proposed differential scheme is about 3 dB away from that of the coherent detection scheme.
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