This paper presents an integration waveform of radar and communication based on the multi-antenna system. The communication data are emitted by utilizing space-frequency coding on the transmit antenna array. By using ...
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ISBN:
(纸本)9781509048281
This paper presents an integration waveform of radar and communication based on the multi-antenna system. The communication data are emitted by utilizing space-frequency coding on the transmit antenna array. By using beamforming technology in the subarray level, wide area detecting as MIMO (multiple-input-multiple-output) radar and directional communication with the cooperative target in the main lobe can be achieved simultaneously. The simulation results confirm that the signal proposed is able to obtain radar detection capacity and reliable communication.
A new adaptive coding and decoding scheme is proposed for distributed space-frequency coding system. Each relay node selects dispersion matrix and modulation type adaptively according to channel state and different de...
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ISBN:
(纸本)9781510819085
A new adaptive coding and decoding scheme is proposed for distributed space-frequency coding system. Each relay node selects dispersion matrix and modulation type adaptively according to channel state and different detection methods are used according to the threshold of channel condition number adaptively. The MATLAB simulation is performed under COST207 typical urban channel model. Simulation results show that the proposed adaptive coding scheme gives a more good performance.
Baseband adaptive array processing is a traditional approach to mitigating interference at a digital receiver. In the presence of sufficiently strong interference, this mitigation fails if receiver (RX) front-end comp...
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ISBN:
(数字)9781665482431
ISBN:
(纸本)9781665482431
Baseband adaptive array processing is a traditional approach to mitigating interference at a digital receiver. In the presence of sufficiently strong interference, this mitigation fails if receiver (RX) front-end components, such as amplifiers and ADCs, are driven into non-linear operation or if the RX responds by decreasing its gain and losing sensitivity to the signal. Instead of requiring costly RX components with high dynamic-range, we explore a novel Multiple-Input Multiple-Output (MIMO) scheme that uses hybrid analog-digital beamforming to mitigate a strong interferer in wideband line-of-sight (LOS) channels. This scheme uses true-time delay analog beamforming within antenna subarrays to mitigate most of the interference ahead of the RX front-end and then linear spatial equalization to mitigate residual interference at baseband. Alamouti space-frequency coding at the transmitter and MIMO receive processing are used to exploit the frequency-selective channel imposed by the analog beamforming stage. We show that this architecture can outperform traditional Single-Input Multiple-Output (SIMO) schemes under strong interference using low complexity processing in a relatively low-complexity hardware implementation. The specific case of intervehicular (V2V) LOS channels is considered in detail.
In this letter, a new channel estimation algorithm is proposed for underwater acoustic channels undergoing Rayleigh fading with impulsive noise. For the channel estimation purpose, the algorithm utilizes the path-base...
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In this letter, a new channel estimation algorithm is proposed for underwater acoustic channels undergoing Rayleigh fading with impulsive noise. For the channel estimation purpose, the algorithm utilizes the path-based channel model characterized by a path delay, a Doppler scaling factor, and an attenuation factor. Assuming antenna diversity coupled with Alamouti's space-frequency block coding, the proposed estimator first employs matching pursuit algorithm for initialization. Then, the iterative algorithm interchangeably employs delay focusing and Doppler focusing approaches for Doppler shifts and delays estimation, respectively, with their corresponding path gains. The performance of the proposed algorithm is then presented in terms of average mean square error and symbol error rate for 16QAM signaling with different pilot spacings. The simulation results show that the proposed approach with the continuous focusing functions can outperform the compressed sensing-based matching pursuit (MP) algorithm and the projected (PMP), and the basis pursuit-based generalized approximate message passing (GAMP) algorithm.
Multipath fading is one of the main challenges in transmission over wireless broadband relay channels due to frequency selectivity, which may deteriorate the received signal. Exploiting the extra source of multipath d...
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Multipath fading is one of the main challenges in transmission over wireless broadband relay channels due to frequency selectivity, which may deteriorate the received signal. Exploiting the extra source of multipath diversity, aside from cooperative (user) diversity, is important when coping with these wireless channel limitations. In this correspondence, we propose a new distributed space-frequency code (SFC) for broadband fading relay channels that can exploit both the spatial and multipath diversities in a distributed fashion. An upper bound for pairwise error probability (PEP) is derived, and from this PEP bound, we show that the proposed code achieves a diversity of order NL, where N is the number of relay nodes, and L is the channel memory length. The decode-and-forward (DF) protocol and erroneous decoding at the relay nodes are considered. Moreover, it is shown that the proposed code structure achieves the maximum coding gain among the linearly coded systems over channels with uniform power delay profiles.
In this article, we propose a time-spreaded quasi-orthogonal space-frequency coded OFDM system with constellation rotation. A constellation rotated quasi-orthogonal OFDM system could offer full rate and full diversity...
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In this article, we propose a time-spreaded quasi-orthogonal space-frequency coded OFDM system with constellation rotation. A constellation rotated quasi-orthogonal OFDM system could offer full rate and full diversity in a frequency selective fading channel. Time spreading can give additional time diversity gain in a fast fading channel. Assuming that complex channel gains between adjacent subcarriers are approximately equal, we develop a coding scheme for 4 x 1 MISO transceiver and its BER performance is evaluated for different Doppler frequencies in an OFDM system. The simulation results show that 2 dB gain can be achieved at BER of 10(-3) using the proposed scheme compared to a scheme without time spreading and constellation rotation when 512 subcarriers are used at maximum Doppler frequency of 300 Hz. Also, the proposed system is analyzed for different delay spread of the channel and the results show that if adjacent subcarriers are correlated, it is better in SF-OFDM decoding.
The wireless communication system frequency diversity can be exploited with the help of spacefrequencycoding. In order to gain maximum frequency diversity various environment criteria needs to be considered. This pa...
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ISBN:
(纸本)9781509002108
The wireless communication system frequency diversity can be exploited with the help of spacefrequencycoding. In order to gain maximum frequency diversity various environment criteria needs to be considered. This paper proposes a practical approach of Distributed spacefrequencycoding [DSFC] for non-identically distributed [i. n. d] fading environment. As the geographical location of nodes is different, accordingly the signal over the link will also experience different fading. One link may experience Rayleigh fading and other link may experience rician fading. When all the nodes are in shadow region, then it obviously shows poor performance as there is no direct line of sight [NLOS]. On other hand, when all link experiences rician fading, then it shows better performance as there is direct line of sight [LOS]. In asymmetric fading, each link experiences different type of fading depending on the location of the receiving node. Two types of Asymmetric Fading scenarios are designed for DSFC with direct link and without direct link. Asymmetric type I is designed for relay nodes that are located in better area compared to destination node. Asymmetric type II is designed for destination node which is located in better area compared to relay nodes. All these symmetrical and Asymmetrical fading scenarios are performed for both Amplify and Forward [AAF] and Decode and Forward [DAF] relaying protocol. Different modulation effect on proposed DSFC is compared for both relaying protocol. For both relaying protocol, it is observed that Asymmetric Type I shows better performance than Asymmetric Type II and Rayleigh fading.
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-boun...
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ISBN:
(纸本)9781424458424
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 nodes and L is the channel memory length. A decode-and-forward (DAF) protocol and erroneous decoding at the relay nodes are considered. To compensate for the diversity loss due to potential error detection at the relay nodes, additional coding at the source node is proposed.
In this paper we investigate the performance of single-relay cooperative scheme, where the source is equipped with a 2-antenna array and both the relay and destination with a single antenna. We consider Amplify-and-Fo...
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ISBN:
(纸本)9781424451234
In this paper we investigate the performance of single-relay cooperative scheme, where the source is equipped with a 2-antenna array and both the relay and destination with a single antenna. We consider Amplify-and-Forward, Decode-and-Forward and Selective Decode-and-Forward relaying protocols and a space-frequency block coding designed for DL OFDM based systems is employed. Signals expressions are derived for each relay protocol under various scenarios, considering power constraint imposed on cooperating nodes. The aim of this work is to evaluate this Virtual MIMO scheme in realistic scenarios (e. g. correlated antennas, precise channel models, Doppler effects) for implementation purposes in a system with LTE based parameters and considering channel turbo coding. The coded performance of the proposed Virtual MIMO scheme is evaluated, and compared against non-cooperative OFDM based systems, for typical pedestrian scenarios based on LTE specifications. The proposed cooperative scheme outperforms the co-located MISO and MIMO for some scenarios.
w A distributed space-frequency (SF) coded cooperative technique is proposed for broadband wireless ad-hoc networks, where both the channels from the source node to relay nodes and from the relay nodes to the destinat...
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w A distributed space-frequency (SF) coded cooperative technique is proposed for broadband wireless ad-hoc networks, where both the channels from the source node to relay nodes and from the relay nodes to the destination node are characterized by frequency-selective fading. Using an SIT coding at the source node and a circular shift at each relay node, we propose a scheme that can achieve both cooperative and multipath diversity. The pairwise error probability is analyzed and the result demonstrates that a diversity gain of min(ML1, ML2) can be achieved, where All is the number of the relay nodes, and L, and L-2 are the number of taps of the multipath fading channels from the source node to the relay nodes and from the relay nodes to the destination node, respectively. Furthermore, the proposed distributed SF coding can achieve full-rate transmission for any number of relay nodes. In particular, it does not need IFFT/FFT processing or decoding at each relay node, thus providing a low-complexity design of the relay nodes in broadband wireless ad-hoc networks.
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