| 1. |
- Tran, Thi-Thuy-Quynh, et al.
(författare)
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Network Coding with Multimedia Transmission and Cognitive Networking: An Implementation based on Software-Defined Radio
- 2020
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Ingår i: REV Journal on Electronics and Communications. ; 10:3-4, s. 72-84
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Tidskriftsartikel (refereegranskat)abstract
- Network coding (NC) is considered a breakthrough to improve throughput, robustness, and security of wireless networks. Although the theoretical aspects of NC have been extensively investigated, there have been only few experiments with pure NC schematics. This paper presents an implementation of NC under a two-way relay model and extends it to two non-straightforward scenarios: (i) multimedia transmission with layered coding and multiple-description coding, and (ii) cognitive radio with Vandermonde frequency division multiplexing (VFDM). The implementation is in real time and based on software-defined radio (SDR). The experimental results show that, by combining NC and source coding, we can control the quality of the received multimedia content in an on-demand manner. Whereas in the VFDM-based cognitive radio, the quality of the received content in the primary receiver is low (due to imperfect channel estimation) yet retrievable. Our implementation results serve as a proof for the practicability of network coding in relevant applications.
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| 2. |
- Duong, Quang Trung, et al.
(författare)
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Ergodic Capacity of Cooperative Networks Using Adaptive Transmission and Selection Combining
- 2009
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Konferensbidrag (refereegranskat)abstract
- Closed-form expressions for channel capacity of repetition-based cooperative networks under adaptive transmission with selection combining are presented under the assumption of independent Rayleigh fading. Specifically, three different adaptive techniques are investigated: optimal simultaneous power and rate adaptation (OPRA), constant power with optimal rate adaptation (OPA) and channel inversion with fixed rate (TIFR). Among them, for an arbitrary number of relays, TIFR gives the worst channel capacity; OPRA gives the best channel capacity and ORA has a channel capacity quality in between the others. The analysis results, based on the upper and lower bound of the end-to-end SNR, agree very well with the simulated results and definitely show the impact of selection combining on the calculated channel capacity per unit bandwidth
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| 3. |
- Al-Qahtani, Fawaz S., et al.
(författare)
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Selection Decode-and-Forward Relay Networks with Rectangular QAM in Nakagami-m Fading Channels
- 2010
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Konferensbidrag (refereegranskat)abstract
- In this paper, we investigate the average symbol error probability (SEP) of fixed decode-and-forward relay networks over independent but not identically distributed Nakagami-m fading channels. We have derived closed form expression of SEP for general rectangular quadrature amplitude modulation (QAM) under relay selection scheme where only the best relay forwards message from the source to the destination. The expressions are in terms of hypergeometric series which can be efficiently numerically evaluated. The numerical results are validated with Monte-Carlo simulations.
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| 4. |
- Bao, Vo Nguyen Quoc, et al.
(författare)
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Cognitive Amplify-and-Forward Relaying with Best Relay Selection in Non-Identical Rayleigh Fading
- 2013
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Ingår i: IEEE Communications Letters. - : IEEE. - 1089-7798 .- 1558-2558. ; 17:3, s. 475-478
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Tidskriftsartikel (refereegranskat)abstract
- This paper investigates several important performance metrics of cognitive amplify-and-forward (AF) relay networks with a best relay selection strategy and subject to nonidentical Rayleigh fading. In particular, assuming a spectrum sharing environment consists of one secondary user (SU) source,K SU relays, one SU destination, and one primary user (PU) receiver, closed-form expressions for the outage probability (OP), average symbol error probability (SEP), and ergodic capacity of the SU network are derived. The correctness of the proposed analysis is corroborated via Monte Carlo simulations and readily allows us to evaluate the impact of the key system parameters on the end-to-end performance. An asymptotic analysis is also carried out and reveals that the diversity gain is defined by the number of relays pertaining to the SU network (i.e., K), being therefore not affected by the interference power constraint of the PU network.
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| 5. |
- Bao, Vo Nguyen Quoc, et al.
(författare)
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Distributed Switch-and-Stay Combining in Cognitive Relay Networks under Spectrum Sharing Constraints
- 2013
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Ingår i: 2013 IEEE GLOBAL COMMUNICATIONS CONFERENCE (GLOBECOM). - : IEEE Communications Society. - 9781479913534 ; , s. 1927-1932
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Konferensbidrag (refereegranskat)abstract
- Distributed switch-and-stay combining (DSSC) has been envisioned as an effective transmission technique to achieve spatial diversity in a distributed fashion, with low implementation complexity. In this paper, we take a step further to incorporate DSSC into spectrum-limited environment, where the operating nodes have to share the frequency radio spectrum with licensed users. In particular, by deploying DSSC scheme in cognitive radio networks, we have shown that the low transmit power at unlicensed users, inflicted by the peak interference power constraint at licensed users, can be alleviated. We present closed-form expressions for outage probability and spectral efficiency, enabling us to evaluate and optimize the considered network performance. Numerical and simulation results show that when the switching threshold is below the outage threshold the full diversity order can be guaranteed at the secondary networks.
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| 6. |
- Bao, Vo Nguyen Quoc, et al.
(författare)
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Effect of Imperfect Channel State Information on the Performance of Cognitive Multihop Relay Networks
- 2013
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Ingår i: 2013 IEEE GLOBAL COMMUNICATIONS CONFERENCE (GLOBECOM). - 9781479913534 ; , s. 3458-3463
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Konferensbidrag (refereegranskat)abstract
- Cognitive relay technology has been envisioned as a promising transmission scheme to enhance the reliability and coverage of secondary networks. However, the performance of cognitive relay networks (CRNs) is limited by the lack of accurate channel state information (CSI). As such, this paper adequately addresses the impact of imperfect CSI on the performance of cognitive multihop networks by proposing a simple yet effective backoff control power method. In addition, novel exact and asymptotic expressions for outage probability and ergodic capacity over Rayleigh fading channels are also derived. These tractable analytical results reveal new insight into the design, e.g., the number of hops for secondary network, and optimization of cognitive multihop networks.
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| 7. |
- Bao, Vo Nguyen Quoc, et al.
(författare)
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Exact Outage Probability of Cognitive Underlay DF Relay Networks with Best Relay Selection
- 2012
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Ingår i: IEICE transactions on communications. - : IEICE. - 0916-8516 .- 1745-1345. ; E95-B:6, s. 2169-2173
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Tidskriftsartikel (refereegranskat)abstract
- In this letter, we address the performance analysis of underlay selective decode-and-forward (DF) relay networks in Rayleigh fading channels with non-necessarily identical fading parameters. In particular, a novel result on the outage probability of the considered system is presented. Monte Carlo simulations are performed to verify the correctness of our exact closed-form expression. Our proposed analysis can be adopted for various underlay spectrum sharing applications of cognitive DF relay networks.
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| 8. |
- Bao, Vo Nguyen Quoc, et al.
(författare)
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On the performance of cognitive underlay multihop networks with imperfect channel state information
- 2013
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Ingår i: IEEE Transactions on Communications. - : IEEE. - 0090-6778 .- 1558-0857. ; 61:12, s. 4864-4873
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Tidskriftsartikel (refereegranskat)abstract
- This paper proposes and analyzes cognitive multihop decode-and-forward networks in the presence of interference due to channel estimation errors. To reduce interference on the primary network, a simple yet effective back-off control power method is applied for secondary multihop networks. For a given threshold of interference probability at the primary network, we derive the maximum back-off control power coefficient, which provides the best performance for secondary multihop networks. Moreover, it is shown that the number of hops for secondary network is upper-bounded under the fixed settings of the primary network. For secondary multihop networks, new exact and asymptotic expressions for outage probability (OP), bit error rate (BER) and ergodic capacity over Rayleigh fading channels are derived. Based on the asymptotic OP and BEP, a pivotal conclusion is reached that the secondary multihop network offers the same diversity order as compared with the network without back off. Finally, we verify the performance analysis through various numerical examples which confirm the correctness of our analysis for many channel and system settings and provide new insight into the design and optimization of cognitive multihop networks.
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| 9. |
- Bao, Vo Nguyen Quoc, et al.
(författare)
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Outage Analysis of Cognitive Multihop Networks under Interference Constraints
- 2012
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Ingår i: IEICE transactions on communications. - : IEICE. - 0916-8516 .- 1745-1345. ; E95-B:3
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Tidskriftsartikel (refereegranskat)abstract
- The closed-form expressions for outage probability, bit error rate, and ergodic capacity of spectrum sharing-based multi-hop decode-and-forward relay networks in non-identical Rayleigh fading channels are derived. Utilizing these precise and tractable analytical formulas, we can study the impact of key network parameters on the performance of cognitive multi-hop relay networks under interference constraints. The analytical expressions are verified by Monte-Carlo simulations.
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| 10. |
- Duong, Quang Trung, et al.
(författare)
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Amplify-and-Forward MIMO Relaying with OSTBC over Nakagami-m Fading Channels
- 2010
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Konferensbidrag (refereegranskat)abstract
- In this paper, we analyze the performance of dual-hop channel state information (CSI)-assisted amplify-andforward (AF) cooperative networks using orthogonal space-time block codes (OSTBCs) over independent but not identically distributed Nakagami-m fading channels. Specifically, we present closed-form expressions of the outage probability (OP) and the symbol error probability (SEP). The analytical results are given in tractable forms which readily allow us to assess the performance of AF relay systems using OSTBCs. For sufficiently large signal-to-noise ratio, we obtain the asymptotic results for OP and SEP which reveal insights into the effect of fading factors on the diversity and coding gains. It has been shown that between the two hops the more severe link solely determines the diversity and coding gains. In particular, these two gains strictly depend on the fading severity parameters and the channel mean powers of the more rigorous hop, respectively. Numerical results are provided showing an excellent agreement between our analytical results and those of Monte-Carlo simulations for selected scenarios.
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