| 1. |
- 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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| 2. |
- 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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| 3. |
- Chow, Lawrence, et al.
(författare)
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Channel Aware Rebuffering for Wireless Media Streaming with Handoff Control
- 2013
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Ingår i: 2013 IEEE GLOBAL COMMUNICATIONS CONFERENCE (GLOBECOM). - : IEEE Press. - 9781479913534 ; , s. 4434-4439
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Konferensbidrag (refereegranskat)abstract
- Packet/frame 'rebuffering' in wireless video streaming typically considers only connectivity from the mobile terminal to its network access point (AP). However, in the presence of multiple APs with the possibility of handoffs, the overall wireless environment should be considered. We develop a model capturing joint rebuffering & handoff dynamics in wireless video streaming, and design a new channel-aware joint rebuffering & handoff control scheme, aiming to minimize the long-run average cost of video jitters and freezes. We first characterize the optimal control in the general case of multiple wireless APs/channels and multiple states per channel. Subsequently, we evaluate the system performance in key important cases, using experimental traces of wireless channel data. We explore the relationship between optimal rebuffering thresholds and overall channel dynamics, and evaluate the associated joint handoff control. The performance results demonstrate the importance of jointly managing rebuffering and handoff controls to achieve high-performance wireless video streaming.
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| 4. |
- Di Marco, Piergiuseppe, et al.
(författare)
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Harmonizing MAC and routing in low power and lossy networks
- 2013
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Ingår i: 2013 IEEE Global Communications Conference (GLOBECOM). - : IEEE. - 9781479913534 ; , s. 231-236
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Konferensbidrag (refereegranskat)abstract
- Medium access control (MAC) and routing protocols are fundamental blocks in the design of low power and lossy networks (LLNs). As new networking standards are being proposed and different existing research solutions patched, evaluating the performance of the network becomes challenging. Specific solutions that can be individually efficient, when stacked together may have unexpected effects on the overall network behavior. In this paper, we provide an analysis of the fundamental MAC and routing protocols for LLNs: IEEE 802.15.4 MAC and IETF RPL. Moreover, a characterization of their cross-layer interactions is presented by a mathematical description, which is essential to truly understand the protocols mutual effects and their dynamics. Novel metrics that guide the interaction between MAC and routing are compared to existing metrics. Furthermore, a protocol selection mechanism is implemented to select the appropriate routing metric and MAC parameters given specific performance constraints. Analytical and experimental results show that the behavior of the MAC protocol can hurt the performance of the routing protocol and vice versa, unless these two are carefully optimized together.
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| 5. |
- Duong, Trung Quang, et al.
(författare)
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Cognitive Cooperative Networks in Dual-Hop Asymmetric Fading Channels
- 2013
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Ingår i: 2013 IEEE GLOBAL COMMUNICATIONS CONFERENCE (GLOBECOM). - 2334-0983 .- 2576-6813. - 9781479913534 ; , s. 955-961
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Konferensbidrag (refereegranskat)abstract
- Previous works on cognitive relay networks (CRNs) considered only symmetric fading channels. However, in practical wireless propagation scenarios, it is likely that the channels of the secondary user (SU) and primary user (PU) may undergo different fading characteristics. In this paper, we assume that the channels of the secondary network (SU-source -> SU-relay -> SU-destination) are subject to Rician fading, whereas the channels of the link from the SU to the PU experience Rayleigh fading. Based on this framework, the end-to-end outage probability (OP) of CRNs is investigated for two different relaying schemes: i) in the absence of the direct link with decode-and-forward (DF) protocol and ii) in the presence of the direct link with incremental DF protocol. In particular, we derive both exact and asymptotic OP expressions for the considered CRNs. Our analysis reveals important insights into the impact of fading parameters on the CRN performance under distinct fading distributions.
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| 6. |
- Ghauch, Hadi, 1986-, et al.
(författare)
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Interference Alignment via Controlled Perturbations
- 2013
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Ingår i: 2013 IEEE Global Communications Conference (GLOBECOM). - : IEEE. - 9781479913534 ; , s. 3996-4001
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Konferensbidrag (refereegranskat)abstract
- In this work, we study the so-called leakage minimization problem, within the context of interference alignment (IA). For that purpose, we propose a novel approach based on controlled perturbations of the leakage function, and show how the latter can be used as a mechanism to control the algorithm's convergence (and thus tradeoff convergence speed for reliability). Although the proposed scheme falls under the broad category of stochastic optimization, we show through simulations that it has a quasi-deterministic convergence that we exploit to improve on the worst case performance of its predecessor, resulting in significantly better sum-rate capacity and average cost function value.
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| 7. |
- Kim, Kyeong Jin, et al.
(författare)
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Two-Way Cognitive Relay Networks with Multiple Licensed Users
- 2013
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Ingår i: 2013 IEEE GLOBAL COMMUNICATIONS CONFERENCE (GLOBECOM). - 9781479913534 ; , s. 992-997
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Konferensbidrag (refereegranskat)abstract
- This paper tackles the important question of how to compensate the inherent spectrum efficiency loss in cognitive relay networks. Particularly, by considering two-way cognitive relaying, we seek to enhance the performance of the secondary network in terms of the reliability due to limited transmit power, and the spectral efficiency of the half-duplex dual-hop relay transmission. We derive new closed-form expressions for the outage probability of a cognitive relay network with two-way communications in the presence of multiple primary users. Our expressions accurately take into account the impact of the maximum allowable interference constraint at the primary users on the secondary network.
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| 8. |
- Soleimani-Nasab, Ehsan, 1984, et al.
(författare)
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Two-way interference-limited AF relaying over Nakagami-m fading channels
- 2013
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Ingår i: Proceedings - IEEE Global Communications Conference, GLOBECOM. - 2334-0983 .- 2576-6813. - 9781479913534 ; , s. 4275-4281
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Konferensbidrag (refereegranskat)abstract
- We investigate the performance of two-way interference-limited amplify-and-forward relaying systems over independent but non-identically distributed (i.n.i.d.) Nakagami-m fading channels. A tight closed-form lower bound on the outage probability of the system is derived, along with a simplified expression in the asymptotically low outage regime. Some special cases of practical interest (e.g., no interference power and interference-limited case) are also examined. The theoretical and numerical results provide important physical insights into the implications of the model parameters on the system performance. © 2013 IEEE.
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| 9. |
- Tanyingyong, Voravit, et al.
(författare)
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Resilient Communication through Multihoming for Remote Healthcare Applications
- 2013
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Ingår i: 2013 IEEE Global Communications Conference (GLOBECOM). - : IEEE. - 9781479913534 ; , s. 1335-1341
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Konferensbidrag (refereegranskat)abstract
- Advancements in today's technologies make it possible to offer competitive home-based healthcare services using software routers based on open source software combined with Commodity-Off-The-Shelf (COTS) hardware. In this paper, we propose resilient communication through multihoming for remote healthcare applications. The solution is based on Bidirectional Forwarding Detection (BFD) for fast failure detection and a customized rerouting operation. We investigate the tradeoff between short reaction times for rerouting and low probability of false alarms. This is challenging to achieve under high traffic loads since the load affects the BFD session which is formed to monitor the bidirectional forwarding capabilities. We propose a simple mechanism that provides fast failover and meanwhile maintains a very low probability of generating false alarms and unwanted rerouting decisions. The mechanism is based on allocation of system resources for processing BFD control messages, and we demonstrate through empirical results that BFD then can be used in software routers to provide average failover times within 200 ms.
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| 10. |
- Wang, Jiaheng, et al.
(författare)
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Robust MIMO Precoding for the Schatten Norm Based Channel Uncertainty Sets
- 2013
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Ingår i: 2013 IEEE Global Communications Conference (GLOBECOM). - : IEEE Communications Society. - 9781479913534 ; , s. 3394-3399
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Konferensbidrag (refereegranskat)abstract
- In this paper, we consider robust MIMO precoding designs against deterministic imperfect channel state information at the transmitter (CSIT). In contrast to the existing works based on one or two particular channel uncertainty models, we consider a general uncertainty set defined by a generic matrix norm, called the Schatten norm, which includes most deterministic imperfect CSIT as special cases. Adopting worst-case robustness, the robust MIMO precoding design is formulated as a maximin problem to maximize the worst-case received signal-to-noise ratio or minimize the worst-case error probability. We show that the robust precoder admits a channel-diagonalizing structure for all Schatten norm based uncertainty sets, and then simplify the complex-valued matrix problem to a real-valued vector power allocation problem. We further show that the simplified power allocation problem can be analytically solved in a waterfilling manner, thus leading to a fully closed-form solution to the robust precoding design. Finally, we also investigate the robustness of beamforming and uniform-power transmission.
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