| 1. |
- Angelakis, Vangelis, et al.
(author)
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A distributed, load-aware, power and frequency bargaining protocol for LTE-based networks
- 2012
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In: 2012 IEEE INTERNATIONAL CONFERENCE ON COMMUNICATIONS (ICC). - Piscataway, NJ, USA : IEEE. - 9781457720529 - 9781457720512 ; , s. 6525-6529
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Conference paper (peer-reviewed)abstract
- A distributed, load-aware, joint power and frequency allocation protocol is introduced for LTE-based cellular networks, and system-level simulations are performed. Our proposed scheme aims to cooperatively limit the impact of Fractional Frequency Reuse (FFR) on the center users throughput compared to the Reuse 1 scheme, while providing sufficient throughput for the edge users. This is achieved through an asynchronous, lightweight scheme of local message exchange between neighboring LTE eNodeBs. The proposed scheme facilitates a type of "bargain" where an overloaded sector requests permission to utilize its neighbors edge bands for its center users at a limited set of transmit power levels. Grants are generated at each neighbor by solving a small-scale optimization problem. Using an LTE simulator we evaluate our scheme on a network with 21 sectors of varying load patterns. The proposed schemes performance for center users is consistently improved with respect to FFR-3, while for edge users the performance degradation is controlled by a parameter we set in the optimization problems definitions; compared to Reuse 1 edge users still have gains. Specifically, we observed up to a 46% gain in the sectors center throughput with a cost below 9% at the edges when compared to the classic FFR scheme, while the overall system throughput goes up by up to 26% in heavily loaded scenarios.
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| 2. |
- Arlitt, Martin, et al.
(author)
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Passive Crowd-based Monitoring of World Wide Web Infrastructure and its Performance
- 2012
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In: Proc. IEEE International Conference on Communications (ICC 2012). - : IEEE. - 9781457720529 - 9781457720512 ; , s. 2689-2694
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Conference paper (peer-reviewed)abstract
- The World Wide Web and the services it provides are continually evolving. Even for a single time instant, it is a complex task to methodologically determine the infrastructure over which these services are provided and the corresponding effect on user perceived performance. For such tasks, researchers typically rely on active measurements or large numbers of volunteer users. In this paper, we consider an alternative approach, which we refer to as passive crowd-based monitoring. More specifically, we use passively collected proxy logs from a global enterprise to observe differences in the quality of service (QoS) experienced by users on different continents. We also show how this technique can measure properties of the underlying infrastructures of different Web content providers. While some of these properties have been observed using active measurements, we are the first to show that many of these properties (such as location of servers) can be obtained using passive measurements of actual user activity. Passive crowd-based monitoring has the advantages that it does not add any overhead on Web infrastructure, it does not require any specific software on the clients, but still captures the performance and infrastructure observed by actual Web usage.
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| 3. |
- Cavdar, Cicek, et al.
(author)
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Design of green optical networks with signal quality guarantee
- 2012
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In: IEEE International Conference on Communications. - : IEEE. - 9781457720529 ; , s. 3025-3030
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Conference paper (peer-reviewed)abstract
- Energy consumption of communication networks is growing very fast due to the rapidly increasing traffic demand. Consequently, design of green communication networks gained a lot of attention. In this paper we focus on optical Wavelength Division Multiplexing (WDM) networks, able to support this growing traffic demand. Several energy-aware routing and wavelength assignment (EA-RWA) techniques have been proposed for WDM networks in order to minimize their operational cost. These techniques aim at minimizing the number of active links by packing the traffic as much as possible, thus avoiding the use of lightly loaded links. As a result, EA-RWA techniques may lead to longer routes and to a high utilization on some specific links. This has a detrimental effect on the signal quality of the optical connections, i.e., lightpaths. In this study we quantify the impact of power consumption minimization on the optical signal quality. and address this problem by proposing a combined impairment and energy-aware RWA (IEA-RWA) approach. Towards this goal we developed a complete mathematical model that incorporates both linear and non-linear physical impairments together with an energy efficiency objective. The IEA-RWA problem is formulized as a Mixed Integer Linear Programming (MILP) model where both energy efficiency and signal quality considerations are jointly optimized. By comparing the proposed IEA-RWA approach with existing RWA (IA-RWA and EA-RWA) schemes, we demonstrate that our solution allows for a reduction of energy consumption close to the one obtained by EA-RWA approaches, while still guaranteeing a sufficient level of the optical signal quality.
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| 4. |
- Dixit, A., et al.
(author)
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Efficient protection schemes for hybrid WDM/TDM Passive Optical Networks
- 2012
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In: Communications (ICC), 2012 IEEE International Conference on. - : IEEE. - 9781457720529 ; , s. 6220-6224
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Conference paper (peer-reviewed)abstract
- Hybrid WDM/TDM Passive Optical Network (PON) is a promising candidate for next-generation optical access (NGOA) solutions as it is able to offer a high splitting ratio and consequently achieves a relatively low cost and power consumption on a per-user basis compared with other NGOA architectures. On the other hand, the end users require a certain level of connection availability while the operators need to reduce the failure impact (i.e. to avoid a huge number of end users being affected by any single failure). Therefore, by evaluating the connection availability and failure impact robustness we identify the most efficient parts to provide resilience in a hybrid WDM/TDM PON from an operator and an end-user perspective. Then, we select the appropriate protection schemes to construct some novel reliable architectures and analyze their reliability performance in urban and rural scenarios. In this way, this paper provides a comprehensive insight into the most relevant protection mechanisms for hybrid WDM/TDM PONs.
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| 5. |
- Duong, Quang Trung, et al.
(author)
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Distributed Space-Time Coding in Two-Way Fixed Gain Relay Networks over Nakagami-m Fading
- 2012
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In: Proceedings of the IEEE International Conference on Communicatons (ICC). - Ottawa : IEEE. - 9781457720512 - 9781457720529 ; , s. 3521-3525
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Conference paper (peer-reviewed)abstract
- The distributed Alamouti space-time code in two-way fixed gain amplify-and-forward (AF) relay is proposed in this paper. In particular, closed-form expressions for approximated ergodic sum-rate and exact pairwise error probability (PWEP) are derived for Nakagami-m fading channels. To reveal further insights into array and diversity gains, an asymptotic PWEP is also obtained. Finally, numerical results are provided to corroborate the proposed theoretical analysis.
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| 6. |
- Dössel, Leefke, et al.
(author)
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Anytime reliability of systematic LDPC convolutional codes
- 2012
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In: Communications (ICC), 2012 IEEE International Conference on. - : IEEE. - 9781457720529 ; , s. 2171-2175
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Conference paper (peer-reviewed)abstract
- We propose a LDPC Convolutional Code ensemble together with an expanding-window message-passing decoder that asymptotically have anytime properties when used for streaming transmission on the binary erasure channel. We show analytically that the decoding erasure probability of these codes decays exponentially over decoding delay and determine the corresponding anytime exponents.
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| 7. |
- Fowler, Scott, et al.
(author)
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Analysis of adjustable and fixed DRX mechanism for power saving in LTE/LTE-Advanced
- 2012
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In: 2012 IEEE International Conference on Communications (ICC). - : IEEE. - 9781457720512 - 9781457720529 - 9781457720536 ; , s. 1964-1969
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Conference paper (peer-reviewed)abstract
- The 4G standard Long Term Evolution (LTE) has been developed for high-bandwidth mobile access for today's data-heavy applications, consequently, a better experience for the end user. To extend the user equipment battery lifetime, plus further support various services and large amount of data transmissions, the 3GPP standards for LTE/LTE-Advanced has adopted discontinuous reception (DRX). However, there is a need to optimize the DRX parameters, so as to maximize power saving without incurring network re-entry and packet delays. In this paper, we take an overview of the fixed frame DRX cycle and compare it against an adjustable DRX cycle of the LTE/LTE-Advanced power saving mechanism, by modelling the system with bursty packet data traffic using a semi-Markov process. Based on the analytical model, we will show the trade-off relationship between the power saving and wake-up delay performance.
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| 8. |
- Gabry, Frédéric, et al.
(author)
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Cooperation for Secure Broadcasting in Cognitive Radio Networks
- 2012
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In: Communications (ICC), 2012 IEEE International Conference on. - : IEEE. - 9781457720529 ; , s. 5613-5618
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Conference paper (peer-reviewed)abstract
- This paper explores the trade-off between cooperation and secrecy in cognitive radio networks. We consider a scenario consisting of a primary and a secondary system. In the simplest case, each system is represented by a pair of transmitter and receiver. We assume a secrecy constraint on the transmission in the sense that the message of the primary transmitter has to be concealed from the secondary receiver. Both situations where the secondary transmitter is aware and unaware of the primary message are investigated and compared. In the first case, the secondary transmitter helps by allocating power for jamming, which increases the secrecy of the first message. In the latter case, it can also act as a relay for the primary message, thus improving the reliability of the primary transmission. Furthermore, we extend our results to the scenario where the secondary system comprises multiple receivers. For each case we present achievable rate regions. We then provide numerical illustrations for these rate regions. Our main result is that, in spite of the secrecy constraint, cooperation is beneficial in terms of the achievable rates. In particular, the secondary system can achieve a significant rate without decreasing the primary rate below the benchmark rate achievable without the help of the secondary transmitter. Finally, we investigate the influence of the distances between users on the system's performance.
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| 9. |
- Hurtig, Per, 1980-, et al.
(author)
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Enhanced Metric Caching for Short TCP Flows
- 2012
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In: Proceedings of the IEEE International Conference on Communications (ICC 2012). - : IEEE Press. - 9781457720512 - 9781457720529 ; , s. 1209-1213
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Conference paper (peer-reviewed)abstract
- Internet-based applications that require low latency are becoming more common. Such applications typically generate traffic consisting of short, or bursty, TCP flows. As TCP, instead, is designed to optimize the throughput of long bulk flows there is an apparent mismatch. To overcome this, a lot of research has recently focused on optimizing TCP for short flows as well. In this paper, we identify a performance problem for short flows caused by the metric caching conducted by the TCP control block interdependence mechanisms. Using this metric caching, a single packet loss can potentially ruin the performance for all future flows to the same destination by making them start in congestion avoidance instead of slow-start. To solve this, we propose an enhanced selective caching mechanism for short flows. To illustrate the usefulness of our approach, we implement it in both Linux and FreeBSD and experimentally evaluate it in a real test-bed. The experiments show that the selective caching approach is able to reduce the average transmission time of short flows by up to 40%.
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| 10. |
- Jónsson, Kristján Valur, et al.
(author)
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Secure distributed top-k aggregation
- 2012
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In: Communications (ICC), 2012 IEEE International Conference on. - : IEEE. - 9781457720529 ; , s. 804-809
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Conference paper (peer-reviewed)abstract
- In-network aggregation is an efficient and scalable distributed approach to global state approximation. However, security remains an open problem in such systems, especially when we consider dynamic network effects, such as mobility, packet loss and churn. In this paper, we consider the reseilience of the top-k aggregate to manipulation by active insider adversaries. Unfortunately, this versatile aggregation function is inherently insecure. We propose a simple, low-overhead solution to the problem of preserving aggregate integrity which leverages the principles of trusted systems. The solution we propose is generally applicable, even to the challenging problem of securing distributed aggregation in a dynamic network.
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