Quality of service adaptive modulation and coding scheme for IEEE 802.11ac

Nowadays, the rising demand for digital communication technologies has contributed to the increase in the volume of traffic. This continuous trend of internet traffic has led to the deterioration of the quality of service (QoS) with reduced throughput and increased latency. This also is due to the proliferation of new broadband applications which require low latency and high throughput such as virtual reality and real-time gaming. Therefore, considering the aforementioned challenge in QoS of wireless networks, a link adaptation method is suggested in this study, in order to enhance the performance of the QoS in IEEE 802.11ac amendment wireless local-area network (WLAN). The proposed technique adaptively changes the transmission data rate by increasing or decreasing the modulation and coding scheme (MCS) level according to the traffic conditions. With the use of an OMNeT++ computer-aided design (CAD)-based simulation model, the effectiveness of the suggested approach is examined. Simulated findings were compared with the link adaptation approach of the default condition. The results of the simulation demonstrate that the proposed technique significantly increases throughput (36.48%) and decreases latency in comparison to the default situation. These findings demonstrate the technique's potential to improve WLAN QoS efficiency, notably in regard to throughput and latency

Cooperative communication in wireless networks: algorithms, protocols and systems

Current wireless network solutions are based on a link abstraction where a single co-channel transmitter transmits in any time duration. This model severely limits the performance that can be obtained from the network. Being inherently an extension of a wired network model, this model is also incapable of handling the unique challenges that arise in a wireless medium. The prevailing theme of this research is to explore wireless link abstractions that incorporate the broadcast and space-time varying nature of the wireless channel. Recently, a new paradigm for wireless networks which uses the idea of 'cooperative transmissions' (CT) has garnered significant attention. Unlike current approaches where a single transmitter transmits at a time in any channel, with CT, multiple transmitters transmit concurrently after appropriately encoding their transmissions. While the physical layer mechanisms for CT have been well studied, the higher layer applicability of CT has been relatively unexplored. In this work, we show that when wireless links use CT, several network performance metrics such as aggregate throughput, security and spatial reuse can be improved significantly compared to the current state of the art. In this context, our first contribution is Aegis, a framework for securing wireless networks against eavesdropping which uses CT with intelligent scheduling and coding in Wireless Local Area networks. The second contribution is Symbiotic Coding, an approach to encode information such that successful reception is possible even upon collisions. The third contribution is Proteus, a routing protocol that improves aggregate throughput in multi-hop networks by leveraging CT to adapt the rate and range of links in a flow. Finally, we also explore the practical aspects of realizing CT using real systems.PhDCommittee Chair: Sivakumar, Raghupathy; Committee Member: Ammar, Mostafa; Committee Member: Ingram, Mary Ann; Committee Member: Jayant, Nikil; Committee Member: Riley, Georg

IST-2000-30148 I-METRA: D6.1 Implications in re-configurable systems beyond 3G (Part 1)

In this activity MIMO HSDPA is evaluated as the UMTS evolution that could allow a combination of high bit rate services, coverage and mobility with a good trade-off between cost and performance. This evaluation requires the definition of an objective framework for comparison between competing air interface technologies for Systems beyond 3G, and should be carried out in cooperation with other IST projects. The deliverable is complemented by analytically assessing channel capacity in flat Rician- and Rayleigh fading when ideal proportional fast scheduling, optimal rate adaptation, and various transmit diversity techniques are used.Preprin

Adaptive multi-PHY IEEE802.15.4 TSCH in sub-GHz industrial wireless networks

To provide wireless coverage in challenging industrial environments, IEEE802.15.4 Time-Slotted Channel Hopping (TSCH) presents a robust medium access protocol. Using multiple Physical Layers (PHYs) could improve TSCH even more in these heterogeneous environments. However, TSCH only defines one fixedduration timeslot structure allowing one packet transmission. Using multiple PHYs with various data rates therefore does not yield any improvements because of this single-packet limitation combined with a fixed slot duration. We therefore defined two alternative timeslot structures allowing multiple packets transmissions to increase the throughput for higher data rate PHYs while meeting a fixed slot duration. In addition, we developed a flexible Link Quality Estimation (LQE) technique to dynamically switch between PHYs depending on the current environment. This paper covers a theoretical evaluation of the proposed slot structures in terms of throughput, energy consumption and memory constraints backed with an experimental validation, using a proof-of-concept implementation, which includes topology and PHY switching. Our results show that a 153% higher net throughput can be obtained with 84% of the original energy consumption and confirm our theoretical evaluation with a 99 % accuracy. Additionally, we showed that in a real-life testbed of 33 nodes, spanning three floors and covering 2550 m(2), a compact multi-PHY TSCH network can be formed. By distinguishing between reliable and high throughput PHYs, a maximum hop count of three was achieved with a maximum throughput of 219 kbps. Consequently, using multiple (dynamic) PHYs in a single TSCH network is possible while still being backwards compatible to the original fixed slot duration TSCH standard

A Survey on Wireless Security: Technical Challenges, Recent Advances and Future Trends

This paper examines the security vulnerabilities and threats imposed by the inherent open nature of wireless communications and to devise efficient defense mechanisms for improving the wireless network security. We first summarize the security requirements of wireless networks, including their authenticity, confidentiality, integrity and availability issues. Next, a comprehensive overview of security attacks encountered in wireless networks is presented in view of the network protocol architecture, where the potential security threats are discussed at each protocol layer. We also provide a survey of the existing security protocols and algorithms that are adopted in the existing wireless network standards, such as the Bluetooth, Wi-Fi, WiMAX, and the long-term evolution (LTE) systems. Then, we discuss the state-of-the-art in physical-layer security, which is an emerging technique of securing the open communications environment against eavesdropping attacks at the physical layer. We also introduce the family of various jamming attacks and their counter-measures, including the constant jammer, intermittent jammer, reactive jammer, adaptive jammer and intelligent jammer. Additionally, we discuss the integration of physical-layer security into existing authentication and cryptography mechanisms for further securing wireless networks. Finally, some technical challenges which remain unresolved at the time of writing are summarized and the future trends in wireless security are discussed.Comment: 36 pages. Accepted to Appear in Proceedings of the IEEE, 201

Final report on the evaluation of RRM/CRRM algorithms

Deliverable public del projecte EVERESTThis deliverable provides a definition and a complete evaluation of the RRM/CRRM algorithms selected in D11 and D15, and evolved and refined on an iterative process. The evaluation will be carried out by means of simulations using the simulators provided at D07, and D14.Preprin