Compressive sensing based opportunistic protocol for exploiting multiuser diversity in wireless networks

Energy-efficient opportunistic scheduling schemes in wireless networks

In this paper, further in-depth asymptotic analysis on the interaction between spatial diversity and multiuser diversity in wireless networks is given, following our recent work [Zhou and Dai, ICC06]. Rigorous proofs and necessarily stronger results in terms of convergence are provided for some intuitions in this area. Equally important, explicit expressions of scheduling gain and average system capacity in various circumstances that reveal interesting inter-connections among key system parameters are given. Our results are general enough to cover many practical scenarios of interesst.

In this paper, a new cross layer design of MAC and Routing protocol for OFDMA-based Multi-hop Ad-hoc Networks is proposed. In wireless network, when a route is established, the radio resource allocation problems at MAC layer may decrease the end to end performance proportionally with the length of each route. The contention at MAC layer may causes routing protocol to respond by finding new routes and routing table updates. The cross layer design allows layers to exchange state information in order to solve the problem and obtain higher performance. The proposed cross layer design of MAC and Routing protocol based the dynamic Sub-channel Assignment Algorithm in [4] to ensure the performance of ad-hoc and multi-hop networks is significantly improved.

The design of an efficient MAC protocol is of paramount importance for the definition of a wireless ATM access. Such a protocol, together with an appropriate traffic scheduler, should guarantee the required QoS for ATM connections. In this paper, we describe the PRAS (polling and reservation access scheme), a TDMA-TDD based MAC protocol with fixed frame duration, using both reservation and polling techniques to assign transmission time slots. In PRAS, each frame consists of variable-length fields, which make the radio access suitable for variable traffic conditions. The scheduling algorithm uses a priority scheme based on the ATM service classes and the maxCTD (cell transfer delay) parameter. A selective-repeat (SR) retransmission procedure is also proposed to correct errored cells due to the noisy channel. Performance results, obtained by simulation, cover different environments and provide many warnings also useful for the in-progress specification activity carried out by the standardization bodies.

Multimedia communication over wireless networks has become the driving technology for many important applications, experiencing dramatic market growth and promising revolutionary experiences in personal communication, gaming, entertainment, military, security, environment monitoring, and more. The advances in wireless communications and growth of real-time applications have necessitated the development of wireless networks that can support high quality of service (QoS) and power control. A node in an ad hoc network is normally battery operated which poses a huge constraint on the power consumption of such a node. Hence, designing a power efficient MAC protocol for ad hoc wireless networks is a major challenge. In this paper, we propose a reservation based, asynchronous MAC protocol called Multi-rate Multi-hop MAC protocol (MMMP) with power control for multi-hop ad hoc networks. The protocol conserves power and provides QoS guarantees for multimedia traffic. MMMP with power control achieves this by having every node maintain two reservation tables to keep track of ongoing transmissions. It calculates the appropriate transmission power (i.e the power level high enough to reach the destination node rather than transmitting at maximum power) based on node distances, which results in energy savings without causing throughput degradation. Simulation results obtained using the C programming language indicate that MMMP-power control outperforms IEEE 802.11 in all performance metrics and can efficiently handle a large range of traffic intensity. It also outperforms other similar state of the art MAC protocols.

Wireless sensor networks are used in many environmental monitoring applications (e.g., to monitor forest fires or volcanoes). In such applications, sensor nodes have a limited quantity of energy, but must operate for years without having their batteries changed. The main mechanism used to allow nodes to save energy is to sequence periods of activity and inactivity. However, the design of MAC and routing protocols for applications with low duty-cycle is still a challenge. In this paper, we propose an efficient flooding-based protocol combined with an unsynchronized MAC protocol operating at very low duty-cycle (≤ 1%) called E-ADCR (Energy-efficient Asynchronous low Duty-Cycle Routing protocol). Although flooding-based routing protocols are usually very simple to implement, they are often costly in terms of bandwidth, due to the large number of data copies. Our flooding-based routing protocol has the following features: (i) it benefits from rare common activities to reduce the amount of data copies generated by the flooding mechanism, (ii) it guarantees the reception of frames by a limited number of receivers by sending frames multiple times during the active period, and (iii) it uses a queue management policy to ensure that frames do not stay to long in queues. With these features and the strong cross-layer design with the MAC protocol, our protocol is able to achieve good performance with this very low duty-cycle.

Cyber-Physical System (CPS) is envisioned to tightly integrate the cyber-world of computation, communication, and control with the physical world. CPS is typically designed as a networked system of interacting sensors, actuators, and embedded computing devices to monitor and control the physical world. Thus, one of the essential building blocks of such a system is a highly efficient networking infrastructure. In this paper, we aims to develop an efficient wireless networking technology which can be utilized in CPS. More specifically, we develop a cross-layer optimization model based on the Network Utility Maximization (NUM) framework and its distributed solution for wireless multihop multicast networks exploiting multi-user diversity. It is known that the capacity of a wireless network can be increased by exploiting different channel conditions at different users, i.e., multi-user diversity; however, it is yet to be determined how much performance gain can be achieved by exploiting multi-user diversity in wireless multihop multicast networks. To address this problem, we extend the NUM framework and derive a new optimization problem including the benefits of multi-user diversity for multicasting scenarios in wireless multihop networks under a probabilistic media access control (MAC). In our problem, multi-user diversity is achieved via opportunistic scheduling. Then, we propose a distributed approximation algorithm for the problem. Our numerical results confirm that the benefit of multi-user diversity is prominent in a wireless multihop network with multicast flows.

The emergence of video streaming over wireless home networks creates renewed interests in design and analysis of new MAC protocols toward QoS provisioning for video applications. IEEE 802.11e Hybrid coordination function Controlled Channel Access (HCCA) exhibits good QoS provisioning for constant bit rate (CBR) video streams in a single collision domain. However, its performance degrades significantly for variable bit rate (VBR) video streams particularly in multicollision domains. In addition, HCCA has the disadvantage of high complexity. In this paper, we introduce a deterministic backoff (DEB) method into the HCCA mechanism, which achieves virtual polling via carrier sense on the wireless channel. DEB intentionally sets each station's backoff counter to a different value, thus stations can access the shared wireless channel at different time slots, which avoids network collisions. By proper controlling of each station's backoff counter, DEB achieves polling like HCCA, but in a more flexible and efficient way. It considerably mitigates inter-AP interference as well due to its carrier sense nature. Results show that, compared to HCCA, DEB always exhibits improvement in performance, particularly in multicollision domains where improvement is remarkable.

The paper presents a dynamic subchannel assignment algorithm based on orthogonal frequency division multiple access technology operating in the time division duplexing and a new cross-layer design based on a proposed routing protocol jointed with the MAC protocol. The proposed dynamic sub-channel assignment algorithm provides a new interference avoidance mechanism which solves several drawbacks of existing radio resource allocation techniques in wireless networks using OFDMA/TDD, such as the hidden node and exposed node problems, mobility, and cochannels interference in frequency (CCI). Besides, in wireless networks, when a route is established, the radio resource allocation problems may decrease the end to end performance proportionally with the length of each route. The contention at MAC layer may cause the routing protocol at network layer to respond by finding new routes and routing table updates. The proposed routing protocol is jointed with the MAC protocol based on dynamic sub-channel assignment to ensure that the quality of service in multihop ad hoc networks is significantly improved.

We propose a middleware platform built on wireless USB (WUSB) over wireless body area networks (WBAN) hierarchical protocol for wearable health-monitoring systems (WHMS). The proposed middleware platform is composed of time-synchronization and localization solutions. It is executed on the basis of WUSB over WBAN protocol at each wearable sensor node comprising the WHMS. In the platform, firstly, the time-synchronization middleware is executed. After that, a WHMS host calculates the location of a receiving sensor node by using the difference between the times at which the sensor node received different WBAN beacon frames sent from the WHMS host. The WHMS host interprets the status and motion of the wearable body-sensor objects.

During some cases, especially when the channel quality varies considerably between the receivers, MU-MIMO transmission may fail to utilize the available MIMO capacity to its full potential. A MAC protocol design that can switch between MU-MIMO and multiple SU-MIMO transmissions after taking into account the achievable performance could be one of the simple yet attractive solutions to address such issue. In this paper, by simply upgrading the WLAN default MAC protocol CSMA/CA, we propose a MAC protocol that is capable of performing such switching task in a forthcoming very high throughput WLAN. The detailed performance analysis demonstrates that the more benefits could be achieved from the proposed scheme in comparison to the conventional MU-MIMO transmission only scheme both in terms of throughput and delay.

This paper presents a distributed MAC protocol switching mechanism for maximizing network throughput in the presence of traffic and topology heterogeneity. The key idea behind dynamic MAC switching is for each node to use its local topology and traffic density information to decide the most suitable MAC protocol that can maximize the MAC layer throughout in the neighborhood. A formal MAC switching rule is developed using analytical formulation of the MAC throughput available in the literature. NS2 based simulation experiments demonstrate that with the proposed MAC switching strategy, nodes in a wireless sensor network are able to achieve maximum MAC throughput by adaptively choosing the appropriate MAC protocol in the presence of heterogeneity in terms of data rate and node population.

Recent environmental changes have shown the world the importance of sustainable development and these changes demand concrete solutions. The Smart Grid solution is recognized as a key technology to cope with these challenges, not just concerning the environmental impact of greenhouse gases but also regarding the increasing electric demand. Smart Grid is a combination of two networks, the first being the electrical transmission and distribution network, while the other is the modern data communication network. The Smart Grid communication network can be divided into three parts, HAN (Home Area Network), NAN (Neighborhood Area Network), and WAN (Wide Area Network). IEEE 802.15.4 and IEEE 802.11 MAC protocols, which are based on the CSMA/CA mechanism, are assumed to be the candidates for the MAC layer of HAN. However, it has latency and energy efficiency problems. In this paper, we have redesigned a tree based TDMA MAC protocol which can be applied in Smart Grid HAN. From the experiments, we verify the performance of our proposed protocol with respect to the network latency, high packet transmission rate and energy efficiency.

Recent Mobile Multimedia innovations evolved for the present society, is a mandatory requirement. To achieve this goal various forums have come forward with several design proposals to suit the group of applications in the Mobile Multimedia Networks (MMNs). In this regard, a new Multi-protocol Architecture for the Medium Access Control is required to seamless mobile multimedia networking. Hence a new Hybrid Multi-protocol Architecture is designed and proposed. Multimedia applications are bursty in nature and require dynamic real time services from the mobile networking. Efficient Resource Management and the Traffic control of mobile networks is very much needed to provide Quality of Service (QoS), in the piconets and in the Metropolitan Area Networks (MANs). Because of the small coverage area of Pico cells and the characteristics of the multi-path and shadow fading radio environment, hand-off events in the future systems will occur at much higher rate that the macro cellular systems in the applications of MAN. With the Technical growth of mobile Wi-Max and powerful end systems, the newly proposed Multi-protocol architecture is likely to support the Multimedia Killer applications. The newly designed and developed MAC architecture is based on the Mixture of Orthogonal Frequency Division Multiple Access (OFDMA), CDMA and TDMA Medium access control protocols for the Pico-nets. This protocol architecture is tested for its performance using the testing tool MATLAB. In this paper, a mixture of new MAC protocol for WLAN is proposed. In this design, the reservation and polling methods of MAC protocols to handle both the low and high data traffic of the mobile users is analyzed. The MAC standard specified by IEEE 802.16 for WIMAX is followed to benchmark and test the designed MAC protocol.

WiMAX based on series of IEEE 802.16 standards and 3GPP LTE are the two important development directions of next generation broadband wireless communication. In physical layers, in order to transmit high speed data flow in limited bandwidth, they both use the OFDM technology and MIMO technology to enhance system capacity and frequency spectral efficiency, avoid inter symbol interference, and improve system performance. But, they have more different methods in design of MAC protocols and sublayer allocation of MAC functions. In this paper, we firstly introduce the MAC protocols in WiMAX 16e and 3GPP LTE Release 8. Then compare their MAC functions in control plane and data plane, and provide the comparison chart of MAC functions between WiMAX and LTE. It shows that they both provide the MAC basic functions though they have various differences in realization mechanism and function division.