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Based on IEEE 802.15.4, a contention-free period (CFP) adopts guarantee time slot (GTS) mechanism to ensure each device can access the radio channel. However, it is hard to get the authority to access the radio channel due to more competitors access the radio channel simultaneously. To cope with this issue, we proposed a guarantee time slot mechanism to enhance the performance and utilization of using...
In this paper, we present an approach to bounded optimal planning and flexible execution for a robot team performing a set of spatially distributed tasks related by temporal ordering constraints such as precedence or synchronization. Furthermore, the manner in which the temporal constraints are satisfied impacts the overall utility of the team, due to the existence of both routing and delay costs...
Orthogonal frequency division multiplexing (OFDM) communication systems require accurate estimation of timing offset and channel impulse response in order to achieve desirable performance. In this paper, we consider the optimal placement of pilot symbols over the OFDM subcarriers in order to minimize a function of the Cramér-Rao bound on these parameters. Previous work has investigated this problem...
Satisfying clock skew constraint is one of the most important tasks in the clock tree synthesis. Moreover, the task becomes much harder to solve as the clock tree is designed under multiple power mode environment, in which the voltage applied to some design module varies as the power mode changes. Recently, it is shown that adjustable delay buffer (ADB) whose delay can be tuned dynamically can be...
Tactical data links are an essential contribution to automatic "real-time" communication. In the current tactical environment, most users are pre-allocated a fixed amount of bandwidth. As a result, there should be bandwidth wastes and no guarantee of QoS. If the network is flooded, delaying of important messages may happen. So We need proper network management framework in TDL system. And...
Traffic splitting plays a very important role in parallel traffic replay since it determines the amount of required PCs and guarantees replay quality for each generated sub-trace. Previously adopted simulation-based method for splitting high-speed network traffic introduces serious performance limitation as it distributes traffic load to the replay PCs in an iterative trial-and-error manner. In this...
There is an increasing demand in high-throughput mobile applications for programmability and energy efficiency. Conventional mobile Central Processing Units (CPUs) and Very Long Instruction Word (VLIW) processors cannot meet these demands. In this paper, we present a novel dynamically reconfigurable processor that targets these requirements. The processor consists of a heterogeneous array of coarse...
The next generation of wireless networks (e.g., Long Term Evolution (LTE)and WiMAX) use multiple techniques to improve channel spectral efficiencies. In this paper we focus on one such technique, namely Coordinated Beam Switching (CBS). With CBS, each sector determines a sequence of beams (possibly with repetitions) over which it continuously cycles. Each sector independently determines its beam pattern...
A key component of an efficient multipath routing is theoptimal resource allocation strategy that deals with how thetraffic should be distributed amongst the multiple paths. Inthis paper, an intelligent traffic distribution policy thatminimise the maximum delay in a multipath routing scenariois proposed. It would be proved that such delay minimisationcan be achieved through delay synchronization....
The next generation of wireless networks (e.g., Long Term Evolution (LTE) and WiMAX) use multiple techniques to improve channel spectral efficiencies. In this paper we focus on one such technique, namely Coordinated Beam Switching (CBS). With CBS, each sector determines a sequence of beams (possibly with repetitions) over which it continuously cycles. Each sector independently determines its beam...
As the number of cores integrated onto a single chip increases, architecture and compiler designers are challenged with the difficulty of utilizing these cores to improve the performance of a single application. Thread-level speculation (TLS) can potentially help by allowing possibly dependent threads to speculatively execute in parallel. Extracting speculative thread from sequential applications...
Recently, there has been a growing interest in monitoring aqueous environments using Underwater Acoustic Sensor Networks (UASNs). In these networks, the Medium Access Control (MAC) protocols are responsible for coordinating the access from active nodes into the acoustic channel, which is characterized by high propagation delay and low data rate, which is challenging for system synchronization, energy...
Joint session scheduling (JOSCH) enables traffic to be split and transmitted over multiple radio access networks (RANs) simultaneously, which improves the quality-of-service (QoS) in terms of transmission rate, reliability and stability. Transmission synchronization is one of the key issues which JOSCH should consider, as it has direct effect on the performance of buffer management and data reassembly...
An inherent performance gap between custom designs and ASICs is one of the reasons why many designers still start their designs from register transfer level (RTL) description rather than from behavioral description, which can be synthesized to RTL via high-level synthesis (HLS). Sequencing overhead is one of the factors for this performance gap; the choice between latch and flip-flop is not typically...
The recently standardized IEEE 802.15.4 protocol is emerging as a basic building block for wireless sensor network applications by providing many appealing features, such as low power, low cost, low data-rate, and simplicity. However, when treating applications with strict timeliness, energy, and bandwidth requirements several problems arise, triggering the need of a solution for an efficient twinning...
Cooperative relaying is a promising technique that improves the end-to-end error performance in multihop vehicular networks. When cyclic delay diversity (CDD) is employed as transmit diversity at each hop, the control of the delay time introduced at each transmitting station improves the diversity gain. In this paper, a novel distributed delay time selection algorithm for cooperative multi-hop vehicular...
In this paper, an energy efficient adaptive modulation scheme is proposed for a wireless cognitive radio ad hoc network, where each node is equipped with cognitive radio and the network is an OFDMA system operating on time slots. In each slot, the users with new traffic demand will sense the spectrum and locate the available subcarrier set. Then they choose subcarriers with favorable channel condition...
Cyclic delay diversity (CDD) is a simple transmit diversity technique for coded OFDM systems with multiple transmit antennas. It is applicable to existed wireless communication systems since it does not need modifications of the standard OFDM receiver. However, CDD causes serious degradation in the performance of post-FFT estimation, i.e., integer frequency offset (IFO). This paper suggests pilot...
In this paper, we propose a robust STBC transmission scheme to combat the timing synchronization errors over frequency-selective multiple-access channels. First, the equivalent channel model in the presence of timing synchronization errors is derived and we find that the synchronization errors result in an equivalent channel model with larger number of correlated channel taps. Based on this correlated...
Three applications in wireless networks where model-free stochastic learning is applicable, are discussed. The learning based optimization problems are formulated and simulation results are presented. Some open issues are also discussed.
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