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In this paper, we study automated network planning for industrial wireless mesh networks. Based on the requirements of routing reliability in WirelessHART network, we propose two network planning approaches following the principles of the shortest hops and the least routers, respectively. We then implement them in Algorithms 1 and 2 respectively to automatically generate the network deployment for a given factory layout. Simulation results show that there exists a performance tradeoff between the two algorithms. The proposed algorithms have also been implemented and validated in an NS-2 WirelessHART network simulation.

We proposed a new RGB coding method in LED/LCD-camera communication link to increase the transmission rate by 3 times. The prototype of our system can achieve 1.5 meter transmission distance with up to 450 Kbit/s transmission rate. The relationship between transmission rate and distance, stabilization effects are also studied in detail to illustrate the advantage and limitation of this system.

As Gaussian minimum shift keying (GMSK) modulation scheme is adopted for body area network (BAN) applications, fast and power efficient synchronization algorithms for GMSK are desired considering the limited resources in BAN. We propose new synchronization algorithms for GMSK with the constraints of low complexity and low signal-to-noise ratio. Our new feedforward timing and frequency recovery algorithms can provide much better performance than those with similar complexity in the literature. The overall bit error rate (BER) performance of the GMSK system is within 1 dB loss compared to that with perfect synchronization.

We propose a symbol-by-symbol (SBS) detector for Gaussian minimum shift keying (GMSK) signals in body area networks (BAN). Our detector exploits the orthogonality between adjacent GMSK-modulated symbols. By dividing the received signals into inphase-/quadrature-channels and odd-/even-streams, the strongest inter-symbol interference (ISI) from the adjacent symbols is removed. A whitened matched filter is designed, and a decision-feedback scheme is proposed to further reduce the residue ISI. This SBS detector has much lower complexity than the conventional maximum likelihood sequence detection schemes using the Viterbi algorithm. Its performance can approach the MSK/BPSK performance which results in high energy efficiency. Thus, our proposed energy-efficient, low-complexity, SBS GMSK demodulator is suitable for BAN which have very limited resources. Based on our demodulator's structure, several other SBS detectors can be obtained straightforwardly.

The problem of carrier and clock synchronization without a training sequence for a robust receiver working at low signal-to-noise (SNR) ratios is considered. Both short packet and long burst transmission scenarios are taken into account. A low-complexity iterative symbol timing and carrier synchronization algorithm making use of the extrinsic information from the soft- input soft-output (SISO) decoder is proposed. The non-data-aided (NDA) algorithms are used for initial synchronization. In order to solve the phase ambiguity problem inherent in the NDA phase synchronization algorithm, two SISO decoders denoted by I and Q decoders, respectively, along with a differential decoder are proposed. The simulation results show that the proposed iterative synchronizer and decoder can reach the ideal performance at very low SNR with an increased allowed residual frequency offset and [-pi,pi] phase uncertainty region.

We consider the problem of carrier frequency and phase synchronization at low SNR without a training sequence for short packet transmission. A low-complexity iterative joint symbol timing and carrier synchronization algorithm making use of the extrinsic information from the soft-input soft-output (SISO) decoder is proposed. The non-data-aided (NDA) algorithms are used for initial synchronization. The simulation results show that the frequency offset estimation is the most critical problem in low SNR region. The proposed low-complexity algorithm can reach the ideal performance with perfect synchronization in the absence of frequency offset at very low SNR. When the frequency offset exists, the proposed algorithm can work effectively and improve the performance significantly.

We consider the problem of symbol timing synchronization at low SNR without a training sequence in this paper. A low-complexity iterative joint symbol timing and carrier synchronization algorithm making use of the extrinsic information from the soft-input soft-output (SISO) decoder is proposed. The nondata-aided (NDA) algorithms are used for initial synchronization. The simulation results show that the proposed low-complexity solution works effectively and can converge after a few iterations. The receiver with the proposed iterative synchronizers can reach the ideal performance with perfect synchronization at very low SNR.

IEEE 802.15.4a Task Group is defining an ultra low power consumption and low cost radio for Wireless Personal Area Networks (WPANs) applications using Ultra-wideband (UWB) technology with high precision ranging capability. Ternary preamble sequences of two different lengths have been proposed and adopted in the IEEE 802.15.4a specification for ranging. In order for a IEEE 802.15.4a low cost UWB device to support multiple frequency bands across the available spectrum and ranging features, as many as twenty-four ternary sequences is required. A sizeable amount of memory is needed to store the codes. In this paper, we propose a method to generate the ternary codes using linear feedback shift registers (LFSRs) as and when it is required, resulting in significant memory savings. The ranging performance using the proposed ternary preamble sequence is evaluated through simulation.

In this paper, a new pulse-based UWB system is proposed with low power ranging. The ternary sequence based common signaling is proposed to support power efficient energy detectors, differential detectors, and coherent detectors simultaneously. The preamble for ranging is designed to have good autocorrelation properties. The on-off keying based power efficient modulation is combined with chip mapping/spreading to provide robust system performance even in a multipath fading channel. Furthermore, a low complexity energy detection receiver structure is elaborated for leading edge detection in a multipath rich channel. System simulations are performed to demonstrate the promising performance of the proposed system

We present a mobility model for simulations of scenarios in UMTS networks. This new model has been developed to overcome the shortcomings of previous models in capturing mobile user behavior. The proposed model strikes a balance between the abstraction level of purely stochastic models which lack certain important properties of the real world and completely deterministic models. The proposed model generates destinations of the mobile users based on the maximization of entropy of the gravity model which was first used in transportation planning and which has proven invaluable in urban planning. Subsequently, the model then allows the detailed tracking of users, in particular, the path of mobile users based on some known statistical behaviors of the mobile users, such as service arrival rates, service holding times, velocities, etc. As tracking is done on a microscopic level, it is possible to simulate and collect parameters which are important for wireless network planning and optimization, without the use of unrealistic assumptions.