Yongnu Jin

Adaptive GTS allocation scheme with applications for real-time Wireless Body Area Sensor Networks

The IEEE 802.15.4 standard not only provides a maximum of seven guaranteed time slots (GTSs) for allocation within a superframe to support time-critical traffic, but also achieves ultralow complexity, cost, and power in low-rate and short-distance wireless personal area networks (WPANs). Real-time wireless body area sensor networks (WBASNs), as a special purpose WPAN, can perfectly use the IEEE 802. 15. 4 standard for its wireless connection. In this paper, we propose an adaptive GTS allocation scheme for real-time WBASN data transmissions with different priorities in consideration of low latency, fairness, and bandwidth utilization. The proposed GTS allocation scheme combines a weight-based priority assignment algorithm with an innovative starvation avoidance scheme. Simulation results show that the proposed method significantly outperforms the existing GTS implementation for the traditional IEEE 802.15.4 in terms of average delay, contention free period bandwidth utilization, and fairness.

A Reconfigurable Digital Receiver for Transmitted Reference Pulse Cluster UWB Communications

The transmitted reference pulse cluster (TRPC) structure for ultrawide bandwidth communications contains compactly spaced reference and data pulses and enables the use of a robust autocorrelation detector at the receiver. Since the digital receiver not only can avoid the problems caused by using the analog autocorrelation but can provide flexibility in its signal processing at the expense of high sampling rate of an analog-to-digital converter (ADC) as well, we consider the digital architecture for the recently proposed TRPC signaling scheme and propose a reconfigurable TRPC (rec-TRPC) receiver. The received signal-to-noise ratio (SNR) can be maximized in the new designed receiver by using the optimum number of delay line (DL) branches. The performance of the rec-TRPC receiver is analyzed, and our semi-analytical and simulation results show that the rec-TRPC receiver structure achieves up to a 2-dB power gain over the original TRPC receiver. Furthermore, the complexity of the rec-TRPC receiver is investigated from an implementation viewpoint and compared with the digital implementation of the original TRPC receiver.

Interference mitigation study for low energy critical infrastructure monitoring applications

Low energy critical infrastructure monitoring (LECIM) applications are rapidly increasing, whose common requirements derived from the type of communications performed include reliable data transfer, energy efficiency, long deployment lifetime, and low infrastructure cost. A low rate wireless personal area network (WPAN) can help control and manage the operations of such applications. To facilitate point to multi-points communication for LECIM devices, the IEEE 802.15.4k task group is formed as an amendment to IEEE 802.15.4. In this paper, we first review the main activities of TG15.4k with the updated status and the structure of LECIM networks. Then, after analyzing the interference issues in the LECIM system, especially for the direct-sequence spreading spectrum (DSSS) physical layer, we propose the interference mitigation schemes by combining time division multiplexing (TDM), frequency division multiplexing (FDM) and code division multiplexing (CDM). Furthermore, to mitigate the homogeneous interference more effectively, the orthogonal variable spreading factor (OVSF) codes based CDM are analyzed. Monte Carlo simulation results show that the proposed interference mitigation schemes has robustness against the interference under the LECIM multi cluster environments.

Improved transmitted reference pulse cluster scheme for ultra wideband communication systems

In this study, from a more practical point of view, the authors develop an improved transmitted reference pulse cluster (iTRPC) scheme. Based on a recently proposed transmitted reference pulse cluster (TRPC) structure, each pulse cluster is broken into reference pulse clusters (RPCs) and data pulse clusters (DPCs). It is observed that by inserting a number of zeros at the end of each RPC and each DPC, inter pulse interference can be dramatically reduced. This also results in more multi-path delayed power being captured for data detection. The performance of the proposed iTRPC scheme is analysed and compared with that of traditional TR and the original TRPC (oTRPC) system. Simulations verify that this iTRPC scheme, with quite low-complexity and not extra energy requirements, achieves more than 7 dB performance improvement over the oTRPC scheme.

Performance analysis of UWB intra-vehicle transmitted-reference communication systems

The applications of ultra wideband (UWB) technologies in commercial vehicles wireless networked control systems (NCS) are attracting attention recently. The transmitted reference (TR) signaling, along with an autocorrelation receiver (AcR), is used for UWB intra-vehicle communication systems. In this paper, we analyze the performance of UWB intra-vehicle NCS with TR signaling under different time-bandwidth products and different numbers of transmitted pulses per symbol conditions. The bit-error probability (BEP) performance of this system is estimated based on the Gaussian approximation and the sampling expansion methods. Through Monte Carlo simulations, we investigate the limitation of the validity of the conventional Gaussian approximation and the sampling expansion methods for the intra-vehicle NCS.

A Transmitted Reference Pulse Cluster Averaging UWB Receiver

The transmitted reference pulse cluster (TRPC) structure for ultrawideband communications enables a more robust autocorrelation receiver (AcR) than a conventional transmitted reference (TR) scheme. In this paper, to further improve the performance of TRPC AcR, we propose a TRPC averaging (TRPC-A) AcR by using a TRPC-A method, which is similar but different from the pulse averaging method used in a conventional TR scheme. The proposed receiver structure is designed in both analog and digital methods, and their implementation complexities are explored. Our analytical and simulation results show that the proposed receiver can greatly improve the performance over the original TRPC receiver. What is more, the required additional implementation complexity of the proposed TRPC-A receiver added to the original TRPC AcR is much less than that of the averaging TR AcR added to conventional TR AcR due to the TRPC signaling characteristics. Therefore, from a practical point of view, the designed TRPC-A AcR is considered as a highly recommended practice, particularly in multiuser access environments.

Cyclic Prefixed Single Carrier Transmission in Intra-Vehicle Wireless Sensor Networked Control Systems

Intra-vehicle wireless sensor network, which is also called networked control system (NCS) is a promising new research area. NCS can not only provide part cost, assembly, maintenance savings, and fuel efficiency through the elimination of the wires, but also enable new sensor technologies to be integrated into vehicles. Ultra wideband (UWB) communication is a competitive candidate for the intra-vehicle NCS. In this paper, the performance of cyclic prefixed single carrier with frequency domain equalization (SC-FDE) transmission is investigated over intra-vehicle NCS propagation environment. The error-rate performance and the implementation complexity are compared among impulse based single carrier UWB (SC-UWB), multicarrier UWB (MC-UWB) employing orthogonal frequency-division-multiplexing (OFDM), and CP-SC under the same transmitting data rate conditions. Simulation results demonstrate conclusive performance advantage of the SC-FDE scheme on the communication of two different intra-vehicle NCS scenarios, especially when minimum mean square error method is taken into account.

Performance analysis of intra-vehicle ultra-wide band propagation in multi-user environments

Ultra wideband (UWB) technology attracts attention from automotive manufacturers as a potential way to construct an intra-vehicle wireless sensor network, which is also called networked control system (NCS). Given that modern vehicles incorporate tens of sensors to provide vital sensor information such as temperature, air quality, tire pressure, distances to nearby objects, etc., for the electronic control units (ECUs), the NCS inevitably operates in a multi-user interference (MUI) environment. This paper investigates the effect of MUI on the performance of intra-vehicle UWB NCS based on the recently proposed intravehicle NCS channel model. Through Monte Carlo simulations, we firstly study the multi user system performance in two different intra-vehicle NCS scenarios, and find that due to the different channel characteristics the multi user performance of the chassis NCS is more sensitive to the number of the total asynchronous users. Furthermore, we compare the multi user performance of the intra-vehicle NCS with that of indoor or outdoor environments.

Performance evaluation of intra-vehicle wireless sensor network systems

Intra-vehicle wireless sensor networks (IVWSNs) enable sensor technologies to be integrated into vehicles and provide part-cost, assembly, and maintenance savings, as well as fuel efficiency through the elimination of wires. Ultra-wide band (UWB) communication is considered a competitive candidate for IVWSNs. Extensive analysis has been done for indoor and outdoor propagation, but the analysis of IVWSNs environments has rarely been studied. In this paper, the error-rate performance of UWB propagation for these IVWSNs is investigated and compared under different transmission schemes. And we also study the effects of some parameters on communication performance, such as the number of rake fingers and direct sequence spread factor of an impulse radio system, the cyclic prefix size of a single carrier block transmission with frequency domain equalisation system, and the delay line time of a transmitted reference pulse cluster autocorrelation receiver. Study results offer valuable insight for the realistic IVWSNs.

A new design of transmitted reference UWB transceiver with non-ideal delay lines

The effect of group delay ripple (GDR) of non-ideal delay line (DL) causes an unexpected type of distortion in transmitted reference (TR) ultra wide bandwidth (UWB) systems. In this paper, we propose a new TR transceiver structure, where the GDR information of DL at the receiver is introduced into the transmitter to mitigate the performance error due to the GDR. Through Monte Carlo simulation, it is proved that this new designed transceiver can greatly reduce the impact of non-ideal DL with GDR on the performance of TR UWB systems.