Liru Lu

Physical layer design and performance analysis on multi-Gbps millimeter-wave WLAN system

60 GHz millimeter wave technology has become an attractive solution for wireless communication in the most recent market. In the draft of IEEE 802.11ad standard, two modulation schemes are being considered in the design of physical (PHY) layer, namely, Single-Carrier (SC), and Orthogonal Frequency Division Multiplexing (OFDM). In this paper, the error performances of both coded modulation schemes under different channel models with hardware impairment are investigated. This hardware impairment includes non-linear distortion induced by 60 GHz power amplifier (PA) and phase noise of 60 GHz Phased Locked Loop (PLL) circuit. The channel models include Line-of-Sight (LOS) and Non-Line-of-Sight (NLOS) conference room models. Simulation results demonstrate that OFDM requires a much higher back-off power than SC to achieve the system requirement. In a realistic 60GHz channel based on measurements provided by 802.11ad, OFDM has gained better performance than SC with hardware impairment under NLOS situation using directional antennae.

Design considerations of IEEE 802.15.4m low-rate WPAN in TV white space

This article provides an overview of technical design considerations for IEEE 802.15.4m LRWPAN operating in TVWS. We summarize and discuss TVWS regulatory requirements and LRWPAN applications, the two major driving forces motivating the formation of the new IEEE 802.15.4m standard. These forces define the criteria necessary for consideration during IEEE 802.15.4m system design to meet regulatory requirements and optimize performance. First, system design is presented from the perspective of LR-WPAN channelization with reference to the TV channel plan. Next, design considerations for network architecture and topology are discussed by relating the architecture requirement in TVWS regulations to that in the legacy IEEE 802.15.4 standard. Third, the PHY and MAC layer designs, which are crucial for meeting the criterion of optimizing LR-WPAN performance to support potential applications, are studied. In the PHY layer, the existing design in IEEE 802.15.4 is listed and discussed with regard to its applicability and reusability in TVWS. In the MAC layer, two functional entities, the TVWS operation-enabling feature and the dynamic frequency-band switching mechanism, are discussed with respect to their necessity and practicality for performance enhancement.

Selection of modulation and coding schemes of single carrier PHY for 802.11ad multi-gigabit mmWave WLAN systems

This paper presents the system design method to determine the modulation and coding schemes according to the given usage models of single carrier transmission in millimeter wave Wireless LAN systems. Various modulation and coding combinations are compared and analyzed based on the BER performance over both AWGN and fading channels. The effects of hardware impairments including power amplifier non-linear effects and phase noise, etc., are considered as well. The system design strategy provides a guideline for the selection of modulation and coding schemes in practical which can fulfill the realistic system requirements.

IEEE 802.15.4m: The first low rate wireless personal area networks operating in TV white space

This paper provides an overview on motivations and process behind the forming of the first low rate (LR) wireless personal area networks (WPAN) operating in the TV white space (TVWS), IEEE 802.15.4m. There are three main forces driving the LR-WPAN community to expand its operational band to the TVWS. First, the change in TVWS-related regulations that opens up new spectrum resources is the key triggering factor. Secondly, there are many potential applications addressed by LR-WPAN systems that are anticipated to benefit from the expansion of the spectrum. Thirdly, the emergence of multiple standardizations targeting on the same types of applications in the same conventional frequency bands, indicating potential congestion and heterogeneous coexistence issues, is also one of the main pushing factor. In this paper, a comprehensive summary of different regulations, list of potential usage models and interactions among conventional LR-WPAN system are presented. A general discussion on how these factors fall in place to realize the forming of IEEE 802.15.4m is given. Finally, the paper concludes with expected functional requirements for the IEEE 802.15.4m system.

An interference management protocol for multiple physical layers in IEEE 802.15.4g smart utility networks

This article reports on the technical design and analysis of an interference management protocol that enables interference avoidance among multiple PHY layer designs in the recently completed IEEE 802.15.4g standard for smart utility networking (SUN). The IEEE 802.15.4g system employs three alternate PHY layer designs for enhanced SUN implementation and deployment targeting different market segments. First, SUN is introduced from different perspectives concerning technology, regulation, and the standardization process. Updates on the IEEE 802.15.4g standardization activities, the SUNrelated rules and regulations, and a summary of system design are presented. Next, the interference management protocol for multi-PHY-layer design in a single network is described and discussed. The impact of interference due to coexisting multiple PHY layer designs is highlighted. The operational procedure and mechanism of the management protocol, known as Multi-PHY Management (MPM), are then described. Finally, performance analysis in the presence of MPM is provided and discussed to justify its significance. It is anticipated that in the near future, this interference management approach will be put to field test and then deployed to provide solutions to mitigate interference among different PHY layer designs in SUN.

On communication and interference range of IEEE 802.15.4g smart utility networks

This paper presents the analysis on communication range and interference range of the IEEE 802.15.4g Smart Utility Networks (SUN). Firstly, error performance analysis corresponding to different propagation environments based on realistic measurement is conducted. Secondly, the effective communication range of SUN devices in these propagation channels are presented and discussed. Thirdly, in the presence of an interfering SUN device, the interference range between the victim and interfering devices are also studied. As a result, we have found that the achievable communication range of SUN devices in the GHz-order bands, the higher-UHF bands and the lower-UHF bands are 33m, 65m and 104m respectively. The critical interferer-to-victim distance below which, causing intolerable degradation to the victim receiver, is found to be 20m for typical urban and 35m for hilly rural environment. Finally, the analysis results are compared with the requirements based on the survey on utility metering device deployment conditions.

Performance and coexistence analysis of multiple IEEE 802 WPAN/WLAN/WRAN systems operating in TV White Space

This paper presents the performance and coexistence analysis of multiple IEEE 802 wireless communication systems operating in TV White Space (TVWS). Three IEEE 802 groups with systems operating in TVWS, namely IEEE 802.15.4m Low-Rate Wireless Personal Area Network (LR-WPAN), IEEE 802.11af Wireless Local Area Network (WLAN) and IEEE 802.22 Wireless Regional Area Network (WRAN) are investigated. First, system performance and achievable operating range for these systems in the absence of interference are evaluated, in accordance to design parameters suited to targeted application scenarios respectively. Then, assuming operation in close proximity, the three systems in the presence of interference are investigated to assess their error performance and critical distances to interfering device. The results highlighted several insightful critical parameter settings such as interferer-to-victim separation and interferer transmit power, beyond or below which, cause intolerable degradation to victim systems as quantified by the minimum required error rate performance.

Greater reliability in disrupted metropolitan area networks: use cases, standards, and practices

Unlike most general wireless users enjoying broadband access to the Internet and so on, a number of mission-critical applications such as PPDR are using narrowband systems that are only capable of transmitting voice and low-rate data. Broadband wireless networks with greater reliability are increasingly demanded by these applications including the emerging Smart Grid. With this vision, the IEEE 802.16 Working Group completed two standard amendments recently, IEEE Std 802.16n-2013 and IEEE Std 802.16.1a-2013. 802.16 network reliability is significantly increased by technical developments dealing with failures of network infrastructure stations, radio path and backhaul connectivity, and so on. This article serves to analyze the envisaged typical use cases of greater reliable broadband wireless networks, outline the main technical developments of the two standards, and introduce a recently developed practical system for PPDR applications in Japan.

An energy-efficient beaconless synchronization mechanism for Smart Utility Networks operating in TV white space

This paper proposes an energy-efficient beaconless synchronization mechanism for SUN operating in the TVWS. From the aspects of fulfilling the pervasive yet stringent requirements of low-energy wireless meters and TVWS regulations, the proposed mechanism is able to prolong battery lifespan beyond the required level for wireless smart meters, and is compliant to the specific network architecture and communication protocols demanded by the TVWS rules. In the MAC layer, a novel design for low duty cycle beaconless synchronization/data exchange is specified. In the PHY layer, the transceiver and realistic channel models applicable to the IEEE 802.15.4g SUN is constructed. Actual data from chip vendors of the wireless meter industry are also included to facilitate a more practical investigation. All the above are combined for performance evaluation to quantify the energy-efficiency and error performance of the proposed mechanism. As a result, it is found that the proposed mechanism enables battery lifespan of more than 10 years in most typical cases. For the system to achieve a ten-year battery lifespan at data transmission interval of 15 minutes, it is recommended that the system duty factor to be controlled in the order of 10-4, and that transmitted data frames to be limited within the length of 50 octets.

Network performance of a low energy IEEE 802.15.4/4e/4m WPAN system utilizing TV white space

This paper presents the network performance analysis of a low energy IEEE 802.15.4/4e/4m LR-WPAN operating in TV White Space. An energy-efficient mechanism optimizing the tradeoff between device sleep time and synchronization strategy is utilized to reduce the total power consumption in a non-beacon-enabled network. To evaluate the performance of the network, we have modeled a cross-layer system starting from the application, transport, network layers, to the MAC layer where the energy-efficient mechanism resides, to the PHY layer where the FSK PHY resides, down to the propagation channel where the VHF/UHF channels applies. Extensive computer simulations were conducted to investigate the performance of this low energy LR-WPAN system. As a result, we have found that a device may consume up to 40% and 2% of its total operation time to perform channel scanning and transmission, respectively. Applying the proposed energy-efficient mechanism, the achievable reduction of channel scanning time and transmission time are 20% and 1% respectively. We have also observed that the average residual battery capacity can be most effectively preserved when the number of devices in the network reaches approximately 30.