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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.

This study evaluates the performance of a practical IEEE 802.15.4/4e/4g low-rate (LR) wireless personal area network (WPAN) with multiple physical (PHY) layers and multi-hop capabilities for smart utility networks, machine-to-machine networks and other advanced sensor networks. The proposal includes realistic design considerations addressing demands of practical applications, country-specific regulatory requirements and technical specification in international standards. A cross-layer open system interconnection model from the application, transport, network, medium access control, down to the multiple PHY layers is constructed based on the specification in IEEE 802.15.4 LR-WPAN and other layer-specific standards. Employing the cross-layer model, extensive computer simulations were conducted to investigate the performance of the LR-WPAN system in this application domain. As a result, the authors have successfully verified the simulated achievable average throughput in both PHY layer designs, multi-rate and multi-regional frequency shift keying (MR-FSK) and multi-rate and multi-regional orthogonal frequency division multiplexing (MR-OFDM) with the theoretical throughput by calculation. Secondly, in a multi-PHY environment with the presence of 30 interferer devices, throughput degradation of the victim system is observed within 30%. Furthermore, when interferer devices transmit frames with interval beyond 1 s, the degradation to the victim system becomes negligible. Thirdly, MR-FSK PHY has a simpler design with higher energy-efficiency, whereas MR-OFDM PHY is more complicated with more resilience to interference. They have found an interference tolerance capability difference of 15 dB between the MR-FSK and MR-OFDM systems. Fourthly, comparing with their single-hop counterparts, multi-hop systems have lower average throughput in MR-FSK by 25% and MR-OFDM by 10%. Finally, comparing with networks with periodical beacon transmissions, asynchronous networks have more inferior average throughput of 20% in MR-FSK and 3% in MR-OFDM, with the advantage of longer battery lifespan.

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.

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.

In this paper, we study the performance of complete complementary code-based spread-time code-division multiple access (CC-ST-CDMA) in frequency-nonselective and frequency-selective fading channels. The theoretical bit-error-rate (BER) expressions conditioned on the number of users and the sequence length (and the number of resolvable paths for multipath frequency-selective fading) are obtained. The theoretical approximation of the BER for the system using long-sequence-length complete complementary codes is investigated as well. The simulations are conducted over flat-fading and two-path frequency-selective fading channels and have been used to verify the theoretical analysis. The results show that the proposed CC-ST-CDMA system has a comparable BER performance with complete complementary code-based multicarrier direct-sequence code-division multiple access (CC-MC-DSCDMA) for a flat-fading channel. However, for a frequency-selective fading channel, the CC-ST-CDMA is found to be more resistant, resulting in about 2-3 dB better performance than the CC-MC-DSCDMA.

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.

Pilot subcarriers are very useful in the measurement of channel indicator such as CINR, frequency offset estimation and channel estimation. They are applied widely in many existing standards such as IEEE 802.11, IEEE 802.16 and IEEE 802.22. In this paper, a set of pilot patten is proposed for a network operating in VHF/UHF band based on 802.16 WiMax design pattern. Rationales behind the choice of the pattern will be explained. Evaluation of the performance for the proposed pilot pattern and the WiMax pilot pattern is carried out with different decoding method under AWGN and under different channel models in the VHF/UHF band. The effects of different pilot symbol insertion schemes on the error performance of OFDM-QPSK are evaluated and a mathematical relationship for calculating the gain shift caused by different pilot symbols occupation rate is derived and discussed.

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.

The Complete Complementary (CC) codes have been able to improve the performance of multicarrier CDMA system for both downlink and uplink transmission. However, the number of users supported by CC code design is limited as its family size is relatively small. In this letter, an extension to CC codes using Zadoff-Chu sequence is proposed. The proposed codes are able to support large number of users and have perfect auto- and cross-correlation function just like CC codes.

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.

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.

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.

Blind identification of parameters in block interleaving has been studied by some researchers. In this paper, we extend the identification algorithm to convolutional type of interleaving. In particular, our algorithm is able to blindly determine the interleaver period, interleaver depth, number of stages in each shift register of interleaver and thus de-interleave the interleaved data streams. The proposed algorithm also requires less number of intercepted data bits compared to previous approaches and is applicable to block-coded block-interleaved data streams.

Spread-time code division multiple access (ST-CDMA) is an alternative CDMA scheme to spread spectrum (SS). The ST-CDMA is proposed for bandlimited multiple access channels, which can be considered the time-frequency dual of SS-CDMA. We propose a new ST-CDMA system based on the orthogonal complete complementary (CC) code. The performance of the proposed system is investigated and the simulation is done to compare with the conventional ST-CDMA system using PN codes. The results show the CC code-based ST-CDMA performs better than the existing system, which can be an additional choice for future multiple access communications systems.

The complete complementary (CC) codes [Suehiro, N et al., 1988] have been used in multicarrier wideband CDMA system [Chen Hsiao-Hua et al., 2001] to improve the performance except that a relatively small number of users can be supported by the codes. In this paper, a general method to construct the orthogonal code set using the sequence with ideal two-level autocorrelation is proposed. The maximal length sequence (M-sequence) is taken as an example to generate the modified M-sequence set. The BER performance of the modified M-sequence is evaluated and compared with the CC code and M-sequence using the simulation. The results indicate that the performance of modified M-sequence is comparable to CC code and much better than M-sequence. The proposed construction method for CC code can remove the drawback of the CC codes, which are limited by relatively small code set