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This article presents an overview of the background, technology, regulation, and standardization in the course of deploying smart utility networks (SUNs) in TV white space (TVWS) communications, two wireless technologies currently receiving overwhelming interest in the wireless industry and academia. They are independent to and uncorrelated with each other, but share the same mission: conserving resources and increasing efficiency. This article reviews the systems as separate technologies, and then combines them to propose a hybrid solution that draws out their respective advantages. The first part focuses on SUNs and describes the SUN usage model with typical application requirements and practical examples, followed by the latest developments in standardization initiatives with emphasis on the currently active IEEE 802.15.4g and 802.11ah groups. The second part discusses TVWS, studying and summarizing the regulations governing its usage, and then reports on the standardization bodies' responses to these regulations with a focus on IEEE 802.11af, 802.19.1, and 802.22. Finally, the third part amalgamates the SUN usage model with TVWS regulations and deployment scenarios, providing relationship mapping between the SUN components and regulation-compliant TVWS devices. Further discussions concentrate on the opportunities and challenges along the path of realizing a practical SUN in the TVWS spectrum under the current technical and regulatory conditions. Several recommendations are made from both regulatory and technical standpoints to further increase utilization of SUNs in TVWS.

This paper proposes a virtual time-slot allocation (VTSA) scheme for throughput enhancement to realize a multi-Gbps time division multiple access (TDMA) wireless personal area network (WPAN) system in a realistic millimeter-wave residential multipath environment. TDMA system without time-slot-reuse mechanism conventionally allocates one TDMA time-slot to only one communication link at a time. In the proposed VTSA scheme, taking advantage on the large path loss in the millimeterwave band, a single TDMA time-slot can be reallocated and reused by multiple communication links simultaneously (hence the name virtual), thus significantly increasing system throughput. On the other hand, allowing multiple communication links to occupy the same time-slot causes the generation of co-channel interference (CCI). The cross layer VTSA scheme is therefore designed to be able to maximize the throughput improvement by adaptively scheduling the sharing of time-slots, and at the same time monitor the potential performance degradation due to CCI. As a result, it is found that the VTSA scheme is capable of improving system throughput as much as 30% in both AWGN and multipath channels (line-of-sight (LOS) and non-line-of-sight (NLOS) environment). Additionally, by coupling with higher-order modulation schemes, the system is able to achieve up to a maximum throughput of 3.8 Gbps. It is also observed that higher-order modulations although have higher maximum achievable throughput in low CCI environment, the tolerance against increasing CCI is considerably lower than that of the lower-order modulations.

This paper proposes a new channel model for millimeter wave (60 GHz) for indoor applications, power amplifier and phase noise models at 60 GHz, an optimal global channelization over 9 GHz bandwidth, common mode signaling to bridge SC (single carrier) and OFDM (orthogonal frequency division multiplex) camps, and a robust payload as well as a header and preamble design for single carrier for practical applications. The computer simulations have validated these new proposals for WPAN (wireless personal are network) design and significantly contributed a lot to global (IEEE802.15.3c) standardization which will be closed in the near future by issuing system specifications.

This paper investigates the impact of adjacent channel interference (ACI) and co-channel interference (CCI) on error performance and throughput of a multi-Gbps millimeterwave wireless personal area network (WPAN) system in a realistic residential line-of-sight (LOS) and non-line-of-sight (NLOS) multipath environment. The main contribution of this paper is providing a multi-Gbps WPAN system design in the challenging multipath environment in the presence of ACI/CCI. Based on the investigation results, we have provided ACI/CCI rejection as a reference for victim receiver protection design. In the NLOS environment, the ACI rejection (i.e. ACI that causes 0.5 dB degradation in the required signal-to-noise ratio (SNR) to achieve bit error rate (BER) of 10-6) for pi/2-BPSK, QPSK, 8 PSK and 16 QAM are 13, 7, 0 and -6dB respectively. And the CCI rejection for similar modulation schemes are -18, -20, -26 and -29 respectively. Secondly, we have clarified the LOS-NLOS relationship of the ACI/CCI impact to system performance. ACI in multipath NLOS environment causes an additional 5 dB degradation to error performance as compared to ACI in the LOS environment. CCI on the other hand, has similar impact on error performance in both LOS and NLOS environment. Thirdly, we have clarified the relationship between modulation spectral efficiency and robustness against ACI/CCI. In an environment with no or low ACI/CCI, the maximum achievable throughput for pi/2-BPSK, QPSK, 8 PSK and 16 QAM in LOS environment are 1.2, 2.5, 3.8 and 5 Gbps respectively. In NLOS environment, the achievable throughput decreases to 1, 1.9, 2.8 and 3.8 Gbps respectively. As ACI/CCI increases, the throughput of higherorder modulation schemes such as 16 QAM decreases the most rapidly, followed by 8 PSK and QPSK. The throughput for pi/2-BPSK has the highest tolerance against increasing ACI/CCI, at the expense of lower maximum achievable throughput.

An exact expression of error rate is developed for maximal ratio combining (MRC) in an independent but not necessarily identically distributed frequency selective Nakagami fading channel taking into account inter-symbol, co-channel and adjacent channel interferences (ISI, CCI and ACI respectively). The characteristic function (CF) method is adopted. While accurate analysis of MRC performance cannot be seen in frequency selective channel taking ISI (and CCI) into account, such analysis for ACI has not been addressed yet. The general analysis presented in this paper solves a problem of past and present interest, which has so far been studied either approximately or in simulations. The exact method presented also lets us obtain an approximate error rate expression based on Gaussian approximation (GA) of the interferences. It is shown, especially while the channel is lightly faded, has fewer multipath components and a decaying delay profile, the GA may be substantially inaccurate at high signal-to-noise ratio. However, the exact results also reveal an important finding that there is a range of parameters where the simpler GA is reasonably accurate and hence, we don't have to go for more involved exact expression.

In this paper, throughput and error performance analysis is conducted on the proposed space-time resource management (STRM) scheme to realize a multi-Gbps millimeter-wave wireless personal area network (WPAN) system. The proposed STRM allows multiple peer-to-peer communication links to occupy the same time-division-multiple-access (TDMA) time slot, in contrary to the conventional TDMA system that allocates only one time slot to one communication link. Theoretical analysis is performed to investigate the achievable system throughput in the presence of co-channel interference (CCI) generated by communication links co-sharing the same time slot. To increase accuracy, the analysis results are validated by Monte Carlo simulations. Firstly, it is found that the upper bound of the achievable throughput increases linearly with the number of communication links sharing the same time slot. However, optimum throughput exists corresponding to the CCI present in the system. Secondly, by manipulating a parameter that controls the allowable CCI in the network, the system throughput can be optimized. Lastly, it is also found that in a millimeter-wave band system, a victim system with transmitter-receiver separation of 1-meter can achieve bit error rate (BER) of 10- 6 provided that the interferer is at least 6-meters away.

We have been investigating an orthogonal frequency division multiple access (OFDMA) based cellular system that is called "dynamic parameter controlled orthogonal frequency and time division multiple access (DPC-OF/TDMA)" for the development of beyond third generation (B3G) mobile communication systems. Moreover, we have already proposed a time alignment control (TAC) to compensate propagation delays that induce a multiple-access interference (MAI) in the uplink OFDMA. However, that TAC includes a large amount of computations. This means that it is quite difficult for the OFDMA systems to implement TAC into volume-limited hardware devices such as field programmable gate array (FPGA). Thus, we propose a new complexity-reduced TAC (CRTAC) in this paper. CRTAC can be implemented into such devices easily. In this paper, we show some computer simulation results, and then evaluate the error rate performances of DPC-OF/TDMA employing CRTAC. Moreover, we also show the benefit of the reasonable level of the implementation complexity made by CRTAC.

This paper proposes a time alignment control (TAC) for reducing an influence of multiple access interference (MAI) due to propagation delays (PDs) in uplink transmission from multiple mobile stations (MSs) to an access point (AP) for an orthogonal frequency division multiple access (OFDMA) based mobile communication system. In addition, this paper presents our evaluation of the proposed TAC as applied to dynamic parameter control orthogonal frequency and time division multiple access (DPC-OF/TDMA) which has been suggested for use in new generation mobile communication system. This paper also proposes several formats for an activation slot (ACTS) in which the GIs are lengthened in order to avoid the MAI because the TAC cannot be performed yet in an initial registration of the MSs. Computer simulation elucidates that lengthening the GIs of data symbols in the ACTS adequately to compensate a maximum delay improves the transmission performance of the ACTS at the initial registration without PDs compensation. The simulation also elucidates that the proposed TAC is performed to reduce the influence of the MAI effectively and that updating the estimates of the PDs every certain period is needed to compensate the PDs accurately under high-mobility environment.

Pilot-symbol-aided (PSA) channel estimation for OFDM wireless access systems enables the periodic estimation of channel frequency response by generating reference data from the received OFDM signals. The accuracy of this channel estimation can be improved through the average over a certain time period in each subcarrier-channel. However, the accuracy of the channel estimates by the average degrades as the Doppler shift is large due to a decrease in the average section size according to the Doppler shift for the tracking of the time-varying channel. This paper proposes a novel PSA channel estimation method to mitigate the influence of the noises and interferences. This method detects the channel estimates affected by the noises and interferences, and then removes them before the arithmetic or harmonic averaging to avoid propagating the influence of the noises and interferences. This paper also evaluated the proposed channel estimation method by clipping log-likelihood ratio (LLR) data to inspect the influence of the channel estimation on the LLR calculation by computer simulation.

Demand for wireless communication is increasing significantly, while the frequency availability for wireless communication is quite limited. Currently, various countries are prompting the use of TV white spaces. IEEE 802.11 WG (Working group) has started a TG (Task Group), namely IEEE 802.11af to develop the international standard for WLAN in TV white spaces. In order to increase maximum throughput, a channel aggregation mechanism is introduced in the draft standard of TGaf. In Japan, ISDB-T based area-one-segment broadcasting system (Area-one-seg) which is a digital TV broadcast service in the limited area have been permitted to do actual services in TV white spaces from April 2012. The operation of the IEEE 802.11af system shall not jeopardize the Area-one-seg system due to the common operating frequency band. If the Area-one-seg partially overlaps with the IEEE 802.11af in some frequency, the IEEE 802.11af cannot use the channel aggregation mechanism due to lack of channels. As a result, the throughput of the IEEE 802.11af deteriorates. In this paper, the physical layer of IEEE 802.11af D2.0 is introduced briefly, and a partial subcarrier system for the IEEE 802.11af is proposed to effective use of TV white spaces and increase throughput. The IEEE 802.11af systems effectively coexist with the Area-one-seg by using null subcarriers. Computer simulation shows up to 60 % throughput gain is achieved with the proposed mechanism.

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.

Cognitive radio based wireless systems using TV white space have been attracting a lot of attentions. In the cognitive radio systems using TV white space, it is desirable to secure a control channel to exchange the information on the availability of white space and the frequency resource such as the frequency channel and the bandwidth. In addition, it is necessary to secure minimum frequency resource for communications if TV white space is unavailable even though TV white space is used on an opportunistic basis. In order to solve these problems, this paper proposes a guard band aggregation scheme, which aggregates the multiple guard bands between digital TV signals and uses them for a control channel and/or a communication channel. This paper shows the performance evaluation results of the digital TV signals when the guard band is used by the proposed scheme. Furthermore, it discusses the permissible transmitting power and occupied bandwidth to avoid the performance degradation of the digital TV signals.

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.

This paper presents the performance analysis of a realistic Smart Utility Network (SUN) system with low duty signaling design. The main focus of this paper is to evaluate the performance of the SUN system based on the specifications in an on-going industrial standardization activity, the IEEE 802.15.4g. For this purpose, a theoretical framework is constructed to model the transceiver with low duty signals over a realistic SUN channel based on actual measurements. The theoretical framework provides the models of multiple access interference (MAI) and inter-symbol interference (ISI). To align the analysis with actual industrial requirements, the developed framework is substituted with parameters from the IEEE 802.15.4g specifications. As a result, it is found that the low duty system (i.e. 0.1%) is capable of supporting up to 100 users in a single network. Additionally, by reducing the duty factor (e.g. from 1% to 0.1%), a 2-digit performance improvement (e.g. bit error rate (BER)=10–5 to BER=10–7) can be achieved as compared to the requirement of IEEE 802.15.4g specifications (i.e. BER ≈ 10–5).

This paper presents research status on public broadband wireless communication (PBB) system. The PBB system uses VHF band between 170 MHz and 205 MHz that is available after termination of analogue TV broadcasting service on July 24, 2011. This paper summarizes the transition of television service from analogue to digital and fundamental specification on spectrum usage, physical and MAC layers.

This paper presents the results of spectrum occupancy measurements carried out in three locations of Kanto area in Japan. Moreover, the collected data corresponding to DTV broadcasting service is analyzed to evaluate the possibilities of secondary systems operating in TV White Spaces (TVWS) in the framework of FCC regulations and Japanese standards. Appropriate propagation models are considered for analyzing the conditions of operation for both, fixed and portable unlicensed devices.

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.

In this paper, we proposes the pro-active beamforming (BF) protocol realized in media access control (MAC) layer following IEEE 802.15.3c criteria for millimeter-wave 60GHz wireless personal area networks (60GHz WPANs). The pro-active BF may be used when the piconet controller (PNC) is the source of data to one or multiple devices (DEVs). It allows multiple DEVs to train their own receiver antennas for optimal reception from the PNC with lower overhead. The pro-active BF realizes part of BF operation in association process, extending the system's BF capability. It also enables DEVs to associate with PNC with directional antenna pattern, thus enlarges the coverage area of a piconet. Since it may train multiple users simultaneously based on the proposed multi-resolution codebooks, it significantly decreases the BF set-up time and mitigates the high path loss of 60GHz WPAN systems. Simulation results show that the proposed pro-active BF further reduce more than 20% of the BF set-up time comparing with on-demand BF in the multiple DEVs scenarios. It is completely compliant to IEEE 802.15.3c, and adopted by IEEE 802.15.3c as an important compliment to the on-demand BF to realize Giga-bit-per-second (Gbps) communication in WPAN Systems.

Millimeter wave (mmWave) wireless personal area networks (WPANs) could provide multi-Gbps based data rate for short range communications. However, this ultra high data rate is sensitive to the co-channel interference (CCI). In this paper we use synchronization frame (sync frame) to mitigate possible interference between WPANs. Sync frames could be simply considered as the copies of beacons, which are relayed via the devices associated with the piconet. By using sync frames, the possible CCI could be reduced by increasing per WPAN coverage range, but meanwhile, the spatial reuse capability is also reduced. Therefore, in this work, we are motivated to investigate the optimized beacon/sync frame range at different link distances and its effect to throughput. Simulation results in 60 GHz system for a 2.5 m link indicate that, sync frames can double the guaranteed throughput. For guaranteed throughput of 1.4 Mbps at a 3.5 m link, beacon range can be 35\% reduced. Another contribution of the paper is investigating the effect of CCI in 60 GHz systems with spreading 2 and 4. Our results indicate a limited increase in robustness at high CCI situation compared to non spreading cases.

This paper introduces NICT's two current on-going projects regarding heterogeneous type and spectrum sharing type cognitive wireless network: Project CWC (Cognitive Wireless Cloud) and Project ASTRA (Advanced Spectrum-Management Technology for Radio Access innovation). For both projects, this paper summarizes the scope, usage model, system requirement, system architecture, prototyping, and standard activities.

This paper proposes a spatial time-division multiple access (STDMA) throughput enhancement scheme for a multi-Gbps millimeter-wave (mmWave) wireless personal area network (WPAN) system. The system design includes in the medium access control (MAC) layer, an interference-monitoring mechanism and a heuristic TDMA time-slot scheduling engine, and in the physical (PHY) layer, a Reed-Solomon (RS) coded phase-shift keying (PSK) system with selective Rake reception over a realistic 60GHz multipath propagation channel. The theoretical analysis of the throughput and error performance is verified by Monte Carlo simulations. Firstly, it is found that the proposed STDMA scheme is capable of improving system throughput as much as 100%. Secondly, the co-channel interference (CCI) in a communication link has to be controlled at/below -15dB in order to achieve the optimum system throughput. Lastly, different tolerable CCI levels to meet respective application requirements are determined.

In order to realize high speed, long range, reliable transmission in millimeter-wave 60 GHz wireless personal area networks (60 GHz WPANs), we propose a beamforming (BF) protocol realized in media access control (MAC) layer on top of multiple physical layer (PHY) designs. The proposed BF protocol targets to minimize the BF set-up time and to mitigate the high path loss of 60 GHz WPAN systems. It consists of 3 stages, namely the device (DEV) to DEV linking, sector-level searching and beam-level searching. The division of the stages facilitates significant reduction in setup time as compared to BF protocols with exhaustive searching mechanisms. The proposed BF protocol employs discrete phase-shifters, which significantly simplifies the structure of DEVs as compared to the conventional BF with phase-and-amplitude adjustment, at the expense of a gain degradation of less than 1 dB. The proposed BF protocol is a complete design and PHY-independent, it is applicable to different antenna configurations. Simulation results show that the setup time of the proposed BF protocol is as small as 2% when compared to the exhaustive searching protocol. Furthermore, based on the codebooks with four phases per element, around 15.1 dB gain is achieved by using eight antenna elements at both transmitter and receiver, thereby enabling 1.6 Gbps-data-streaming over a range of three meters. Due to the flexibility in supporting multiple PHY layer designs, the proposed protocol has been adopted by the IEEE 802.15.3c as an optional functionality to realize Gbps communication systems.

In Japan, the current analogue terrestrial TV broadcasting service is scheduled for retirement on July 24, 2011. It was considered that the 10 MHz band on the UHF band from 715 to 725 MHz band would be used for the use of ITS. This paper summarizes the latest research and development results on IV communication systems on UHF band regarding use case, PHY and MAC layers and a prototype.

In this paper, we propose a radio resource allocation (RRA) scheme for multiuser multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing access (OFDMA) systems in order to achieve the optimal system throughput. The proposed RRA algorithm adaptively schedules 3-dimension (3-D) (space, frequency and time) slots to different users according to various channel state information (CSI). Different from most of conventional RRA algorithms, the proposed algorithm joins scheduling process with power allocation, that is, iteratively allocating total transmit power into resource block (RB) during 3-D slot assignment. The power allocation is an extension of the space-frequency waterfilling algorithm, and is adapted to an equivalent 1-D single input single output (SISO) channels. The equivalent SISO channels are obtained from the original 3-D RBs in the sense of the same maximum achievable throughput. The proposed algorithm was confirmed in the Worldwide interoperability for Microwave Access (WiMAX) systems following IEEE 802.16e media access control (MAC) protocols. It is shown that the proposed RRA algorithm significantly simplifies the scheduling process and achieves more throughput than round robin (RR) scheme.

This paper presents throughput and error perfor- mance analysis of the proposed space-time resource management (STRM) scheme for a multi-Gbps millimeter-wave system. The proposed STRM allows multiple peer-to-peer communication links to occupy the same time-division-multiple-access (TDMA) time slot, in contrary to the conventional TDMA system that allocates only one time slot to one communication link. In this paper, theoretical analysis is conducted to investigate the achievable throughput in the presence of co-channel interference (CCI) generated by communication links co-sharing the same time slot. Firstly, it is found that the upper bound of the achievable throughput increases linearly with the number of communication links sharing the same time slot. Secondly, by preseting a parameter that manages the allowable CCI in the network, the system throughput can be optimized. The optimum preset allowable CCI values are found to be in the range of -13dB≤CCI≤-11dB. Lastly, it is also found that in a millimeter- wave band system, a victim system with transmitter-receiver separation of 1-meter can achieve its targeted bit error rate (BER) provided that the interferer is 6 meters away.

The paper proposes a codebook design to support beamforming mechanism in a wide band millimeter-wave 60GHz wireless personal area networks (60GHz WPANs) in a realistic millimeter-wave environment. The codebooks are designed sym- metrically in order to mitigate the possible beam shift due to the large differences of wave lengthes at different sub-bands of a wide band communication system. In order to provide a high data rate and high performance with minimum power consumption in 60GHz systems, the codebooks are generated with 90 degree phase resolution without amplitude adjustment. The codebooks are designed for different numbers of antenna elements, supporting a multitude of antenna configurations. The paper provides codebook design mechanism, some example codebooks and some analysis on antenna gain loss due to phase shift errors of phase shifters. Simulation results shows that: (1) To keep the gain loss at the intersections of any two patterns inside the codebook lower than 1dB, the number of patterns inside the codebook shall be at least 2 times of the number of antenna elements used for pattern generation; (2) The designed codebooks are robust to phase shift errors: the gain loss is lower than 1dB with only 10% outage probability when standard deviation of phase shift errors at phase shifters is 0.5 (28.6 degree). The proposed codebooks are a feasible design, they are the key basis of the beamforming protocol in 60GHz WPANs (IEEE 802.15.3c).

Multi-Input-Multi-Output (MIMO) is an emerging technology for the 4th-generation mobile communication systems due to the capability of high-speed data transmission. There have been only a few literatures regarding MIMO propagation characteristics under outdoor condition, and most of which have focused only on 2 GHz bands for existing cellular systems. However, since 3.4-3.6 GHz band will be allocated as one of frequency bands for the 4th-generation mobile communication systems, the channel characteristics at this band should be carefully considered. This report presents the outdoor MIMO channel characteristics measured by a 2×2 MIMO channel sounding system at the center frequency of 3.35 GHz in urban environment. In this measurement system, the 9-stage PN signals are transmitted by controlling the transmission timing in each transmitter, and hence, the complex MIMO channel impulse responses can be obtained by using same PN sequence in the receiver. From the measured MIMO channel characteristics, we computed the channel capacity based on each eigenvalue that was obtained through singular value decomposition (SVD). In addition, we evaluated the channel capacity for line-of-site (LOS) and non-line-of-site (NLOS) environments with respect to the antennas distance.

This paper investigates the interference mitigation capability of a millimeter-wave wireless personal area network (WPAN) in a realistic 60GHz channel. The interference mitigation mechanism employs farther-reaching beacon signals and device-relayed synchronization command frames (sync frames) to further extend the protection range of the victim (a.k.a. primary) network. Firstly, it is found that the sync frame is capable of extending the 'interference-free' region as a function of network-controller-to-device distance and the location of the interferer. Secondly, it is found that in the interference-free region extended by the beacon/sync frame, the probability of interference is near zero. Finally, interference, when taking place, impacts high speed (3~5Gbps) links 5~8dB more significantly than their low speed (1~3Gbps) counterparts.

Inter-symbol/frame interference analysis is pre- sented for pulsed direct sequence (DS) and hybrid direct sequence time hopping (DS/TH) ultra-wideband (UWB) communications considering a frequency selective Nakagami fading channel. Following the analysis, error rate expressions are developed and performance comparison is presented for the systems. It is found that the performance of pulsed DS system may depend on pulse repetition rate (PRR), number of combined paths by Rake receiver and the channel profile in a kind of unpredictable man- ner. For low PRR, the DS system performs better than DS/TH irrespective of the channel profile. For medium to high PRR, DS and DS/TH systems may perform comparably in a channel with a single decaying profile. However, if the channel contains more than one decaying profiles like as in Saleh-Valenzuela model, the performance of DS may drastically degrade and perform worse than DS/TH at some values of PRRs. The performance of DS/TH is relatively less influenced by the shape of the channel profile. Theoretical results are verified by simulations.

This paper investigates the impact of adjacent channel interference (ACI) and co-channel interference (CCI) on the error performance and throughput of a multi-Gbps millimeter-wave wireless personal area network (WPAN) system in both residential multipath line-of-sight (LOS) and non-LOS (NLOS) environment. It is found that the ACI that causes 0.5dB degradation in signal-to-noise ratio (SNR) for BPSK, QPSK, 8-PSK and 16-QAM systems are 13, 7, 0 and -6 dB respectively. And the CCI that causes similar SNR degradation for BPSK, QPSK, 8-PSK and 16-QAM are -18, -20, -26 and -29 dB respectively. Additionally, multipath NLOS environment in the presence of ACI is found to cause an extra 5 dB degradation on error performance as compared to ACI in LOS environment. On the other hand, CCI in both LOS and NLOS environment display approximately similar impact on error performance. In extremely low ACI/CCI environment, the maximum achievable throughput for BPSK, QPSK, 8-PSK and 16-QAM in NLOS environment are 1.1, 2.2, 3.4 and 4.6Gbps respectively. Then as ACI/CCI increases, the throughput of 16-QAM decreases the most rapidly, followed by 8-PSK, QPSK and pi/2-BPSK. It is also found that system tolerance against ACI/CCI can be increased by employing modulation schemes with lower modulation level, at the expense of lower maximum achievable throughput.

This paper proposes a Virtual Time-slot Allocation (VTSA) throughput enhancement scheme with multiple modulation methods to realize a multi-Gbps time division multiple access (TDMA) wireless personal area network (WPAN) system in a realistic millimeter-wave residential multipath environment. The VTSA scheme allows multiple communication links in the network to simultaneously use the same time-slot, thus increases system throughput. Additionally, by coupling to higher-order modulation schemes, higher data rate can be achieved. The combination of both is found to be capable of realizing a multi-Gbps WPAN system. However, the employment of the VTSA scheme causes the generation of co-channel interference (CCI) in the system, and CCI is found to affect the modulation schemes differently. This paper investigates the tradeoff parameters between varying CCI due to the employment of the VTSA scheme, and the higher-order modulations applied. As a result, it is found that the VTSA scheme is capable of increasing 30% of the system throughput. It is also found that in low CCI environment, 16QAM offers the highest achievable system throughput, whereas when CCI becomes higher, the more-robust BPSK offers the highest throughput.

In this paper we present preamble design for millimeter-wave single carrier wireless personal area networks. Several factors are considered for a successful preamble design, such as sequence complexity, operation range, associated delay, robustness to frequency offset. Complementary Golay sequences are selected, which combine flexibility and performance. Simula- tion results indicate at optimum threshold level, it is possible to reduce both false alarm probability and miss detection probability less than 10 �3 in non-line-of-sight channels.

The paper presents a signal-to-noise ratio (SNR) mapping scheme for single-carrier (SC) frequency domain equalization (FDE) based millimeter-wave wireless personal area networks (WPANs). The effective SNR, defined as an average SNR over whole data frame after equalization, is a one-to-one mapper of the SNR in practical scenario in the sense of the same bit error rate (BER) performance. As the mapping is based on theoretical calculation instead of the simulation on a specific channel model, the defined effective SNR is suitable to be used as a metric, such as threshold for link adaptation, because it decides system BER performance just based on theoretical BER performance of AWGN channel instead of channel-model dependent SNR-BER table. The close form of effective SNR is proposed. A link adaptation method based on the defined effective SNR is given to show how our defined effective SNR simplifies system design. Both theoretical analysis and simulation results show that the defined effective SNR is channel-model independent and it is accuracy enough with variance of mapping error lower than 1 dB, it is therefore useful, especially for the system possibly involved in several different wireless communication scenarios.

In order to design a simple and highly accurate channel estimator for wireless personal area network systems, this paper proposes Golay sequence aided channel estimation. To evaluate the performance of proposed channel estimation, bit error rate performance of single-carrier transmission with frequency-domain equalization has been analyzed by computer simulation. When 8PSK modulation and Reed-Solomon coding RS(255, 239) as forward error correction are used, the proposed Golay sequence aided channel estimation works very well in millimeter-wave and non line-of-sight fading environments with a 1.8 dB degradation of Eb/N0 at 10-6 of bit error rate against the ideal channel estimation, which is practically acceptable. Moreover, comparing with Chu sequence aided channel estimation, the proposed Golay sequence aided channel estimation improves 0.4 dB of Eb/N0 at the bit error rate while achieving much less hardware than Chu sequence aided one, which is very important for mobile terminal applications.

This paper investigates the adjacent channel interference (ACI) resistance of a multi-Gbps single carrier wireless personal area network (WPAN) operating in the 60 GHz millimeter-wave band. The significance of performance degradation due to ACI is investigated corresponding to varying factors such as types of modulation and radio frequency (RF) hardware impairments. The level of modulation scheme is found to change the system resistance against ACI considerably. RF hardware impairments such as power amplifier (PA) non-linearity and phase-locked loop (PLL) phase noise are also major factors affecting ACI generation. The tolerable ACI for WPAN system design is defined as the ACI that causes 0.5 dB degradation in required signal to noise ratio (SNR) at bit error rate (BER)=10-6. It is found that for a system employing pi/2 binary phase shift keying (BPSK) with PA output backoff (OBO)=3 dB, ACI=13.5 dB causes 0.5 dB BER degradation. For systems employing quadrature phase shift keying (QPSK) modulation, the tolerable ACI with PA OBO=3 dB and 5 dB are observed at 9 dB and 15 dB, respectively. For modulation schemes with higher levels such as the 16-quadrature amplitude modulation (QAM) system with PA OBO=3 dB and 5 dB, the tolerable ACI of 1 dB and 5 dB are observed. Next, the maximum ACI resistance is defined as the tolerable ACI by the system before the BER performance degrades and saturates towards 0.5. The performance of pi/2-BPSK system with PA OBO=3 dB has maximum resistance against ACI up to 25 dB before the BER saturates towards 0.5. Similar performance can be observed in QPSK system, but with PA OBO increased to 5 dB. Systems with 16-QAM are found to saturate to BER=0.5 beyond ACI=10 dB. Additionally, the presence of PLL phase noise is found to severely compromise the system performance particularly those with higher modulation levels. ACI as low as 0 dB is found to cause error floor to 16-QAM systems.

High-definition video streaming and peripheral device communication on wireless access are promising applications of multi-gigabit 60-GHz wireless personal area networks (WPANs). For such different requirements, a frame design methodology is required which is different from that applied for the conventional wireless local area network (WLANs) and WPANs. This paper proposes a novel frame design methodology on PHY layer for the multi-gigabit 60-GHz WPANs supporting those applications. The proposed methodology is that preamble and header are designed to be further protected against payload, on the basis of 2-digit improvements in synchronization error probability and header error rate over payload bit error rate. In addition, the paper describes frame structures for control and data-communication in accordance with the proposed methodology. Performance evaluation is done by computer simulation to validate the proposed methodology. These frame structure designed by the proposed metrology has been applied in IEEE 802.15.3c WPANs systems.

The multi-Gbps wireless personal area network (WPAN) using 60-GHz is being standardized in the task group of IEEE 802.15.3c. In the physical (PHY) layer design, there are two competitive techniques, one is orthogonal frequency division multiplexing (OFDM) and the other is single-carrier frequency-domain equalization (SC-FDE), a.k.a., single-carrier block transmission (SCBT). This paper compared the performance of low-density parity-check (LDPC) coded OFDM and SC-FDE under hardware impairments including analog-to-digital converter (ADC) resolution, non-linear distortion induced by 60- GHz power amplifier (PA), and phase noise of 60-GHz PLL circuits. The simulation results show that SC-FDE has much better performance than OFDM under hardware impairments of 60-GHz devices and circuits.

60-GHz band is a popular choice of industry for next generation wireless personal area networks, which will enable data rates in the order of Gbps. Single-carrier frequency domain equalization (SC-FDE) systems are proposed to obtain such high data rates in low-power and low-cost consumer products. In this paper, we are suggesting to use simple zero- forcing equalization to reduce the complexity requirement. We test system performance through simulations and find associated range of the WPAN. Our simulations take into account non-line- of-sight (NLOS) multipath channel model, channel estimation errors and RF impairments of phase noise and power amplifier distortion, to obtain realistic results. Our results show zero- forcing equalization can be employed in applications robust to delay such as file transfer between PCs and peripherals up to 4 meters. This result encourages the usage of 60-GHz band in low-power devices such as cellular phones and cameras. For applications which are sensitive to delay such as video streaming, more complex MMSE equalizer is required.

We propose a new space division multiplexing-orthogonal frequency division multiplexing system using reduced-complexity-and-latency detection and channel estimation algorithms. It is important to reduce a latency from receiver processing because the latency degrades performances of wireless systems in a mobile fading environment. In this paper, we evaluate and discuss bit error rate performance and computational complexity of the proposed system. From simulation results, we observe that our proposed estimation scheme improves the accuracy more than conventional minimum mean square error based schemes, and that the proposed system outperforms a maximum likelihood detection based system in a mobile fading environment. Moreover, we confirm that the proposed system is superior to the conventional schemes from the points of not only the performance but also the complexity.

The millimeter-wave 60-GHz wireless personal area network (WPAN) is being standardized by the IEEE 802.15 Alternative PHY Task Group 3c (IEEE 802.15.3c). The physical (PHY) layer design targets data rates of multi-giga bits per second (multi-Gbps). In this paper, two physical (PHY) layer designs based on single-carrier frequency-domain equalization (SC-FDE) and orthogonal frequency division multiplexing (OFDM) were compared in packet error rate (PER) and throughput. The performance evaluation and comparison were conducted with the non-linear distortion, induced by the 60-GHz power amplifier (PA), taken into account. It was shown that the PHY layer design based on SC-FDE has much better PER performance and higher throughput than the one based on OFDM. The SC-FDE based PHY layer design exhibits itself as a strong candidate for the 60-GHz WPAN (IEEE 802.15.3c) standard.

This paper proposes an air interface for ultra high-speed millimeter wave (60 GHz) systems which have been under standardization process at IEEE 802.15.3c: the proposed channel plan permits ease of portable device implementation employing the major crystal oscillator used in CDMA cellar phones. The proposed transmission modes offer much greater scalability, covering from several tens Mbps to over 4 Gbps. The proposed preamble employs Golay codes, providing sufficient robustness against wireless environment being subject to the characteristics of millimeter wave with reduced hardware complexity. Common mode is a novel technique to communicate with single carrier (SC) and OFDM camps with multi rates up to around 1.5 Gbps. This technique gives the proposed systems easy expandability from SC to OFDM or other SCs and vice versa.

In one-cell-frequency-reuse MIMO (multi input multi output) - OFDMA based TDMA (OF/TDMA) systems, we face a problem that communication is blocked by interferences from adjacent cells. To solve this problem, an AMC (adaptive modulation and coding) scheme that is controlled by estimating DUR (desired signal to undesired signal power ratio) would be most promising. However, there is no accurate DUR estimation method using spreading codes for OF/TDMA systems due to the asynchronous FFT so far. In this paper, we propose a novel DUR estimation method by adding IFFT and time-window and introducing CI (carrier interferometry). The proposed DUR estimation method can separate the desired signal from a received signal even if FFT is asynchronous