This paper presents the experimental performance evaluation results of the IEEE 802.15.4/4g/4e Smart Utility Networks (SUN) in applications suited for outdoor environment. SUN is an advanced wireless communications network designed for reliable, low data rate, and low energy consumption networks for command-and-control applications like utility service, sensor network, and so on. IEEE 802.15.4g/4e is the international standard for SUN supported by multiple utility providers and product vendors. In this paper, a comprehensive field test was conducted by employing the implementation we have developed to evaluate the performance of the SUN devices based on IEEE 802.15.4/4g/4e standard. The output power of the implementation is 250 mW for extended range, reducible to 20 mW for short-range scalability and battery preservation. Results showed that in an outdoor line-of-sight environment, the achievable one-hop range of a 50 kbps SUN device was 450 m. Next, in a non-line-of-sight environment involving typical residential concrete building, the communications could be established penetrating obstructions to reach above the 11th storey, reaching the performance degradation limits at the 20th storey. Next, the network of the SUN system was proven to be capable of supporting a typical multihop tree network in a dense populated building, meeting the required performance by the standard.

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 paper presents the evaluation on energy consumption of power saving mechanisms in recent IEEE 802.15.4 Low-Rate Wireless Personal Area Network (LR-WPAN) systems. The LR-WPAN applications share a common system requirement of high energy efficiency through power saving mechanisms to prolong battery lifespan. First, the recent IEEE 802.15.4 standard amendments including, but not limited to IEEE 802.15.4/4e/4f/4g/4j/4k/4m and their targeted applications are listed and discussed. Then, the applications are categorized based on different energy consumption models which are interconnected with the radio operations of the proposed power saving mechanisms. Next, addressing pervasive demands and respective energy consumption models in multiple application scenarios, three power saving mechanisms for LR-WPAN are proposed and evaluated taking into consideration realistic parameters. As a result, it is found that the power saving mechanisms are capable of supporting battery lifespan up to typically 3 years. Out of the three proposed mechanisms, two are found to be more suitable for deployment of symmetrical energy consumption model where all devices share similar burden of radio operations, while one is found to be otherwise, optimized for asymmetrical energy consumption model where some devices have larger burden as compared to others.

This paper presents the performance analysis of an IEEE 802.15.4g multi-hop orthogonal frequency division multiplexing (OFDM) system in a network with multiple physical (PHY) layer design. Identified usage models for the IEEE 802.15.4g standard are low energy wireless sensor network and smart grid/utility network applications. For that, a total of three PHY layer designs under a unified medium access control (MAC) are specified to address different market segments. The multi-PHY layer architecture has an advantage of covering a wide range of pervasive use case scenarios, at the expense of inter-PHY interference (IPI) among respective PHY layers. This paper focuses on the OFDM PHY that promises high data rate and superior propagation performance. To enable optimized operation in the targeted applications, a multi-hop MAC layer design is specified to extend the operating range of the network, while low energy features are designed to increase energy efficiency of the system. Additionally, an IPI mitigation technique is also developed to combat IPI generated from the interfering network. As a result, it is found that the average throughput of a multi-hop OFDM network is 8% lower than that of a single-hop OFDM network, but with larger achievable operating range. Secondly, with the proposed IPI mitigation technique, no degradation among devices with different PHY layer designs is observed to take place. Thirdly, with the energy-efficient non-beacon-enabled mode, devices are consuming less power, at the expense of immunity reduction against interferer.

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.

This paper analyzes the performance of a realistic multi-PHY layer IEEE 802.15.4g Smart Utility Networks (SUN) design and proposes a coexistence approach for multi-PHY interference management. Technical details of the design such as network architecture, mechanism protocols, signal formats, device interfaces, regulatory requirements and channel characterization are implemented following the IEEE 802.15.4g SUN specification. The performance evaluation is conducted in a cross-layer computer simulation based on the MAC (medium access control) and multi-PHY technical specification in the standard with realistic application scenarios and channel characteristics. To manage the interference in the system, a Multi-PHY Management (MPM) protocol is proposed and evaluated. The MPM is adopted in the current IEEE 802.15.4g standard. As a result, the coexistence mechanism is observed to be able to improve the victim throughput performance up to 25%. It is also found that the throughput degradation in a non-beacon-enabled network is 50% worse than the degradation in a beacon-network.

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.

This paper proposes a generic enhanced beaconless synchronization mechanism for industrial standard IEEE 802.15.4g Smart Utility Networks (SUN) in multiple regulatory domains globally. IEEE 802.15.4g has specified different regulatory domains for SUN applications, each with a distinctive set of channelization and corresponding operating parameters such as center frequency, channel width and channel spacing. This has added new challenges not limited to, but particularly in beaconless synchronization mechanism supporting low energy consumption demands in conventional IEEE 802.15.4 low rate wireless personal area networks (WPANs). This paper first provides the updates in the SUN technical specification, identifies the challenges due to the effort of addressing multi-regional governing regulatory demands and then proposes a generic solution to tackle the problem. This simple but straightforward approach is preferable in industrial applications with strict energy efficiency requirement. The proposed beaconless synchronization mechanism has outlined two metrics with conflicting interest, namely required time to achieve synchronization and effective bandwidth for data communication. As a result, it is found that as the input radio resource increases, the effective communication bandwidth increases exponentially, while the required time for synchronization increases only linearly.

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.

This paper proposes a hybrid SDMA/TDMA scalable heuristic scheduling scheme for throughput enhancement in practical multi-Gbps millimeter-wave systems with directional antenna. A theoretical cross layer design framework is proposed taking into consideration the MAC layer, PHY layer and millimeter-wave propagation channels based on actual measurements. The proposed generalized framework can be well suited into two of the most prominent industrial wireless communication standards, namely IEEE 802.15.3c WPAN and IEEE 802.11ad WLAN. Employing the developed theoretical framework, evaluation for throughput and error performance is conducted with validation of computer simulations. Firstly, it is found that the proposed STDMA scheme is capable of improving system throughput in the order of typically 4 to 8dB. Secondly, the proposed scheduling scheme offers superior design flexibility through its scalability features, with the optimum heuristic order observed at the 13-th order, a reasonably low value considering the performance enhancement that can be obtained. Lastly, the typical allowable interference in a network due to coexisting communication links sharing the same time slot is recommended to be controlled below -20dB. Numerical results other then the typical findings are detailed in the paper.

This paper describes the challenges of frequency channel selection for WLANs operating in the TV White Space (TVWS) and proposes a dynamic frequency selection (DFS) technique as a solution. Based on the statistics gained from past usage experience of channels, of the TVWS channels' vacancies and channel occupation by the adjacent WLANs, each WLAN evaluates and prioritize the channels independently using a priority function. Then by selecting the channel of the highest priority among vacant channels, each WLAN can quickly find a channel in the low interference regime and whose vacancy is adaptive to its traffic load distribution as well. Performance of the proposed DFS is evaluated through simulation using QualNet, based on TVWS channels with realistic feature and by setting the weight factors of different metrics in the priority function to different values. The evaluation results show that compared to conventional DFS, the proposed DFS avoids adjacent APs selecting the same channel and reduces channel switch rate, and is more adaptive to diverse environments. As a consequence, it maximally reduces total time consumption of channel switch by 40% than random selection.

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)=10-5to BER=10-7) can be achieved as compared to the requirement of IEEE 802.15.4g specifications (i.e. BER ≈ 10-5).

This paper proposes a scalable heuristic spatial time division multiple access (STDMA) time-slot scheduling algorithm for millimeter-wave wireless personal area network (WPAN) with spatial division multiple access (SDMA) through directional antenna system. A detailed cross layer design is proposed including the medium access control (MAC) layer and the physical (PHY) layer designs. The proposed hybrid STDMA/SDMA scheduling engine possesses the capability of flexible throughput-enhancement employing different levels (i.e. heuristic order) of algorithm complexity. Firstly, it is found that the scheduling engine with exhaustive searching algorithm is able to improve up to 9-fold of the achievable system throughput. Secondly, it is determined that heuristic order of 5 is sufficient to provide optimum throughput enhancement with minimized system complexity. Thirdly, the analysis of required overhead to perform the STDMA scheduling engine is also discussed.

In this paper, we propose a spacial time slot scheduling algorithm for relay operation to improve the throughput performance of millimeter-wave wireless personal area network (mmWave WPAN) systems which employ directional antenna. The upcoming mmWave WPAN is designed for high definition TV (HDTV) transmission, high speed wireless docking and gaming, etc. Based on the fact that the significant path loss of millimeter-wave environments provides good space isolation, we have proposed a coexistence mechanism by sharing time slots for relay with direct transmission to guarantee throughput for the above data-rate-greedy applications. This paper is an extension that addresses spacial time slot scheduling for relay operation taking the effect of directional antenna into consideration. We model the throughput maximization with scheduling as an integer optimization and solve it by transforming the problem to a max-weight matching problem of a bipartite graph. We propose a scheduling algorithm based on the Kuhn-Munkres algorithm which can be used to solve the max weight matching problem. Simulation results show that there is up to 25% throughput improvement achieved compared with random scheduling method.

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 develops a cross layer model for both interference and coexistence analysis of a multi-Gbps millimeter-wave wireless personal area network (WPAN) system with directional antennas. The model takes into consideration realistic 60 GHz propagation channel and high-speed physical layer design in actual WPAN network scenario. The model facilitates the analysis of directional interference and coexistence unique to the millimeter-wave frequency band. Employing the developed model, we found that in order to generate minimum interference to the victim receiver, the interferer has to be angularly located at least 1.3 times the victim's beamwidth away from the victim's antenna pointing direction, and/or the interferer's antenna has to be angularly pointing towards at least 1.3 times its beamwidth away from the location of the victim. Additionally, to mitigate interference and still maintain the desired link connectivity, the victim receiver may shift its antenna beam away from the location of the interferer, as much as the angle between the victim's antenna pointing direction and the interferer's location minus 1.3 times the victim's beamwidth. Lastly, we have also introduced the quantification of coexistence availability between interfering and desired links, taking into consideration requirements and parameters in the physical layer.

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.

This paper proposes a spatial time-division multiple access (STDMA) throughput enhancement scheme for a multiGbps 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 60 GHz 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 -15 dB in order to achieve the optimum system throughput. Lastly, different tolerable CCI levels to meet respective application requirements are determined.

In this paper, we propose a feasible beamforming (BF) scheme realized in media access control (MAC) layer following the guidelines of the IEEE 802.15.3c criteria for millimeterwave 60 GHz wireless personal area networks (60 GHz WPANs). The proposed BF targets to minimize the BF set-up time and mitigates the high path loss of 60 GHz WPAN systems. It is based on designed multi-resolution codebooks, which generate three kinds of patterns of different half power beam widths (HPBWs): quasi-omni pattern, sector and beam. These three kinds of patterns are employed in the three stages of the BF protocol, namely device-to-device (DEV-to-DEV) linking, sector-level searching and beam-level searching. All the three stages can be completed within one superframe, which minimizes the potential interference to other systems during BF set-up period. In this paper, we show some example codebooks and provide the details of BF procedure. Simulation results show that the setup time of the proposed BF protocol is as small as 2% when compared to the exhaustive searching protocol. The proposed BF is a complete design, it re-uses commands specified in IEEE 802.15.3c, completely compliant to the standard; It has thus been adopted by IEEE 802.15.3c as an optional functionality to realize Giga-bit-per-second (Gbps) communication in WPAN Systems.

This paper proposes the virtual time-slot allocation (VTSA) scheme for throughput enhancement to realize a Gbps-order time division multiple access (TDMA) wireless personal area network (WPAN) system in a realistic millimeter-wave residential multipath environment. Conventional TDMA system allocates each time-slot to only one communication link, which is insufficient to achieve Gbps-order throughput, particularly in severe channel conditions of multipath environment. In this paper, the proposed VTSA scheme enables a single time-slot to be reused for multiple communication links simultaneously (hence the name virtual), thus significantly increases system throughput. However, this generates co-channel interference (CCI) among the communication links occupying the same time-slot. The proposed cross layer VTSA scheme is therefore designed to be able to schedule the sharing of time-slots among multiple communication links, and at the same time monitor to minimize performance degradation due to CCI. Two time-slot reuse methods are proposed and compared in this paper, namely the minimum-CCI slotting method and the random slotting method. As a result, it is found that the VTSA scheme is capable of increasing the system throughput as much as approximately 30% in the additive white Gaussian noise (AWGN), line-of-sight (LOS) and the non-line-of-sight (NLOS) multipath channel. It is also found that the minimum-CCI slotting method has 10% better performance as compared to the random slotting method.

In this paper, we propose a solution to resolve link blockage problem in 60 GHz WPANs. Line-of-Sight (LOS) link is easily blocked by a moving person, which is concerned as one of the severe problems in 60 GHz systems. Beamforming is a feasible technique to resolve link blockage by switching the beam path from LOS link to a Non-LOS (NLOS) link. We propose and evaluate two kinds of Beam Switching (BS) mechanisms: instant decision based BS and environment learning based BS. We examine these mechanisms in a typical indoor WPAN scenario. Extensive simulations have been carried out, and our results reveal that combining angle-of-arrival with the received signal to noise ratio could make better decision for beam switching. Our work provides valuable observations for beam switching during point-to-point communication using 60 GHz radio.

This paper investigates the interference mitigation capability of a millimeter-wave wireless personal area network (WPAN) in a realistic 60 GHz 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 (3~5 Gbps) links 5~8 dB more significantly than their low speed (1~3 Gbps) counterparts.

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. Simulation results indicate at optimum threshold level, it is possible to reduce both false alarm probability and misdetection probability less than 10-3in non-line-of-sight channels.

In this paper, we propose a deflection routing scheme for throughput improvement to realize Gbps millimeter-wave wireless personal area network (mmWave WPAN) system. The upcoming mmWave WPAN system is designed to support transmission of uncompressed high definition TV (HDTV), high speed wireless downloading and docking etc. These data-rate-greedy applications require Gbps-order throughput which can be met by the capability of mmWave PHY. However, because of the ad-hoc formed network topology, it is easily happening that the line-of-sight (LOS) path may be blocked, while the non-line-of-sight (NLOS) path is not sufficient to guarantee Gbps throughput due to signal degradation. In this paper, we propose a cross-layer deflection routing (DR) scheme to solve the issue. When the direct path is blocked, the source device finds a relay to form deflection route, send the data to the destination through this alternative route. To avoid throughput degradation due to the consumption of extra time for relay operation, the deflection route is designed to share time slots with other transmissions on direct path. Two routing algorithms are proposed, namely random fit DR (RFDR) and best fit DR (BFDR). They search appropriate relay and time slots that provides sufficient isolation of co-channel interference (CCI) between the transmissions on direct path and deflection route. Computer simulations show that, in realistic 60 GHz environment, Gbps-order system throughput is achieved under blocking condition. There is up to 35% system throughput improvement compared to the conventional relay scheme.

Inter-symbol/frame interference analysis is presented 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 manner. 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 presents throughput and error performance 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 presenting 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 millimeterwave 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 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.

Abstract-The paper proposes a codebook design to support beamforming mechanism in a wide band millimeter-wave 60 GHz wireless personal area networks (60 GHz WPANs) in a realistic millimeter-wave environment. The codebooks are designed symmetrically 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 60 GHz 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 ldB, 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 ldB 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 60 GHz WPANs (IEEE 802.15.3c).

In this paper, we propose a cross-layer deflect routing scheme that improves effective throughput of multi-hop millimeter-wave wireless personal area network (mmWave WPAN) system. The upcoming mmWave WPAN is designed to provide Gbps-order transmission capability, targeting applications like high definition TV (HDTV) transmission, high speed wireless docking and gaming etc. Adopting multi-hop relay offers solutions to the issues existing in mmWave WPAN system such as limited coverage range caused by the significant path loss, dramatic communication link change due to the unexpected blockage of the line-of-sight (LOS) path etc. However, multi-hop relay on the other hand decreases the effective throughput because of the required extra time. As a result, the compromised throughput may not be able to support the above applications which are greedy for data rate. Inspired by the fact that the significant path loss of millimeter-wave environment can provide good space isolation, our proposed scheme manages to improve the multi-hop throughput by sharing time slots for relay path with direct path for other transmissions. We also propose two algorithms, namely random fit deflect routing (RFDR) and best lit deflect routing (BFDR), to find the relay path on which the interference due to time slot sharing is low enough to guarantee the concurrent transmissions. Computer simulations show that, in realistic 60 GHz environment, the effective multi-hop throughput can be improved up to 45%.

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.

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.

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.

In this paper, we propose a deflection routing scheme that improves effective throughput (defined as the successfully transmitted bits over the duration between two available sequential time slots) of millimeter-wave wireless personal area network (mmWave WPAN) systems. The upcoming mmWave WPAN is based on dynamic time division multiple access (TDMA) and designed to guarantee Gbps-order transmission capability for high definition TV (HDTV) transmission, high speed wireless docking and gaming, etc. The decode-and-forward (DF) type of relay offers a simple solution to the issues of mmWave WPAN systems, such as limited coverage range and unexpected blockage. However, due to the required extra time, DF relay on the other hand decreases the effective throughput, and may not be sufficient to satisfy the requirement of the above data-rate-greedy applications. Inspired by the fact that the significant path loss of a millimeter-wave environment can provide good space isolation, we propose a deflection routing scheme to improve the effective throughput by sharing time slots for direct path with relay path. Based on the sub-exhaustive search, a routing algorithm, named as best fit deflection routing (BFDR), has been developed to find the relay path with the least interference that maximizes the system throughput. To reduce the computational complexity of the BFDR, we have also developed a sub-optimal algorithm named as random fit deflection routing (RFDR). The RFDR algorithm finds the sub-optimized relay path, where the interference may not be the least but is sufficiently low to guarantee the concurrent transmissions. Computer simulations show that, in realistic 60 GHz environments, the effective system throughput can be improved up to 28% under grid topology and 35% under random topology. RFDR achieves almost the same order of throughput improvement with only 10% of the computational complexity of BFDR.

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.

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.

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.

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.

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/N0at 10-6of 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/N0at 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.

The multi-Gbps wireless personal area network (WPAN) operating at 60-GHz is being standardized in the task group of IEEE 802.15.3c. To deal with the multi-path delay spread in non-line-of-sight (NLOS) environments, single-carrier frequency-domain equalization (SC-FDE), a.k.a., single-carrier block transmission (SCBT), is used in the physical (PHY) layer design. The low-density parity-check (LDPC) coding is considered as the high-performance channel coding scheme due to its good tradeoff between performance and complexity. A series of structured LDPC designs with very short codeword length of 576 are being adopted in one of the major proposals for IEEE 802.15.3c. The short codeword length helps to reduce the decoding complexity of LDPC. We evaluated the 576- length structured LDPC codes in SC-FDE system and found they have very good fixed point decoding performance. They are very promising in supporting ultra high-data-rate transmission with low complexity in 60-GHz WPAN (IEEE 802.15.3c).

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.