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Non-binary symbol transmission such as Ternary Phase Shift Keying (TPSK) and Hexagonal Quadrature Amplitude Modulation (HQAM) can achieve the superior performance to the PSK or square QAM in the band-limited and peak-to-average power ratio (PAPR) limited channel due to its excellent natures of PAPR, spurious characteristic, and minimum Euclidean distance. However, these non-binary symbol transmissions are not suitable for the transmission of binary information, because there is mapping loss in the bit-to-symbol mapping due to non-power-of-two number of constellation points. The aim of this work is to alleviate its loss by using spatial modulation and then improve the bit-error performance. Spatial modulation has been proposed as a spatial domain modulation, which can efficiently work only in the case of power-of-two number of antennas. By jointly desingning spatial modulation and non-binary amplitude phase modulation, the system can be more flexibly designed and then achieve better performance. Furthermore, we study the coding scheme for this non-binary symbol transmission in the PAPR limited channel. Computer simulations confirm that the proposed system with non-binary turbo code can significantly improve BER performance.

In order to guarantee the QoS (Quality of Service) for current or future multimedia application services over wireless networks, we have proposed a cross-layer design framework which is jointly optimized among physical, data link, and network layers. In our proposed scheme, we classify the various application services into two QoS classes, i.e., streaming and downloading types of data transmissions. This paper focuses on a frame fragmentation method in data link layer to improve both latency and throughput performances in network layer. The proposed scheme properly controls the packet length based on the QoS classes as well as CSI (Channel State Information). The computer simulations reveal that our proposed scheme improves latency and throughput performances by 8.52–10.5 dB and 12.4–12.7%, respectively.

Minimally invasive medical care by the aid of ICT (Information Communication Technology) has been paid a lot of attention. Micro robots within the bio-sensor network have been utilized without heavy patient burden. In order to control the micro robots properly, it is important to obtain the accurate position information. This paper provides an effective positioning method based on detection of small magnetic field generated from a micro robot. The proposed method can achieve the accurate positioning with low cost and simple procedure.

Recently, wireless sensor networks have received considerable attention. In order to realize these networks, it is very important to estimate the position of indivisual nodes. The purpose of this study is to improve the accuracy of positioning. In wireless sensor networks, since a large number of sensor nodes are densely distributed over the target field, the sensor are closely located. As a result, the sensing data of nearby nodes have some correlation. Moreover, the closer the sensors are located, the higher the correlation the sensing data have. We propose a novel positioning method based on the above fact. Concretely, we combine the conventional positioning method which consists of the ToA ranging method and the proposed method considering the relationship between the data correlation and the distance. Computer simulations show that our proposed positioning method can improve the accuracy of positioning compared with the conventional ones.

This paper provides the practical design of the transmit diversity technique with a nested coding technique and evaluates its performance via computer simulations. Similar to network coding techniques, the nested transmit diversity combines the transmit data with XOR operation. As a characteristic of the proposed transmit diversity, it can obtain diversity gain without some extra resources (e.g., transmit/receive antenna). In the proposed system, the transmitter simultaneously transmits two or more data sequences with a superposition technique, namely, nested coding technique. Suppose the case of two data superposing, the transmitting signal is composed of two data sequences, one is the data sequence to be currently transmitted, the other is the previously transmitted data sequence. In this case, the receiver has two types of decoding method corresponding to the previous decoding result. When successfully decoded at previous time slot, since the receiver knows the data-sequence transmitted at previous time slot which is referred to as superposition factor, it can completely remove the superposition factor with XOR manner. Different from a network coding, even if the receiver does not know the superposition factor (failed to decode the data), it can attempt to decode both data sequences. In this paper, we focus on the pragmatic design of nested transmit diversity. In order to achieve further improvement, we propose a reverse order decoding scheme. We reveal that the proposed nested transmit diversity can achieve diversity gain without extra resources.

This chapter contains sections titled: Introduction Designing a C/M Scheme: The Gaussian Channel Perspective Wireless Channel: A New Perspective Flat Independent Fading Channel Block-Fading Channel Interference-Limited Channel Conclusions This chapter contains sections titled: References

This chapter contains sections titled: Introduction Standardization Efforts Related to Broadband Wireless Access Standardization on Radio Access Layer [10] Standardization on Mobile ATM [13-15] Conclusions This chapter contains sections titled: References

This chapter contains sections titled: Introduction Multiple Access Techniques Demand-Assign-Based Multiple Access Random Multiple Access Summary This chapter contains sections titled: References

This chapter contains sections titled: Introduction Background to WCDMA UMTS/IMT-2000 System Overview WCDMA Radio Protocol Operation WCDMA Physical Layer WCDMA Radio Resource Management Performance-Enhancing Technologies This chapter contains sections titled: References

This chapter contains sections titled: Introduction Wireless ATM Architecture WATM Radio Access Layer Mobile ATM Network QoS Control in Wireless ATM Concluding Remarks This chapter contains sections titled: References ]]>

This chapter contains sections titled: Introduction Current Scene in Wireless Communications 3G Scene for the Beginning of the 21 st Century Post-3G Systems Global Family of AD Hoc Networks Peering Through the Future Haze This chapter contains sections titled: References

This chapter contains sections titled: Overview ITU's IMT-2000 Standardization Efforts 3G Standardization Consortia Evolving Radio Standards Evolving Network Standards Related Standardization Efforts Summary This chapter contains sections titled: References

This chapter contains sections titled: Introduction Background Physical Layer Link Layer EGPRS Performance Conclusions This chapter contains sections titled: References

This chapter contains sections titled: Future Wireless Network Vision Future Wireless Network Architecture Wireless Packet Network Evolution Migration of Wireless Radio Access to Packet Data Network (Including M-IP and GPRS) Wireless Packet Network Summary This chapter contains sections titled: References

This chapter contains sections titled: Introduction Empirical Models Analytical Models Deterministic Methods Summary This chapter contains sections titled: References

This chapter contains sections titled: Introduction Outline of Modulation and Demodulation Techniques GMSK QPSK ?>/4-QPSK M-ary QAM Pilot Signal-Aided Fading Compensation Techniques Orthogonal Frequency Division Multiplexing Adaptive Modulation Summary This chapter contains sections titled: References

This chapter contains sections titled: Overview Macrocellular Measurements Microcellular Measurements Indoor Measurements Summary This chapter contains sections titled: References

This chapter contains sections titled: Introduction Mobile Satellite Services Proposed Global Satellite Phone System Designs Data and Multimedia Services Concluding Remarks

WLAN (Wireless LAN) is useful access method to realize high-speed data transmission. WLAN is mainly used under indoor environment. In this case, transmission performance such as BER (Bit Error Rate) and throughput are evaluated under non-fading or slow-fading conditions. However, transmission performance of outdoor vehicular environment should be evaluated in order to adopt WLAN to realize high-speed signal transmission systems such as DSRC (Dedicated Short Range Communications) in ITS (Intelligent Transportation Systems). With this motivation, we conducted field test measurement by using officially licensed amateur radio station. In this paper, transmission performance of 5 GHz band WLAN under mobile environment is described based on the results of measurement. Communication systems using WLAN is also described.

The new spread ALOHA system based on the multi level transmission technique is proposed. The spread ALOHA system with the three-valued signaling and code shift keying (CSK) are combined in the proposed system. This system can reduce the packet length of the spread ALOHA system without extension of the frequency bandwidth. It is expected to improve the system performance. In this paper, the throughput performance of the proposed system are evaluated by theoretical analysis. Moreover, throughput performances of the spread ALOHA systems without CSK are compared. It is shown that the proposed system is superior to conventional spread ALOHA systems when Eb/N0 is larger than 10[dB]

Wireless ad hoc networks have been studied from several viewpoints. However, the studies have not focused on the relationship between ad hoc networks and other wireless networks or the characteristics of combined networks. This paper describes a mobile radio communication system with multi-layered wireless network that uses ad hoc networks. The major purposes of the proposed system are to obtain anti-shadow fading characteristics and to disperse the traffic in a service area. First, the multi-layered wireless network architecture is described. Then, the spectrum efficiency is given while taking into account the number of hoppings among the ad hoc networks. Finally, as an example of the multi-layered wireless network system, a positioning system with ten times higher accuracy than a conventional PHS (personal handy phone system) based system is introduced.

Currently, 3G mobile radio communications (IMT-2000) are being introduced for application to multimedia signal transmission. User movement and multimedia traffic have a great impact on networks. A traffic model for the multimedia signal is necessary for the design of a mobile radio communication network. However, no traffic model has yet been proposed that takes into account both the effect of multimedia signal transmission and inter-cell user mobility. This paper describes a traffic model that takes the effect of multimedia services and the user mobility of a mobile communication network into consideration. After giving the mobility model and multimedia signal characteristics, the relationship between the amount of multimedia traffic and call loss probability as well as the relationship between user mobility and call loss probability are clarified by computer simulation. As a result, we found that it is important to consider both user mobility and multimedia traffic in designing a mobile radio communication network.

The third generation (3G) mobile telecommunication systems (IMT-2000) are under consideration. The systems will be put into commercial use in the year 2000 and later. At the beginning of their operation, the second-generation systems seem to be coexisting. Therefore, the transceiver equipment of the base station (BS) and mobile station (MS) should support the operation of these systems from the viewpoint of system compatibility. In this case, so-called multi-mode/multi-band operation is required for users' convenience. Furthermore, realization of small sized and low power consumption handy terminals is necessary. The software radio approach is one of the most promising techniques for this purpose. This paper describes the application of software radio technique to realize the multi-mode transceiver for 3G system.

In mobile and personal radio, direct sequence code division multiple access (DS-CDMA) systems are attracting attention because of their inherently high capacity. Furthermore, the DS-CDMA system is a flexible system which can accommodate various user rates easily. As many user will occupy the same frequency band simultaneously, the traffic capacity of a DS-CDMA system is determined by the interference power. Interference cancellation is one of the important techniques in decreasing the interference power and increasing the traffic capacity. We propose the delayed symbol combining interference canceller which can suppress the interference from various users sending at different information rates. Its performance is calculated by computer simulations from the viewpoint of bit-error-rate (BER). In the flat fading environment, it is found that the E/sub b//N/sub o/ degradation by the interference is suppressed to 3 dB at a BER of 10/sup -3/ with 24 users. In the frequency selective fading environment, it is found that the required E/sub b//N/sub o/ of the frequency selective fading canceller is about 11 dB better than that of the flat fading canceller to establish the BER of 10/sup -3/.

This paper describes a wireless access method, suitable for personal communications, that is based on the concept of inter-cell access using direct sequence code division multiple access (DS-CDMA). The system provides high-speed and high-quality transmission and is characterized by microcell layout, wideband transmission, bit-rate flexibility, and decentralized/autonomous control. The system has a two layer configuration, surface node (SN) and access layer (AL). Personal stations (PSs) access the base stations (BSs) in both layers using a common air interface.

It is necessary to establish high data rate transmission to support multimedia services. This requires a determination of access scheme's performance and a clarification of the selection criteria. We present the transmission performance of a CDMA system with a RAKE receiver. The relationship between the root mean square delay spread normalized by the chip period at a minimum BER and the number of RAKE fingers is evaluated. The BER performance of CDMA multi-code transmission is also evaluated. It is found that single code transmission has a better performance than multi-code transmission. The BER performance of a TDMA system with an equalizer is also presented. It is found that as the number of combined symbols becomes larger the root mean square delay spread normalized by the symbol period at the minimum BER increases. The TDMA system BER performance is compared with the CDMA system performance. For example, when the processing gain is 16, the number of RAKE fingers is 4, and the number of combined delayed symbols in the equalizer is 4, if the root mean square delay spread normalized by the information symbol period is larger than 0.27, TDMA offers a better BER performance.

A high-capacity and wide coverage cell station (CS) for PHS has been developed. The developed CS employs a modified coherent demodulator with 4-branch MRC diversity and a burst-by-burst AFC to enhance the coverage. The proposed burst-by-burst AFC, which eliminates frequency errors of slotted random access signals, flattens the BER performance of the uplink control channels regardless of the carrier frequency errors. The proposed coherent demodulator achieves BER of 10/sup -2/ at received signal strength=2 dB/spl mu/V in the uplink traffic channels. The developed CS also employs an antenna-sharing diversity transmission to incorporate three transmitters in a small unit with a high power efficiency. The developed CS can be applied not only for personal communication services but also wireless local loop services.

IMT-2000/FPLMTS are, as third generation land mobile radio communication systems, under study in ITU-R. These systems should provide multimedia signal transmission services such as voice, image, video, and data. Systems based on CDMA are among the most promising candidates. A wideband DS-CDMA method with a two-layer structure for microcell layouts has been proposed (Ogose et al. 1996). This paper describes a personal multimedia communication system based on wideband DS-CDMA that combines the capabilities of circuit switched signal transmission and non-circuit connection packet switched signal transmission. The former signal is connected to PSTN/ISDN, while the latter one is connected to a computer network such as the open computer network (OCN). In this paper, we call these types of transmission connection operation and connectionless operation, respectively. The system concept is given first. Technical requirements on the system from the viewpoints of network architecture and the air-interface are then given. We also describe the system capacity and required bandwidth by computer simulation.

This paper presents laboratory test measurement results from a post-detection RAKE receiver system with a time-window control loop (TWCL) as the code synchronization scheme under a frequency-selective fading environment. RAKE combining methods, a simple integral demodulation method within a time-window and a recursive least squares (RLS) demodulation method within the time-window that uses the RLS algorithm to realize maximal ratio combining, are investigated. The result shows that the TWCL provides good acquisition and tracking performance under the fading conditions experienced with maximum Doppler frequencies from 5 to 80 Hz. It is also shown that the required E/sub b//N/sub 0/ when the bit-error rate must be 10/sup -3/ under the double-spike frequency-selective Rayleigh-fading model is reduced by 10 dB compared to the non-selective Rayleigh-fading model. The difference of the path-diversity effect between the two RAKE combining methods is only 1 dB.