This paper outlines the perspectives on Software Defined Radio (SDR) technology in viewpoint of the standardization of the future mobile communication systems. The activities of ITU-R SG8 Working Party 8F (WP8F) and mITF (mobile IT Forum) of Japan for systems beyond IMT-2000 (B3G) or 4-th generation mobile systems are firstly summarized. The latest discussions relating to SDR technology in the both parties are reported. It is followed by consideration on both expectations and technical issues on SDR in order to realize the technology in the future mobile communication systems. They are clarified in the viewpoint of standardization activity on B3G. Also some regulation issues are lastly summarized.

The field of mobile communications has continued to spread with astonishing speed in recent years. The expansion of mobile communications and the Internet has not only brought changes to communications services but also exerted huge effects on the economy and daily life. IMT-2000, International Mobile Telecommunications, is the next generation system for mobile communications systems currently being implemented. Standardization and development of IMT-2000 are in much progress under international frameworks to start commercial service by around the year 2001. This paper focuses in particular on radio transmission technology, giving an overall view of IMT-2000 standardization and technological status, as well as future technical directions extending beyond IMT-2000.

This paper reports the field test performance of a base station (BS) equipped with a linear parallel multi-stage interference canceller for uplink of wideband CDMA in a suburban area. The field test was performed with one desired mobile station (MS) moving around the BS, and three fixed interfering MSs having a target SIR 11 dB higher than that of the desired MS. The field test clearly demonstrates that using interference cancellation with a proper suppression factor (or weighting factor), can reduce the transmission power of the desired MS by around 6 dB. This performance was also compared with calculated data and the interference canceller was verified to function as theoretically expected. The receive power capture ratio was estimated at around 96%. This paper therefore establishes that interference cancellation performance of CDMA systems in the field can be found by estimating the receive power capture ratio and the theoretical results of interference cancellation.

Research and standardization activities on FPLMTS are under way throughout the world. This paper shows recent study results on radio transmission technologies in ARIB (Association of Radio Industries and Businesses), which in the standardization organization in Japan. On-going study shows two TDMA based and four CDMA based radio transmission technologies under study. These technologies need to be further studied in detail. The proposal from ARIB is expected to be summarized around the end of the year 1996.

As one functionality of the wireless distributed network (WDN) enabling flexible wireless networks, it is supposed that a dynamic spectrum access is applied to OFDM systems for superior radio resource management. As a basic technology for such WDN, our study deals with the OFDM signal detection based on its cyclostationary feature. Previous relevant studies mainly relied on software simulations based on the Monte Carlo method. This paper analytically clarifies the relationship between the design parameters of the detector and its detection performance. The detection performance is formulated by using multiple design parameters including the transfer function of the receive filter. A hardware experiment with radio frequency (RF) signals is also carried out by using the detector consisting of an RF unit and FPGA. Thereby, it is verified that the detection characteristics represented by the false-alarm and non-detection probabilities calculated by the analytical formula agree well with those obtained by the hardware experiment. Our analysis and experiment results are useful for the parameter design of the signal detector to satisfy required performance criteria.

A newly devised beam-steerable antenna which is capable of steering its radiation beam without moving a main reflector is presented. This is the offset type spherical reflector antenna with two specific subreflectors. With the application of mathematical programming, a new technique to determine the shapes of the subreflectors is proposed in order to compoensate for the spherical aberration and the asymmetrical distortion of the aperture distribution, which deteriorates the electric characteristics. An experimental antenna has demonstrated its excellent performance and supported the adequacy and availability of the designing procedure. The results suggest the feasibility of the beam-steerable antenna for satellite communication use.

This paper deals with a problem of maximizing directivity of a uniformly spaced broadside array under constraints on the specified sidelobe level. For this purpose, we use a quadratic programming in order to clarify the properties of the radiation pattern with high directivity and low sidelobe level. In resulting radiation patterns, the first sidelobes are suppressed to the specified level and other sidelobes decrease gradually in magnitude similarly to a Taylor pattern. The number of sidelobes in equal magnitude is determined by the specified sidelobe level. These properties are still held for both isotropic and parallel dipole elements.

The next generation mobile system “5G” are under research, development and standardization for a service start of around year 2020. It is likely to use frequency bands higher than existing bands to have wider bandwidth for high throughput services. This paper reviews technical issues on higher frequency bands applying mobile systems including system trials and use case trials. It identifies expectations for antennas & propagation studies toward 5G era.