Beyond 5G is the next generation mobile communication system expected to be used from around 2030. Services in the 2030s will be composed of multiple systems provided by not only the conventional networking industry but also a wide range of industries. However, the current mobile communication system architecture is designed with a focus on networking performance and not oriented to accommodate and optimize potential systems including service management and applications, though total resource optimizations and service level performance enhancement among the systems are required. In this paper, a new concept of the Beyond 5G cross-industry service platform (B5G-XISP) is presented on which multiple systems from different industries are appropriately organized and optimized for service providers. Then, an architecture of the B5G-XISP is proposed based on requirements revealed from issues of current mobile communication systems. The proposed architecture is compared with other architectures along with use cases of an assumed future supply chain business.

Recently, new optimization machines based on non-silicon physical systems, such as quantum annealing machines, have been developed, and their commercialization has been started. These machines solve the problems by searching the state of the Ising spins, which minimizes the Ising Hamiltonian. Such a property of minimization of the Ising Hamiltonian can be applied to various combinatorial optimization problems. In this paper, we introduce the coherent Ising machine (CIM), which can solve the problems in a milli-second order, and has higher performance than the quantum annealing machines especially on the problems with dense mutual connections in the corresponding Ising model. We explain how a target problem can be implemented on the CIM, based on the optimization scheme using the mutually connected neural networks. We apply the CIM to traveling salesman problems as an example benchmark, and show experimental results of the real machine of the CIM. We also apply the CIM to several combinatorial optimization problems in wireless communication systems, such as channel assignment problems. The CIM's ultra-fast optimization may enable a real-time optimization of various communication systems even in a dynamic communication environment.

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.

It is necessary to estimate channel state information coherently to equalize the received signal in wireless communication systems. The pilot symbol, known at the receiver, aided channel estimator degrades the transmission efficiency because it requires the signal spaces and the energy for the transmission. In this paper, we assume a fixed wireless communication system in line of sight slowly varying channel and propose a new blind channel estimation method without help from the pilot symbol for Orthogonal Frequency Division Multiplexing systems. The proposed estimator makes use of the Expectation-Maximization algorithm and the correlation property among the channel frequency responses by considering the assumed channel environment. By computer simulations, we show that the proposed estimator can asymptotically achieve bit error rate performance by using the ideal channel estimation.

As the demand for higher transmission rates and spectral efficiency is steadily increasing, the research and development of novel mobile communication systems has gained momentum. This paper focuses on providing a comprehensive survey of research and development activities on fifth generation mobile communication systems in Japan. We try to survey a vast area of wireless communication systems and the developments that led to future 5G systems.

This paper presents a novel electrical polarization forming antenna for mobile satellite communication systems using linear polarization. To electrically form the desired polarization, it is necessary to excite the two orthogonal polarization antenna planes with appropriate weights. The proposed antenna uses digitally-based polarization and calibration functions to characterize the two RF paths. The calibration techniques used are critical to accurately forming the desired polarization. Proposed calibration techniques are very simple; the feedback signal consists of just amplitude levels. The proposals are validated by polarization forming measurements conducted on a fabricated antenna.

In this paper, we analyze the impact of channel estimation errors for both decode-and-forward (DF) and amplify-and-forward (AF) cooperative communication systems over Nakagami-m fading channels. Firstly, we derive the exact one-integral and the approximate expressions of the symbol error rate (SER) for DF and AF relay systems with different modulations. We also present expressions showing the limitations of SER under channel estimation errors. Secondly, in order to quantify the impact of channel estimation errors, the average signal-to-noise-ratio (SNR) gap ratio is investigated for the two types of cooperative communication systems. Numerical results confirm that our theoretical analysis for SER is very efficient and accurate. Comparison of the average SNR gap ratio shows that DF model is less susceptible to channel estimation errors than AF model.

A site-general type prediction formula is created based on the measurement results in an urban area in Japan assuming that the prediction frequency range required for Fourth -- Generation (4G) Mobile Communication Systems is from 3 to 6 GHz, the distance range is 0.1 to 3 km, and the base station (BS) height range is from 10 to 100 m. Based on the measurement results, the path loss (dB) is found to be proportional to the logarithm of the distance (m), the logarithm of the BS height (m), and the logarithm of the frequency (GHz). Furthermore, we examine the extension of existing formulae such as the Okumura -- Hata, Walfisch -- Ikegami, and Sakagami formulae for 4G systems and propose a prediction formula based on the Extended Sakagami formula.

We address reliable key distribution scheme for lossy channels such as wireless or power line. In the key distribution over these lossy channels, if key information is lost, there is critical issue that the subsequent communication is disabled. In this paper, we show that our proposal has more reliable property than the related works and has the reliable property equivalent to the dedicated communication channels such as Ethernet.

A chaotic UWB communication system based on IEEE 802.15.4a is proposed for wireless connectivity applications. A compact and simple architecture is implemented by using a chaotic UWB signal and a non-coherent detection scheme. The chaotic UWB signal has noise-like characteristics in time and frequency domains and naturally wide spectrum within a limited bandwidth. The chaotic UWB signal generator is designed on two methods with the bandwidth of 3.1 to 5.1 GHz, and a baseband process is realized on an FPGA including an adaptive decision and a channel code for non-source coded data stream. The system performance is evaluated by transmitting MP3 audio/voice with 32-byte length PSDUs and measuring PERs for assessing the system sensitivity and the interferer compatibility. The proposed system can be an excellent candidate for short-range connectivity services, as well as an inexpensive system with good capability for narrow-band interferences.

We study asynchronous SSMA communication systems using binary spreading sequences of Markov chains and prove the CLT (central limit theorem) for the empirical distribution of the normalized MAI (multiple-access interference). We also prove that the distribution of the normalized MAI for asynchronous systems can never be Gaussian if chains are irreducible and aperiodic. Based on these results, we propose novel theoretical evaluations of bit error probabilities in such systems based on the CLT and compare these and conventional theoretical estimations based on the SGA (standard Gaussian approximation) with experimental results. Consequently we confirm that the proposed theoretical evaluations based on the CLT agree with the experimental results better than the theoretical evaluations based on the SGA. Accordingly, using the theoretical evaluations based on the CLT, we give the optimum spreading sequences of Markov chains in terms of bit error probabilities.

Smart or adaptive antennas promise to provide significant space-time communications against fading in wireless communication systems. In this paper, we propose multiple-input multiple-output (MIMO) beamforming for frequency-selective fading channels to maximize the Signal-to-Noise and Interference Ratio (SINR) based on an iterative update algorithm of transmit and receive weight vectors with prior knowledge of the channel state information (CSI) at both the transmitter and receiver. We derive the necessary conditions for an optimum weight vector solution and propose an iterative weight update algorithm for an optimal SINR reception. The Maximum Signal-to-Noise (MSN) method, where noise includes the additive gaussian noise and interference signals, is used as a criterion. The proposed MIMO with M N arrays allows the cancellation of M + N - 2 delayed channels. Computer simulations are presented to verify our analysis. The results show that significant improvements in performance are possible in wireless communication systems.

The traditional approach for establishing the correctness of group communication protocols is through rigorous arguments. While this is a valid approach, the likelihood of subtle errors in the design and implementation of such complex distributed protocols is not negligible. The use of formal verification methods has been widely advocated to instill confidence in the correctness of protocols. In this paper, we describe how we used the SPIN model checker to formally verify a group membership protocol that is part of an intrusion-tolerant group communication system. We describe how we successfully tackled the state-space explosion problem by determining the right abstraction level for formally specifying the protocol. The verification exercise not only formally showed that the protocol satisfies its correctness claims, but also provided information that will help us make the protocol more efficient without violating correctness.

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.

Radio access networks (RANs) for new generation mobile communication systems are required to construct economical high capacity networks. An optical wireless link is expected as a solution to the linking method in the construction of these networks. The optical wireless link provides high bit-rate transmission and allows for easy installation. However, optical-waves are severely attenuated in free-space transmission due to weather conditions and cannot provide a high level of link availability in long-distance communications. This paper describes the applicability of an optical wireless link to the RAN based on obtained atmosphere propagation properties from experiments on an 800-nm band optical wireless link from the viewpoint of link availability. The experimental results show that the BER performance of the optical wireless link exhibits a sufficiently low power penalty of less than 1 dB compared to that of the optical fiber link. Moreover, the results confirm that atmosphere attenuation of an 800-nm band optical wave due to fog and rainfall can be estimated by using a simple estimation equation. The optical wireless link could be used for RAN approach links with the range of less than 350 m to achieve the link outage rate of 0.004% from the viewpoint of the link budget design.

Datacycle is an information delivery system designed in Bellcore . It uses broadcast delivery and multiple channels of an optical fiber to provide a large volume of information to many users. In this system, the mean access time depends on the broadcast delivery schedule because different information items (called pages) may have different popularity and there are multiple channels for concurrent broadcast delivery. In this paper, we design broadcast delivery schedules for M channels where M 2 and our objective is to minimize the mean access time. We show that this design problem can be divided into two subproblems: (1) divide the pages into M partitions such that the pages of each partition are broadcast in a distinct channel and (2) determine a broadcast schedule for the pages of each partition. We analyze and solve these subproblems, and we demonstrate that the schedules found can nearly reach a lower bound on the minimal mean access time.

Intelligent paging uses the sequential paging technique with additional user information in order to reduce the paging delay cost and the paging load cost. Our proposed paging scheme uses distribution density information of users as required additional user information. This letter addresses an optimal paging sequence and introduces formulas to calculate the paging costs. These formulas are necessary to evaluate the performance of location management. The paging delay cost and the paging load cost for the proposed paging scheme and two other paging schemes are calculated and numerical analyses for these paging schemes are performed. Results show how the paging delay cost and the paging load cost vary as either the paging request arrival rates or the number of cells in an LA increases. The proposed paging scheme is more efficient in view of both the paging delay cost and the paging load cost.

The plan of High Altitude Platform Station (HAPS) is considered as a revolutionary wireless system plan with several economic and technological advantages over both space- or ground-based counterparts. In this paper, we propose a joint system of terrestrial and HAPS cellular for Wideband-CDMA mobile communication. This system makes the conventional terrestrial W-CDMA cellular area smaller and the remainder area covered by HAPS to increase the total capacity. Furthermore in down link channel, we introduce the polarized wave and doughnut-like radiation. However, in the proposed system, the performance would be dependent on the terminal position especially near the boundary of doughnut-like cell zone. To overcome this, site diversity that uses both signals from terrestrial Base Station and HAPS Base Station is also introduced. To confirm the availability of the proposed system, we evaluate the system performance by computer simulation.

Mobile computing networks make it possible to offer information access to mobile users. In order to transfer data over mobile networks efficiently, appropriate data transmission control methods for mobile terminals must be established. This paper focuses on spot communication systems to transmit data at high speeds between base stations and mobile terminals. It proposes a flexible and efficient data transmission method that is suitable for spot communication systems. The proposed method transfers subsets of the data to the base stations that are best sited relative to the mobile terminal. This helps to reduce the traffic load of the network significantly. Simulation results confirm the validity of the proposed method. Furthermore, the data receiving time of the mobile terminal, which is an important measure in evaluating the Quality of Service (QoS) for data transmission is analyzed. The result shows that the traffic load in the network is reduced significantly while the QoS is well maintained.

Packet concentrators are used in many high-speed computer communication systems such as fast packet switches. In these systems, the time available for concentration is very short. It is therefore desirable to realize the packet concentrators as hardware chips for fast concentration. The knockout concentrator was proposed for hardware realization. In this paper, we improve this concentrator to reduce the probability of packet loss, and the improved concentrator is called wraparound knockout concentrator. This concentrator has several wraparound paths within it, and it does not require any additional pin per chip. After contention among the packets in a slot, each winner goes to a distinct output, some losers circulate along the wraparound paths for contention in the subsequent slot, and the remaining losers are discarded. In this manner, some losers are not discarded immediately and they still have the chance to go to the outputs in the subsequent slot, thereby reducing the probability of packet loss. We analyze the number of logic gates required and the probability of packet loss. The numerical results show that if the proposed concentrator has a few wraparound paths, the probability of packet loss can already be reduced by orders of magnitude.