The exciting goals of ubiquitous computing and communication services can only be achieved if we can increase the efficiency with which the location of mobile terminals can be managed; current mobile infrastructures are not efficient since they treat all mobile terminals uniformly despite that fact that many mobiles often move together (i.e. passengers on the same train or a group of cars on a road). This paper presents a hierarchical location management scheme that handles such grouped mobiles collectively and so reduces the overhead costs of location management. In our scheme, mobiles that move together for long enough form a mobile network and make a hierarchy in the wireless access network. The scheme also adjusts the number of mobile networks to keep communication overhead low. We apply the scheme to Mobile IPv6 and evaluate the resulting performance improvement. Simulation results confirm that our hierarchical approach can greatly reduce the overhead costs of location management, and that it is very practical since it can flexibly develop suitable mobile networks.

This innovative traffic-monitoring-system makes it possible to observe data-communication traffic on an oscilloscope-style display. It provides an efficient way of evaluating streaming-data quality. The monitoring system has a high time-resolution traffic value sampling function and a real-time data representation/recording mechanism that operate in synchrony. The user can directly evaluate the traffic shape with the monitoring system. In this paper, after describing the concept of the traffic monitoring system, we will describe a prototype built with programmable network equipment called A-BOX. We will then review a performance evaluation and other experimental results to prove that our monitoring system is suitable for video streaming.

This paper describes two algorithms based on Boolean formulations aimed at solving scheduling, the main subtask of data path synthesis. Using the first algorithm, all possible scheduling solutions can be obtained under a time constraint, something that cannot be accomplished with other available systems. The second algorithm produces feasible solutions without increasing the complexity of the problem. The effectiveness of the algorithms is confirmed through experimental studies.

We propose a high-level synthesis method that uses data path information given by a designer. The main purpose of this method is to generate a control unit, one of the most difficult aspects of hardware design. In general, designers can specify data paths easily. Therefore, we believe that basing a method on specified data path information is the best way to synthesize hardware that more closely satisfies the designer's requirements. Moreover, a datapath-constrained scheduling algorithm can perform both "scheduling" and "resource allocation" at the same time. In particular, the resource allocation explicitly decides used paths as well as functional modules in each execution state. This cannot be done with previously reported algorithms.

This paper describes the concept of an adaptive network, that is, a network environment that can rapidly and autonomously adapt its behavior according to network conditions and traffic status. The user interface of the adaptive network can access any resource in the network as a memory-mapped I/O device, as if it were attached to the local bus of the user's PC. This network concept has several benefits. From the application development viewpoint, no network related programming is required, and applications do not have to be modified even if the network topologies and protocols are changed. Network maintenance and upgrading can be done anytime without having to worry about the application users, because the network itself is concealed from the applications. In addition, the reconfigurable hardware technology functions as an autonomous network control through the use of a lower-layer protocol. We developed a testbed that makes heterogeneous resources available to users and used it to demonstrate the feasibility of our concept by implementing and running some applications over it.

Real-world IP networks are heterogeneous in terms of server and link capacities. A sophisticated and comprehensive load balancing method is essential if we are to avoid congestion in the servers and links of heterogeneous networks. If such a method is not available, network throughput is limited by bottleneck servers or links. This paper proposes an anycast technique that achieves load balancing under heterogeneity. The proposed method well suits implementation on active networks. By taking advantage of the processing ability provided by active nodes, the method can decide packet routes flexibly on the basis of various criteria to realize a variety of load balancing schemes. Some of these schemes can successfully prevent the congestion of heterogeneous networks by tackling bottlenecks in both server and link capacities. The method is also advantageous given its light control load even when using many mirrored servers. Computer simulations confirm the effectiveness of these features.

This paper proposes a new processor architecture for manipulating the protocols of digital signal transport systems. In order to offer various kinds of telecommunication services, flexibility as well as high performance is required of digital signal transport systems. To realize such systems, this architecture consists of a core CPU, memories, and dedicated application-specific hardware. Software on the core CPU offers flexibility, while the dedicated hardware provides performance. A computer simulation confirms the efficiency of the architecture.

This paper presents an architecture for a table-lookup (TLU) engine that allows the real-time operation of complicated TLU for telecommunications, such as the longest prefix match (LPM) and the long-bit match in packet classification. The engine consists of many CAM (Content Addressable Memory) chips, which are classified into several groups. When actual TLU is performed, the entries in each CAM group are searched simultaneously, and the best entry candidate in each group is selected by an intra-group arbiter. The final output, the entry desired, is decided by an inter group arbiter that selects one group. This hierarchical structure of arbitration is the key to the scalability of the engine. To accelerate the operation speed of the engine, we introduce a novel mechanism called "hit-flag look-ahead" that sends a hit-flag signal from each matched CAM chip to the inter group arbiter before each intra group arbiter calculates the best CAM output in the group. We show that a TLU engine based on the above architecture achieves significantly fast performance compared to engines based on conventional techniques, especially in the case of a large number of entries with long-bit matching. Furthermore, our architecture can realize an 33.3 Mlps (lookups per second) within a 128 bit 300,000-entry table at wire speed.

The present paper introduces a novel method for the construction of a class of sequences that have a zero-correlation zone. For the proposed sequence set, both the cross-correlation function and the side lobe of the auto-correlation function are zero for phase shifts within the zero-correlation zone. The proposed scheme can generate a set of sequences of length 8n2 from an arbitrary Hadamard matrix of order n and a set of 2n trigonometric-like function sequences of length 4n. The proposed sequence construction can generate an optimal zero-correlation zone sequence set that satisfies the theoretical bound on the number of members for the given zero-correlation zone and sequence period. The auto-correlation function of the proposed sequence is equal to zero for all nonzero phase shifts. The peak factor of the proposed sequence set is √2, and the peak factor of a single trigonometric function is equal to √2. Assigning the sequences of the proposed set to a synthetic aperture ultrasonic imaging system would improve the S/N of the obtained image. The proposed sequence set can also improve the performance of radar systems. The performance of the applications of the proposed sequence sets are evaluated.

Caching web files reduces user response time as well as network traffic. When implementing caches, the file caching problem must be addressed; the problem is how to determine which files should be evicted from a cache when there is insufficient space for storing a new file so that the sum of the mis-hit (fault) file costs is minimized. Greedy-Dual-Size (GDS) is the best online algorithm in terms of competitiveness, i. e. , (k)/(k-h+1)-competitive, where k and h are the storage space of, respectively, GDS and an optimal offline algorithm. GDS performs very well even in trace-driven simulations. The worst-case time taken to service a request is another important measure for online file caching algorithms since slow response times render caching meaningless from the client's view point. This paper proposes a fast randomized (k)/(k-h+1)-competitive algorithm that performs in O(2log ^* k) time per file eviction or insertion, whereas GDS takes O(log k) time, where 2log ^* k is a much slower increasing function than log k. To confirm its practicality, we conduct trace driven simulations. Experimental results show that our algorithm attains only slightly worse byte hit rates and sufficiently large reduced latency in comparison with GDS, and our algorithm is a good candidate for caches requiring high-speed processing such as second-level caches in the large networks.

After a natural disaster it is critical to urgently find victims buried under collapsed buildings. Most people habitually carry smartphones with them. Smartphones have a feature that periodically transmits Wi-Fi signals called “Probe Requests” to connect with access points. Moreover, smartphones transmit “Clear to Send” when they receive a “Request to Send” alert. This motivated us to develop a hand-held smartphone finder system that integrates a novel method for accurately locating a smartphone using the Wi-Fi signals, to support rescue workers. The system has a unique graphical user interface that tracks target smartphones. Thus, rescue workers can easily reach victims who have their smartphones with them under collapsed buildings. In this paper, after introducing the localization method, the system architecture of the smartphone finder and its prototype system are described, along with some experimental results that demonstrate the effectiveness of the smartphone finder prototype.

In recent years, checking sleep quality has become essential from a healthcare perspective. In this paper, we propose a respiratory rate (RR) monitoring system that can be used in the bedroom without wearing any sensor devices directly. To develop the system, passive radio-frequency identification (RFID) tags are introduced and attached to a blanket, instead of attaching them to the human body. The received signal strength indicator (RSSI) and phase values of the passive RFID tags are continuously obtained using an RFID reader through antennas located at the bedside. The RSSI and phase values change depending on the respiration of the person wearing the blanket. Thus, we can estimate the RR using these values. After providing an overview of the proposed system, the RR estimation flow is explained in detail. The processing flow includes noise elimination and irregular breathing period estimation methods. The evaluation demonstrates that the proposed system can estimate the RR and respiratory status without considering the user's body posture, body type, gender, or change in the RR.

Performance measurements are indispensable for managing the Internet. Among the performance measurement techniques known, passive measurement is attractive because of its accuracy; user traffic is observed without inserting additional test traffic. However, the technique is handicapped by its large storage and bandwidth costs. This paper proposes a passive packet loss measurement technique that effectively avoids the difficulty of the conventional passive measurement approaches. Its key advance is utilizing the packet feature computed by a hash function. Since the feature can identify a packet with a short length of data, it becomes possible to greatly decrease the storage and bandwidth costs of passive measurements. The paper details the measurement procedure and assesses the design parameters used in the method. In addition, the validity of the proposed method is confirmed through experiments. The experiments also show the advantage of the method over the conventional active measurement.

The algebraic path problem (APP) is a general framework which unifies several solution procedures for a number of well-known matrix and graph problems. In this paper, we present a new 3-dimensional (3-D) orbital algebraic path algorithm and corresponding 2-D toroidal array processors which solve the nn APP in the theoretically minimal number of 3n time-steps. The coordinated time-space scheduling of the computing and data movement in this 3-D algorithm is based on the modular function which preserves the main technological advantages of systolic processing: simplicity, regularity, locality of communications, pipelining, etc. Our design of the 2-D systolic array processors is based on a classical 3-D2-D space transformation. We have also shown how a data manipulation (copying and alignment) can be effectively implemented in these array processors in a massively-parallel fashion by using a matrix-matrix multiply-add operation.

Blockchain-based voting, including liquid voting, has been extensively studied in recent years. However, it remains challenging to implement liquid voting on blockchain using Ethereum smart contract. The challenge comes from the gas limit, which is that the number of instructions for processing a ballot cannot exceed a certain amount. This restricts the application scenario with respect to algorithms whose time complexity is linear to the number of voters, i.e., O(n). As the blockchain technology can well share and reuse the resources, we study a model of liquid voting on blockchain and propose a fast algorithm, named Flash, to eliminate the restriction. The key idea behind our algorithm is to shift some on-chain process to off-chain. In detail, we first construct a Merkle tree off-chain which contains all voters' properties. Second, we use Merkle proof and interval tree to process each ballot with O(log n) on-chain time complexity. Theoretically, the algorithm can support up to 21000 voters with respect to the current gas limit on Ethereum. Experimentally, the result implies that the consumed gas fee remains at a very low level when the number of voters increases. This means our algorithm makes liquid voting on blockchain practical even for massive voters.

The present paper introduces the construction of quadriphase sequences having a zero-correlation zone. For a zero-correlation zone sequence set of N sequences, each of length l, the cross-correlation function and the side lobe of the autocorrelation function of the proposed sequence set are zero for the phase shifts τ within the zero-correlation zone z, such that |τ|≤z (τ ≠ 0 for the autocorrelation function). The ratio $rac{N(z+1)}{ell}$ is theoretically limited to one. When l=N(z+1), the sequence set is called an optimal zero-correlation sequence set. The proposed zero-correlation zone sequence set can be generated from an arbitrary Hadamard matrix of order n. The length of the proposed sequence set can be extended by sequence interleaving, where m times interleaving can generate 4n sequences, each of length 2m+3n. The proposed sequence set is optimal for m=0,1 and almost optimal for m>1.

After large-scale disasters, information sharing among people becomes more important than usual. This, however, is extremely difficult to achieve in disaster zones due to serious damage to the existing network infrastructure, power outages, and high traffic congestion. For the quick provision of alternative networks to serve heavy communication demands after disasters, establishing local area networks (LANs) consisting of portable servers with data storage has been considered as one of the most promising solutions. Based on the established LAN and a data server in each area, people can share many kinds of disaster-related information such as emergency information and supply/demand information via deployed neighboring servers. However, due to the lack of stable Internet connection, these servers are isolated and cannot be synchronized in real time. To enable and guarantee more efficient information sharing across the whole disaster-hit area, data stored on each server should be synchronized without the Internet. Our solution is to propose an intermittent data synchronization scheme that uses moving vehicles as relays to exchange data between isolated servers after disasters. With the objective of maximizing the total number of synchronized high priority data under the capability constraints of mobile relays, we first propose a data allocation scheme (DAS) from a server to a mobile relay. After that, we propose a trajectory planning scheme for the relays which is formulated as a Mixed Integer Linear Fractional Programming (MILFP) problem, and an algorithm to solve it efficiently. Extensive simulations and comparisons with other methods show the superior performance of our proposals.

We have developed a Field-Programmable Multi-Chip Module (FPMCM) whose component is the telecommunication-oriented FPGAs, called PROTEUS. The module consists of 3 3 PROTEUS FPGAs and its size is 114 mm square. Each PROTEUS chip is mounted on the MCM substrate using Tape Automated Bonding (TAB) technology so as to minimize the size of the MCM and the production cost. The interconnection topology among the FPGAs is a simple mesh. However, the connection can be changed logically, because PROTEUS itself has a special inter-I/O bypass resource in it. Using this mechanism, the interchip connection delay can be reduced without sacrificing the flexibility, compared to the previous FPMCM implementation using some other interconnection switches which often have a large propagation delay. The interchip connection delay is 200 ps. We have also developed a rapid prototyping system comprising several MCMs, and implemented telecommunication circuits in it.

Network caches reduce network traffic as well as user response time. When implementing network caches, the object replacement problem is one of the core problems; The problem is to determine which objects should be evicted from a cache when there is insufficient space. This paper first formalizes the problem and gives a simple but sufficient condition for deterministic online algorithms to be competitive. Based on the condition, a general framework to make a non-competitive algorithm competitive is constructed. As an application of the framework, an online algorithm, called Competitive_SIZE, is proposed. Both event-driven and trace-driven simulations show that Competitive_SIZE is better than previously proposed algorithms such as LRU (Least Recently Used).

Conventional array processors randomly access input/coefficient data stored in memory many times during three-dimensional discrete cosine transform (3D-DCT) calculations. This causes a calculation bottleneck. In this paper, a 3D array processor dedicated to 3D-DCT is proposed. The array processor drastically reduces data swapping or replacement during the calculation and thus improves performance. The time complexity of the proposed NNN array processor is O(N) for an N3-size input data cube, and that of the 3D-DCT sequential calculation is O(N4). A specific I/O architecture, throughput-improved architectures, and more scalable architecture are also discussed in terms of practical implementation. Experimental results of implementation on FPGA (field-programmable gate array) suggest that our architecture provides good performance for real-time 3D-DCT calculations.