There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

Wireless indoor positioning systems have become very popular in recent years. These systems have been successfully used in many applications such as asset tracking and inventory management. This paper provides an overview of the existing wireless indoor positioning solutions and attempts to classify different techniques and systems. Three typical location estimation schemes of triangulation, scene analysis, and proximity are analyzed. We also discuss location fingerprinting in detail since it is used in most current system or solutions. We then examine a set of properties by which location systems are evaluated, and apply this evaluation method to survey a number of existing systems. Comprehensive performance comparisons including accuracy, precision, complexity, scalability, robustness, and cost are presented.

Survey of Wireless Indoor Positioning Techniques and Systems

National Institute of Standards and Technology における超伝導研究及び生活

We present a new block cipher LED. While dedicated to compact hardware implementation, and offering the smallest silicon footprint among comparable block ciphers, the cipher has been designed to simultaneously tackle three additional goals. First, we explore the role of an ultra-light (in fact non-existent) key schedule. Second, we consider the resistance of ciphers, and LED in particular, to related-key attacks: we are able to derive simple yet interesting AES-like security proofs for LED regarding related- or single-key attacks. And third, while we provide a block cipher that is very compact in hardware, we aim to maintain a reasonable performance profile for software implementation.

The LED block cipher

In this paper we propose a new family of very efficient hardware oriented block ciphers. The family contains six block ciphers divided into two flavors. All block ciphers share the 80-bit key size and security level. The first flavor, KATAN, is composed of three block ciphers, with 32, 48, or 64-bit block size. The second flavor, KTANTAN, contains the other three ciphers with the same block sizes, and is more compact in hardware, as the key is burnt into the device (and cannot be changed).

The smallest cipher of the entire family, KTANTAN32, can be implemented in 462 GE while achieving encryption speed of 12.5 KBit/sec (at 100 KHz). KTANTAN48, which is the version we recommend for RFID tags uses 588 GE, whereas KATAN64, the largest and most flexible candidate of the family, uses 1054 GE and has a throughput of 25.1 Kbit/sec (at 100 KHz).

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KATAN and KTANTAN -- A Family of Small and Efficient Hardware-Oriented Block Ciphers

IEEE 1588 is a new standard for precise clock synchronization for networked measurement and control systems in LAN environment. This paper presents the design and implementation of an IEEE 1588 PC software prototype for Wireless LANs (WLAN). Accuracy is improved using two new developed methods for outbound latency estimation. In addition, an algorithm for adjusting the local clock is presented. The achieved accuracy is measured and compared between WLAN and fixed LAN environments. The results show that 2.8 μs average clock offset can be reached on WLAN, while wired Ethernet connection enables 2.5 μs.

Precision Time Protocol Prototype on Wireless LAN

This paper presents an energy-efficient multi-hop routing protocol for wireless sensor networks. The protocol uses cost metrics to create gradients from a source to a destination node. The cost metrics consist of energy, node load, delay, and link reliability information that provide a trade-off between performance and energy usage. A node can query routes from its neighbors, which allows efficient recovery from route losses. The protocol is the first cost-field based WSN routing protocol suitable for low processing and memory capacity nodes that is tested in a practical real-world environment. The protocol performance is evaluated on full scale prototype implementation consisting of 38 ultra-low power nodes in indoor environment. Compared to traditional flooding, the protocol requires only 25% of the bandwidth, while having smaller end-to-end delays.

Cost-Aware Dynamic Routing Protocol for Wireless Sensor Networks - Design and Prototype Experiments

This paper presents a medium access control (MAC) protocol called TUTMAC for a new wireless local area network (TUTWLAN). The design objective has been to develop a simple, multimedia service capable protocol that provides sufficient medium utilisation efficiency and guarantees QoS (quality of service) parameters. The developed system utilises a centralised (base station controlled) network architecture. A limited number of portable stations can be associated with the same base station, i.e. in the same TUTWLAN cell. TUTMAC is connection oriented: the bandwidth is allocated deploying constant bit-rate TDMA based data channels that are reserved by exchanging short control messages. The connection parameters can be dynamically altered during the data exchange session. Currently, a TUTWLAN prototype is being developed comprising both TUTMAC software and platform hardware modules. The prototype will support up to eight simultaneous data-transfer connections each having 64 to 512 kbit/s data transmission bandwidth.

TUTMAC: a medium access control protocol for a new multimedia wireless local area network

This paper presents three implementations of triple data encryption standard (3DES) algorithm on a configurable platform. Implementations are aimed at the medium access control (MAC) protocol of a multimedia-capable wireless local area network (WLAN). For this reason, very strict timing constraints as well as demands for area-efficiency are present. The MAC processing is handled by a digital signal processor (DSP) and a Xilinx Virtex field programmable gate array (FPGA) chip. The latter one is also used for the presented encryption implementations. As a result of the study, 3DES implementations with small area and reasonable throughput and, on the contrary, with large area and very high throughput are realized. Even though 3DES turns out to be quite large and resource-demanding, the implementations still leave enough chip area for the other MAC functions. Consequently, the set requirements are met and the cipher can be integrated into the system.

Configurable hardware implementation of triple-DES encryption algorithm for wireless local area network

This paper presents the design and implementation of a unique multi-radio Wireless Sensor Network (WSN) platform compared to current WSN nodes that have only one radio interface. Four independent, low energy radio transceivers allow simultaneous reception and transmission to either another multi-radio WSN node or up to four different WSN nodes. This also enables high interference tolerance, low latency, and high mesh-networking performance. The platform is based on synthesizable multi-processor System-on-Chip implementation on FPGA. The radios are compatible with ultra-low energy microcontroller based WSN nodes, which can be freely mixed in the network. The platform applicability is demonstrated by an ultra low latency WSN router and high data rate file transfer applications. Theoretical hop delay is as low as 106 µs, while 3.3 Mbps network throughput is achievable. Performance measurements for up to four parallel Nios II softcore processors are also presented.

Marko Hännikäinen

Papers

Precision Time Protocol Prototype on Wireless LAN

Cost-Aware Dynamic Routing Protocol for Wireless Sensor Networks - Design and Prototype Experiments

TUTMAC: a medium access control protocol for a new multimedia wireless local area network

Configurable hardware implementation of triple-DES encryption algorithm for wireless local area network

High-performance multi-radio WSN platform