Performance and flexibility of mobile radio systems essentially depend on the choice of the multiple access scheme. The novel MC-CDMA scheme which is the topic of this thesis is a promising alternative to conventional FDMA, TDMA, and CDMA schemes. With MC-CDMA, each data modulated chip of the user specific spreading code is mapped onto a separate subcarrier, so that the chips of the spreading c...

Radio Frequency Identification (RFID) system allows automatic identification of items with RFID tags using radio-waves. As the RFID tag has its unique identification number, it is also possible to detect a specific region where the RFID tag lies in. Recently it is widely been used in mobile robot navigation, localization, and mapping both in indoor and outdoor environment. This paper represents...

Abstract— In this paper, we propose the introduction of space diversity techniques to the code acquisition of an indoor packet radio communication system with directsequence spread-spectrum technique. In the proposed scheme, the base station has several radio ports each with a cluster of antennas, and the mobile station also has multiple antennas. As the result, we show great performance improv...

MIMO and relay technology is currently being promoted within the IEEE to enhance performance of broadband wireless standards such as WiMAX. However, due to licensed spectrum, it is necessary to implement highly efficient radio resource management. For optimal system design, it is beneficial to achieve higher system data throughput with fewer radio resources employed. This paper presents a compr...

We deal with the problem of frequency assignment in mobile and general radio networks, where the signal interferences are modeled using an interference graph G. Our approach uses graph theoretic and optimization techniques. We rst study on-line algorithms for frequency assignment in mobile networks. We prove that the greedy algorithm is-competitive, where is the maximum degree of G. We next emp...

Partially, the future of mobile and cellular networks will be about energy consumption savings, at the network infrastructure side. In the heterogeneous cellular networks environment, these can be achieved based on bandwidth adaptation, discontinuous transmission, relays, or even Base Stations (BSs) shutdown when possible. This paper proposes an approach for power savings using Vertical Handove...

Traffic loads and local user densities in mobile radio networks vary, resulting in temporarily overloaded cells. To reduce their call or handover blocking rates, three basic methods of balancing the spatial traffic load are presented. The key principle is to modify the coverage area of radio cells: Adapting the handover hysteresis, a threshold used at call setup, that balances the reception pow...

The position of a mobile phone can be located using information from the radio network it uses. This paper presents two applications that make use of Wireless Application Protocol (WAP) and mobile positioning technology to provide location-based information to the user in real time. The applications use the user’s position to generate dynamic information. Besides, both applications also have a ...

The authors have been developing the mobile robots which can cooperation between robots. The robots should communicate with each other in order to cooperate together. Therefore, the inter communication between robots is very important problem to be solved. These robots generally utilize wireless transmission system. The transmission sets send and receive on the same frequency or channel to esta...