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In this paper, we report on a mobile broadband wireless access (MBWA) system field trial with Fast Low-latency Access with Seamless Handoff Orthogonal Frequency Division Multiplexing (FLASH-OFDM), which was carried out at Sendai city in Japan. This paper describes coverage estimates of an downlink 64 quadrature amplitude modulation (QAM) signal under the condition of constant base-station output power...
In this paper, we propose the Nash bargaining solution for the interference problem in cellular networks. The base-stations of neighboring cells negotiate with each other to determine the best number of channels that should be allocated to their edge users. While cells optimize the allocated resources on a local level, the bargaining process acts as a common framework that combines the optimization...
The present article describes the experimental result of victim system detection by UWB wireless system to contribute for Japanese UWB regulatory discussion, in which a mitigation, including detect-and-avoid (DAA), technology implementation in the frequency range of 3.4 to 4.8 GHz is a major technical topic. A FPGA based MB-OFDM UWB receiver with 528 MHz sampling rate and 128 points FFT capability...
In this paper, we propose a subcarrier suppressed transmission scheme that improves the frequency utilization efficiency of STICS (Satellite/Terrestrial Integrated Mobile Communication System), which shares the same frequency band between satellite and land mobile systems. Applying our proposal to the OFDM-based land system overcomes the resource assignment limits of the frequency sharing scheme and...
OFDMA is the preferred multiple access technique to provide high data rate services in mobile environment due its resilience against multipath propagation impairment and flexibility to provide multi-rate data services. However, it also has issue with susceptibility to ICI (inter-carrier interference) caused by frequency offset and Doppler spread due to mobility. Thus, OFDMA with certain number of...
In these theses in common considered objectives of development of the LTE standard and also the advantages of application of this technology, meeting requirements of subscribers and operators of services. The article describe OFDM technology and possibilities of 3GPP standard.
Orthogonal frequency division multiple access (OFDMA) has been adopted by all the proposals which have been considered for the fourth generation (4G) wireless technologies. Specifically, the two main contenders in the 4G marketplace are likely to be evolutions of WiMAX and LTE. In this work, we compare the use of OFDMA in these standards.
This paper presents a novel multiple access scheme for uplink of future mobile communications using MultiSymbol Encapsulated Orthogonal Frequency Division Multiplexing (MSE-OFDM). MSE-OFDM is a bandwidth efficient OFDM scheme, where a number of OFDM symbols are grouped together as a frame and protected by one single cyclic prefix (CP). This reduces the extent of redundancy caused by the CP and increases...
A growing number of mobile WiMAX deployments are in progress world-wide and the technology is anticipated to play a key role in next generation mobile broadband wireless networks. However, although the theoretical potential of WiMAX technologies is already well established, independent, publicly released, thorough evaluations of WiMAX network performance in the real world are yet to become available...
This paper presents the results of an experimental work where coherence bandwidth of an urban environment was measured in order to estimate the delay spread of this channel. An OFDM mobile communication system was assembled and the level of the pilot carriers was individually measured to produce the coherence bandwidth. The results have shown the expected difference between the delay spread on line-of-sight...
In this paper, a distributed mobile relay power control (DMRPC) scheme for maximizing individual cell throughput is proposed for mobile relay station (MRS) aided system. In the system with DMRPC, the power levels of MRSs are controlled by individual cell without cell cooperation and signaling overhead, and the appropriate power levels of MRSs are selected to maximize the cell throughput of their individual...
This paper presents the interference of ultra wide-band (UWB) sensor applied in Korea into wireless broad-band (WiBro) system based on orthogonal frequency division multiplexing (OFDM) using frequency of 2.3 GHz. The minimum coupling loss (MCL) method and spectrum engineering advanced Monte Carlo analysis tool (SEAMCAT) are used to evaluate the interference effects of UWB sensor on WiBro. The required...
This paper discusses an interference DAA (Detection And Avoidance) technique for coexisting pulse based UWB and OFDM systems when the both systems are operated in the same frequency band. In a UWB transmitter-receiver, utilization of the OFDM system is detected by correlating with the GI (Guard Interval) signals. And also timing of the GI period is detected for interference mitigation. The UWB signal...
In this paper we determine the optimal fractional frequency reuse (FFR) and resource allocation in OFDMA system. Since the users at the cell edge are more exposed to inter-cell interference therefore each cell is partitioned into two regions; inner region and outer region. We determine the optimal FFR factor for the outer region, bandwidth assigned to each region and subcarrier and power allocation...
This article addresses downlink resource allocation in multi-cell OFDMA mobile WiMAX systems using zone switching diversity method. We propose to use fractional frequency reuse for guaranteeing the quality of service for different service flows (SFs) in the system. Our approach includes an architecture which coordinates the allocation of resources in terms of slots (the basic allocation unit in time...
In this paper, the channel estimation methods to resolve the error floor for SUI-5 channel are investigated. Since the pilot allocation is solid with the FUSC model, only we can do is to incorporate two OFDM symbols to estimation the channel response, and it can improve the channel estimation performance, but it canpsilat cancel the error floor exhaustively. So we combine the preamble and pilot carrier...
Non-contiguous orthogonal frequency division multiplexing (NC-OFDM) system is used in the wide-band communications, especially for the wide-band cognitive radio, e. g., IEEE 802.22. However, in the high speed mobile environment, NC-OFDM suffers from inter-carrier interference (ICI). Due to the non-uniformed Doppler spread in the wide-band, it is not efficient to use the traditional ICI cancelation...
In this paper we study the capacity of the OFDMA- based IEEE802.16 WiMAX network in the presence of two types of traffic: real-time and non-real-time, including adaptive modulation and coding (AMC) with user intra cell mobility. Our work deals with the performance of the connexion admission and resource allocation algorithm over a general ranging arrival process: it has been recently proved that the...
The frequency synchronization issue of multiuser in the uplink of an orthogonal frequency-division multiple-access (OFDMA) system is investigated in this letter. We develop a subspace based blind carrier frequency offsets (CFOs) estimation algorithm for the base station (BS) equipped with uniform linear array (ULA). Due to the adoption of ULA at the BS and the narrowband signal assumption, CFOs of...
A new cognitive mobile communication system (CCMCS) is proposed in this paper, which can utilize the unlicensed frequency sufficiently, protect the investment of networks existed and support its evolution. Through the effective application of variable-band OFDM and multiband OFDM, the system can connect several narrow bands into a wideband, and support high speed data transmit. Synchronization to...
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