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It is well known that broadband wireless communications (BWC) are necessary for high speed vehicles since passengers need many broadband wireless multimedia services. However, one design challenge is to identify sufficient spectrum resource to support BWC in high speed vehicles. Recently, cognitive radios (CRs) are being considered as a promising technology to solve scarcity problem of spectrum resource...
The femtocell network is regarded as an effective approach to provide better services for indoor users with higher capacity. However, the spectrum allocation problem of the femtocell network is challenging for the wireless operator, since the added femtocell tier either requires additional spectrum resource or brings interference to the existing cellular network. In this paper, we consider the methods...
In this paper, we propose a novel scheme to improve the throughput of femtocell networks. The proposed scheme consists of two steps: spectrum allocation for femtocells and dealing with nearby macro-users with access control strategy. Since the positions of femtocells are relatively stable, we firstly deal with inter-femtocell interference and formulate it as an integer programming problem. Then we...
To improve the spectrum utilization, more and more attention was paid to OFDM based opportunistic spectrum access (OSA) systems in recent years. In this paper, to enable coexistence between a secondary user and a primary user, a novel method called EAIC was proposed for spectral sculpting of OFDM signal effectively. In EAIC, however, the cancellation signals cause self-interferences to OFDM data tones...
Coexistence of different users in cognitive radio (CR) network sharing the same frequency band can cause severe in-band interference. In this paper, we propose a novel scheme of joint interference estimation and decoding to combat the narrowband interference for OFDM-based (orthogonal frequency division multiplexing) CR systems in an iterative way. Moreover, we present some complexity reduction techniques...
To enable coexistence between an OFDM based opportunistic spectrum access system and a primary user, we proposed two novel methods called EAIC (Extended Active Interference Cancellation) and EAIC-H (EAIC-Hybrid) for spectral sculpting of OFDM signal. In EAIC and EAIC-H, cancellation signals are added to OFDM signal to cancel interference in target spectrum band caused by data tones, so that interference...
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