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OFDM signal classification has become an important requirement in many cognitive radios and military systems. Implementing such a requirement under Frequency Selective Rayleigh fading is a challenging task. In this paper, we explore different blind OFDM parameter and channel estimation techniques based on Maximum Likelihood techniques and higher order signal processing to ascertain the reception of...
In this work we present various blind algorithms for estimating signal parameters of unknown OFDM signal waveforms in frequency-selective Rayleigh channels. These algorithms are meant to alleviate some of the challenges facing unauthorized receivers and cognitive radios where many received signal parameters are unknown. Previously known single-symbol algorithms for Maximum Likelihood (ML) Timing and...
With the evolving of the network technology, the number of terminal equipping with multiple network interfaces keeps increasing because of the deploying of various access methods and the price descending of access devices. However, the terminals can not make full use of multiple interfaces concurrently in conversional network. In this paper, we motivate the advantages of simultaneously using multiple...
The distributed hash tables (DHTs) exhibit several interesting properties, such as self-configuration, self-maintenance, scalability and robustness that are clearly desirable for many kinds of applications in the Internet. However, Most of DHT approaches have high resolution latency because each lookup need contact several servers in sequence, typically O(log n) hops (n is the number of peers in the...
Deploying femtocell networks embedded in the Macrocell coverage greatly benefits communication quality in variety manners. However, the lack of schemes to effectively mitigate detractive interference, fully utilize radio resources and provide quality-of-service (QoS) guarantee (in terms of delay) creates challenges to practically facilitate the concept of femtocell. To tackle these challenges to achieve...
Cognitive radios (CRs) opportunistically sharing the wireless spectrum with the legacy primary system (PS) are promising to improve the spectrum utilization. However, this cognitive spectrum hole access makes the bandwidth of the cognitive radio network (CRN) formed by multiple CRs varies severely, which makes providing quality-of-service (QoS) guarantee over the CRN a very challenging task. Considering...
Accurate identification of Link4A is the premise of performing effective jamming. Based on instantaneous information identification algorithm, three key features, including two new ones, are extracted which are used to identify 2FSK modulation signal: the maximum value of the spectral power density of the normalized-centered instantaneous amplitude gammamax, the mean of the absolute value of instantaneous...
Timing and frequency offset estimation based on the second order cyclostationarity have been explored in many literatures. In this article, we revisit the class of these estimators and propose for both single carrier and OFDM systems, a new method for timing and frequency offset estimation. Different from the previous methods, here, the estimation of timing and frequency offset process are independent...
Cyclostationarity is a significant feature of numerous physical and man-made processes. Specially in wireless communications, it has been explored and applied for many processing, like timing and frequency synchronization, channel estimation, and modulation classification. In this paper, we notice that the second order time varying auto-correlation of the received communication signal contains a cyclostationary...
In this paper, a wide-range operation and phase error calibration DLL-based clock generator is proposed. By using multi-band voltage controlled delay line (MBVCDL) and frequency multiplier to expand the operation frequency range of clock generator. The proposed clock generator uses detect window phase detector (DWPD) to effectively reduce phase error. The proposed DLL can reduce the maximum phase...
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