This paper proposes an iterative cancellation technique for adjacent channel interference (ACI), induced by amplifier nonlinearity in millimeter wave (mmW) communication systems. In mmW communications, a large spectrum leak is expected because of the amplifier nonlinearity, and such a spectrum leak disturbs multichannel utilization. In order to mitigate the ACI, iterative interference cancellation in the receiver side is designed in this paper. Typically, iterative interference cancellation is conducted by generating a soft replica of interference from the feedback of the decoder, and subtracting the replica from the received signals. In this case, the canceller must know the amplifier nonlinearity in order to regenerate a soft replica of ACI. In this paper, amplifier nonlinearity is estimated by subjecting the received pilot signals to polynomial regression. We reveal that using only pilot signals in estimating amplifier nonlinearity is insufficient for guaranteeing replica accuracy. To address this issue, the proposed scheme exploits the detected data sequence in the regression analysis. We demonstrate that the proposed ACI cancellation technique can effectively mitigate ACI in multichannel utilization.

We discuss the division of radio resources in the time and frequency domains for wireless local area network (WLAN) devices powered with microwave energy. In general, there are two ways to avoid microwave power transmission (MPT) from influencing data communications: adjacent channel operation of continuous MPT and WLAN data transmission and co-channel operation of intermittent MPT and WLAN data transmission. Experimental results reveal that, even when we implement these methods, several problems arise because WLAN devices have been developed without supposing the existence of MPT. One problem clarified in our experiment is that adjacent channel operation at 2.4GHz does not necessarily perform well owing to the interference from MPT. This interference occurs regardless of the frequency separation at 2.4GHz. The other problem is that intermittent MPT could result in throughput degradation owing to the data rate control algorithm and the association scheme of the WLAN. In addition, the experimental results imply that a microwave energy source and a WLAN device should share information on the timings of intermittent MPT and data transmission to avoid buffer overflow.

An OFDMA-based (Orthogonal Frequency Division Multiple Access-based) channel access scheme for dynamic spectrum access has the drawbacks of large PAPR (Peak to Average Power Ratio) and large ACI (Adjacent Channel Interference). To solve these problems, a flexible channel access scheme using an overlap FFT filter-bank was proposed based on single carrier modulation for dynamic spectrum access. In order to apply the overlap FFT filter-bank for dynamic spectrum access, it is necessary to clarify the performance of the overlap FFT filter-bank according to the design parameters since its frequency characteristics are critical for dynamic spectrum access applications. This paper analyzes the overlap FFT filter-bank and evaluates its performance such as frequency characteristics and ACI performance according to the design parameters.

In this paper, we analyze the coexistence issues of M-WiMAX TDD and WCDMA FDD systems. Smart antenna techniques are applied to mitigate the performance loss induced by adjacent channel interference (ACI) in the scenarios where performance is heavily degraded. In addition, an ACI model is proposed to capture the effect of transmit beamforming at the M-WiMAX base station. Furthermore, a MCS-based throughput analysis is proposed, to jointly consider the effects of ACI, system packet error rate requirement, and the available modulation and coding schemes, which is not possible by using the conventional Shannon equation based analysis. From the results, we find that the proposed MCS-based analysis method is quite suitable to analyze the system theoretical throughput in a practical manner.

An exact expression of error rate is developed for maximal ratio combining (MRC) in an independent but not necessarily identically distributed frequency selective Nakagami fading channel taking into account inter-symbol, co-channel and adjacent channel interferences (ISI, CCI and ACI respectively). The characteristic function (CF) method is adopted. While accurate analysis of MRC performance cannot be seen in frequency selective channel taking ISI (and CCI) into account, such analysis for ACI has not been addressed yet. The general analysis presented in this paper solves a problem of past and present interest, which has so far been studied either approximately or in simulations. The exact method presented also lets us obtain an approximate error rate expression based on Gaussian approximation (GA) of the interferences. It is shown, especially while the channel is lightly faded, has fewer multipath components and a decaying delay profile, the GA may be substantially inaccurate at high signal-to-noise ratio. However, the exact results also reveal an important finding that there is a range of parameters where the simpler GA is reasonably accurate and hence, we don't have to go for more involved exact expression.

In this paper an adjacent channel interference (ACI) cancellation scheme with undersampling for multi-channel reception is proposed and investigated. Low-IF receiver architecture is used in the multi-channel reception scheme. In this system, signal in the adjacent channel causes interference to the desired signal. The ACI cancellation scheme with analog filter bank has been proposed to mitigate the influence from the adjacent channel [10]. Undersampling technique is applied in this system in order to lower the required sampling frequency and power consumption. The effects of the adjacent channel to the undersampling technique in this scheme is examined and discussed.

In this paper a new adjacent channel interference (ACI) cancellation scheme for multi-channel signal reception with low-IF receivers is investigated through the experiment. In the low-IF receivers, the signal in the mirror frequency causes interference to the desired signal. In the proposed analog-digital signal processing scheme, channel selection is made by analog complex band pass filter and the signal is reconstruct by Wiener filter to eliminate the interference effect in order to improve the performance.

A novel reconfigurable architecture has been proposed for a mobile terminal receiver that can drastically reduce power dissipation dependant on adjacent channel interference. The proposed design can automatically scale the number of filter coefficients and word length respectively by monitoring the in-band and out-of-band powers. The new architecture performance was evaluated in a simulation UTRA-TDD environment because of the large near far problem caused by adjacent channel interference from adjacent mobiles and base stations. The UTRA-TDD downlink mode was examined statistically and results show that the reconfigurable architectures can save an average of up to 75% power dissipation respectively when compared to a fixed filter length of 57 and word length of 16 bits. This power saving only applies to the filter and ADC, not the whole receiver. This will prolong talk and standby time in a mobile terminal. The average number of taps and bits were calculated to be 14.98 and 10 respectively, for an outage of 97%.

While higher chip rate can provide better performance for Direct Sequence/Code Division Multiple Access (DS/CDMA) systems due to larger process gain, it may also induce spectrum emission to adjacent channels, i. e. , adjacent channel interference. Especially, if different operators use adjacent channels in the same area with uncoordinated power levels, such interference becomes large, and excessively higher chip rate will decrease the efficiency of a system. In this context, this paper evaluates the relation between chip rate and capacity in DS/CDMA cellular communication systems considering adjacent channel interference from other systems. First, the classification of adjacent channel interference between two independent DS/CDMA systems is described, and the concrete interference levels are calculated for several chip rates. Then, by using computer simulation, the system CDMA capacity is evaluated under adjacent channel interference. From these results, we can find that the excessively higher chip rate can not always provide the larger system CDMA capacity in spite of the larger process gain, and there exists the appropriate chip rate for a certain given bandwidth.