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In the coexistence scenario of NB-IoT and LTE system, several factors affect the evaluating indicators of system performance. Considering the narrow bandwidth character of NB-IoT system, the simulation result would be over-optimistic if the evaluation method about ACLR and ACS in coexistence study of LTE system is still used. In this paper, a new evaluation method about ACLR and ACS is proposed aimed...
This paper proposes a resource allocation scheme for enhanced inter-cell interference coordination (eICIC) in heterogeneous networks. In the eICIC system, the macro eNBs will stop data transmission in almost blank subframes (ABSs), where the UEs in small cells can be protected. The proposed scheme takes into account both the number of the ABSs configured at the macro eNBs and the UE partition scheme...
A gain compensated op-amp for discrete-time ΣΔ modulators is described. The method greatly reduces the integrator's phase error caused by low DC gain on amplifiers. The scheme uses an additional unity gain buffer to correct the error caused by gains as low as 20 dB, thus enabling high-performance ΣΔ modulators in nanometer-scale CMOS technologies. Design strategies for op-amps and buffer designed...
This paper proposes a simple method of realization of center-frequency adaptive filters for high-accuracy detection of band-pass signals immersed in a broadband signal. Our method extends the conventional method proposed by Kumar and Pal. While the conventional center-frequency adaptive filters were mathematically difficult to describe in the case of high filter order, our method provides a simple...
To preserve the frame error rate (FER) of multimedia applications in the polling-based HCCA of 802.11e/a WLAN is important especially under low signal-to-noise ratio (SNR) conditions. MAC frame retransmission is an effective technique to reduce the FER, especially when there has no better modulation and coding scheme (MCS) can be selected. The Surplus Bandwidth Allowance (SBA) field in the Traffic...
OFDM is playing a more and more important role in wireless communication systems. Unfortunately, it is not trivial to conduct a performance analysis of OFDM systems. Therefore, it is highly desired to develop an analytical design and performance analysis framework for OFDM channels. In this paper, we consider a unified performance metric for OFDM channels, which we shall refer to as outage exponent...
In this paper, the outage performance is investigated for orthogonal frequency division multiplexing (OFDM)-based selective amplify-and-forward cooperative networks over independent but not identically distributed (i.n.i.d.) Nakagami-m fading channels, with integer values of parameter m. A unified closed-form expression for the outage probability is derived for three selective relaying schemes. The...
A wide-bandwidth low-power CT ΣΔ modulator with 10MHz signal bandwidth is implemented in TSMC 0.18 µm CMOS process in this paper. To realize such application scenario, the proposed modulator comprises a third-order active-RC loop filter and a 4-bit internal quantizer operating at 320 MHz clock frequency. To reduced clock jitter sensitivity, non-return-to-zero (NRZ) DAC pulse shaping is used. The excess...
Radar altimeter is applied to measure the height of an aircraft above the ground in terrain contour matching system(TERCOM). The total performance of the TERCOM is almost determined by the height-measuring algorithms embedded in the radar altimeter. When facing a complex terrain area with a large degree of fluctuation, the traditional radar altimetry height-measuring algorithm performance will be...
This paper describes the architecture for an adaptive multimodal RF sensor that is capable of both a wide and narrow field of view. The architecture consists of a test-bed that will enable the generation of linear frequency modulation waveforms of various bandwidths. This paper discusses the proposed architecture, multimodal algorithm and simulation results.
In this paper we proposed two extensions to the recently proposed Phase Forward (PF) relaying strategy for cooperative communication. One extension is the replacement of CPFSK modulation by the more practical Gaussian filtered minimum shift keying (GMSK) modulation scheme. The second extension is the incorporation of antenna selection at the relay. Semi-analytical expressions for the bit error probabilities...
Inter-cell Interference (ICI) is a key issue in orthogonal frequency-division multiple access (OFDMA) systems. Since OFDMA was proposed to be used in next generation networks several schemes have been investigated for mitigating the ICI. One of the techniques that promises improvement in reducing ICI is partial frequency reuse (PFR). In this paper we investigate a flexible bandwidth allocation (FBA)...
In this paper, we propose an RNS arithmetic based FH pattern design approach that is well suited and easy to implement for practical OFDMA systems. The proposed RNS aided FH scheme not only guarantees orthogonality among intra-cell users but also randomizes inter-cell interference. We present detailed construction procedures and performance analysis for both independent and cluster hopping scenarios...
A time-interleaved ADC system is an alternative choice to implement a high speed rate ADC with relatively low speed ADCs operating at interleaved sampling times. However, the system resolution always degrades due to mismatches such as offset, gain, bandwidth and timing mismatches between different ADC channels. Previous analyses showed these mismatch effects individually. This paper derives explicit...
The performance of non-data-aided feedback-loop symbol timing synchronization operating with the raised-cosine (RC) and the "better than" raised-cosine (BTRC) pulses is investigated. The individual effects of additive channel noise, self noise, and their product on the variance of the jitter are studied for the two pulses. The BTRC pulse is shown to have better synchronization performance...
An algorithm is presented for direct acquiring PRN code based on sub-sampling, utilizing the auto correlation characteristic of the long period PRN code in DSSS (direct sequence spread spectrum) system. As decreasing signal-to-noise, the performance of algorithm is analyzed, and it is proved effectively by simulation, under sub-sampling.
Using dasiabetter thanpsila Nyquist pulse the average bit error rate performance of a time-hopping pulse position modulation and TH-binary phase shift keying ultra-wideband systems has been evaluated in the presence of multiple access interference and additive white Gaussian noise for different system and pulse parameters such as repetition code length, roll-off factor and the symbol repetition rate...
In this paper, an energy efficient adaptive modulation scheme is proposed for a wireless cognitive radio ad hoc network, where each node is equipped with cognitive radio and the network is an OFDMA system operating on time slots. In each slot, the users with new traffic demand will sense the spectrum and locate the available subcarrier set. Then they choose subcarriers with favorable channel condition...
Spectrum sensing in the context of wireless microphone (WM) signals is considered in this paper. The spectrum sensing algorithm developed in this study makes use of the property that the bandwidth of the WM signal is narrow compared with the bandwidth of a digital television (DTV) channel. As a result, the power of the WM signal is highly concentrated in the frequency domain and there are apparent...
This paper describes a comparative analysis between two topologies of operational amplifiers to design a 40 MS/s 12-bit pipeline analog to digital converter (ADC). The analysis includes AC and transient simulation to select the proper topology. This ADC is implemented in a 0.35 mum AMS CMOS technology with 3.3 V single power supply. The capacitors and selected operational amplifiers were scaled for...
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