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Emerging wireless communication services require the efficient use of available spectrum and improved co-existence of different standards placed in adjacent frequency bands. Co-existence with leakage from primary users in adjacent channels, which falls in the band of interest, is a primary concern for existing and emerging technologies. In this paper, a mixed signal IC technique based on direct sequence spread spectrum is proposed to improve co-existence of radar systems with commercial wireless communication systems. A sinusoid-like pseudo-random sequence is introduced to reduce leakage from radar systems into adjacent channels. The proposed approach reduces the radar signal leakage on adjacent channels by about 22dB when compared with the conventional binary pseudo-random sequence. The proposed technique randomizes narrow and wideband systematic in-band interference, after which interference power can be effectively attenuated through averaging techniques. Experimental results from a 40nm CMOS technology modulator/demodulator prototype demonstrates the feasibility of the proposed architecture. The modulator and demodulator system requires a silicon area of 0.0459mm2 and consumes 4.33mW in total. [ABSTRACT FROM AUTHOR]

Analog-to-digital and digital-to-analog conversion devices for signals with very large bandwidth are not always available due to technical or cost issues. This limits the realization of very high data-rate digital communication systems. In this paper, we propose a dual pulse shaping (DPS) transmission scheme, which can achieve full Nyquist rate transmission with only a half of the sampling rate for each of the two data streams. Two classes of ideal complementary Nyquist pulses are formulated assuming raised-cosine (RC) pulse shaping. The condition for cross-symbol interference (CSI) free transmission is derived and validated for the proposed pulses. Structures of the DPS transmitter and receiver are described and low-complexity equalization techniques tailored to DPS are proposed. With DPS, a millimeter wave system with commercially available and affordable data conversion devices is exemplified for achieving high-speed low-cost wireless communications. Simulation results with two sets of practical dual spectral shaping pulses are provided. The results verify the effectiveness of the proposed scheme, with comparison to the benchmark conventional Nyquist pulse shaping system. [ABSTRACT FROM AUTHOR]

This paper presents an analysis based on the impulse sensitivity function to precisely characterize and estimate the jitter caused by the common-mode interference (CMI). Unlike the conventional common-mode rejection ratio concept, the proposed method considers the CMI jitter in a transient rather than in an ac perspective. Inspired by the analytical results, we propose a clock receiver circuit (CRC) based on the self-bias amplifier topology. The accuracy of the analysis and the efficiency of the proposed CRC are verified both in simulations and measurements. A 1-GS/s ADC was fabricated in 65-nm CMOS containing simultaneously three CRCs, including an inverter-chain, a differential amplifier and the proposed structure, serving as the sampling clock. Both simulation and measurement results show a good agreement with the presented analysis. The proposed CRC achieves a 30-fsms jitter with a 620- \mu \textW power at 1.2 V supply. With a similar CMI rejection and random jitter performance, the proposed CRC exhibits a 20-fold power reduction when compared with the state-of-art designs. [ABSTRACT FROM PUBLISHER]

Owing to the emerging techniques such as heterogeneous network and cognitive radio that allow a large number of wireless networks to intensively and flexibly use resources of radio spectrum, the network densification and dynamic spectrum access have become two important trends of wireless networking systems, so that the spectral environments will be increasingly crowded in the near future. Under such a background, this study addresses the stability related problem of the power control in multiple coexisting wireless networks. We develop an analytical framework that is capable of utilizing the small-gain theorem to show the considered power control is bounded-input bounded-output (BIBO) stable in the sense of the \mathscr L2 gain if proper sufficient conditions are satisfied. Through modeling the power control as a feedback system and making use of the uncertainty representation, this framework can derive generalized results for the power-control algorithms that emerge in previous works. The framework developed in this study also admits the incorporation of multipath propagation that is a very common phenomenon in wireless communication systems. Within our derivation, making use of the theory for positive systems dramatically simplifies the analysis and leads to many refined results. [ABSTRACT FROM AUTHOR]