Hong-Chuan Yang

Joint Adaptive Modulation, Diversity Combining, and Power Control for Uplink Transmission in Two-cell Wireless Networks

We consider the joint application of power control, adaptive modulation and diversity combining in the uplink of a two-cell wireless network. The goal is to derive a practical low-complexity, bandwidth-efficient, and battery-power efficient transmission scheme addressing the particular challenges of uplink transmission. Employing dynamic spectral reuse, we allow for coordination of the transmit power levels to minimize the sum transmit power, and thus implicitly the interference to co-existing systems and cells. Based on assumed transmitter knowledge of the channel fading, the proposed schemes adaptively select the signal constellation. We show that the novel scheme provides significant average transmit power reductions, yielding a substantial increase of battery lifetime, and decreased interference, while maintaining high average spectral efficiency, and compliance with bit error rate constraints.

Order Statistics in Wireless Communications: Digital communications over fading channels

An implantable AM receiver having a variable threshold which can detect signals above a changing noise level. An AM receiver is provided which provides a modulation envelope corresponding to the amplitude of a pulse-modulated RF signal radiated by an external device. A voltage signal is developed which is at least equal to the amplitude of the modulation envelope, but which decays at a predetermined rate if the modulation envelope drops to a value below the voltage signal. The voltage signal is then scaled to a predetermined percentage of a value corresponding to the value of the modulation envelope, and biased so that it cannot drop below a predetermined minimum level. The scaled voltage signal comprises the variable threshold and is compared by a comparator to the modulation envelope. If it is below the modulation envelope, the comparator outputs a voltage having a first state; if it is above the modulation envelope, the comparator outputs a voltage having a second state.