Abstract-A 43-GHz wireless inter-chip data link including antennas, transmitters, and receivers is presented. The industry standard bonding wires are exploited to provide high efficiency and low-cost antennas. This type of antennas can provide an efficient horizontal communication which is hard to achieve using conventional on-chip antennas. The system uses binary amplitude shift keying (ASK) modulation to keep the design compact and power efficient. The transmitter includes a differential to single-ended modulator and a two-stage power amplifier (PA). The receiver includes a low-noise amplifier (LNA), pre-amplifiers, envelope detectors (ED), a variable gain amplifier (VGA), and a comparator. The chip is fabricated in 180-nm SiGe BiCMOS technology. With power-efficient transceivers and low-cost high-performance antennas, the implemented inter-chip link achieves bit-error rate (BER) around 10 8 for 6 Gb/s over a distance of 2 cm. The signal-to-noise ratio (SNR) of the recovered signal is about 24 dB with 18 ps of rms jitter. The transmitter and receiver consume 57 mW and 60 mW, respectively, including buffers. The bit energy efficiency excluding test buffers is 17 pJ/bit. The presented work shows the feasibility of a low power high data rate wireless inter-chip data link and wireless heterogeneous multi-chip networks.Index Terms-Bond-wire antenna, high-speed link, on-chip antenna, wirebond antenna, wireless inter-chip link, wireless transceiver.

Abstract-Energy conservation is essential in wireless sensor networks (WSNs) because of limited energy in nodes' batteries. Collaborative beamforming uses multiple transmitters to form antenna arrays; the electromagnetic waves from these antenna arrays can create constructive interferences at the receiver and increase the transmission distance. Each transmitter can use lower power and save energy, since the energy consumption is spread over multiple transmitters. However, if the same nodes are always used, these nodes would deplete their energy much sooner and this sensing area will no longer be monitored. To avoid this situation, energy consumption for collaborative beamforming needs to be balanced over the whole network by assigning the transmitters in turns. The transmitters in each round are selected by a scheduler and the energy carried in each node is balanced to increase the number of transmissions. The lifetime of a network is the number of transmissions until a certain percentage of the nodes depletes their energy. This paper proposes an algorithm to calculate energy-efficient schedules based on the remaining energy and the phase differences of their signals arriving at the receiver. Compared with an existing algorithm, our algorithm can extend the network lifetime by more than 60%.

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A fast and power efficient phase difference and frequency offset estimation technique for collaborative beamforming in a wireless sensor network is presented. Common radio blocks are used to implement the phase difference estimation technique and we present an analytical expression for the phase difference estimation accuracy in an AWGN channel. The analysis including the effect of noise and multipath on the estimation accuracy shows the effectiveness of the proposed estimation technique for collaborative beamforming applications.

Collaborative beamforming (CB) is an energy efficient transmission scheme in wireless sensor networks (WSNs).Despite the promising aspects of CB, its practical implementation remains largely unexplored and the challenges, namely frequency, phase, and data synchronization, must be addressed for successful deployment. We propose a CB protocol with a compatible transceiver architecture. The protocol uses a phaselocked loop (PLL) continuously operating in closed-loop for frequency synchronization, a local two-way phase estimation and remote one-way calibration technique for phase synchronization, and a data entrainment technique to achieve data synchronization with minimal data traffic. The efficiency analysis including carrier jitter demonstrates the feasibility of the proposed CB protocol.