This paper presents the design, fabrication, and experimental evaluation of a prototype lead zirconium titanate (PZT) matrix transducer with an integrated receive ASIC, as a proof of concept for a miniature three-dimensional (3-D) transesophageal echocardiography (TEE) probe. It consists of an array of 9 × 12 piezoelectric elements mounted on the ASIC via an integration scheme that involves direct electrical connections between a bond-pad array on the ASIC and the transducer elements. The ASIC addresses the critical challenge of reducing cable count, and includes front-end amplifiers with adjustable gains and microbeamformer circuits that locally process and combine echo signals received by the elements of each 3 × 3 subarray. Thus, an order-of-magnitude reduction in the number of receive channels is achieved. Dedicated circuit techniques are employed to meet the strict space and power constraints of TEE probes. The ASIC has been fabricated in a standard 0.18-μm CMOS process and consumes only 0.44 mW/channel. The prototype has been acoustically characterized in a water tank. The ASIC allows the array to be presteered across ±37° while achieving an overall dynamic range of 77 dB. Both the measured characteristics of the individual transducer elements and the performance of the ASIC are in good agreement with expectations, demonstrating the effectiveness of the proposed techniques.@en

The Current system design of mobile ad hoc networks (MANET), derived from their traditional fixed counterparts, cannot fully meet the requirements inherent to the dynamic nature of such networks. Cross-layer (CL) designs, a modification of the classic protocol stack, are envisioned as a solution for this problem. Many CL design approaches are proposed, each for a different optimization purpose. Mobile terminals require a variety of optimizations that can be provided only by using different CL designs. Consequently, the coexistence and interaction of such designs needs attention. The lack of common interface and infrastructure among different CL designs, however, makes their interaction a significant problem. The proposed common interaction infrastructure is able to compensate for the negative effects introduced by particular CL design by using runtime information from all CL implementations involved in the system. This paper first presents an analysis of the weaknesses of standalone CL designs. Furthermore, this paper introduces a novel architecture to ensure optimal interaction of multiple CL designs according to different QoS requirements. A piggybacked signaling protocol using XML based internal messaging format is introduced. The proposed architecture and three CL designs were simulated for various network scenarios and compared in terms of delay and network efficiency (using the throughput percentage). The results show that the performance with the interaction framework is averagely within 3% to that of the best individual case and maybe up to 4.5% better. In addition, the QoS requirements are always respected.@en