{"id":5399,"date":"2012-07-18T22:28:42","date_gmt":"2012-07-18T22:28:42","guid":{"rendered":"https:\/\/mtlsites.mit.edu\/annual_reports\/2012\/?p=5399"},"modified":"2012-07-18T22:28:42","modified_gmt":"2012-07-18T22:28:42","slug":"an-ultra-low-power-ism-band-transmitter-with-tunable-channel-network-coding","status":"publish","type":"post","link":"https:\/\/mtlsites.mit.edu\/annual_reports\/2012\/an-ultra-low-power-ism-band-transmitter-with-tunable-channel-network-coding\/","title":{"rendered":"An Ultra-low-power ISM-band Transmitter with Tunable Channel-Network Coding"},"content":{"rendered":"
Designing a low-power wireless communication system involves two major milestones: use of very efficient RF architectures, including circuits for power amplifiers, mixers, etc., as well as employing the appropriate protocol-level algorithms, such as forward error correction (FEC) codes, CRCs, etc. Although these two steps are usually performed in isolation, the result has been extremely successful for designing efficient long-distance communication systems. However, this approach is highly suboptimal for short-range communication systems (i.e., Body Area Networks), where the power consumption of these two components can be comparable [1<\/a>] <\/sup>. For this reason, very careful, system-level analysis is required to achieve the minimum energy consumption in transmitting the required information.<\/p>\n We have designed a flexible, ultra-low-power ISM-band transmitter, including baseband processing and basic protocol functionality (i.e., packetization, CRC calculation), using a 65-nm TSMC process. The simplistic block diagram of the transmitter is shown in Figure 1. The fabricated chip includes four memory banks to store incoming data, a tunable convolutional encoder optimized for short-distance RF modules, and an RF transmitter that utilizes a high-Q FBAR resonator as a local oscillator [2<\/a>] <\/sup>. The transmitter has an output power of ~-10dBm and supports 1Mbps OOK and FSK modulation.\u00a0 An on-chip FIR filter implements Gaussian pulse shaping for GFSK modulation. In addition to the FEC code, the transmitter has a dedicated accelerator implementing a new form of coding, called network coding (NC) [3<\/a>] <\/sup>, which can increase the reliability of the communication system under challenged channel conditions and potentially reduce the required amount of energy communicating information.<\/p>\n