Abstract: Reducing the energy consumption is one of the main design goals of battery-operated wireless communication devices. Since the RF front-end energy consumption is significant, it is very important that it be included in the computation of the energy metric of these devices. In this dissertation, the energy consumed in the RF front-end is explicitly considered, and energy-saving policies that span the data link layer and physical layer are proposed. The first problem addressed is the development of an accurate and comprehensive energy model for each of the components in the analog front-end. The energy model was parameterized with respect to signal bandwidth, PAR, symbol rate, modulation level, signal center frequency, transmission distance, antenna gain, BER, pulse-shaping roll-off factor, data converter sampling frequency and thermal noise floor. This model is used to evaluate the energy consumption and communication quality of three representative systems: a single user point-to-point wireless data communication system, a multi-user CDMA based system and a receive-only video distribution system. For the single user system, the effect of occupied signal bandwidth, PAR, symbol rate, constellation size, and pulse-shaping filter roll-off factor is studied; for the CDMA based multi-user system, the effect of the number of users in the cell and the MAI along with PAR and filter roll-off factor is studied; for the receive-only system, the effect of 1/f noise and the IF frequency for low-IF architecture is studied. Next, the problem of designing energy-efficient wireless video transmission schemes is addressed. In these schemes, the effect of physical layer parameters, such as modulation level, bit rate and variation, BER and MAI, and link layer specifications, such as buffer status, idle and active time, on the RF circuit dissipation energy is considered. For the single user system, the Frame by Frame, the GOP by GOP, the CBEVT and the energy-efficient optimal smoothing schemes with different QoS performance, are proposed. Simulations results show that up to 53.24% energy-saving is achievable in the RF front-end through the CBEVT algorithm. For the CDMA based multi-user system, an RF front-end energy model under perfect power control is proposed and the corresponding MBEVT algorithm is presented. Simulation results show that this algorithm achieves up to 37.9% energy-saving for a 6-user CDMA system with an independent 16MB buffer for every uplink.