Transmitter Transmission Research Articles

On Exploiting Concurrent Transmissions Through Discernible Interference Cancellation

This paper represents the design, feasibility evaluation, and performance validation of ICMR, a novel cross layer protocol that can maximize concurrent transmissions and avoid data frame interference in wireless networks, achieving a higher throughput comparing with the 802.11 standard and other state-of-the-art protocols. Observations on the 802.11 standard reveal that nodes around both the transmitter and receiver of the ongoing link waste concurrent transmission opportunities, degrading the network throughput dramatically. A state-of-the-art protocol IRMA is proposed to improve the network throughput through exploiting concurrent transmissions at the transmitter side. In this paper, a new ICMR protocol focuses on the receiver side to further improve the network throughput, through exploiting discernible interference cancellation, a physical layer mechanism that can successfully detect data frames when collided by control frames. We analyze the concurrent transmission opportunities of one link from the transmitter's transmission opportunities and the receiver's reception opportunities, then formulate the opportunities and give theoretical analysis to indicate that ICMR will have a higher opportunity over other protocols. Feasibility of the discernible interference cancellation mechanism is demonstrated through experiment results based on USRP2, and the throughput improvement of ICMR comparing with the other protocols is confirmed through simulations based on ns-2.

A Relay-Aided Transmission Power Control Method in Wireless Body Area Networks

Reliability is one of the most important communication metrics in wireless body area networks especially for medical applications. However, traditional one-hop transmission power control methods failed to guarantee the reliability when the transmission distance is large. Two-hop relaying transmission can provide reliable transmission but energy consumptions for relay nodes are high resulting in the reduction of network lifetime. In this paper, a relay-aided transmission power control method is proposed to provide reliable transmission and at the same time alleviate the relaying burden on relay nodes. The proposed method automatically switches transmitter's transmission strategy between the direct transmission and the relay-aided transmission based on the channel condition to address long distance problem and then adaptively adjusts the transmission power according to the received signal strength indicator feedback to guarantee the reliable transmission and conserve the energy of relay nodes as much as possible. In addition, parameters in the proposed method are tunable according to the application scenarios to make tradeoff between reliability and energy efficiency. The simulation results demonstrate that the proposed method can effectively guarantee the transmission reliability and conserve the energy of relay nodes, which in turn prolongs the network lifetime.

Cooperative Spectrum Sharing With Bidirectional Secondary Transmissions

Existing cooperative spectrum-sharing protocols either separate the primary and the secondary transmissions or allow the secondary user (SU) to transmit only in the time slot when it is relaying the primary user's signal. In this paper, we propose a new cooperative spectrum-sharing protocol that multiplexes the secondary transmissions with both the primary and the relay transmissions. This way, a pair of SUs can bidirectionally communicate with each other while one of them is serving as a relay to assist in the transmission from the primary transmitter to the primary receiver. Specifically, the transmission is on a two-time-slot basis. In the first time slot, in addition to the primary transmitter's transmission, the SU who does not act as the relay also transmits. In the second time slot, the SU who acts as the relay will split its power to relay the primary signal to the primary receiver while transmitting its own signal to the other SU. In particular, it is considered that the relay SU is equipped with multiple antennas, while all the other terminals have a single antenna each. Based on the proposed protocol, we consider two decode-and-forward (DF) schemes and one amplify-and-forward (AF) scheme. We evaluate the achievable rate regions of the rate of the primary link versus the sum rate of the secondary links of the proposed schemes. The Pareto boundary of the achievable rate region is found by optimizing the transmit power, the beamforming vectors, and the power splitting factor at different nodes to maximize the sum rate of the secondary links for a given rate of the primary link. It is demonstrated through numerical results that our proposed bidirectional protocol allows the SUs to utilize the spectrum in a more efficient way without sacrificing the primary link's rate, as compared with the existing one-directional scheme in the literature.

Joint Algorithm of Channel Allocation and Power Control in Multi-channel Wireless Sensor Network

In the wireless sensor network, the interference incurred by another transmitter's transmission may disturb other receivers' correct receptions of packets, thus, the add of a new transmission must consider its effect on other transmissions. Additionally, in order to reduce the interference and increase QoS, multi-channel technology is introduced into wireless communication, but the energy cost by the channel switch increases with the interval of channels increasing. Based on the above analysis, we consider an energy efficient joint algorithm of channel allocation and power control (JCAPC) for wireless sensor network. In JCAPC, each link firstly establishes its available channel set on which the transmitter of the link can guarantee its transmission successfully and don't disturb other receivers' transmissions, and then each link chooses a channel from the available channel set according to the energy cost on anti-interference and channel switch. After that, we formulate power control on each channel as a non-cooperative game with utility function including Signal-to-Interference-and-Noise Ratio (SINR) price. In order to reduce the energy cost of the information exchange during the traditional game, we introduce the thought of game virtual playing, in which each link can decide its own transmission power by imitating the game among links with its once collected information. Consequently, JCAPC can not only increase the transmission efficiency but also reduce the nodes' energy waste. Moreover, the existence of Nash Equilibrium (NE) is proven based on super-modular game theory, and it's able to obtain the unique NE by relating this algorithm to myopic best response updates. The introduction of game virtual playing saves the energy cost of network further more by reducing the number of information exchange. Simulation results show that our algorithm can select a channel with good QoS using less energy consumption and provide adequate SINR with less transmit power, which achieves the goal of efficiently reducing energy waste.