A kind of hidden terminal problem, called the POINT problem, which is caused by the expansion of the interference range of the receiver due to the controlled transmission power of the sender, is deemed a notorious problem in wireless ad hoc networks. This paper utilizes physical and virtual carrier-sensing schemes to avoid the POINT problem. We analyze the relationships among the transmission range, the carrier-sensing range, and the interference range in case power control is adopted, and based on the analyzed results, we propose four mechanisms to prevent the POINT problem from occurring in wireless ad hoc networks. This paper further analyzes the superiority of each mechanism under certain situations and proposes an adaptive range-based power control (ARPC) MAC protocol to make use of the advantages of the four mechanisms to avoid the POINT problem from happening. The proposed protocol cannot only prevent collisions caused by the POINT problem, but it can also reduce the energy consumption of STAs. Simulation results also verify the advantages of the proposed protocol.

In IEEE 802.11 standard, the use of multi-channel is one of the most important characteristic features contributing to the improvement of the overall network throughput. However, the channel utilization based on the use of multi-channel is relatively low because most medium access control (MAC) protocols were designed based primarily on the application of non-overlapping channels. This paper analyzes the channel utilization for the schemes using both non-overlapping and overlapping channels. Based on the analysis, we propose a scheme to exploit overlapping channels with collision avoidance mechanism. The proposed scheme makes use of the non-overlapping channels to increase the network throughput and it also takes into account the transmissions on different channels in order to maximize the throughput. Simulation results verify the effectiveness of the proposed scheme.

The paper proposes a multi-rate supported power control, named MRPC, MAC protocol to avoid the LIRC (Large Interference Range Collision) problem for wireless ad hoc networks. The main concept of the MRPC protocol is to protect the current reception by means of the carrier-sensing range of the previous transmission to cover the induced interference range of the current reception. Based on the concept, MRPC formulates the requirements of a successful transmission and figures out the appropriate power strength for transmissions. Furthermore, since the threshold values of SNR and receiver sensitivity values are changed with the data transfer rates, MRPC also takes the different threshold values in multi-rate environments into consideration in formulating these requirements. MRPC can reduce the energy consumption and increase the spatial reuse due to the controlled transmission power. It is further shown that MRPC can also work correctly in multi-rate environments. Simulation results show that MRPC performs much better than the related work in terms of network throughput as well as the energy efficiency.

Resolving hidden terminal problem is one of the major responsibilities in designing MAC protocols for wireless ad hoc networks. The paper proposes a fragmentation-based MAC protocol with power control, named F-RCRC MAC protocol, to avoid the LIRC (large interference range collision) problem, a kind of hidden terminal problem, for wireless ad hoc networks. F-RCRC designs a new interframe space, named FIFS, to reduce the overhead caused by the fragmentation scheme. With the fragmentation, the design of FIFS can effectively avoid the hidden STAs interfering with the receivers' receiving. Moreover, a dynamic transmission power scheme is devised to actively and timely warn the hidden STAs such that the possible collision is avoided. Thus, the LIRC problem can be solved and the network throughput is increased accordingly. In addition, F-RCRC can reduce the energy consumption and increase the spatial reuse due to the controlled transmission power. Simulation results show that F-RCRC performs much better than the related work in terms of network throughput as well as the power throughput.

The paper analyzes the relationships among the transmission range, carrier sensing range, and interference range in case that power control is adopted and proposes an adaptive range-based power control (ARPC) MAC protocol for wireless ad hoc networks to avoid collisions. Based on the analysis results, four mechanisms, STRC, RTRC, SCRC, and RCRC are proposed to prevent from collisions. The paper further analyzes the superiority of each mechanism under certain situations and proposes the ARPC MAC protocol to make use of the advantages of the four mechanisms to avoid collisions. The proposed protocol can not only reduce energy consumption of STAs, but also prevent from collisions. Simulation results also verify the advantages of the proposed protocol.

Event detection and tracking are attractive research issues in the wireless sensor network (WSN). The paper proposes a fully distributed protocol, CollECT, to event detection and tracking in a Wireless Heterogeneous Sensor Network (WHSN), composed of many kinds of sensors. In CollECT, three major procedures, vicinity triangulation, event determination, and border sensor selection are used to construct the logical triangle in the vicinity of a sensor, to determine the event, and to select the border sensor to identify the event boundary, respectively. The procedures perform repeatedly to both detect and track events. Simulation results demonstrate that CollECT is promising for event detection and tracking due to satisfactory event accuracy and reasonable fitness of border sensors.