A Power Saving MAC Protocol by Increasing Spatial Reuse for IEEE 802.11 Ad Hoc WLANs

[[abstract]]Scarce resources of wireless medium (e.g., bandwidth, battery power, and so on) significantly restrict the progress of wireless local area networks (WLANs). Heavy traffic load and high station density are most likely to incur collisions, and further consume bandwidth and energy. In this paper, a distributed power-saving protocol, power-efficient MAC protocol (PEM), to avoid collisions and to save energy is proposed. PEM takes advantage of power control technique to reduce the interferences among transmission pairs and increase the spatial reuse of WLANs. Based on the concept of maximum independent set (MIS), a novel heuristic scheme with the aid of interference relationship is proposed to provide as many simultaneous transmission pairs as possible. In PEM, all stations know when to wake up and when they can enter doze state. Thus, stations need not waste power to idle listen and can save much power. The network bandwidth can be efficiently utilized as well. To verify the performance of PEM, a lot of simulations are performed. The experimental results show that with the property of spatial reuse, PEM not only reduces power consumption, but also leads to higher network throughput in comparison with the existing work, such as DCF, DCS, and DPSM.[[sponsorship]]IEEE Computer Society Technical Committee on Distributed Processing (TCDP); Tamkung University[[conferencetype]]國際[[conferencetkucampus]]淡水校園[[conferencedate]]20050328~20050330[[iscallforpapers]]Y[[conferencelocation]]臺北縣, 臺

PALM: A Partition Avoidance Lazy Movement Protocol for Mobile Sensor Networks

[[abstract]]The paper proposes a distributed partition avoidance lazy movement (PALM) protocol for mobile sensor networks (MSNs). In general, connectivity and coverage are two major factors to the success of a sensor network. Therefore, PALM takes both connectivity and coverage into account to avoid network partition and keep high sensing quality. Since sensor movement is the major source of energy consumption, thus, in order not to cause frequent movement, PALM triggers sensor movement only when the network has a risk of partition, but not when coverage holes appear. The paper proposes a sufficient condition of keeping a network connected. Based on the condition, PALM adopts the lazy movement policy for a sensor to determine when to move and uses the principles of an effective movement for a sensor to decide where to move. Accordingly, PALM can keep the network connected and can make the effective coverage as large as possible to maintain high sensing quality. In comparison with the related work, PALM can reduce the energy consumption and further extend the network lifetime due to the lazy movement policy and the principles of an effective movement. Simulation results also verify the advantages of the proposed protocol.[[conferencetype]]國際[[conferencedate]]20070311~20070315[[iscallforpapers]]Y[[conferencelocation]]Kowloon, Hong Kon

On QoS routing in TDMA-based mobile ad hoc networks

[[abstract]]With the popularity of multimedia, QoS service is demanding from day to day. The mobile ad hoc network is an important wireless network architecture, which is self-organized and without the assistance of basic infrastructures. QoS routing in mobile ad hoc networks is an important issue for wireless technology. The paper presents a distributed slots reservation protocol (DSRP) for QoS routing on TDMA-based mobile ad hoc networks. According to one-hop neighbor's information, some strategies to select the time slots in order to satisfy the QoS requirement and not to violate the hidden-terminal and exposed-terminal problems are proposed. Route maintenance and improvement are also provided to maintain or improve a route when the network topology is changed. According to the simulation results, the proposed protocol can not only increase the findings of a route with bandwidth requirement guaranteed but also raise the throughput and efficiency of the network.[[sponsorship]]I-Shou University;Technical Co-Sponsored by IEEE, Taipei Section; National Science Council;Ministry of Education; MTECH Corporation Ltd.;Winbond Electronics Corp.,etc.[[notice]]補正完畢[[conferencetype]]國際[[conferencedate]]20031214~20031216[[booktype]]紙本[[iscallforpapers]]Y[[conferencelocation]]高雄, 臺

An Intruder Avoidance Vulnerable Path Adjustment Protocol for Wireless Mobile Sensor Networks

[[abstract]]The paper proposes a protocol to adjust the vulnerable path by using mobile sensor networks. The objective of vulnerable adjustment is to protect some important areas, named TBP (to-be-protected) areas in the paper, from being attacked. In the paper, Voronoi diagram is utilized to And a vulnerable path, which is a path that an intruder may pass through. While the vulnerable path passes over a TBP area, a backward tracing and critical sets selection schemes are used to move the fewest number of sensors such that the vulnerable path can be changed and the new vulnerable path will not pass over the TBP area. Moreover, a moving schemes is proposed to decide where mobile sensors shall move. Since sensor movement is the major resource of energy consumption, thus, in order not to cause much movement, the proposed mechanism can move the fewest number of sensors with the shortest distance. Simulation results also verify the advantages of the proposed mechanism.[[sponsorship]]IEEE Taipei Section; National Science Council; Ministry of Education; Tamkang University; Asia University; Providence University; The University of Aizu; Lanzhou University[[conferencetype]]國際[[conferencetkucampus]]淡水校園[[iscallforpapers]]Y[[conferencelocation]]Tamsui, Taipei, Taiwa

A Fragmentation-Based Data Collision Free MAC Protocol with Power Control for Wireless Ad Hoc Networks

[[abstract]]Resolving hidden terminal problem is one of the major responsibilities in designing MAC protocols for wireless ad hoc networks. IEEE 802.11 DCF, currently the most popular used MAC protocol, adopts four-way handshake to prevent hidden terminal problem. However, it has been pointed out that four-way handshake cannot completely prevent hidden terminal problem because the STAs which are out of the transmission ranges of both the transmitter and the receiver may still interfere with the receiver. As a result, the paper proposes a fragmentationbased 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. It is further shown that FRCRC can also solve the POINT problem and work correctly in multi-rate environments. Simulation results show that F-RCRC performs much better than the related work in terms of network throughput as well as the power throughput.[[sponsorship]]亞洲大學資訊學院[[conferencetype]]國內[[conferencedate]]20080331~20080331[[conferencedate]]20071220~20071221[[booktype]]紙本[[conferencelocation]]臺中, 臺

A power control MAC protocol to increase spatial reuse for IEEE 802.11 Ad-Hoc wireless LANs

[[abstract]]The paper proposed a distributed spatial reuse MAC protocol (named DSR) for IEEE 802.11 ad-hoc wireless LANs to increase bandwidth utilization and reduce power con-sumption. Through power control, the sender uses the right power to send to the receiver. In this way, the transmission range and the power consumption can be decreased while the spatial reuse can be increased. The communications that do not interfere to each other are allowed to be done simultaneously. Therefore, the overall efficiency and effectiveness of IEEE 802.11 ad-hoc wireless LANs can be enhanced. DSR could allow the maximum number of interference-free communication pairs to transmit in parallel and prevent them from collisions. According to the experiment results, DSR is much better than traditional wireless LAN protocol, IEEE 802.11 DCF, and the related work. The protocol indeed could effectively enhance the overall wireless LANs efficiency.[[sponsorship]]長庚大學資訊工程學系；交通大學資訊工程學系; 國科會工程處工程科技推展中心；台灣聯合大學系統尖端資訊系統與電子研究中心(CAISER); 國科會後卓越計畫---後三代全IP無線網路技術；台灣微軟股份有限公司[[notice]]補正完畢[[conferencetype]]國內[[conferencedate]]20050331~20050331[[booktype]]紙本[[conferencelocation]]桃園縣, 臺

On Barrier Coverage in Wireless Camera Sensor Networks

[[abstract]]The paper proposed a distributed algorithm, namely CoBRA (Cone-based Barrier coveRage Algorithm), to achieve barrier coverage in wireless camera sensor networks (WCSNs). To the best understanding, CoBRA is the first algorithm which try to deal with the barrier coverage issue in WCSNs. Based on some observations, the basic concept of CoBRA is that each camera sensor can determine the local possible barrier lines according to the geographical relations with their neighbors. A sink in a WCSN initiates Barrier Request (BREQ) messages to form the possible barrier lines. Afterward, a barrier line is constructed by the Barrier Reply (BREQ) message initiated by another sink. CoBRA mainly includes three phases: Initial Phase, Candidate Selection Phase, and Decision Phase. In the Initial Phase, each camera sensor collects the local information of its neighbors and estimates the possible barrier lines. In the Candidate Selection Phase, a sink initiates the BREQ packets and forwards the BREQ packets to camera sensors. Camera sensors receiving the BREQ then reforward the BREQ packets to its neighbors who are capable of forming a barrier line. All camera sensors receiving the BREQ will forward the BREQ to their neighbors again in the same manner. Finally, in the decision phase, after the BREQ message is transmitted through the whole monitoring area, a BREP message is used by the sink to select a barrier line in a WCSN. The barrier coverage is achieved by finding the barrier line in the monitoring area. Experiment results show that CoBRA can efficiently achieve barrier coverage in WCSNs. Comparing to the ideal results, CoBRA can use fewer nodes to accomplish barrier coverage in random deployment scenarios.[[conferencetype]]國際[[conferencedate]]20100420~20100423[[iscallforpapers]]Y[[conferencelocation]]Perth, WA, Australi

Disciplining CBDCs: Achieving the Balance between Privacy Protection and Central Bank Independence

Central bank digital currency (“CBDC”) is a crucial FinTech development that aspires to overhaul the current payment system. In the wake of the COVID-19 pandemic, CBDCs’ promises to reduce personal contact, facilitate socially desirable use of money, and initiate more targeted monetary measures have increased their popularity. In addition, CBDCs can potentially serve as a tool to internationalize a sovereign’s currency. World central banks, thus, have gradually formulated a consensus on structuring CBDCs, leaving the regulatory aspects of CBDCs deserving more attention. Among the regulatory issues related to CBDCs, observers often mentioned their association with privacy concerns, but comprehensive studies on this aspect of CBDCs remain limited. In this paper, we discuss the privacy concerns associated with CBDCs and attempt to introduce discipline upon CBDCs and their issuing central banks. We first demonstrate the privacy implications of CBDCs and highlight the risks that issuing sovereigns misuse CBDCs to serve their agendas. We then discuss, in a domestic context, several architectural designs proclaimed to address CBDCs’ privacy concerns and propose further disciplinary mechanisms that may credibly enforce privacy protection laws against issuing central banks and other governmental authorities. We finally highlight the extraterritorial character of modern privacy laws, which allows foreign privacy protection regulators to discipline the CBDCs of other sovereigns. Through this analysis, we argue that applying modern privacy laws with proper supporting mechanisms may effectively discipline CBDCs and their issuing central banks