22-09-2014, 03:33 PM
Energy-Efficient Strategies for Cooperative Multichannel MAC Protocols
Energy-Efficient.pdf (Size: 1.17 MB / Downloads: 27)
INTRODUCTION
USING multiple channels in communication is key to improving the quality of service for
wireless networks, and multichannel MAC protocol design has thereby attracted substantial
attention from the research community. Various design approaches have been proposed in
the last decade or so, but most of them require either multiple radios or time synchronization.
Recently, Luo et al. proposed a distinct approach called Distributed Information SHaring
(DISH), which uses a single radio but operates asynchronously. The authors designed a
DISH-based protocol called CAM-MAC [2], in which neighbouring nodes share control
information with each sender-receiver pair to facilitate it to choose collision-free channels or
to avoid busy receivers. DISH is essentially a form of node cooperation, but the key
difference is that, in traditional cooperation, intermediate nodes help relay data for source
and destination nodes, but DISH, on the other hand, only requires control information to be
sent. Therefore, the former can be called data-plane cooperation and the latter can be called
Energy-Efficient Multichannel MAC Protocols
There are a few proposals on this new topic. In ad hoc networks, PSM-MMAC[56] lets nodes
to choose to be awake or doze based on the estimated number of active links, queue length,
and channel condition. TMMAC [11]uses the 802.11 ATIM window like MMAC [10], but in
addition to negotiating channels, it also negotiates time slots for nodes to sleep in.
In wireless sensor networks (WSNs), MMSN [57] was proposed to use multiple channels.
However, energy saving is not one of its design goals, but is a natural and common
consequence of using multiple channels (as interference is reduced). Also, when the number
of channels is small, it can be seen from the paper that MMSN consumes more energy than
single-channel CSMA. Chen et al. [58] propose another protocol for cluster-based WSN. The
protocol is shown to be more energy efficient than MMSN by assuming 1) all cluster heads
can directly communicate with each other and 2) there are many sink nodes and hence no
single-sink bottleneck. The practicality of these assumptions can be questioned. CMAC [59],
unlike MMSN and [58] which are both synchronous protocols, does not require time
synchronization. However, it needs to assign every node a channel that does not overlap with
any other node in 2-hop range. This means that for a network with a node density of, say,
10=r2, at least 126 channels are needed, which is generally not feasible.
Methodologies supported
Eclipse is methodology independent. If you work in a traditional waterfall
process-where you design the system, write the code, and then rest-you cause the
platform with your tools and progress through the phases of development. If you prepare
to use a methodology similar to extreme programming, where you frequently integrate
through your code and testing, you will enjoy the right integration provided by the java
tools, the debugging environment, and the platform.
Accessibility
Eclipse is easy to access. It is user friendly, so that even people with disabilities
can still productively use all the functions provided. In windows, eclipse uses Microsoft
active accessibility APIs to make the user interface accessible to assistive technology.
Eclipse works with screen reader software to have audio services, which describes the
contents of the screen. In addition, voice recognition software can be used to enter
information and navigate the system.