Smart shopping tips for wireless mesh

Joel K. Young
13 Feb 2009
00:00
News
Features

Want to build a wireless mesh network‾ There are plenty of technologies to choose from, but one size does not fit all. Here's the roster of mesh protocols on the market, and what criteria you should use to rate them

Over the past few years, mesh networks have become more popular, following the trend to create more wireless things. As with other technology trends, as mesh networking has developed, so has a plethora of different mesh networking technologies and architectures. This article is intended to bring order to the mess of mesh networks.

First, we should look at the most useful criteria for comparing different mesh networks: security, reliability, power management, scalability, data movement, and cost.

Security. This is as much about the perception of threat as actual threat. Nonetheless, we can evaluate security using the traditional factors that are well understood in the industry: encryption, authentication of users and/or nodes, and authorization. Other factors are associated with the ease of distributing and configuring the authorization and authentication mechanisms.

Reliability. The best way to think of reliability is the ability of a message to be delivered to the desired destination on time. The components for evaluating reliability for wireless mesh networks involve the following:

  • Frequency agility: Detecting potential interference and adapting the network around it.
  • Message loss potential: A measure of whether messages get lost in the shuffle.
  • Adaptability: Best described as the network's ability to change the routing to accommodate for nodes disappearing while still preventing lost messages.
  • Single points of failure: Are there any, what is the risk of them failing, and how is recovery handled‾

Power Management. Within the context of network architecture, power management is analyzed in terms of end nodes, router nodes, and network coordinators. It is most important to have low-powered, power-efficient end nodes because they are most likely to be located far from traditional wired power sources. In terms of routers, battery-powered routers or routers that sleep extend the flexibility of the architecture.

Scalability. Scalability is related both to reliability mechanisms and to the nature of the application. If a network never experiences problems that cause rerouting, then network routing tables will never change, meaning cached routes will always work and that there will be few retransmissions or reroutes because of failures. The other aspect concerns the type and volume of data and these can be categorized as dribble data, bursty data, or streaming data. A network can be very large if the traffic is made up of dribble data because the flow follows consistent patterns, with plenty of bandwidth. Sleeping networks do well with dribble data, but scale poorly with streaming data.

Data Movement. In evaluating networks for data movement, consider a combination of the following five variables: data rate, latency, packet size, fragmentation, and range.

Cost. Cost is measured by the individual unit cost as well as the cost to maintain the network. In this context, maintenance is often difficult to quantify and deployment cost is often forgotten. It is easiest to quantify those variables that are most perceptible, namely the actual purchase cost of a transceiver system per node. But the cheapest radio may not be the best for the application.

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