MuniWireless

When deploying a mesh network, a system integrator can choose between single-radio or multi-radio mesh. Which one is better? Making that decision is not as simple as you might think. When deploying Wi-Fi mesh networks, system integrators can choose among single-radio or multi-radio mesh node equipment. The single-radio models, such as what Tropos offers, uses a solitary 2.4GHz radio for connecting user client devices to the mesh network and interfacing mesh nodes together. This requires both users and node-to-node traffic to share a single radio. With single-radio systems, the radios in neighboring mesh nodes are set to the same RF channel; otherwise, the mesh nodes can’t communicate with each other. With a common channel, a user device transmitting data to a mesh node precludes the mesh node from transmitting data to an adjacent mesh node (and vice-versa).

Other vendors, such as Cisco and Strix, offer multi-radio mesh nodes. In the multi-radio case, one radio in the mesh node interfaces users to the mesh network, and an additional radio, operating at a different frequency, provides communications between mesh nodes. This allows traffic between a user and the mesh node and between the mesh node and neighboring mesh nodes to occur simultaneously.

Which approach is better? One would think that more radios means better performance, and that’s generally true. Keep in mind, however, that the single-radio hardware is significantly less expensive as compared to multi-radio versions. This should encourage you to consider the tradeoff between performance and price. If the potentially lower performance of the single-radio system is sufficient to meet requirements, then the single-radio system is the one that you should strongly consider. If requirements dictate higher capacity, then look closely at whether a multi-radio system is really necessary and cost-effective. This just offers some broad direction. Of course you should also think about other parameters, such as security, operational support, and support for newer technologies.

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Jim Geier is an independent consultant and founder of Wireless-Nets, Ltd (www.wireless-nets.com), a consulting firm assisting municipalities, enterprises, hospitals, airports, and equipment providers with the development and deployment of wireless networks. Jim is the author of several books, including Deploying Voice over Wireless LANs (Cisco Press), Wireless LANs (SAMS), Wireless Networks ‚Äö?Ñ?¨ First Step (Cisco Press), Wireless Networking Handbook (Macmillan), and Network Reengineering (McGraw-Hill).