Are Mesh Networks Coming?
from the expand-that-wifi dept
For years people have been talking about the idea of “mesh networks”, where each wireless access point can connect to any other access point (within a certain range) to allow data to hope from point to point until it reaches a line back to the internet backbone. Plenty of companies have tried to work on this, but usually come up with something less than useful. This article talks (with some skepticism) about a company that is selling inexpensive boxes that will act as a mesh network. The boxes are just modified computers. Buy a few of them, and you can cover a large area with a single high speed internet connection. The writer of the article fears that too many people will look at the faults of this solution, and spend time trying to create their own competing solutions, rather than working on actually building up some mesh networks. The problem that I see, is that this either needs to be rolled out on a large scale (by a phone company, for example) or through a tremendous amount of cooperation between neighbors. Whereas a straight WiFi system directly benefits the person who sets it up (assuming they have their own broadband connection), the only reason to set up a similar mesh node is to purposely help your neighbors out. While that’s a nice thought, I’m not sure people want to go to the extra expense just to help their neighbors.
Comments on “Are Mesh Networks Coming?”
Limitations of Conventional Mesh Networks
There is more hype than reality around mesh networking. In the end, that can cause the bubble around mesh to bust – rapidly. Its time for a reality check on what mesh can and cannot do.
First, Mesh networks are not a new concept. In some ways, the internet is a mesh network. And it works, despite its size – because it does not suffer from the limitations of conventional wireless mesh networks:
1-Radio is a shared medium and forces everyone to stay silent while one person holds the stage. Wired networks, on the other hand, can and do hold multiple simultaneous conversations.
2-In a single radio ad hoc mesh network, the best you can do is (1/2)^^n at each hop. So in a multi hop mesh network, the Max available bandwidth available to you degrades at the rate of 1/2, 1/4, 1/8. By the time you are 4 hops away the max you can get is 1/16 of the total available bandwidth.
3-That does not sound too bad when you are putting together a wireless sensor network with limited bandwidth and latency considerations. It is DISASTROUS if you wish to provide the level of latency/throughput people are accustomed to with their wired networks. Consider the case of just 10 client stations at each node of a 4 hop mesh network. The clients at the last rung will receive -at best- 1/(16,0000) of the total bandwidth at the root.
4-Why has this not been noticed as yet? Because first there are not a lot of mesh networks around and second, they have not been tested under high usage situations. Browsing and email don?t count. Try video – where both latency and bandwidth matter – or VOIP where the bandwidth is a measly 64Kbps but where latency matters. Even in a simple 4 hop ad hoc mesh network with 10 clients, VOIP phones wont work well beyond the first or second hop ? the latency and jitter caused by CSMA/CA contention windows (how wireless systems avoid collisions) will be unbearable.
Mesh networks are a great concept. But the challenge lies in managing the dynamics of mesh networks so users receive an acceptable level of performance in terms of both latency and throughput.
Its time to focus on solving some real problems to make mesh networks scale and provide stable performance.
Founder and CTO
You are right...
What’s the incentive to create the outer edge of a mesh network? There is none other than altruism. It is much better to bet that an overlapping WiFi network will emerge, simply because, as you say, there is a direct benefit to the network owner.
Re: You are right...
How about this for a reason other than altruism :
I have no broadband to my house, and it seems unlikely that it will come soon. There is broadband availabe realtively near however, so by building a mesh I can get access where I had none before and so can others, and we can share the cost of the installation and the broadband connection. Communal ownership works you see.