Software Patent of the Week: Wireless + Dining Philosophers = Non-Obvious?

by on January 19, 2007 · 38 comments

Ordinarily, my software patent series focuses on patents that have been granted by the patent office and the subject of litigation. I’m going to break that pattern this week because reader Richard Bennett pointed to one of his own patent applications as an example of a worthwhile software patent. Since I frequently ask supporters of software patents to point out a good one (a request that’s almost always ignored) I thought I’d analyze Bennett’s patent application to see what we can learn. Below the cut are my thoughts on it.

Now, I’m at a little bit of an disadvantage in this case because the subject of the patent–low-level wireless networking–is not one I know well. That makes it difficult to judge the obviousness of the more technical aspects of the patent. However, it strikes me that you don’t have to know very much about wireless technology to see that it’s broader claims, at least, are too obvious to merit a patent.

Here is the patent application, and here is the first claim:

In a wireless network incorporating a medium access control (MAC) protocol, a MAC reservation-sensing mechanism for facilitating network use by a plurality of stations, comprising: listening to network traffic by a first station desiring to transmit on the network; determining the existence of reservation time slots on the network; identifying free time slots; broadcasting a reservation request for an identified free time slot to a second station on the network; coordinating, between the first station and the second station, to confirm that the identified free time slot is available; and iff there is no conflict on the network for the identified free time slot and the identified free time slot is confirmed to be free, transmitting data from the first station to the second station.

Subsequent claims describe a variety of additional strategies that a broadcasting station might use to deal with resource contention.

It’s not clear to me what’s novel or non-obvious about these claims. There’s a voluminous literature in computer science on concurrency and access to shared resources. For example, as an undergrad, I encountered the dining philosophers problem, which is a case study in coordinating among five agents (the philosophers) who must coordinate the use of five shared resources (forks) without a centralized decision maker. That’s obviously not quite the situation under discussion here, but it’s not too terribly wide of the mark. I’d bet money that someone who knows the relevant literature well could point to papers dealing with exactly the kind decentralized coordination problems Bennett’s patent is designed to solve.

Of course, it’s possible that none of those papers deal specifically with coordination in the context of MAC protocol wireless networks. But I don’t see how that renders the idea non-obvious. There’s nothing magical about wireless networking. The techniques described here to reserve wireless time slots would almost certainly be recognizable to people writing software to manage other kinds of shared resources in a computer system.

I should emphasize that I mean no disrespect to Mr. Bennett, who is, I’m sure a skilled network engineer who is developing some great products. But I just don’t see how giving Mr. Bennett a fairly broad monopoly on devices that negotiate access to a wireless network in a decentralized manner is consistent with the purposes of patent law. It will doubtless be good for Mr. Bennett and for the lawyers who filed and will litigate the patent, but I don’t see how it’s good for the rest of us.

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