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I'm the main inventor. Thanks a lot for the positive feedback! You are actually right, similar ideas have already been proposed before. The main novelty here i

by hrzn 12y ago

I'm the main inventor. Thanks a lot for the positive feedback! You are actually right, similar ideas have already been proposed before. The main novelty here is that the algorithm adapts not only the channel (center frequency), but also the bandwidth (i.e., the actual amount of spectrum that is consumed). Adapting the bandwidth gives a precious additional degree of freedom; in particular, in a case with many competing WLANs, the algorithm would typically tend to reduce the bandwidth consumed by each WLAN (assuming the interfering WLANs are not idle and actually sending traffic). Reducing the bandwidth potentially reduces the available capacity (if you were alone), but it's still much more efficient than letting Wi-Fi use the time domain to avoid interference, so it results in increased throughput compared to current situations. It turns out that adapting the bandwidth is becoming a necessity, because newer versions of Wi-Fi consume more and more bandwidth. This is better if you are alone, but may be harmful if you have many neighbors.

azinman2 12y ago
Are you going to release this algorithm in any of the open source router projects like ddwrt?
- hrzn 12y ago
  I'm thinking about it, but the current implementation that I wrote (which runs on OpenWrt) is currently somewhat too constrained to my Atheros hardware. I'll try to improve it though.
cesarb 12y ago
> in a case with many competing WLANs, the algorithm would typically tend to reduce the bandwidth consumed by each WLAN Wouldn't that use more battery, since for a narrower channel the radio would have to be kept on for longer to transmit (or receive) the same amount of data?
- hrzn 12y ago
  Usually, 802.11 devices don't turn off between transmissions, so this has no effect. In fact, it's actually the opposite; using a narrower channel requires a slower clock rate, which also significantly reduces power consumption of the wireless device.
darkmighty 12y ago
I have a few questions! First, what do you think of the b/g/n wireless structure? If you could redesign it from the ground up what would you change to maximize performance (given the same bandwidth)? Second: would allowing routers to communicate improve your solution significantly? Thanks, great work btw
- hrzn 12y ago
  Well, I think that 802.11 is not that bad. Conceptually, the way it schedules packet transmissions over time turns out to be quite efficient (at least in WLANs scenarios), even though this efficiency is somewhat reduced with newer and faster PHY layers (packets transmission being faster, the time spent in backoff to avoid collisions increases the overhead). From an engineering point of view, my personal opinion is that the fact that 802.11 operates in a completely decentralized way is probably more desirable than having a more complicated solution that would require AP-to-AP communication but would most likely provide only marginal gains (several researchers have shown the close-to-optimal nature of purely decentralized CSMA-style scheduling). In case of spectrum assignment, it can benefit from AP-to-AP communication, especially if you want or need to enforce particular optimization criteria, such as maximizing throughput or fairness (I've personally experimented with that kind of algorithms as well). But often the overall gain does not justify the extra complexity.

by hrzn 12y ago

azinman2 12y ago

Are you going to release this algorithm in any of the open source router projects like ddwrt?

hrzn 12y ago
I'm thinking about it, but the current implementation that I wrote (which runs on OpenWrt) is currently somewhat too constrained to my Atheros hardware. I'll try to improve it though.

cesarb 12y ago

> in a case with many competing WLANs, the algorithm would typically tend to reduce the bandwidth consumed by each WLAN Wouldn't that use more battery, since for a narrower channel the radio would have to be kept on for longer to transmit (or receive) the same amount of data?

hrzn 12y ago
Usually, 802.11 devices don't turn off between transmissions, so this has no effect. In fact, it's actually the opposite; using a narrower channel requires a slower clock rate, which also significantly reduces power consumption of the wireless device.

darkmighty 12y ago

I have a few questions! First, what do you think of the b/g/n wireless structure? If you could redesign it from the ground up what would you change to maximize performance (given the same bandwidth)? Second: would allowing routers to communicate improve your solution significantly? Thanks, great work btw

hrzn 12y ago
Well, I think that 802.11 is not that bad. Conceptually, the way it schedules packet transmissions over time turns out to be quite efficient (at least in WLANs scenarios), even though this efficiency is somewhat reduced with newer and faster PHY layers (packets transmission being faster, the time spent in backoff to avoid collisions increases the overhead). From an engineering point of view, my personal opinion is that the fact that 802.11 operates in a completely decentralized way is probably more desirable than having a more complicated solution that would require AP-to-AP communication but would most likely provide only marginal gains (several researchers have shown the close-to-optimal nature of purely decentralized CSMA-style scheduling). In case of spectrum assignment, it can benefit from AP-to-AP communication, especially if you want or need to enforce particular optimization criteria, such as maximizing throughput or fairness (I've personally experimented with that kind of algorithms as well). But often the overall gain does not justify the extra complexity.