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I don't think you understood the article. It is not about the physical restrictions and trade-offs of mobile broadband. It is about the inefficiency of TCP on s

by soult 15y ago

I don't think you understood the article. It is not about the physical restrictions and trade-offs of mobile broadband. It is about the inefficiency of TCP on such connections. Current TCP implementations are optimized for wired networks which usually have fixed bandwidth and latency. They use dropped packages for congestion avoidance, interpreting package loss as a signal to slow down transmission. Wireless networks with their higher packet loss (compared to wired ones) fool the sender into believing that the connection is satured. Combine this with the enormous buffer sizes used by mobile broadband systems and the TCP congestion control algorithm throttles the connection to an unusably slow level. The author is not making a case for trading speed for reliability by using a different PHY, he is making a point for embracing the package loss and delays that exist in current mobile broadband systems and using those characteristics to create a smarter transport layer protocol to replace TCP on mobile devices.

PaulHoule 15y ago
Yes, I do recognize that. In the big picture, however, it's generally better to fix the part of a system that's broken (the PHY) than it is to try to compensate for the underlying problem in upper layers. It's also good to be careful about your terms. "Mobile" means operation out of a car or other motorized moving platform. "Portable" means a device that's being carried by a pedestrian. When the bandwidth of a radio channel gets wide, these become very different environments. All I can say about new protocols is that you can go to your local Uni and find (quite literally) a ton of conference proceedings on this very topic. It seems that somebody has been funding a ludicrous amount of research on TCP replacements for decades without anything practical coming out of it. Out of all that literature you ought to be able to find something that works or find a good reason why it can't be done.
- gte910h 15y ago
  Mobile also means "As in it's carried around as well as used in cars". It's a term for smartphone. They're using modern parlance to talk about smartphones, not radio parlance.

by soult 15y ago

PaulHoule 15y ago

Yes, I do recognize that. In the big picture, however, it's generally better to fix the part of a system that's broken (the PHY) than it is to try to compensate for the underlying problem in upper layers. It's also good to be careful about your terms. "Mobile" means operation out of a car or other motorized moving platform. "Portable" means a device that's being carried by a pedestrian. When the bandwidth of a radio channel gets wide, these become very different environments. All I can say about new protocols is that you can go to your local Uni and find (quite literally) a ton of conference proceedings on this very topic. It seems that somebody has been funding a ludicrous amount of research on TCP replacements for decades without anything practical coming out of it. Out of all that literature you ought to be able to find something that works or find a good reason why it can't be done.

gte910h 15y ago
Mobile also means "As in it's carried around as well as used in cars". It's a term for smartphone. They're using modern parlance to talk about smartphones, not radio parlance.