



Signal Handoff Could Mean Roaming VoIP over WiFi 91
wassup writes "According to this article in MIT tech review (and here), researchers at University of California San Diego have developed a technology called SyncScan that will reduce handoff delay in WiFi networks to a few milliseconds. VoIP roaming will be here soon!"
voip-a-doip (Score:2, Funny)
just wait... (Score:5, Insightful)
Re:just wait... (Score:2)
And cell phone operators will lobby congress to label WiFi as a "telecommunications service", thus increasing regulation of WiFi. Will Joe User with an open WiFi access point have to pay taxes as a telecommunications service provider?
Cell phone? (Score:1)
Re:Cell phone? (Score:1, Interesting)
Re:Cell phone? (Score:1, Interesting)
Re:Cell phone? (Score:2)
I for one am sick of the low quality audio used in cellphone networks and I would like to see them put the additional bandwidth to good use.
Re:Cell phone? (Score:1, Informative)
In addition to the slow roll out of UMTS, the issue is the cost to change all the user terminals, the sound quality the handset can provide, and that most of the other telecommunication network entities (your house phone and all the ot
Re:Cell phone? (Score:1)
So maybe in the not so distant future...
Re:Cell phone? (Score:1)
Re:Cell phone? (Score:1)
Re:Cell phone? (Score:2)
Roaming VOIP (Score:2, Funny)
2. duct tape a voip converter box to toolbelt.
3. add a power supply (solar panels or car battery
4. Save money on your mobile voip setup.
5. Profit!
What about TCP/IP handoff? (Score:5, Informative)
This will definitely be an annoying delay.
Re:What about TCP/IP handoff? (Score:3, Insightful)
Re:What about TCP/IP handoff? (Score:2)
VoIP generally runs over UDP. TCP is just used for session establishment, if at all. (Can SIP run over UDP? If it's stateless and can recover from lost packets/responses, it certainly can.)
Re:What about TCP/IP handoff? (Score:1, Informative)
Ummm no, try again. They don't call it VOTCP for a reason. VOIP is a generic term for ANY technology or implementation of voice communication over IP. So it could be TCP, UDP, or even some other protocol (though this is unlikely as it would cause compatibility issues, and UDP serves the need just fine).
Furthermore, the actual voice traffic is generally transported over UDP in almost all cases.
Anyway, it would be my guess that what these guys are designing is made to
Re:What about TCP/IP handoff? (Score:5, Informative)
In fact, the Internet Society point out that IPv6 is necessary for mobile and wireless internet. [isoc.org]
Re:What about TCP/IP handoff? (Score:5, Interesting)
Re:What about TCP/IP handoff? (Score:2)
Re:What about TCP/IP handoff? (Score:1)
Yes, in theory, you could switch quickly, but you could easily missing the very reason you were switching back and forth...getting the DHCP packet.
Re:What about TCP/IP handoff? (Score:3, Informative)
Re:What about TCP/IP handoff? (Score:2, Informative)
Re:What about TCP/IP handoff? (Score:3, Informative)
The last time I checked, my VoIP infrastructure used UDP.
I suspect that there are enough implementations out there now to make 'VoIP' a useless term for determining the underlying technology.
A.
Re:What about TCP/IP handoff? (Score:1)
VOIP is a general term whereas specific protocol identifiers exist, such as SIP and IAX which define exactly how the 'voice' travels.
Also, VOIP is unfortunately sometimes used where the voice doesn't travel over IP, or be encapsulated in it at all. Sooner or later, when such things are so commonplace, they'll just be called 'voice calls'; there won't be any clear difference between the softphone on my PC and the cellphone
Re:What about TCP/IP handoff? (Score:3, Informative)
is to have them all on the same subnet. Then the act of roaming between APs
is scoped to L2.
That leaves a couple different sources for delay/glitch:
One is if the wireless client were to set the WiFi interface "down" upon
dissassociating with the initial AP, then setting the interface back "up"
once it associates with the next AP. This may have the affect of triggering
the IP stack to release it's address information, and then resta
Re:What about TCP/IP handoff? (Score:2)
Last I checked, VOIP uses TCP sockets.
It seems that most people have corrected you on this point already.
When you move between WiFi base stations, you first must discover your new DHCP server, then get a new local IP address, then reconnect to the VOIP server.
This think that this aspect of mobility is a good concern. GSM networks go to great lengths to co-ordinate handovers such that the delay is minimised as much as possible. I'm not sure that wifi has been designed with the same concerns, and
Re:What about TCP/IP handoff? (Score:2)
Re:What about TCP/IP handoff? (Score:1)
Furthermore, if you're using WPA2, you can use pre-authentication to use a cached authentication key if your APs support it.
bah... (Score:2)
Re:bah... (Score:1)
I just hope (Score:4, Funny)
"checks ... only at the precise times ..." (Score:2, Insightful)
If you're on one of 11 channels and you spend 10ms every 100ms checking for a beacon on each of the other 10 channels it takes you one second to check 1/10 of the channel-beacon slots. So, after 10 seconds, you've got all slots nailed down to 10ms windows. Once you have all the slots you can update the signal strengths on the active channels once per second and discover any new beacon within 10 seconds.
Yep, pretty cool....
Re:"checks ... only at the precise times ..." (Score:1)
It might be pretty cool in terms of Wifi.. but compared to 3G it's pretty lame.
With WCDMA 3G, the network tells the UE (user equipment == phone, laptop, PDA, whatever) which are the surrounding cells it must look for. Not only that, but when the UE starts getting a good signal from another cell, the network will add a new radio link from that cell so that the UE can have links to more than one cell at a time. The handover is completely seamless. It's called soft handover.
By the way, strictly speaking ro
Better go catch it (Score:1, Funny)
Re:Better go catch it (Score:1)
Why do people love wifi everywhere so much ? (Score:2, Insightful)
And why would you want to join an untrusted network anyway ? So the admin of that network can keep nice juicy logs of everything you are doing ?
Strange.
Re:Why do people love wifi everywhere so much ? (Score:2)
Re:Why do people love wifi everywhere so much ? (Score:1)
Sorry, the last Cellular provider who actually charged for service and not for pure profit was Aerial. when Cingular bought them, the cell phone quickly died in my corner and I enjoyed $50 a month for something... productive.
Re:Why do people love wifi everywhere so much ? (Score:2)
J.
UCSD network folks doing good stuff... (Score:2)
--Seen
Don't worry... (Score:5, Funny)
Re:Don't worry... (Score:4, Insightful)
NO thanks (Score:5, Funny)
Obvious really (Score:2, Interesting)
I hope they get paid for this.
Of course, this will only work for APs that you have legitimate access to, so if you come within reach of a restricted AP
Re:communications 'revolution' a joke? (Score:1)
some of US should consider ourselves very fortunate to be among those scheduled to survive after the big flash/implementation of the creators' wwwildly popular planet/population rescue initiative/mandate.
of course.. how could I not have seen
Too bad the handoff between hotspots.. (Score:2)
But in a closed environment like a school, this technology might be useful for VoIP.
VoIPoWiFi (Score:2, Interesting)
Re:VoIPoWiFi (Score:2)
Phone companies work on the assumption -- and it's a good one -- that you want service 24/7/365. Even wireless companies (and I'm no huge fan, trust me) put some thought into taking transmitters on and offline so as not to blackout huge service areas.
I'm not sure I'd want to replace that with a patchwork of small transmitters, each running for their own reasons and on their own schedules, with my phone service basically as an afterthought.
This is why I think
Re:VoIPoWiFi (Score:1)
WiMax will break the cell operators backs (Score:4, Interesting)
Cell operators like Verizon spend BILLIONS on proprietary "3G" networks. Their networks require lots of towers, yet have poor coverage and lots of "signal shadows". WiMax access points have ranges from 30-50 MILES and don't have the same signal shadow problems. WiMax phone networks will steamroll cell operators with cheap networks yet better coverage and service.
Re:WiMax will break the cell operators backs (Score:2)
Re:WiMax will break the cell operators backs (Score:1)
Actually, they aren't proprietary. They are according to 3GPP Standards (www.3gpp.org).
And anyway, who do you think will be deploying these Wimax networks? My guess is large telecoms corporations.. the very same ones you claim will be destroyed by this.
WiMax does change the laws of physics... (Score:1)
By the way, that is precisely why roaming between Wi-Fi access points
Re:WiMax will break the cell operators backs (Score:3, Informative)
WiMax supports huge distances, sure. But in order to avoid needing a line of sight with the tower, you need to use low frequencies - that multiple-tens-of-GHz mumbo-jumbo is useless for penetrating things like trees, buildings, and cars.
Thankfully, old analog TV spectrum (such as the lower 700MHz band [fcc.gov]) is suitable and available for use in this way.
But realize that there's only so much information bandwidth that can be squeezed out of a slice of spectrum, and that the f
VOIP WiFi won't replace cell phones until... (Score:1)
however, given that certain cities are deploy WiFi hardward throughout the city giving everyone free wireless internet, VOIP WiFi is an excellent idea to start testing there. i personally make 90% of my calls within the city. sometimes i make calls from the
Actually (Score:5, Insightful)
Actually VOIP over WiFi is more likely to be useful in deserts and other remote areas because those who care can setup their own network. It might not be worthwhile for a cell phone company to put up a cell tower, but a farmer can put a WiFi station on his silo and get pretty good coverage of his ranch. Sure it won't have a large coverage areas, but it covers his needs.
Re:Actually (Score:2)
Yeah... Isn't that what cordless phones are all about?
I'm all for solving problems in a more complicated matter than something that has e
Re:Actually (Score:2)
Depends, can your cordless phone roam all over your ranch? The US has limits on range, which means they can't cover the ranch. WiFi roaming means you can put up several base stations (solar powered or something) around the ranch to get service where you want it.
When your bring your cordless phone to the neighbors or town does it still have your phone number? WiFi, when in range, makes this easy. The phone always has your number, just like a cell phone. Perhaps you have noticed the access points are
We've had this for a while (Score:1)
When (Score:2)
The really badass cisco servers have been able to do this for like 40 years.
But it never filtered down, it would have been awsome to have 2 Modems and phone lines or Use Both my and My neighbors Cable while he used both his and mine.
I guess they are making good use of the wifi channels but this could still be better
Re:When (Score:1)
its been done. (Score:1)
VoIP roaming already here! (Score:2)
Already here. It's called a cell phone.
This is not new (Score:2)
And they'll call it... (Score:2)
Just noise... (Score:1)
As others have pointed out, this doesn't solve the issue of AP's being on different networks. But that's not an issue on many campus's. (Educational & Industrial)
It also doesn't address the increased power needs that such an algorithm would create, nor the performance problems that might be created as well.
On the whole, either
Re:Just noise... (Score:2)
Professor Stefan Savage, of the Jacobs School of Engineering, and graduate student Ishwar Ramani have a patent pending on the basic invention behind a technology known as SyncScan.
Now, if this thing is patented, it will either never serve anyone, or it has already been bought by verizon & friends