Frankly, I'd be scared to death to use LTE-U for my cellphone because it's extremely unclear that it would NOT be
subject to interference of some sort, and that's rather disquieting should someone need to call 911...
LTE-U works by providing two connections - one in licensed and one in unlicensed. Your phone would be connected to both at all times. The phone sends back measurements of the quality of the unlicensed connection back to the LTE small cell. If the LTE small cell sees reports that the unlicensed connection is degrading due to interference, it'll allocate you more bandwidth from the licensed connection instead. That's why LTE-U is such a powerful concept. Capacity and bandwidth from unlicensed when it makes sense, and the safety and reliability of licensed if things go awry.
Who said anything about drowning out other people's? Where in the spec for the technology do you see that? A single LTE carrier channel is limited to 20MHz bandwidth. Smartphones that support LTE-U will at most be able to take advantage of 40MHz of spectrum (if 2 LTE-U channels are used). That's out of hundreds of MHz of available bandwidth in the unlicensed bands. There would be no need to drown out anyone because (1) it's not technically possible given max LTE bandwidth limitation and (2) the plentiful spectrum that's available in the band. Additionally, if and when LTE-U has to share the channel with an existing Wi-Fi access points, it *deterministically* takes up 50% of the air time. If it has to share with 2 Wi-Fi APs, it takes only 33% of the time. And so on.
I would be glad to give you more details if you want of the co-existence mechanisms in LTE-U. And BTW, repeated testing has shown that is works, and works better, than sharing mechanisms in Wi-Fi.
It offers greater network capacity, and thus by extension, better user throughputs. It does so by using carrier aggregation technology - bonding together an LTE connection in the licensed spectrum with an LTE connection in unlicensed spectrum (both broadcast from the same LTE small cell).
LTE-U is not a wide coverage technology. The intention is to deploy it in high congestion areas - airport, mall, public park, busy downtown street corner, etc. You hit the nail on the head with the FCC power requirements - that's exactly the point. The LTE-U small cell would not be able to transmit at power levels higher than is allowed by the FCC, so it will have limited range. But where it does have coverage, it'll provide additional capacity boost that improves the UX for all users. That's the point.
LTE-U is not transmitted by big cell towers. It's a "small cell" technology - i.e. it is transmitted from small boxes that are no bigger than a Wi-Fi access point, and transmit radio waves at the same output power as Wi-Fi access points.
When cable companies use unlicensed spectrum to deploy their own Wi-Fi networks (as Comcast, TWC, and other cable companies do), is that also a spectrum grab?
Pitting LTE-U against standard WiFi, and it being a commercial service, should be unthinkable.
Unlicensed spectrum is already used by many entities for commercial services.
For example, every hotel or airport that charges money for Wi-Fi is using unlicensed spectrum for commercial, for-profit services. Boingo and other Wi-Fi ISPs use Wi-Fi on unlicensed spectrum for commercial services. Cable companies setting up Wi-Fi access points (e.g. the nationwide CableWiFi network) are using unlicensed spectrum for commercial services.
But it doesn't just stop at Wi-Fi. Utilities use the unlicensed 2.4GHz band and the 900MHz band to deploy smart meter connections (e.g. using ZigBee, other 802.15.4-based protocols, or even completely proprietary radios and protocols).
The point is that unlicensed spectrum has long been used for commercial services. As long as the users abide by the power output limits set forth by the FCC, anyone can use the spectrum. That's kind of the point of unlicensed spectrum.
LTE-U doesn't use the 2.4GHz spectrum. It only uses a fraction of the channels in the 5GHz UNII band (only UNII-1 and UNII-3...no UNII-2). That means that LTE-U actually leaves the vast majority of spectrum in the 2.4GHz and 5GHz unlicensed bands exclusively for use by Wi-Fi and other unlicensed technologies.
Hi everyone,
Since the article was one-sided and didn't ask for comments from Qualcomm, I thought I would offer everyone a chance to ask me question regarding LTE-U.
Please go ahead.
Regards,
Sherif
Slashdot Mirror
But cable companies, Boingo, hotels, airports, countless others also charge for use of "public spectrum". Nobody is crying foul over that, are they?
Frankly, I'd be scared to death to use LTE-U for my cellphone because it's extremely unclear that it would NOT be subject to interference of some sort, and that's rather disquieting should someone need to call 911...
LTE-U works by providing two connections - one in licensed and one in unlicensed. Your phone would be connected to both at all times. The phone sends back measurements of the quality of the unlicensed connection back to the LTE small cell. If the LTE small cell sees reports that the unlicensed connection is degrading due to interference, it'll allocate you more bandwidth from the licensed connection instead. That's why LTE-U is such a powerful concept. Capacity and bandwidth from unlicensed when it makes sense, and the safety and reliability of licensed if things go awry.
Who said anything about drowning out other people's? Where in the spec for the technology do you see that? A single LTE carrier channel is limited to 20MHz bandwidth. Smartphones that support LTE-U will at most be able to take advantage of 40MHz of spectrum (if 2 LTE-U channels are used). That's out of hundreds of MHz of available bandwidth in the unlicensed bands. There would be no need to drown out anyone because (1) it's not technically possible given max LTE bandwidth limitation and (2) the plentiful spectrum that's available in the band. Additionally, if and when LTE-U has to share the channel with an existing Wi-Fi access points, it *deterministically* takes up 50% of the air time. If it has to share with 2 Wi-Fi APs, it takes only 33% of the time. And so on. I would be glad to give you more details if you want of the co-existence mechanisms in LTE-U. And BTW, repeated testing has shown that is works, and works better, than sharing mechanisms in Wi-Fi.
It offers greater network capacity, and thus by extension, better user throughputs. It does so by using carrier aggregation technology - bonding together an LTE connection in the licensed spectrum with an LTE connection in unlicensed spectrum (both broadcast from the same LTE small cell).
LTE-U is not a wide coverage technology. The intention is to deploy it in high congestion areas - airport, mall, public park, busy downtown street corner, etc. You hit the nail on the head with the FCC power requirements - that's exactly the point. The LTE-U small cell would not be able to transmit at power levels higher than is allowed by the FCC, so it will have limited range. But where it does have coverage, it'll provide additional capacity boost that improves the UX for all users. That's the point.
LTE-U is not transmitted by big cell towers. It's a "small cell" technology - i.e. it is transmitted from small boxes that are no bigger than a Wi-Fi access point, and transmit radio waves at the same output power as Wi-Fi access points.
When cable companies use unlicensed spectrum to deploy their own Wi-Fi networks (as Comcast, TWC, and other cable companies do), is that also a spectrum grab?
Pitting LTE-U against standard WiFi, and it being a commercial service, should be unthinkable.
Unlicensed spectrum is already used by many entities for commercial services. For example, every hotel or airport that charges money for Wi-Fi is using unlicensed spectrum for commercial, for-profit services. Boingo and other Wi-Fi ISPs use Wi-Fi on unlicensed spectrum for commercial services. Cable companies setting up Wi-Fi access points (e.g. the nationwide CableWiFi network) are using unlicensed spectrum for commercial services. But it doesn't just stop at Wi-Fi. Utilities use the unlicensed 2.4GHz band and the 900MHz band to deploy smart meter connections (e.g. using ZigBee, other 802.15.4-based protocols, or even completely proprietary radios and protocols). The point is that unlicensed spectrum has long been used for commercial services. As long as the users abide by the power output limits set forth by the FCC, anyone can use the spectrum. That's kind of the point of unlicensed spectrum.
LTE-U doesn't use the 2.4GHz spectrum. It only uses a fraction of the channels in the 5GHz UNII band (only UNII-1 and UNII-3...no UNII-2). That means that LTE-U actually leaves the vast majority of spectrum in the 2.4GHz and 5GHz unlicensed bands exclusively for use by Wi-Fi and other unlicensed technologies.
Hi everyone, Since the article was one-sided and didn't ask for comments from Qualcomm, I thought I would offer everyone a chance to ask me question regarding LTE-U. Please go ahead. Regards, Sherif