Documents and opinions of LAA/WiFi

This is an important breaking story. I’m posting here all primary documents I can find as well as any responses from the companies. I hope this is helpful to reporters and others looking for information. Some of these articles contradict others, often because there is no consensus. The spin on this in Barcelona is extreme. My opinions at http://5gwnews.com/90-r/149-verizon-ericsson-want-wifi-spectrum-for-ltehttp://5gwnews.com/90-r/170-qualcomm-makes-the-rules-for-qualcomm-lte-wifi and more shortly to come. (LAA, also called LTE-U, is a proposal tp use some WiFi unlicensed spectrum for telephone company LTE..) 

WiFi & LTE about equivalent. Tony Melone, Verizon

“utilizing unlicensed spectrum for LTE will be similar to Wi-Fi in terms of power requirements et cetera. So the advantage we will have is we will have centralized control and knowledge of the interference condition, so we’ll be able to bring that unlicensed spectrum in to play when it’s available, when it can provide a good experience for our customers and again use it as a supplemental downlink to augment capacity.”the technology itself, the cost of some of the equipment and the capacity that you get out of the small cell has significantly increased. Interference management techniques which are also an important part of having a highly dense network of sales has improved. And then just the proliferation of fiber, the competitiveness of that environment, the cost points associated with that, all these things combined are a big part of that.

And then, finally, the cost of new spectrum. I mean certainly at a time where spectrum was at a certain price per megahertz POP that was a very effective solution; as those prices increased small cell technology with the improvements there just the balance of the comparison between the two changed dramatically.

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“Looks like it’s back to the drawing board” Joey Padden CableLabs Lead Architect  

Wi-Fi vs EU LBT: Houston, we have a problem

Licensed Assisted Access using LTE is the nascent LTE tech that puts cellular signals into the unlicensed spectrum. It goes by LAA-LTE or LTE-U for short. By all accounts the blitz is on to push this new tech into the field as fast as possible. NTT DoCoMo and Verizon have already announced their testing LTE-U. In addition the effort in 3GPP (the mobile standards body) on the approved study item is going fast & furious after kicking off at RAN1 78bis in Ljubljana Slovenia in early October.

The “license assisted” moniker is an indication of something unique: though it uses unlicensed spectrum, it is actually linked to licensed spectrum. This is a technology for mobile operators to supplement their networks by integrating unlicensed spectrum. Unlicensed spectrum will “assist” licensed LTE.

Having already decided to retain this link to licensed networks, 3GPP is now turning its attention to implementation. A key issue for 3GPP to tackle when creating LAA-LTE is how to modify LTE so that it can fairly share spectrum with other technologies e.g. Wi-Fi. As some have pointed out (see blog 1, blog 2,blog3, and most recently blog4) it is still hotly debated how nicely LTE-U will ultimately play with Wi-Fi. Much more

“There is a lot of work left to do before we see the fair and friendly coexistence solution that Wi-Fi users want” Padden

If the duty cycle period is configured as too low, the throughput of a Wi-Fi network sharing the channel will be negatively impacted. On the other hand, if the duty cycle period is too high, the latency of a Wi-Fi network sharing the same channel will be negatively impacted. much more

Padden’s articles come closer than others to be intelligible to a layment but all of this is can be hard for someone non-technical.

 

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“Causing heated debate” Antti Toskala, head of Radio Standardization at Nokia

Toskala goes on to conclude LTE-U & WiFi will work well together and his company is designing products.(ed) “unlicensed spectrum has long been the preserve of Wi-Fi. Wi-Fi is well established, low cost and embedded in billions of devices. On the other hand, LTE is spectrally more efficient to deliver a larger capacity bang, offers dynamic off-loading, delivers greater coverage for the same power, and is easy to integrate into an operator’s existing radio networks. Such advantages are leading some people in the industry to think that LTE-U could kill off Wi-Fi in the long run.”

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Huawei working with NTT DOCOMO

August 21, 2014 DOCOMO and Huawei Confirm LTE Network over Unlicensed Spectrum

— Key advancement toward the global standardization of LAA technology —

TOKYO, JAPAN, August 21, 2014 — NTT DOCOMO, INC., a personalized mobile solutions provider for smarter living, together with DOCOMO Beijing Communications Laboratories Co., Ltd. and Huawei announced today that their joint test has successfully demonstrated that LTE can be deployed over the 5GHz unlicensed spectrum, which is widely used for wireless LAN networks in many countries today. more pr

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“Wi-Fi is significantly impacted by LTE transmissions” Nokia team, 2013 

IEEE Vehicular Technology, Spring 2013 

 

The deployment of modern mobile systems has faced severe challenges due to the current spectrum scarcity. The situation has been further worsened by the development of different wireless technologies and standards that can be used in the same frequency band. Furthermore, the usage of smaller cells (e.g. pico, femto and wireless LAN), coexistence among heterogeneous networks (including amongst different wireless technologies such as LTE and Wi-Fi deployed in the same frequency band) has been a big field of research in the academy and industry. In this paper, we provide a performance evaluation of coexistence between LTE and Wi-Fi systems and show some of the challenges faced by the different technologies. We focus on a simulator-based system-level analysis in order to assess the network performance in an office scenario. Simulation results show that LTE system performance is slightly affected by coexistence whereas Wi-Fi is significantly impacted by LTE transmissions. In coexistence, the Wi-Fi channel is most often blocked by LTE interference, making the Wi-Fi nodes to stay on the LISTEN mode more than 85% of the time. This reflects directly on the Wi-Fi user throughput, that decreases from 50% to ~100% depending on the scenario. Finally, some of the main issues that limit the LTE/Wi-Fi coexistence and some pointers on the mutual interference management of both the systems are provided.

 

ICC 2013 – 2013 IEEE International Conference on Communications (ICC)
IEEE
The recent development of regulatory policies that permit the use of TV bands spectrum on a secondary basis has motivated discussion about coexistence of primary (e.g. TV broadcasts) and secondary users (e.g. WiFi users in TV spectrum). However, much less attention has been given to coexistence of different secondary wireless technologies in the TV white spaces. Lack of coordination between secondary networks may create severe interference situations, resulting in less efficient usage of the spectrum. In this paper, we consider two of the most prominent wireless technologies available today, namely Long Term Evolution (LTE), and WiFi, and address some problems that arise from their coexistence in the same band. We perform exhaustive system simulations and observe that WiFi is hampered much more significantly than LTE in coexistence scenarios. A simple coexistence scheme that reuses the concept of almost blank subframes in LTE is proposed, and it is observed that it can improve the WiFi throughput per user up to 50 times in the studied scenarios.
(editor’s note. Nokia’s Antti Toskala came to a different conclusion, above)

 

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