More details on NTT Docomo's Xi Femtocell

Japanese operator, NTT Docomo recently published some more details about its Xi Femtocell service. The Femtocell is a dual mode LTE-WCDMA femtocell. WCDMA is mainly used as a CS Fallback option when used with LTE device. In this case if the WCDMA part stops working for some reason then depending on the macro availability, it may hand the UE back to Macro or just keep using the LTE only service.

I could not completely figure out but it also looks like the Femtocell operates in co-channel with the Macro. During the power on, SON algorithms device the codes, the power of the femtocell, etc.

The complete article is embedded below:

W-CDMA/LTE dual-mode Ultra-compact Base Station (Xi Femtocell) from Zahid Ghadialy

Enterprise Small Cells - Small Cell Forum Release Two

The long awaited "Release Two" from the Small Cell Forum is finally here.



Gordon Mansfield is explaining this Release two in the video above.

Small Cell Forum (SCF) also released a Small cell market update. As per the market report, as of October 2013, there were:

• 7.2 million residential femtocells deployed
• 168,000 indoor small cells deployed
• 2,700 outdoor small cells deployed

There is a good summary of this Release on ThinkSmallCell and TMN. Definitely worth a read.

There are a lot of documents released or revised as part of Release-2. You can access all the Enterprise related documents at http://www.scf.io/en/use_case_documents/Enterprise.php. You can also start with just the overview document at http://www.scf.io/en/documents/102_-_Release_Two_-_Enterprise_Overview.php

Finally, for more technical minded people, they can directly jump to the Enterprise small cell network architectures document at http://scf.io/en/documents/067_-_Enterprise_small_cell_network_architectures.php

LTE-U: First step towards 'Operator-neutral' Small Cells

3GPP member companies have decided to take the Small Cells vs WiFi fight back into the Wi-Fi camp by unveiling the initiative to have LTE in the unlicensed band (officially known as LTE-U but another interesting term uLTEA has been proposed unofficially too). 

Mike Roberts wrote an interesting post on ITM Blog:

Qualcomm has launched a radical initiative to deploy LTE Advanced in the unlicensed 5GHz band, which has traditionally been the preserve of Wi-Fi devices. If the initiative gains support, it could be a hammer blow to carrier Wi-Fi, though Qualcomm says it is still a strong supporter of all types of Wi-Fi, given its Qualcomm Atheros division, which is a leading producer of Wi-Fi chipsets. 

Qualcomm CEO Paul Jacobs unveiled the company’s initiative for LTE Advanced in unlicensed spectrum at its financial-analyst day in New York on Nov. 20. It was interesting timing, considering that the main annual carrier Wi-Fi event, the Wireless Broadband Alliance’s Wi-Fi Global Congress, was taking place on the same day on the other side of the world, in Beijing. 

The chipset giant followed the announcement by its CEO with detailed presentations on the initiative at Informa’s LTE North America event in Dallas on Nov. 21-22. The essence of Qualcomm’s proposal is that it is complicated to integrate LTE and Wi-Fi to create carrier Wi-Fi, so a better option could be to use LTE Advanced to extend LTE into unlicensed spectrum, thus eliminating the need for Wi-Fi in that context....So how does Qualcomm plan to square this circle and offer reliable mobile services in unreliable unlicensed spectrum? By using LTE Advanced to create a hybrid system operating in both licensed and unlicensed spectrum at the same time. Specifically, Qualcomm is proposing a system that uses the carrier-aggregation (CA) feature of LTE Advanced to aggregate licensed LTE spectrum with unlicensed spectrum in the 5GHz band. The unlicensed spectrum, which would be aggregated with licensed spectrum on the downlink only, would only be used for data services. The licensed spectrum would be used for uplink and downlink and would support network control as well as voice and data services. Given the power limits placed on devices using the unlicensed 5GHz band, uLTEA would be used mainly in small cells, similar to Wi-Fi.

'All about 4G' did a good quick write-up on this topic from standards perspective, as follows:

Qualcomm has recently floated the idea of deploying LTE in unlicensed bands, particularly focusing on the 5GHz band, which is currently used mostly for WiFi. According to a document (RP-131635) submitted to the upcoming 3GPP plenary meeting, the proposal is to deploy LTE as Supplemental Downlink (SDL) in 5725-5850 MHz in USA, with the PCell (Primary Cell) always operating on a carrier in a licensed band. Verizon has also submitted a Work Item Proposal (RP-131680) to to introduce the new band for SDL usage. There’s also a Study Item proposal from Ericsson (RP-131788) is the rapporteur to study the modifications necessary to the LTE radio.

One of the big issue (though small cell vendors often play it down) that has been delaying the rollout of Small Cells has been interference management in co-channel deployment cases. The operators are worried about ad-hoc small cells creating interference with the properly planned and optimized Macro cells (though in practice its not as bad as they think it is). With LTE-U, this issue can be put to rest.

I can see LTE-U, if adopted, can also help create new business models around Small cells. Neutral Small cells, deployed in the hotspots like stadiums, shopping malls, etc. can serve users of all networks. The signalling can take care of each user connecting to its own network using backhaul.

Femto as a Service (FaaS) and Small Cells as a Service (SCaaS) would probably become a common approach as there would be no concerns about which spectrum is being used. 

There would be a small concern about interference between Wi-Fi and Small cells. Most of the existing Wi-Fi and other devices that use unlicensed spectrum use the 2.4GHz band with a few using 5GHz band now. If LTE-U uses the 'Listen Before Talk' approach, other technologies can be enhanced to probably do the same. Another thing worth remembering is that there is nearly 300MHz of spectrum in 5GHz band available universally. In certain countries the available spectrum can be as much as 500MHz. This should be enough for LTE-U as well as other technologies in the unlicensed spectrum.

The complete Qualcomm presentation is embedded below and is available to download from here:

Wi-Fi as the preferred cellular access and barriers to roaming

Republic Wireless, a regional carrier in the USA is doing some interesting stuff with Wi-Fi and is possibly going to create some interesting challenges for established cellular carriers. An extract from a recent article in Washington post as follows:

Consider Republic Wireless, a Raleigh-based business that announced this month it would sell Motorola's new flagship phone, the Moto X. Republic enjoys all the traditional advantages of an MVNO — low capital expenditures on infrastructure and spectrum — but it's taken the additional step of cutting out 3G and 4G data use whenever it can. Technically, Republic operates on Sprint's network, but it's more appropriate to think of Sprint as a backup for when a call or message can't be completed over WiFi.

Yes, you read that right: WiFi. Republic's business depends on shunting all of your communications — data, voice, everything — onto the free stuff you get in your office or in coffee shops. What makes this beautiful is that whenever a Republic customer chooses to place a call over WiFi, that saves Republic money. As a result, Republic can offer a $5-a-month plan for unlimited talk, text and data. For another $5 a month, customers get access to Sprint's cellular network (minus 3G). Higher-tier plans provide 3G and 4G Internet on Sprint, though it's almost a joke to call them "higher-tier" when the most expensive plan tops out at just $40 a month. The tiered plan supersedes an old, $19-a-month all-you-can-eat plan.

"The crazy plans at $5 and $10 have never been tried," said CEO David Morken. "That's because we focus on unlicensed spectrum as the primary, and licensed spectrum as the secondary."

This approach can be quite disruptive for the MNO's. With NGH / HS2, soon MVNO's like republic wireless will be able to offer roaming on WiFi, thereby cutting the costs while not in the home market.

WBA released an Industry report recently (embedded below) which had some interesting findings.

Industry bodies, vendors and device manufacturers are working hard to get rid of some of these limitations and barriers. Once these limitations are gone, there is going to be a good business case for offering of global Wi-Fi roaming for example.

Another interesting question in the survey was what would be your preferred means of building Wi-Fi footprint. One of the answers is shown above, a similar question was asked in a webinar and posted in the 3G4G blog post here.

Finally, since the WBA report mentions about Wi-Fi and Small cells data offload, you may find a previous post of interest here.

The complete WBA report as follows:

Wireless Broadband Alliance Industry Report 2013: Global Trends in Public Wi-Fi from Zahid Ghadialy

SUPER cell, by SK Telecom (SKT)

This looks very interesting and similar to some other concepts that I have discussed on 3G4G blog. One of them is the Multi-stream Aggregation (MSA) that allows aggregation of data from different radio access technologies. Another is the Phantom Cell concept, proposed by NTT Docomo, where control plane is handles by one cell and data by another. Small cells would generally do only data or larger cells would do control plane. Of course you can have different combinations as can be seen in the picture above.

This also reminds me of the earlier post about Super Macros. Is this SUPER cell a Phase 2 of the Super Macro kind of architecture? Or is it just a future 5G concept? Please feel free to add your comments.

Here is the embed of their complete presentation:

SUPER Cell – SK Telecoms’ Network Evolution Vision from Zahid Ghadialy

What are Homespots?

Recently I got introduced to the term 'Homespots'. While I knew what they are, I wasn't aware there was a term for them

The slide above and below are from a recent webinar by Maravedis-Rethink (embedded at the end of the post)

In UK we have BT FON and Openzone which are both Wi-Fi hotspot services. Openzone is actually a hotspot deployed and maintained by them while FON is actually a Homespot, which uses spare capacity from the open Home Hubs deployed in the homes. BT has some details about it here.

Anyfi whitepaper shows (see above pic) some of the technical challenges that need to be kept in mind while deploying Homespots.

Anyway, here is complete presentation from the webinar mentioned above

Video Offload -Six trends you NEED to understand! from Zahid Ghadialy

KDDI Japan, Traffic Offloading Strategy

While going through some KDDI presentations, came across how they planned and perform Offloading. In fact, even before the deployment of LTE, they were aware that the network capacity would not be enough for the savvy Japanese mobile phone users. They had to start planning for how to offload the users as soon as possible. 

au Wi-Fi is their Wi-Fi offloading strategy where they make Wi-Fi hotspots available for the users. They even claim that with Wi-Fi on, the baattery life could be 1.5 times the normal 3G battery life.

UQ WiMAX is another KDDI company that allows users with compatible handsets to offload to WiMAX. KDDI have their own WiMAX branded services as well, see here.

Finally, with the LTE rollout they have different hierarchical cells available that the user could be moved to if one of the layers is congested. 

Small Cells and Wi-Fi in 3GPP Releases

Here is a quick chart of features of Small Cells and Wi-Fi introduced by 3GPP in different releases. Please feel free to suggest anything that has been missed out.

Optimizing Small Cells and the HetNets

Came across a whitepaper from JDSU, not so new but its got some interesting stuff. In an earlier post here, we saw the challenges for small cells deployment, the picture above shows another view.

Another interesting item is adding intelligence to small cells. This can mainly help by reducing the traffic back to the core. This also relies on predicting the user behaviour which could be a challenge in it self. There is a lot more interesting stuff in the paper, which is embedded below:

JDSU: Optimizing Small Cells and the Heterogeneous Network (HetNet) from Zahid Ghadialy

New opportunities in Carrier Wi-Fi & Wi-Fi offload

Interesting webinar from Maravedis-Rethink exploring the new opportunities with Carrier-WiFi and Offloading. Embedded below is the video and presentation:

Carrier Wi-Fi & Wi-Fi offload from Zahid Ghadialy