Friday, 31 October 2014

Non-ideal backhaul for Small Cells

Recently I came across this Linkedin discussion on What is "non-ideal backhaul" so I thought it may be worth adding it to the blog. The simplest of explanation can be seen from the picture above that is extracted from 3GPP TR 36.932.

An ideal backhaul is defined as latency less than 2.5 microseconds and a throughput of upto 10Gbps. All other types of backhaul is non-ideal.

Another way of putting this is: If you look at the Release 12 study and technical report on Small Cell Enhancements, it is regarded as a backhaul that cannot carry a RRH to eNodeB link, which in turn has been interpreted as not meeting CPRI round trip and bandwidth requirements (via Kit Kilgour)

If you know anything additional, please feel free to add it in comments.

Sunday, 26 October 2014

In-building Wireless Solutions Webinar

Last month, David Chambers from ThinkSmallCell held a webinar exploring available In-building solutions and comparing the advantages and disadvantages of each solution, also looking at the approach taken by different vendors. Worth a look. The presentation and Youtube video are both embedded below.

Monday, 20 October 2014

Small Cells Equipment Magic Quadrant, by Gartner

Source: Gartner (October 2014)

Gartner has an excellent analysis of Small Cell equipment manufacturers with regards to their strengths and weaknesses. They have analysed the following 16 vendors:

Accelleran, Airspan, Airvana, Alcatel-Lucent, Argela, Cisco, Ericsson, Fujitsu, Huawei, ip.access, NEC, Nokia Networks, Ruckus Wireless, Samsung, SpiderCloud Wireless, ZTE

If interested, have a read here.

Friday, 10 October 2014

Small Cells: Interoperability and Plugfests for Multi-vendor HetNet's

Our recent Small Cells SIG in Cambridge Wireless was another full house with the topic under discussion being Small Cells Deployment: Whats the hold-up. One of the areas being tackled by Small Cell Forum is to have plugfests to identify the issues that are causing hold ups and fix them. There were two interesting presentations with interesting take on this topic. The first was by Neeraj Gupta and Kreso Bilan of NEC who are both very active in this interoperability and plugfests. Their presentation which doesnt need any explanation is embedded below:

The other presentation was by Nick Johnson of IP.Access who listed the problems and the source of the problems that gave rise to the interoperability issues and also gave a quick summary of what the plugfests achieved (see picture above). His slides are embedded below:

The conclusion of the event was that there are no issues or reasons for these hold-ups. The operators have been over cautious and preferred to play a waiting game but are now getting confidence and starting to deploy small cells. Some minor issues in interoperability revolves around X2 interface and SON but they should get ironed out in the couple plugfests planned for next year (see NEC slides).

Sunday, 28 September 2014

HetNet Strategies with Oi Brazil

Brazil has been in limelight since the beginning of the year. Initially, the focus was on how the FIFA World Cup may fail but later on for the way everything came together at the last minute and everything worked. From a technology point of view, WiFi was a big saviour in the stadiums, allowing good connectivity for everyone wishing to add the things they liked on social networks as soon as they can.

An example was this chart tweeted by Ruckus Wireless to proudly show what their achievement was with stadium WiFi.

Recently, Maravedis-rethink conducted a webinar with the Brazilian operator Oi, regarding their HetNet strategies. The video for the relevant part is embedded in the end. Two slides caught my attention. The first was about the different technologies and their concerns (above). For example for a HetNet to be successful, all components should synchronised and have a strict time accuracy requirements. The Backhaul & Fronthaul requirements are equally interesting for different cases.

The second interesting slide is the final one where they have their wish list to what they would like to do in near-term and long-term. WiFi features in all the scenarios except for the rural case (as expected). Anyway, here is the video:

You can download the slides from Slideshare here.

Sunday, 14 September 2014

Airvana's OneCell™ with C-RAN and Super-cell

Airvana recently announced its OneCell™ system was named the winner in the “In-Building Wireless – Small Cell, Wi-Fi, LAN” category of CTIA’s annual Emerging Technology (E-Tech) Awards competition. I remember back in June, it received a lot of praise for this product. So what exactly is so unique in this OneCell™.

From their press release back in June:

Based on cloud RAN principles, the OneCell system consists of a Baseband Controller and multiple Radio Points. Together they form a single "super" cell that delivers consistently high quality LTE service across indoor spaces ranging from 50,000 to 1,000,000 square feet without handovers or inter-cell interference issues. OneCell supports plug-and-play deployment over standard Ethernet cabling and switches, eliminating the need for proprietary networks or expensive optical links. Further, its unique small cell cloud RAN architecture dramatically simplifies radio frequency planning and integration with wireless macro networks.

There is a mention of C-RAN (though I have had discussion where this claims have been disputed), Super-cell and is pitched towards enterprises.

Airvana's website has a good picture explaining how a super-cell gets rid of interference on cell edges as all the cells work together as a single large cell.

In fact the scheduler can cleverly assign the same resource blocks to different users and hence increase capacity.

Below is a video explaining their solution in more details:

Wednesday, 3 September 2014

Wi-Fi Evolution and its Role in 5G Networks

Picture Source: EE Times Asia
'5G' is becoming a  very popular term. Every other day there is some sort of a press release about some company working on a 5G technology. Those who follow my blogs will nevertheless know that I think there will be an intermediate stage which we term as 4.5G where Wi-Fi and Cellular will work together, in harmony.

While the Release-12 of 3GPP standards have been focussing on many areas, the headline grabbing technology has been Carrier Aggregation (CA). 3 bands CA in the downlink and 2 band CA in the uplink is expected to become a norm. New UE categories 9 and 10 have been defined for this.

While 802.11n, 802.11ac and 802.11ad is now starting to gain popularity, discussion about the next generation of Wi-Fi standards, 802.11ax has just begun.

I recently came across an interesting presentation from Ericsson on this topic and I think it may be worth watching. The presentation is available here and video of the presentation is embedded below:

There are lots of other talks and presentations from the Johannesberg Summit 2014 that is available here.

Monday, 25 August 2014

Case Study: Deployment scenarios with DAS, RRH, Small Cells and Wi-Fi

I attended an interesting webinar (details in the end) from Infonetics Research, EXFO and ExteNet Systems where one of the areas of discussion was around which technology for which scenario. The four main technologies being considered was DAS, RRH, Small Cells and Wi-Fi. There was some interesting deployment examples that I have embedded below:

NOTE: If the slides are not working, please view it on Slideshare - slides 21 to 24

To watch the webinar recording and download slides, please follow this link:

Tuesday, 5 August 2014

New types of HetNet's Cell coordination

Came across this HetNet Infographic from Ericsson here. They are proposing something interesting as can be seen in the picture above. From the infographic:

Macro for downlink, micro for uplink
In the imbalance area, the downlink signal from the macro is the strongest, because it transmits at a much higher power, whereas the uplink signal from the pico node is much stronger, because it is closer. This provides the user with significantly higher uplink speeds than would be possible with macro coverage alone.
So if we have a macro with an overlay of small cells then the Macro can be used for DL and Small Cells for UL. This scheme is a counterintuitive to what I would have thought. Since there is a higher requirement in DL as opposed to UL, the uplink could be received by Macro and the DL could be sent from pico node. The macro also has bigger antennas and can process weak signals from the UE.


Ericsson and the South Korean operator, SK Telecom recently also demonstrated 'Elastic Cell'. As per Telecom TV:
The telco has confirmed that Elastic Cell technology is based on the 3GPP Release 11 CoMP specification, but with improved scheduling, energy efficiency, and cost efficiency. SK Telecom says it has applied downlink CoMP since early 2012 and uplink CoMP in April 2014, and both technologies are proprietary technology. Because coordination between networks will still be very important in 5G technologies, SK Telecom expects that Elastic Cell will become a key enabler for 5G.

Another similar approach that is proposed by NTT Docomo is the 'Phantom Cell' concept as described here. Their proposal is to separate control and user planes. Macro used for signalling (C-plane) and Small cells in higher frequencies for data (U-plane)

Finally, we also have the SK Telecom's SUPER Cell concept and blogged here. There is a lot of cell splitting in this but again we have the main frequency (lower) being able to do both control and data while the higher frequency is only to do data. Sounds a bit like the Phantom Cell and 'New Carrier Type' as blogged here before.

Are there any other types of cell coordination being discussed. Do you have any opinion on them? Feel free to add comments.

Thursday, 31 July 2014

Wi-Fi and Cellular: Authentication & Security

While in the past WiFi was considered not as secure as the cellular counterpart, things have been changing slowly and steadily. While the cellular is able to offer authentication using the EPS-AKA, Wi-Fi is now able to offer EAP-AKA and EAP-SIM. 

In fact the above table is quite interesting to know about. Recently I was following a discussion that talked about the lack of QoS support in WiFi. As we can see, its supported but not guaranteed. 

Devices that contain the USIM card can use EAP-AKA while that without one can offer EAP-SIM. EAP-AKA works in a similar way to the cellular authentication protocol EPS-AKA. For anyone who is interested in reading more details about the authentication and how it works, including signalling, see this whitepaper here.

If you haven't seen our whitepaper on Cellular and WiFi integration, please check it out here.