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.

Wednesday, 23 July 2014

SDN and Distributed NFV for Small Cell Mobile Backhaul

An interesting presentation on how Distributed NFV can be used for Small Cell backhaul. The calculations show that 80% TCO savings. The presentation is embedded below and the video is available for viewing here.

Monday, 21 July 2014

Case Study: Fastback IBR Small Cell Backhaul Usage Scenarios

An interesting presentation from the recent Small Cells World Summit 2014 (kindly shared by Lance Hiley of Fastback Networks). The first part is a trial by Virgin Media and the later part is the case study by Fastback networks where they used their Intelligent Backhaul Radio and reduced the number links required to obtain similar performance as compared to a 'line of sight' solution. The presentation is embedded as follows

Wednesday, 16 July 2014

Huawei's Lampsite

Huawei unveiled its 'Lampsite' for 'Deep Indoor Coverage' back in 2013. This is what they announced then:
LampSite includes a comprehensive set of BBU, RemoteHUB(rHUB) and PicoRRU(pRRU) products along with accompanying transmission solutions. The compact pRRU supports multiple bands and modes and can simultaneously support LTE TDD, LTE FDD, UMTS and GSM. A LampSite indoor coverage network can also be deployed simultaneously with Huawei’s SingleRAN solution. 
Thanks to BBU’s baseband sharing feature, one fiber is used for several cells, saving up to 87% of fiber typically used for indoor deployments. rHUB connects to pRRU by cable, and support power over Ethernet (PoE) to simplify site construction and reduce total deployment costs. 
In an early deployment phase, individual pRRU cells aggregate into one cell to reduce interference. Once the network offloads heavy traffic, the cells are split again and Adaptive SFN is enabled to balance capacity and interference. Huawei iManager system and evaluation tools are then used to accurately monitor and intelligently optimize indoor hotspot traffic.

This innovative solution has not only helped them to win contracts with China UnicomTDC Denmark and Telenor Norway but according to TMN magazine article, "Huawei is shipping more than 10,000 PRRUs (Pico Remote Radio Units) per month in some countries and regions for its LampSite in-building system, according to Peter Zhou, Huawei's President of Small Cell & WiFi, Wireless Network."

Recently Huawei and Telenor also won an award in the LTE World Summit for "Innovation in HetNet Development". With Huawei’s LampSite, Telenor is able to provide average downlink throughput of 46Mbps at any location in a building and significantly cut costs. Deployment of each pico Remote Radio Unit takes only three hours – from site survey, through installation, commissioning, to going live, ensuring rapid rollout in areas with weak signal penetration.

Based on presentations in different events, looks like Huawei is not complacent with its achievements. It plans to develop the next generation or NG Lampsite to achieve 1Gbps Indoor throughput with whole lot of technologies to help achieve this. Multi-stream Aggregation (MSA) being the key. See my earlier post on MSA on the 3G4G blog here.

Tuesday, 8 July 2014

Tight, Tighter and Very Tight Integration between LTE and WiFi Networks

For those who are unfamiliar about the trusted and non-trusted access, I strongly recommend reading our whitepaper on Cellular and WiFi Integration here.
The standard and the most popular Integration approach between LTE and Wi-Fi is via the Trusted architecture as shown above.

There is a proposal for RAN level Integration which would result in Even Tighter Integration of WiFi

Now some researchers are proposing a Very Tight coupling between LTE and Wi-Fi which would mean that regardless of the access, the UE can be sent data from the same data stream over WiFi and LTE. Though this is radical, these approaches are already being thought about for '5G'. Whether it will happen in a future release of 4G or 4.5G remains to be seen. Here is the complete paper embedded below:

Tuesday, 1 July 2014

3GPP Definitions of Small Cells

While the Small Cell Forum defines the different types of Small cells clearly and these Small Cells can be said to contain the complete/partial functionality of the eNodeB, 3GPP definitions of Small Cells can be a bit fuzzy sometimes.

Generally, in the 3GPP documentation, there is a reference to Femtocells and Picocells. Femtocells are Small Cells that are defined as Closed Access (see my old post here) by 3GPP. The open access small cells are referred to as Picocells. Sometimes remote radio heads (RRH's) are also referred to as Small cells, open access type.

Relays, even though not referred to as Small Cells by 3GPP, is also referred to as Small Cells by some people.

Do you know of anything else?

Sunday, 15 June 2014

Small Cells World Summit (#SCWS14) Video and Summary Articles

The Small Cells World Summit concluded last week. The main highlight was the Release 4 of Small Cell Forum on Urban, building on top of Release 3 - Urban foundations

Around 20 new documents have been published, available here on this release. Land Mobile has more details about this launch by Small Cell Forum here.

There were couple of interesting videos from the event by ThinkSmallCell and ConvergeDigest, they are embedded below:

Other related links (new links will be added as and when available):

Wednesday, 11 June 2014

X2: The necessity for Interoperability and Interference management in HetNets

Recently I wrote an article in the TMN magazine here about HetNet co-ordination. One important point that I mentioned here (and in several of the trainings that I do) is that X2 can be quite a useful interface, especially when you want to manage Interference between just macro cells or between different types of cells, as in HetNet environment. From the TMN article:

The initial deployments of LTE did not pay too much emphasis on X2 interface being present. Inter-operability was another issue for which X2 didn’t work very well. One of the major benefits of having an X2 interface is that different base stations or eNodeB’s (hereafter referred to as just eNB’s) can talk to each other and coordinate to make sure interference is kept at the minimum, especially on the cell edges. The Macro-cell’s had the provision for the X2 interface from the beginning, which formed the basis for Inter-Cell Interference Coordination (ICIC). Initially, the Small-cell’s didn’t have a facility for an X2 interface amongst them or with the Macro-cell. The support of X2 for Small-cell’s was added in 3GPP Release-10 and 3GPP Relese-11 (hereafter referred to as just Release-10 and Release-11) as seen in the picture. X2 for Small-cell’s is crucial for Interference management in HetNets.

The Small Cell Forum just published a whitepaper called "X2 interoperability in multi-vendor X2 HetNets". This paper is quite interesting with just the right amount of details. In their own words:

A key area of standardization needed to support small cells relates to the procedures to assist co-ordination with macrocells over LTE’s ‘X2’ interface. This document surveys standards currently in place to support frequency domain interference coordination,time domain interference coordination, mobility robustness and mobility load balancing. 

The whitepaper is available to download from here and is embedded below:

Sunday, 8 June 2014

The role of Small Cells, CoMP and Massive MIMO in 5G

Embedded below is a recent paper from IEEE Communications Magazine on the role of various techniques in 5G. The main focus is achieving higher spectral efficiency. From the paper: "From a high-level perspective, there are three main contributors to reaching higher spectral efficiency: advanced interference mitigation, small cells for densification of the network nodes, and massive multiple-input multiple-output (MIMO), that is, a significant increase in the number of antennas at the base station and potentially also at the terminal."