eMBMS Release-11 enhancements

Continuing on the eMBMS theme. In the presentation in the last post, there was introduction to the eMBMS protocols and codecs and mention about the DASH protocol. This article from the IEEE Communications magazine provides insight into the working of eMBMS and what potential it holds.

Evolved Multimedia Broadcast/Multicast Service (eMBMS) in LTE-Advanced: Overview and Rel-11 Enhancements from Zahid Ghadialy

eMBMS rollouts gathering steam in 2013

Its been a while since I last posted something on eMBMS. Its been even longer that we saw anything official from 3GPP on eMBMS. Recently I have seen some operators again starting to wonder if eMBMS makes business sense, while the vendors and standards are still working hard on the technology.

Not so long back, HEVC/H.265 codec was standardised. This codec helps transmission of the video using half the bandwidth. This means that it would be economical to use this for broadcast technologies. No wonder Nokia, Thompson and NTT Docomo are excited.

Interesting picture from a Qualcomm presentation (embedded in the end) shows how different protocols fit in the eMBMS architecture. My guess would be that the HEVC  may be part of the Codecs.

On the operators front, Korea Telecom (KT) has intentions for countrywide rollout. Korea is one of the very few countries where end users have embraced watching video on small form factors. Verizon wireless has already signalled the intention to rollout eMBMS in 2014; its working out a business case. Telenor Sweden is another player to join the band with the intention of adopting Ericsson's Multi screen technology.

One of the main reasons for the lack of support for the 3G MBMS technology was not a compelling business case. Qualcomm has a whitepaper that outlines some of the potential of LTE Broadcast technology here. A picture from this whitepaper on the business case below:

Finally, a presentation from Qualcomm research on eMBMS embedded below:

LTE eMBMS Technology Overview from Zahid Ghadialy

Cell Range Expansion (CRE)

The intention of the Pico Cells is to offload traffic from the Macro cells to increase the system capacity. As a result, when Macro cell becomes overloaded, it would make sense to offload the MUE’s in the vicinity of the Pico cell to it. This can/should be done even if the UE is receiving a better signal from the Macro cell. The expansion of the range of the Pico cell is termed as CRE or Cell Range expansion.

To make sure that the UE does not fail in the handover process, the Time domain ICIC should be used and Macro cell should use ABS. The UE’s can be configured to do measurements on the Pico when the Macro is using ABS. The MUE now reports the Measurement reports to the Macro and are handed over to the Pico to act as PUE.

Myths and Challenges in Future Wireless Access

Interesting article from the recent IEEE Comsoc magazine. Table 1 on page 5 is an interesting comparison of how different players reach the magical '1000x' capacity increase. Even though Huawei shows 100x, which may be more realistic, the industry is sticking with the 1000x figure. 

Qualcomm is touting a similar 1000x figure as I showed in a post earlier here.

Interference Management in HetNets

Interference Management is a big topic in HetNet's. An earlier blog post here on similar topic was very popular. The above picture shows a Heterogeneous cellular network topology incorporating different forms of small cell deployments as an overlay on the macrocell network. Small cells would generally use secure tunnels back to the core network using existing broadband infrastructure. Whereas in the HCS (Hierarchical Cell Structures), different layers have different frequencies, thereby not causing radio frequency interference, in HetNets same frequencies can be used between different layers. The same frequencies can cause radio frequency Interference and necessitates the use of advanced Interference avoidance techniques.

CTTC has another interesting presentation on Interference Management in HetNets that I am embedding below as slides and video:

Interference Management in Co-Channel Femtocell Deployment from Zahid Ghadialy

The 'Phantom Cell' concept in LTE-B

One of the LTE-B proposals by NTT Docomo is this 'Phantom Cell' concept. A recent article from the IEEE Communications Magazine expands this further:


Phantom Cell Concept — In the current deployments, there are a number of capacity solutions for indoor environments such as WiFi, femtocells, and in-building cells using distributed antenna systems (DAS). However, there is a lack of capacity solutions for high-traffic outdoor environments that can also support good mobility and connectivity. Thus, we propose the concept of macro-assisted small cells, called the Phantom Cell, as a capacity solution that offers good mobility support while capitalizing on the existing LTE network. In the Phantom Cell concept, the C-plane/U-plane are split as shown in Fig. The C-plane of UE in small cells is provided by a macrocell in a lower frequency band, while for UE in macrocells both the C-plane and U-plane are provided by the serving macrocell in the same way as in the conventional system. On the other hand, the Uplane of UE in small cells is provided by a small cell using a higher frequency band. Hence, these macro-assisted small cells are called Phantom Cells as they are intended to transmit UE-specific signals only, and the radio resource control (RRC) connection procedures between the UE and the Phantom Cell, such as channel establishment and release, are managed by the macrocell.

The Phantom Cells are not conventional cells in the sense that they are not configured with cell specific signals and channels such as cell-ID-specific synchronization signals, cell-specific reference signals (CRS), and broadcast system information. Their visibility to the UE relies on macrocell signaling. The Phantom Cell concept comes with a range of benefits. One important benefit of macro assistance of small cells is that control signaling due to frequent handover between small cells and macrocells and among small cells can be significantly reduced, and connectivity can be maintained even when using small cells and higher frequency bands. In addition, by applying the new carrier type (NCT) that contains no or reduced legacy cell-specific signals, the Phantom Cell is able to provide further benefits such as efficient energy savings, lower interference and hence higher spectral efficiency, and reduction in cellplanning effort for dense small cell deployments.

To establish a network architecture that supports the C/U-plane split, and interworking between the macrocell and Phantom Cell is required. A straightforward solution to achieve this is to support Phantom Cells by using remote radio heads (RRHs) belonging to a single macro eNB. This approach can be referred to as intra-eNB carrier aggregation (CA) using RRHs. However, such a tight CA-based architecture has some drawbacks as it requires single-node operation with low-latency connections (e.g., optical fibers) between the macro and Phantom Cells. Therefore, more flexible network architectures should be investigated to allow for relaxed backhaul requirements between macro and Phantom Cells and to support a distributed node deployment with separated network nodes for each (i.e., inter-eNB CA).

LTE for Public Safety Networks

The last presentation on this topic couple of months back has reached nearly 7K views so here is another one from a recent article on the same topic from IEEE Communications Magazine

From M2M Communications to IoT

M2M was again in the news recently when a new report suggested that it would be $1 Trillion industry. Back in december I posted a detailed presentation on M2M that has now crossed over 6K views. This shows that there is an appetite for this topic. So here is a three part presentation on M2M and IoT. In fact as I pointed out in a post last year, it is very often referred to as IoE (Internet of Everything) rather than IoT (Internet of Things). If this is a topic close to your heart then please do come to the Future of Wireless International Conference (FWIC) organised by Cambridge Wireless on 1st and 2nd July 2013. Details here.

What is WebRTC and where does it fit with LTE and IMS

This simple video from MWC should give an idea on what WebRTC is and can do:


So what exactly WebRTC is in technical terms. Here is a recent presentation from WebRTC Conference and Expo

WebRTC Technical Overview and Introduction from Zahid Ghadialy

And here is another presentation that explains where it fits in with the LTE Architecture.

Extending 4G Communications with WebRTC IMS and WebRTC from Zahid Ghadialy

Dean Bubley from Disruptive Analysis has writted extensively on this topic and his recent post "Is the telephony "threat" from VoIP & WebRTC about competition or contextualisation?" is an interesting read.

Iain Sharp from Netovate recently pointed out that 3GPP have 'nearly' approved a work item for WebRTC access to IMS.

It would be interesting to see how operators will view WebRTC. As an opportunity or as a threat. Please feel free to air your opinions via comments.

DAS or 'Small Cells' and What is DAS anyway?

Its been a while I posted something on DAS (a.k.a. Distributed Antenna System). The articles I have posted have been mainly from AT&T and are here, here and here.

Picture source: The IET

Recently I read something interesting from IDG here:

According to Rob Bruce, Chief Operating Officer at distributed antenna system (DAS) vendor Axell Networks, a building is an asset, and that asset wants to deliver all the services it can in the simplest and most economical way.

"You wouldn't put five separate lighting systems into a building because there are five separate tenants in that building. You would put one in, and it becomes a utility for that building," Bruce told Techworld.

"Our view of life is it's the same for cellular coverage. You put one system in which covers the building. That is then a utility for the building, and operators can then connect into that infrastructure - that's how a DAS system works."

Bruce said that small cells are very good for single operator environments, when a single operator wants to add some capability into a particular area. But if they want to put multiple technologies into that environment then they have to put in multiple small cells.

So if a company in the UK wants to put GSM, UMTS and LTE into an office block, it has to install three small cells. If it wants to make that truly operator agnostic, it will probably have to put in 12 units, because each of the four operators uses at least three spectrum bands.

Axell Wireless recently installed a multi-operator DAS in The Shard in London, using 20 remote units to cover the whole building. Bruce claimed that, if the same thing had been done using small cells, it would involve over 100 units.

"So the building owner is saying I've got 100 lumps of intelligent electronics gadgetry that is scattered all over my building, and there's 4 different operators wanting access to all those different things in private flats, hotels and offices - it's just an operational nightmare," said Bruce.

Complete article is available here.

This is an interesting point because the Small Cells are still not evolved enough so that a single one can serve multiple operators, etc. Note that I am differentiating the closed residential femtocells from the public access small cells. Maybe a service such as FaaS or 'Femto as a Service' can help solve this problem. Based on my previous sentences, some of you may say that it should be called Small Cell as a Service (SCaaS) rather than FaaS but unfortunately that term has come to mean something else as can be seen here.

While initially the in-building solutions were mainly for coverage reasons, this may no longer be the only reason. Capacity is also an issue, especially in-building. Small cells can certainly help in the capacity area much more than DAS. Fortunately as most new phones are coming with inbuilt Wi-Fi chipsets and WiFi is available indoors in plenty, the capacity issue may no longer be a problem indoors. Again this is an area where we can have lots of discussions and each party with a vested interest can argue their case.

Here are couple of interesting videos from youtube that explain DAS:




There is also an interesting presentation by NEC in the Small Cell Americas event, embedded below:

Optimising Small Cells Architectures for In-Building Solutions from Zahid Ghadialy