Improvement in Interference Rejection and Suppression Technology

In the last post where I talked about FeICIC I mentioned about the advanced Interference rejecting receivers, here is one very good article from NTT Docomo technical journal. The following is from this article:

Rel. 11 LTE has introduced MMSE-Interference Rejection Combining (MMSE-IRC) receivers as a mobile terminal interference rejection and suppression technology to mitigate the effects of these interference signals and increase user throughput even in areas that are recently experiencing high interference. Rel. 8 LTE receivers support MIMO transmission technology, so receivers were equipped with at least two antennas since it was first introduced. The MMSE-IRC receivers in Rel. 11 LTE, are able to use the multiple receiver antennas to create points, in the arrival direction of the interference signal, where the antenna gain drops (“nulls”) and use them to suppress the interference signal (Figure 1). The terminal orients a null toward the main interference signal, which is the signal that particularly affects the degradation of throughput, thereby improving the Signal-to-Interferenceplus-Noise power Ratio (SINR) and improving throughput performance.

However, with the original MIMO multiplexed transmission, which realized high throughput using multiple transmit and receiver antennas, the receiver antennas are used to separate the signals between layers, so interference from adjacent cells cannot be suppressed and throughput cannot be improved, particularly for mobile terminals with two receiver antennas.

On the other hand, the 3GPP has already included interference rejection and suppression technology in performance specifications for mobile terminals equipped with W-CDMA/High-Speed Downlink Packet Access (HSDPA) in Rel. 7 of the Universal Mobile Telecommunications System (UMTS). With W-CDMA, receivers normally use one receiver antenna and perform Rake reception, but the effects of multipath interference degrading reception performance was an issue.

Thus, the following three receiver extensions were studied and introduced.
• Type 1/1i extends the Rake receiver to use two antennas.
• Type 2/2i extends the Rake receiver to an MMSE receiver that suppresses multipath and adjacent-cell interference.
• Type 3/3i extends the MMSE interference-suppressing receiver defined in Type 2/2i to use two receiver antennas.

The functional extensions in receivers in Rel.7 UMTS and Rel. 11 LTE are summarized in Table 1. The MMSE-IRC receivers in Rel. 11 LTE incorporate receiver algorithms that are generally equivalent to those in the Type 3/3i receivers introduced in WCDMA/HSDPA. However, in the WCDMA/HSDPA receivers they also operate to suppress inter-coding interference within a cell. There is no interference within a cell in LTE systems, so in the MMSE-IRC receivers introduced in Rel. 11 LTE, they operate to suppress interference arriving from adjacent cells.

From my understanding, a similar approach is being proposed for the Mobile Relay Node (MRN)

Anyway, the complete article is as follows:

Improved Interference Rejection and Suppression Technology in LTE Release 11 Specifications from Zahid Ghadialy

WebRTC (Web Real-Time Communication) Updates

Its been a while since I last blogged about WebRTC. Things have been progressing as rather fast pace in this area.



WebRTC capabilities have quietly sneaked in our browsers. There is a debate about who would move to WebRTC before, Apple or Microssoft; Tsahi Levent-Levi makes his predictions here.



As per Light Reading, Japanese operator NTT has opened a WebRTC based chatroom recently.



The Korean operator SK Telecom as been showing off its WebRTC interworking with IMS platform.



The problem with WebRTC can be as seen in the slide above. Classic problem of what was promised and whats the reality.

There are 2 interesting presentations that I am embedding below that I found useful:

Additional Reading:

• Alan Quayle: IMS and WebRTC Workshop
• Disruptive Analysis WebRTC Market Status & Forecast Update - March 2014
• Snapchat made a secret acquisition to power its new video chat - Verge

Further enhanced Inter-Cell Interference Coordination (FeICIC)

Recently while delivering a training, I realised that this is a topic that I haven't covered in the blog before, even though I have been talking about it for a while. FeICIC has been introduced in Release-11 and there are a few enhancements as shown above. The main being that instead of an Almost Blank Subframe (ABS) with no other information except for the reference signals, now there is a possibility of reduced power ABS where the data on PDSCH can still be transmitted but on a reduced power level. This would ensure that the capacity of the interferer is not wasted.

Another enhancement on which FeICIC depends on are the advanced receivers (should do a post on it sometime soon). Another feature that allows a better probability of reception is the Transmission Mode 9 (TM9 - see blog post here)

An interesting comment that I received on my Deployments Dilemma Post is also relevant to the discussion here:

The ground reality is generally a lot different than theory. Metrocells often face interference not just from Macrocells but also other Metrocells. The ABS patterns are not just straightforward Macro to pico case but even pico to pico and multiple macros to pico.

Until all the handsets and other dongles could be upgraded with advanced interference cancellation receivers, there would be many scenarios where deployment option 2 may be chaotic. Deployment option 1 can serve the users well in the meantime. 

We can sacrifice efficiency for reliability in the meantime.

I recently posted the Small Cells Research Bible on the Small Cells blog here, the following is the Interference Management part that would help anyone willing to learn more about this feature.

Recent Advances in Wireless Small Cell Networks from Zahid Ghadialy

LTE Deployment Dilemma

Earlier this month during our Cambridge Wireless Small Cells SIG event, I presented a small quiz in the final session. The first part of the quiz was titled "LTE Deployment Dilemma" and it generated lots of interesting discussions. After the event, I did a more detailed writeup of that and Cisco has kindly published it in their SP Mobility Blog. Since many people have told me that they cannot anonymously post comments there, I am now bringing it to this blog. I am interested in hearing what others think.

Here is the complete post

LTE Deployment Dilemma from Cisco Service Provider Mobility

Different flavours of Bluetooth: 4.0, 4.1, Low Energy, Smart, Smart Ready...

Once upon a time, Nokia proposed a standard called Wibree. That standard was good enough to be merged with Bluetooth SIG and then become part of Bluetooth Low Energy (Bluetooth LE or BLE) standards.

The Bluetooth Low Energy standards comes in two different flavours, 'Smart' and 'Smart Ready'

The Smart and Smart Ready were introduced in 2011 to explain which devices will be compatible to what. Here is a table which explains how interoperability would work.

One of the obvious use of Bluetooth Low Energy is in Beacons. Here is an excellent presentation on Bluetooth 4.0:

Bluetooth 4.0: Low Energy from Zahid Ghadialy

Bluetooth 4.1 brings new capabilities in Bluetooth for it to become a challenger for Internet of Things (IoT). Here is an extract from an article in Network Computing:

With 4.1, the Bluetooth SIG is aiming to become a major player in the much-hyped Internet of Things (IOT) market. While 4.0 steps on Wi-Fi’s turf for location-based interaction with client devices, Bluetooth 4.1 looks to leverage Bluetooth's broad name recognition, widespread acceptance, and new low-power capabilities to compete with technologies that also want in on the IOT. These include ZigBee and Near Field Communication, both which are arguably niche technologies that just aren't familiar to many people.

As IoT looms larger for environments of all sizes, Bluetooth 4.1 allows client devices to daisy-chain to each other and multiple devices simultaneously for larger networks that are more Zigbee-like. Perhaps the biggest change for those of us who have to guide our network environments into the future: Bluetooth’s latest version lays the groundwork for dedicated device channels and the use of IPv6 for smart sensors to bridge themselves out of the isolated PAN world and into the IOT. This represents a major and substantial change to the Bluetooth mission, and will absolutely impact the Zigbee market in some substantial way.

Other features with Bluetooth 4.1 make it generally better in its PAN role. Bluetooth has been improved to ensure that nearby LTE radios (frequently under the same device hood) are not interfered with. It has a longer allowable interval between service advertisements, for better battery life and less chatter in the busy 2. GHz band. One of the big gains with 4.1 is the Bulk Transfer feature. For example, the feature would allow my fitness gizmo to auto-transfer all the data it's recorded of my gym activities when I get within range of my cell phone to update the app that tracks my activities.

An FAQ from the Bluetooth SIG on 4.1 is embedded below:

BLUETOOTH® 4.1 FREQUENTLY ASKED QUESTIONS from Zahid Ghadialy

International LTE Data and VoLTE Roaming - NTT Docomo

Quick recap of the Bearer Architecture: Remember the interface between S-GW and P-GW is known as S5/S8. S5 in case the S-GW and P-GW are part of the same network (non-roaming case) and S8 in case where P-GW belongs to another network than S-GW (roaming case). The S5/S8 interfaces are generally exactly the same. There is a possibility of different types of S5/S8 interfaces like GTP based and PMIP based but lets not discuss that here.

NTT Docomo published an excellent article in their magazine recently showing the different approaches to International Data roaming.

The different scenarios above are based on the guidelines provided in GSMA PRD IR.88. Each operator has to adopt one of the scenarios above, NTT Docomo has selected scenario 4. The Home PLMN (HPLMN) and the Visited PLMN (VPLMN) connect via IP eXchange (IPX).

As can be seen above, the MME in VPLMN communicates with HSS in HPLMN using Diameter Edge Agent (DEA).

Finally, it is well known that NTT Docomo is not launching VoLTE untill 2015. The above is their proposal on how they handle VoLTE while in Japan and when roaming.

The paper is an interesting read, embedded below:

NTT Docomo: Implementing LTE International Data Roaming from Zahid Ghadialy

Another article worth a read is the VoLTE roaming with RAVEL here.

LTE-Broadcast of the operator, by the operator, for the operator!

Heard an insightful talk from EE in the CW event this week. While I agree with the intentions and approaches, I still think there may be too many assumptions in the eMBMS business model. I have made my intentions known all but too well in my earlier blog post here.

Some of the insights that I have gained in the last couple of months with regards to the way operators are planning to use the LTE broadcast is through the OTT Apps. Take for instance an OTT application like iPlayer or Hulu and some popular program is about to be broadcast, that program can be sent using LTE-B. Now some people may watch on the time (linear) and some may watch at a later time (non-linear or time-shifted). The App can be intelligent enough to buffer the program so there is no delay required when the user wants to watch it. This can open all sorts of issues like the user may have watched one episode on his device while the current one is being watched on his digital television. While the program is being buffered the battery and memory of the device is being consumed. How long should a program be stored on the device. There can be many other open issues.

Another question I had was how would the users be billed for these things. Would it be free since the data was received over LTE-B. Matt Stagg from EE said that the users would be billed normally as if they received it in case of streaming. He was more pragmatic though. He clearly said that in the initial phase everything would have to be free. This will ensure that any technical issues are ironed out and at the same time the users become familiar with how all this works.

Finally a point worth remembering, users prefer watching videos on their tablets. Most tablets are WiFi only which means the LTE-Broadcast wont work on it.

The presentation is embedded as follows:

LTE as a TV and Video Distribution Network - EE from Zahid Ghadialy

Some interesting April Fools' Day 2014 Technology Jokes

Its very interesting to see all the companies proposing very interesting concepts on the 1st of April. I was told that not everyone knows what April Fools day means so here is the link to Wikipedia.

Samsung Fly-Fi: Samsung has come up with some interesting ideas, the first being Wi-Fi for everyone powered by Pigeons. They have a website here with Video.




Looks like since we have Pigeons everywhere, so they are always used in one way or the other. The best prank ever in my opinion was the PigeonRank by Google, back in 2002. I spent a few hours that day trying to figure out how they were actually doing it.

Smart Wear was always going to be the big thing. Quite a few smart wearables this year.

Bonobos has done a good job with with TechStyle. See video below:



Samsung has a glove called Samsung Fingers here. The best thing I liked was 'Talk to the Hand'



HTC came up with similar concept called Gluuv



Toshiba's DiGiT is as interesting. See the video:


Virgin Mobile, Canada has come up with SmartKicks. See here.



Roku Watch is not too bad:


Virgin America even convinced Sir Richard Branson to appear in the April Fools ad along with Tony Faddell, the CEO of Nest. Funny Youtube video here.

Sony Power Food was just okay, video here.

Toshiba Spehere is a funny Gaming concept, see here.

Nokia reviewed its most popular phone 3310 with modern day features here. Coloured screen with 41Megapixel camera.

Google wants to Emojify the web here.

Google Japan has a magic hand here.

Selfiebot by Orbotix is a cool concept, here.

Twitter Helmet didnt make me laugh though. See here.

Is there some others that I missed? Please feel free to add it in the comments.

MNO, MVNO, MVNA, MVNE - The different types of operators

A new video and simplified presentation on this topic is available on 3G4G page here.

It took me quite a while trying to understand the different types of operators and the differences between them. Here is a short summary. Please feel free to add more information or correct me where needed


Mobile Network Operator (MNO): The MNO is the most commonly visible mobile network operator. Examples would be the likes of Vodafone, Verizon, T-Mobile, Orange, Telefonica, etc. These MNO's are responsible for creating the mobile network. They have to purchase/lease the spectrum from the regulatory body of the country and then purchase/lease the network equipment from the vendors. They have to then get into an agreement with various handset suppliers, do various testing, etc. They are responsible for the day to day running of the network and would be blamed if there are problems or if the quality of experience is not as expected.

The MNO has to maintain its own Operation Support Systems (OSS) and Business Support Systems (BSS). They are responsible for billing the direct customers and may also be responsible for indirectly billing the customers of MVNO's.


Mobile Virtual Network Operator (MVNO): An MVNO relies on the infrastructure and most other things provided by the MNO. The MNO may have plenty of spare capacity that it may be willing to sell at a cheaper price or a different rate. They wouldn't want to do this themselves as this may dilute the brand. To solve this they may sell the messages, voice minutes and data at a much cheaper price in wholesale to an MVNO. Examples of popular MVNO's include Virgin Mobile, Lyca Mobile, Walmart mobile, Lebara Mobile, etc.

A full fledged MVNO will have its own OSS/BSS software and would be responsible for billing its own customers but a smaller MVNO may rely on the MNO to provide usage information for its customers that it can bill.


Mobile Virtual Network Aggregator (MVNA): Sometimes, it makes little or no sense to have many small MVNO's connected to the MNO. As a result, MNO may decide to only sell the discounted bundles to really big players. An MVNA can aggregate lots of small MVNO's and using the collective might, be able to connect to the operator as a single MVNO. MVNA's will typically not have direct subscribers but only other smaller MVNO's that connect to it. It would typically have to have an own OSS/BSS to be able to provide accurate billing information to the MVNO's.


Mobile Virtual Network Enabler (MVNE): An MNO may decide to outsource all functionality related to virtual networks to an MVNE. The MVNE may do similar functionality like an MVNA or it may even allow MVNA to connect to the MNO via itself. It may allow MVNO's to connect to MNO's through it and in special cases, it may even provide sell services directly to customers. The main reason for it being called an Enabler is because its enables smaller MVNO's to be created. It can provide services to such as billing, network element provisioning, administration, operations, support of OSS/BSS, etc. to MVNOs. An MVNE typically would not have any relationship with end-user customers, instead focussing on providing infrastructure and services to enable MVNO's to offer services and have a relationship with end-user brand, customer loyalty and marketing and leave the back-end enablement to MVNE's.

The MVNO's could be Full or Light MVNO's. The above picture shows different variants but in simple terms a Full MVNO has its own HLR while the Light(er) MVNO's use the HLR of the MNO where it enters the details of its own subscribers. A Full MVNO has considerably more power as it may decide to move to another MNO for service if its not happy with the service provided by an MNO. It would definitely also mean a lot more investment as opposed to the lighter models.

Sometimes MVNOs refer to themselves as Skinny, Thin or Thick as can be seen in the picture above. My guess is that its just another term for Full, Light or Branded resellers.

Finally, we may be in what is being termed as MVNO 3.0. As per this PwC article:

The first generation of MVNOs was spawned during an era of regulatory concerns and rapid growth in the wireless industry. They struggled to compete with the very network owners who were selling them capacity. The second generation, known in some circles as MVNO 2.0, sought to change the playing field by basing customer relationships on innovative devices such as the iPhone and the Jitterbug. Could we be witnessing the end of the era of the branded network operator? Here are four key changes currently underway that could make MVNO 3.0 a reality.

Finally, if you have enough time and patience, there is an interesting list of articles to read on this topic.

Additional reading:

• MVNA MVNE MVNO MNO - SIM Surprise
• WHAT IS AN MVNO, MVNE, MVNA? - http://www.mobile-virtual-network.com/
• InvesTelecom - MVNO, MVNE
• Prospering in a new MVNO hype cycle - Informa
• What do MVNA’s bring? - Cognatel
• Full MVNO and LIght MVNO - Georges-Harald Bernard's blog
• The Coming of MVNO 3.0 - PWC
• Insight: MVNO 3.0
• MVNOs explained

A quick case study on Smartwatches

My presentation from the Cambridge Wireless Connected devices SIG event "On Trend – High Fashion meets High Technology" held today, is embedded below. One of my favourite ads that highlights our fascination with the smart watches has been shown very well in a advert by Samsung mobile USA as follows:



I believe there is an opportunity and a market for the smart wear and smartwatches. There is a need for just the right kind of products to capitalise on the demand.