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Friday, 21 November 2014

In-flight broadband connectivity service with speeds up to 75Mbps


Came across the following Inmarsat press release:

The new network represents two world-beating achievements for Inmarsat and its partners. It will be the world’s first truly hybrid aviation network, consisting of an S-band satellite (Europasat), constructed by Thales Alenia Space, and a Europe-wide S-band ground network. Over the integrated network, based on state-of-the-art LTE technology and access to sufficient spectrum resources, Inmarsat will be offering airlines the world’s fastest in-flight broadband connectivity service with speeds up to 75Mbps, far in excess of the limited capabilities of North American ATG systems.
Alcatel-Lucent and Inmarsat will work together to develop the ground infrastructure component of the new Europe-wide network. Alcatel-Lucent has proven expertise in the development of 4G LTE-based air-to-ground technology and was the world’s first company to field trial this technology in 2011. The initial contract awarded to Alcatel-Lucent will see the global telecommunications equipment company adapting their existing 4G LTE technology to support the S-band spectrum.
Recently Christophe WILHELM, Senior VP Strategy & Innovation, Thales Alenia Space gave a presentation in the Digiworld Summit 2014.



His presentation is above and the video is as follows. Please forward to 1:36:00 to watch his part



Tuesday, 18 November 2014

SON Update from 3GPP SA5

Below is a presentation from Christian Toche, 3GPP SA5 chairman in the SON Conference last month. I also blogged about his presentation last year which is available here.



Sunday, 16 November 2014

Is mobile eating the world?

Another interesting and thought provoking presentation by Ben Evans. His earlier presentation which was very popular as well, is here. The video and slides are embedded below.


How Mobile is Enabling Tech to Outgrow the Tech Industry from Andreessen Horowitz on Vimeo.




And a recent interview by Benedict Evans with Bloomberg TV on the same topic as follows:


Tuesday, 11 November 2014

New Spectrum Usage Paradigms for 5G

Sometime back I wrote a post that talked about Dynamic Spectrum Access (DSA) techniques for Small Cells and WiFi to work together in a fair way. The Small Cells would be using the ISM bands and Wi-Fi AP's would also be contending for the same spectrum. For those who may not know, this is commonly referred to as LTE-U but the correct term that is being used in standards is LA-LTE, see here for details.

IEEE Comsoc has just published a whitepaper that details how the spectrum should be handled in 5G to make sure of efficient utilisation. The whitepaper covers the following:

Chapter 2 – Introduction, the traditional approach of repurposing spectrum and allocating it to Cellular Wireless systems is reaching its limits, at least below the 6GHz threshold. For this reason, novel approaches are required which are detailed in the sequel of this White Paper.

Chapter 3 - Spectrum Scarcity - an Alternate View provides a generic view on the spectrum scarcity issue and discusses key technologies which may help to alleviate the problem, including Dynamic Spectrum Management, Cognitive Radios, Cognitive Networks, Relaying, etc. 

Chapter 4 – mmWave Communications in 5G addresses a first key solution. While spectrum opportunities are running out at below 6 GHz, an abundance of spectrum is available in mmWave bands and the related technology is becoming mature. This chapter addresses in particular the heterogeneous approach in which legacy wireless systems are operated jointly with mmWave systems which allows to combine the advantages of both technologies. 

Chapter 5 – Dynamic Spectrum Access and Cognitive Radio: A Current Snapshot gives a detailed overview on state-of-the-art dynamic spectrum sharing technology and related standards activities. The approach is indeed complementary to the upper mmWave approach, the idea focuses on identifying unused spectrum in time, space and frequency. This technology is expected to substantially improve the usage efficiency of spectrum, in particular below the 6GHz range. 

Chapter 6 – Licensed Shared Access (LSA) enables coordinated sharing of spectrum for a given time period, a given geographic area and a given spectrum band under a license agreement. In contract to sporadic usage of spectrum on a secondary basis, the LSA approach will guarantee Quality-of-Service levels to both Incumbents and Spectrum Licensees. Also, a clear business model is available through a straightforward license transfer from relevant incumbents to licensees operating a Cellular Wireless network in the concerned frequency bands. 

Chapter 7 – Radio Environment Map details a technology which allows to gather the relevant (radio) context information which feed related decision making engines in the Network Infrastructure and/or Mobile Equipment. Indeed, tools for acquiring context information is critical for next generation Wireless Communication systems, since they are expected to be highly versatile and to constantly adapt. 

Chapter 8 – D2DWRAN: A 5G Network Proposal based on IEEE 802.22 and TVWS discusses the efficient exploitation of TV White Space spectrum bands building on the available IEEE 802.22 standard. TV White Spaces are indeed located in highly appealing spectrum bands below 1 GHz with propagation characteristics that are perfectly suited to the need of Wireless Communication systems. 

Chapter 9 – Conclusion presents some final thoughts. 

The paper is embedded as follows:



Wednesday, 5 November 2014

2015 will finally be the year of Voice over LTE (VoLTE)


On 4th Nov. 2009, the One Voice initiative was published by 12 companies including AT&T, Orange, Telefonica, TeliaSonera, Verizon, Vodafone, Alcatel-Lucent, Ericsson, Nokia Siemens Networks, Nokia, Samsung and Sony Ericsson. These all agreed that the IMS based solution, as defined by 3GPP, is the most applicable approach to meet their consumers expectations for service quality, reliability and availability when moving from existing CS based voice services to IP based LTE services.

On 15th Feb 2010, GSMA announced that it has adopted the work of the One Voice initiative to drive the global mobile industry towards a standard way of delivering voice and messaging services for LTE. The GSMA’s VoLTE initiative was supported by more than 40 organisations from across the mobile ecosystem, including many of the world’s leading mobile communication service providers, handset manufacturers and equipment vendors, all of whom support the principle of a single, IMS-based voice solution for next-generation mobile broadband networks. This announcement was also supported by 3GPP, Next Generation Mobile Networks alliance (NGMN) and the International Multimedia Teleconferencing Consortium (IMTC).

GSMA has produces various reference documents that map to the 3GPP standards documents as can be seen above.



As per GSA71 operators are investing in VoLTE studies, trials or deployments, including 11 that have commercially launched HD voice service. The number of HD voice launches enabled by VoLTE is forecast to reach 19 by end-2014 and then double in 2015. In July 2014 GSA confirmed 92 smartphones (including carrier and frequency variants) support VoLTE, including products by Asus, Huawei, LG, Pantech, Samsung and Sony Mobile. The newly-announced Apple iPhone 6 & 6 Plus models support VoLTE.

Things are also moving quickly with many operators who have announced VoLTE launches and are getting more confident day by day. Du, Dubai recently announced Nokia as VoLTE partner. KDDI, Japan is launching au VoLTE in December. Telstra, Australia has already been doing trials and plans to launch VoLTE network in 2015. Finally, Verizon and AT&T will have interoperable VoLTE calls in 2015.

Below is my summary from the LTE Voice Summit 2014. Let me know if you like it.


Saturday, 1 November 2014

4G Security and EPC Threats for LTE

This one is from the LTE World Summit 2014. Even though I was not there for this, I think this has some useful information about the 4G/LTE Security. Presentation as follows:


Thursday, 30 October 2014

Codecs and Quality across VoLTE and OTT Networks

Codecs play an important role in our smartphones. Not only are they necessary and must for encoding/decoding the voice packets but they increase the price of our smartphones too.

A $400 smartphone can have as much as $120 in IPR fees. If you notice in the picture above its $10.60 for the H.264 codec. So its important that the new codecs that will come as part of new generation of mobile technology is free, open source or costs very little.


The new standards require a lot of codecs, some for backward compatibility but this can significantly increase the costs. Its important to make sure the new codecs selected are royalty-free or free license.

The focus of this post is a presentation by Amir Zmora from AudioCodecs in the LTE Voice Summit. The presentation below may not be self-explanatory but I have added couple of links at the bottom of the post where he has shared his thoughts. Its worth a read.



A good explanation of Voice enhancement tools as follows (slide 15):

Adaptive Jitter Buffer (AJB) – Almost all devices today (Smartphones, IP phones, gateways, etc.) have built in jitter buffers. Legacy networks (which were LAN focused when designed) usually have older devices with less sophisticated jitter buffers. When designed they didn’t take into account traffic coming in from networks such as Wi-Fi with its frequent retransmissions and 3G with its limited bandwidth, in which the jitter levels are higher than those in wireline networks. Jitter buffers that may have been planned for, say, dozens of msec may now have to deal with peaks of hundreds of msec. Generally, if the SBC has nothing to mediate (assume the codecs are the same and the Ptime is the same on both ends) it just forwards the packets. But the unexpected jitter coming from the wireless network as described above, requires the AJB to take action. And even if the network is well designed to handle jitter, today’s OTT applications via Smart Phones add yet another variable to the equation. There are hundreds of such devices out there, and the audio interfaces of these devices (especially those of the Android phones) create jitter that is passed into the network. For these situations, too, the AJB is necessary.

To overcome this issue, there is a need for a highly advanced Adaptive Jitter Buffer (AJB) built into the SBC that neutralizes the incoming jitter so that it is handled without problem on the other side. The AJB can handle high and variable jitter rates.

Additionally, the AJB needs to work in what is called Tandem scenarios where the incoming and outgoing codec is the same. This scenario requires an efficient solution that will minimize the added delay. AudioCodes has built and patented solutions supporting this scenario.

Transcoding – While the description above discussed the ability to bypass the need to perform transcoding in the Adaptive Jitter Buffer context, there may very well be a need for transcoding between the incoming and outgoing packet streams. Beyond being able to mediate between different codecs on the different networks on either end of the SBC, the SBC can transcode an incoming codec that is less resilient to packet loss (such as narrowband G.729 or wideband G.722) to a more resilient codec (such as Opus). By transcoding to a more resilient codec, the SBC can lower the effects of packet loss. Transcoding can also lower the bandwidth on the network. Additionally, the SBC can transcode from narrowband (8Khz) to wideband (16Khz) (and vice versa) as well as wideband transcoding, where both endpoints support wideband codecs but are not using the same ones. For example, a wireless network may be using the AMR wideband codec while the wireline network on the other side may be using Opus. Had it not been for the SBC, these two networks would have negotiated a common narrowband codec.

Flexible RTP Redundancy – The SBC can also use RTP redundancy in which voice packets are sent several times to ensure they are received. Redundancy is used to balance networks which are characterized by high packet loss burst. While reducing the effect of packet loss, Redundancy increases the bandwidth (and delay). There are ways to get around this bandwidth issue that are supported by the SBC. One way is by sending only partial packet information (not fully redundant packets). The decoder on the receiving side will know how to handle the partial information. This process is called Forward Error Correction (FEC).

Transrating – Transrating is the process of having more voice payload ‘packed’ into a single RTP packet by increasing the packet intervals, thus changing the Packetization Time or Ptime. Ptime is the time represented by the compression of the voice signals into packets, generally at 20 msec intervals. In combining the payloads of two or more packets into one, the Transrating process causes a reduction in the overhead of the IP headers, lowering the bandwidth and reducing the stress on the CPU resources, however, it increases delay. It thus can be used not only to mediate between two end devices using different Ptimes, but also as a means of balancing the network by reducing bandwidth and reducing CPU pressure during traffic peaks.

Quality-based Routing – Another tool used by the SBC is Quality-based routing. The SBC, which is monitoring all the calls on the network all the time, can decide (based on pre-defined thresholds and parameters) to reroute calls over different links that have better quality.

Further reading:


Thursday, 23 October 2014

Detailed whitepaper on Carrier Aggregation by 4G Americas

4G Americas has published a detailed whitepaper on Carrier Aggregation (CA). Its a very good detailed document for anyone wishing to study CA.


Two very important features that have come as part of CA enhancements were the multiple timing advance values that came as a part of Release-11 and TDD-FDD joint operation that came part of Release-12

While its good to see that up to 3 carriers CA is now possible as part of Rel-12 and as I mentioned in my last post, we need this to achieve the 'Real' 4G. We have to also remember at the same time that these CA makes the chipsets very complex and may affect the sensitivity of the RF receivers.

Anyway, here is the 4G Americas whitepaper.


LTE Carrier Aggregation Technology Development and Deployment Worldwide from Zahid Ghadialy

You can read more about the 4G Americas whitepaper in their press release here.

Sunday, 19 October 2014

What is (pre-5G) 4.5G?

Before we look at what 4.5G is, lets look at what is not 4.5G. First and foremost, Carrier Aggregation is not 4.5G. Its the foundation for real 4G. I keep on showing this picture on Twitter


I am sure some people much be really bored by this picture of mine that I keep showing. LTE, rightly referred to as 3.9G or pre-4G by the South Korean and Japanese operators was the foundation of 'Real' 4G, a.k.a. LTE-Advanced. So who has been referring to LTE-A as 4.5G (and even 5G). Here you go:


So lets look at what 4.5G is.
Back in June, we published a whitepaper where we referred to 4.5G as LTE and WiFi working together. When we refer to LTE, it refers to LTE-A as well. The standards in Release-12 allow simultaneous use of LTE(-A) and WiFi with selected streams on WiFi and others on cellular.


Some people dont realise how much spectrum is available as part of 5GHz, hopefully the above picture will give an idea. This is exactly what has tempted the cellular community to come up with LTE-U (a.k.a LA-LTE, LAA)

In a recent event in London called 5G Huddle, Alcatel-Lucent presented their views on what 4.5G would mean. If you look at the slide above, it is quite a detailed view of what this intermediate step before 5G would be. Some tweets related to this discussion from 5G Huddle as follows:

Finally, in a recent GSMA event, Huawei used the term 4.5G to set out their vision and also propose a time-frame as follows:



While in Alcatel-Lucent slide, I could visualise 4.5G as our vision of LTE(-A) + WiFi + some more stuff, I am finding it difficult to visualise all the changes being proposed by Huawei. How are we going to see the peak rate of 10Gbps for example?

I have to mention that I have had companies that have told me that their vision of 5G is M2M and D2D so Huawei is is not very far from reality here.

We should keep in mind that this 4G, 4.5G and 5G are the terms we use to make the end users aware of what new cellular technology could do for them. Most of these people understand simple terms like speeds and latency. We may want to be careful what we tell them as we do not want to make things confusing, complicated and make false promises and not deliver on them. 

Tuesday, 14 October 2014

'Real' Full Duplex (or No Division Duplex - NDD?)

We all know about the two type of transmission schemes which are FDD and TDD. Normally, this FDD and TDD schemes are known as full duplex schemes. Some people will argue that TDD is actually half-duplex but what TDD does is that it emulates a full duplex communication over a half duplex communication link. There is also a half-duplex FDD, which is a very interesting technology and defined for LTE, but not used. See here for details.


One of the technologies being proposed for 5G is referred to as Full Duplex. Here, the transmitter and the receiver both transmit and receive at the same frequency. Due to some very clever signal processing, the interference can be cancelled out. An interesting presentation from Kumu networks is embedded below:



The biggest challenge is self-interference cancellation because the transmitter and receiver are using the same spectrum and will cause interference to each other. There have been major advances in the self-interference cancellation techniques which could be seen in the Interdigital presentation embedded below: