Thursday, 20 October 2016

Carrier Aggregation (CA) and Dual Carrier (DC) enhancements in Release-13

Recently I posted a summary whitepaper of 3GPP Release-13 by 5G Americas. This article from NTT Docomo technical journal complements that nicely and provides in depth analysis of selected features.

The article (embedded below) focuses on Carrier Aggregation (CA),Dual Carrier (DC) enhancements, LAA and LWA. In this post, I am going to restrict the discussion to CA and DC.

The following is from the magazine article:

Carrier Aggregation (CA):

Up to Release 12 CA, a maximum of 5 LTE carriers called “Component Carriers” (CCs) could be configured for a User Equipment (UE). This enables a maximum 100 MHz bandwidth for data communications, which achieves a theoretical peak data rates of approximately 4 Gbps, assuming eight Multiple Input Multiple Output (MIMO) layers and 256 Quadrature Amplitude Modulation (QAM) for downlink, and 1.5 Gbps assuming four MIMO layers and 64QAM for uplink.

In Release 13, the maximum number number of CCs that can be configured for a UE simultaneously was increased to 32 to archive higher data transmission rates with wider bandwidths. This enables a maximum 640-MHz bandwidth for data transmission, achieving peak data rates of approximately 25 Gbps for downlink with 8 MIMO layers and 256QAM, and 9.6 Gbps for uplink with 4 MIMO layers and 64QAM.
Release 13 introduced the new function to enable PUCCH configuration for a Secondary Cell (SCell) in addition to the PCell in uplink CA. When CA is performed with this function, CCs are grouped together either with the PCell or SCell with PUCCH (PUCCH-SCell). UE sends UCI for CCs within each group by using the PCell or PUCCHSCell. With this new function, uplink radio resource shortages can be resolved by offloading UCI from macro cell to the small cells while keeping the macro cell as the PCell.

Dual Carrier (DC):

Release 12 designed DC to achieve user throughput comparable with that of CA by aggregating multiple CCs across two eNBs. In release 13, DC was further enhanced with higher uplink throughput and more flexible deployment.

In DC, separate eNBs allocate uplink resources independently for a UE. Hence, Release 13 addresses how to allocate adequate uplink resources on multiple CCs for UE. Typically, eNB calculates the required uplink resources based on the uplink buffer amount reported from UE. In DC, since both eNBs calculate the amount of uplink resources based on the report and allocate them to the UE independently, excess uplink resource allocation over actual amount of remaining data will occur. In particular, with small data packets, if resources are allocated by both eNBs, the UE may send all data to only one of them, and send padding (meaningless bit strings) to the other eNB, which wastes radio resources.

To prevent the excess uplink resource allocation for the small data packets described above, new uplink transmission control methods were introduced. In Release 13 DC, UE buffer status reporting and uplink data transmission are controlled based on the amount of uplink data buffered in the UE.

If the amount of the buffered data is smaller than the threshold configured by the eNB, the UE performs buffer status reporting and uplink data transmission only to one of the eNBs, just like DC in Release 12. In contrast, if the amount of the buffered data is larger than the threshold, the UE transmits to both eNBs. This buffer size-based mechanism solves the uplink resource over-allocation problem since only one eNB is aware of the buffered data and allocates resources when the amount of the buffered data is small.

The paper is embedded as follows:

Related posts:

Saturday, 8 October 2016

Thursday, 22 September 2016

Small Cell Forum workshop on 5G

I was having a twitter discussion earlier today as to whether 2G/3G should be switched off to make room for the more efficient 4G/4G+. While I agree with regards to the efficiency of 4G/4G+, there is still plenty of room for existing technologies, including 2G for a long time. 

While 5G is great and as can be seen in the picture above, a very optimistic picture has been painted with regards to LTE/5G.

Small cell forum recently held a workshop on 5G in Rome. Though it doesn't say explicitly, I am assuming the focus was Small Cells and 5G. It wouldn't be surprising as most of mmWave deployments would be comparatively small as compared to macrocells today.

I like this picture below as it shows that there are practical problems to solve today then worry about the 5G deployments of 2020. Having said that, the mobile community has to start preparing for it now to be ready by early 2020's  

Huawei had another interesting concept of how 5G HetNets will look

Nokia suggested that the lessons learned from Small Cells will help vendors with 5G deployments.

You can see all the presentations available here.

If you found something very interesting, please share in comments.

Monday, 5 September 2016

LTE Relay as a disruptive backhaul technology for Small Cells?

Came across this interesting presentation from Airspan which their CTO Paul Senior delivered at Small Cells World Summit in May. Here they are suggesting that relays could be used used on the cell edge to backhaul small cells and hence improve throughput for a UE that is camped on small cell. Probably much easier to understand from the picture below.

This approach is similar to in-band backhaul that is used by other vendors. I gave an example of in-band backhaul from Parallel Wireless in my Rural coverage post here. The advantage of relays & in-band backhaul is that the small cells could be deployed easily and also moved/relocated later on as there is no limitation due to backhaul provision.

In an article from last year on ThinkSmallCell, Paul said:

The 3GPP standard includes a feature to support remote relays at the cell edge, which only needs power to rebroadcast the signal into poor coverage areas. However, this requires a separate protocol stack in the macrocell – something which not all vendors have implemented.

Instead, we've built a simple relay using a directional antenna to the macro which operates at a different frequency band, say 2.6GHz TD-LTE, and rebroadcasts at 1800MHz FDD-LTE. The antenna form factor and design enables much better utilisation of the link that when serving smartphones directly, using 64QAM rather than QPSK to achieve much higher throughput within the same spectrum and macrocell resources. The short range radio link to the end users also provides the potential for higher speeds and better service quality. It's a quick and effective solution for enterprise buildings at the edge of coverage.

The potential capacity of an LTE Relay isn't insignificant. If we used LTE with 256QAM, 8x8 MIMO we could see a consistent throughputs of 450Mbps.

I could also see this being useful in transport applications, such as for Connected Cars. We'll be releasing products later this year for vehicle based solutions at various frequency bands.

They did demo some of the products in SCWS2016, which can be seen in another ThinkSmallCell report here.

The Airspan presentation is as follows:

Related posts:

Thursday, 25 August 2016

Small Cells vs Macro Cells Densification

Here is a presentation by KPN from Small Cells World Summit 2016 explaining how densification using small cells makes more sense than using macro cells. They have presented case study of Rembrandtplein to explain this. Feel free to add your views as comments.

Related posts:

Wednesday, 17 August 2016

Drone cells are becoming a reality

Back in early 2015, the then EE CEO Olaf Swantee said, "We will begin exploring 'Air Masts', essentially aerial small cells positioned in the sky above a hard-to-reach area, using either tethered balloons or unmanned craft, bridging the UK's transmission gap."

The vision has not changed a lot. I recently blogged about 'EE's vision of Ultra-Reliable Emergency Network'. If you look at the slide above you will notice temporary solutions include Air masts, UAV's and Network in a box (NIB).

Nokia recently did a trial with EE where they used a drone to carry a tiny base station to remote areas around Inverness. Weighing in at only 2 kg, the Nokia Flexi Zone Pico cell has all the punch of LTE in a very compact package, allowing 4G services to be provided wherever a drone can reach. High quality LTE voice calls between responders, video streaming and up to 150 Mbps data throughput were all achieved, with no need for a connection to an external core network.

While it doesn't exactly say the area that was covered, I would expect it to be able to do at least 1 km diameter to be effective in an emergency scenario.

According to a recent International Business Times article, US operator AT&T is trying something similar to deal with the struggle to provide enough wireless data are large venue events to please customers. The mobile operator says that drones known as "Flying Cell on Wings (COWs)" could make all the difference. The idea would be that the drone would be tethered to the ground so they would hover in one place, sort of like a portable hovering small cell. 

Finally, Ericsson and China Mobile conduct world’s first 5G drone prototype field trial. In their recent press release it says:

In the trial, held in Wuxi in China’s Jiangsu province, a drone was flown using operator’s cellular network with 5G-enabled technologies and with handovers across multiple sites. In order to demonstrate the concept’s validity in a real-world setting, the handovers were performed between sites that were simultaneously in use by commercial mobile phone users.

The potential use cases for this technology include mission-critical applications such as support for emergency services. However, end-to-end low latency needs to be guaranteed by the operator’s network to ensure the safety and reliability of such services.

I am sure we will be hearing more on this topic soon.

Tuesday, 2 August 2016

Small Cells: Best solution for rural coverage?

I drive around the UK a great deal. While I rely mostly on my phone to call and message/text, I also use it to check tweets, Facebook, emails and most important of all as a Satnav (I'm a big fan of Waze). I often end up in scenarios where I have no coverage so a wrong turn results in my Satnav route failure. This can mean I have to drive around for miles before I can get back on route.

In most countries (including UK) when an operator mentions its coverage, its means population based coverage. The problem is that one may have reasonable coverage in a big town/cities but not on small roads and villages but the operator would have still met their coverage obligation. However this will be changing, at least in UK, with the announcement by EE that they will do a 95% geographic coverage. Kudos to them!

Picture Source: Point-Topic

This map I came across recently shows the rural challenges in Europe for providing connectivity. Whilst not that detailed, I can definitely say from a UK point of view, there are many places outside big towns and cities that have coverage gaps.

As can be seen above, a similar problem is present in Africa and Carribean and Latin America (CALA). In these regions, in addition to the coverage gap, affordability and lack of relevant content are also major issues.

To put it simply in most countries, there is that last 10% of the population for whom coverage is not deemed feasible for the operator.  The problem is that the investment would generally outweigh the revenues. The installation (site, backhaul, etc.) and the maintenance cost would almost always outweigh the profits.

This is one of the challenges that Parallel Wireless* is trying to solve.

What if you can make the deployment very simple and reduce the installation cost and have minimal maintenance cost?

The operator would be far more willing to give it a try. There was an announcement between Parallel Wireless and Telefonica I+D for exactly this reason recently. The small communities wherein these small cells are deployed also have a vital role to play. Not only could they help by making sites available, they can have directly report any issues that would arise. An example of this can be seen in the picture above, demonstrating a small cell deployment in a community center.

An important thing to bear in mind is the support for different types of backhaul for small cells. While cellular/LTE backhaul can allow quick deployment, additional type of backhaul can become available much quicker than anticipated. The small cell deployment should be flexible enough to be able to handle this new change.

A real life example of the above statement can be seen in the picture from a recent site survey.

Finally, I would like to embed this video that explains the Parallel Wireless Rural Solution very well.

Please feel free to add your suggestions in the comments below.

*Full Disclosure: I work for Parallel Wireless as a Solutions Architect. This blog is maintained in my personal capacity and expresses my own views, not the views of my employer or anyone else. Anyone who knows me well would know this.

Sunday, 24 July 2016

LIGHT-Net: China Unicom's mobile service booster

Another presentation from the Small Cells Word Summit 2016. China Unicom refers to LIGHT-Net. The definition of LIGHT-Net can be seen above but based on the translation of the press release here, LIGHT-Net stands for LTE Technology Innovation and Network Evolution Solutions. Continuing from the press release:

Experts said, LIGHT-Net will have five characteristics: First, the asset-light (the Low-cost) , the software-defined (SDN) to achieve a flexible network, reducing CAPEX and OPEX ; followed by intelligence (the Intelligent) , will enable the network automatic planning, optimization and automatic interference avoidance; third is green (green) , to achieve low power consumption, low radiation, low noise; fourth is efficient (High-efficiency) , improve resource scheduling capabilities and spectrum utilization efficiency; the fifth is close (Tight) , to achieve macro-micro coordination and heterogeneous integration.
Overall, LIGHT-Net research program can be divided into three steps. The first stage, based on the interference coordination LIGHT-Net microsite deployment: the introduction of micro-station deployment, absorbing macro hotspot network data traffic; the introduction of interference coordination technology to solve interference problems caused by increased cell. The second phase, enhanced collaboration processing, macro and micro interoperability: Promoting co-processing technology macro and micro cells, pico cells between the cell edge coverage to enhance performance and user access experience. The third stage, an access integration, multi-stream merge: the ideal backhaul carrier aggregation, non-ideal backhaul dual link technology between macro and micro HSAP / LTE -system multi-stream merger.

I think the small cells maybe Huawei's lampsite as I had mentioned earlier.

Anyway, the presentation is embedded below. As usual, if you have more details, please add as comments below.

Saturday, 9 July 2016

MEC, Small Cells & IoT

Here is a presentation from Vodafone on how Mobile Edge Computing and Small Cells can play a big role in Internet of Things.

Vint Cerf, who is universally recognised as one of the founding fathers of Internet recently said that there will be 1 Trillion devices on the net by 2036, many of them being IoT devices.

This presentation also lays out use cases for IoT. As always, I am interested in hearing your thoughts.

Sunday, 26 June 2016

Underground Small Cells

Following on from my earlier post on 'Small Cells & Wi-Fi in the pavements & roads', here are some more details about these underground small cells, see video below.

From Ericsson's press release:

Swisscom and Ericsson have deployed the world’s first vault site for LTE and small cells in Switzerland. Some 250 further rollouts are due in the country’s cities during 2016.

Swisscom and Ericsson have proved that city manholes can be used worldwide to improve capacity with small cells – even below street level – using the Ericsson Vault Remote Radio Unit and Kathrein’s Street Connect, an in-ground microcell antenna system. The use of existing street manholes where fiber and power already exists lowers total cost of ownership by 50 percent.

This, the world’s first vault site for LTE and small cells has been approved by the Swiss authorities, and 250 new rollouts are due during 2016 in the country’s cities. The solution effectively addresses cities’ needs by enabling the reuse of existing assets and underground space.

This site solution offers the best network capabilities in Switzerland by supporting the upcoming rollout of 5G.

Here is the video: