Small Cells and X2 Interface

In the Release-8/9 of 3GPP, X2 interface between Small Cells and between Small Cells and Macro cells was not available. In Release-10 and 11, this was made available as shown in the picture above.

X2 is not only useful for lossless handovers in LTE/LTE-A but is also very useful for Interference management using eICIC (enhanced Inter Cell Interference Management) feature introduced in Rel-10.

More details on this enhancement is available in 3GPP TS 36.300 here.

Case Study: Mexico Prisons and Metrocells

Couple of interesting tweets from the Small cells world Summit recently caught my attention, unfortunately I am not able to find more information. Having said that the tweets are self-explanatory:

#SCWS2013 Mexican prisons use jammers to block prisoners making calls. This jamming bleeds outside the prison grounds causing problems!
— Small Cells (@small_cells) June 6, 2013

#SCWS2013 Solution was metro cells located in the residential areas outside the prison - to give the people connectivity - not the prisoners
— Small Cells (@small_cells) June 6, 2013

Here is a link about the Mexican prison jammers blocking neighbours cellular service.

Small Cell World Summit 2013: Video and Report

David Chambers, Think Small Cell, has compiled a quick summary of the recently concluded Small Cells World Summit which is worth reading and available here. A video made by him is embedded below:

'China Mobile' and 'Ericsson' deploy GSM Picocell/Metrocell in Nanning, the capital of China's Guangxi region

While the whole world has been focussing on HSPA+ and LTE small cells, a recent press release from Ericsson told us about GSM based 'City Site' deployed in Nanning. From the press release:

Currently, China’s urban construction is in full swing, and its mobile network coverage is rising. In the increasingly crowded urban environment, however, ensuring the quality of mobile-network coverage has become a problem.

In order to meet this challenge, Ericsson has launched the City Site integrated solution, and successfully applied it to China Mobile’s GSM network in Nanning, Guangxi. The City Site, which has been deployed with the standard RBS6601 base station, has an integrated Omni Antenna, which only covers a small area and is, therefore, easy to deploy. It could also be launched with just access to power and transmission cables.

According to the test of the live network, the City Site has effectively met the capacity and quality needs of network coverage, as well as ensuring excellent user experience.

Metrocells to help cut energy consumption in telco systems upto 90% by 2020

From a recent news article in Rethink Wireless:

Greentouch believes three key changes will make the difference to cellular networks' power hunger and CO2 emissions levels. These are the use of smaller, low power metrocells to add capacity in dense areas; wider infrastructure sharing; and techniques to match power consumption flexibly to the level of usage of the network at any time.

"We need to make resource usage proportional to the amount of traffic the network is handling," said Klein.

Smart antenna technologies will also be vital. Greentouch revealed first results of a key low energy project in 2011, demonstrating proof of concept base stations that use large arrays of up to 1,000 smart antennas to cut power consumption. The trial found that the energy needed to power each one dropped significantly as more were added, without impacting the range or capacity of the cell. The team was using fairly standard MIMO techniques, but harnessing the arrays not to boost capacity, but to reinforce a single transmission, creating a single strong beam from many low power signals.

LTE-A Metrocells to boost the data capacity capabilities in HetNet base stations

From Business Weekly:

A transatlantic technology collaboration between Cambridge Consultants in the UK and Florida-based Airspan Networks is set to enhance speed and capacity over the transformational LTE (long term evolution) platform.

The partners have unveiled an LTE-Advanced metrocell boost for mobile broadband; 4G LTE, is a standard for wireless communication of high-speed data for mobile phones and data terminals.

Cambridge Consultants has collaborated with Airspan, a leading vendor of LTE small cells and broadband wireless products and solutions, to boost the data capacity capabilities of the US company’s heterogenous network (HetNet) base stations.

Deutsche Telekom: Tackling the data deluge with help from customers' Wi-Fi

From a recent ZDNet article:

...Deutsche Telekom putting its foot firmly in the Wi-Fi offload camp, and marks a further signal of Wi-Fi's growing importance to operators who seek alternative ways of managing rampant mobile data traffic.

"The astonishing increase in data traffic calls for network optimisation and expansion, as well as the implementation of new high-speed networks," said Deutsche Telekom spokesman Dirk Wende, citing comments made by outgoing Deutsche Telekom CEO Rene Obermann. "The partnership with FON fits perfectly with Telekom's network expansion strategy. Wi-Fi and hotspots can be used to divert heavy data traffic to fixed-line networks and thus reduce the load on mobile networks."

Deutsche Telekom sees Wi-Fi as complementary to its existing services, and certainly has no plans to blanket Germany (a geographically large country) with its own Wi-Fi hotspots.

Multi-standard Metrocells (MSM): 'Still a year away'

From a recent Fierce Broadband Wireless article:

The carrier is also working on what it calls Multi-Standard Metrocells (MSMs), or small cells that combine LTE, HSPA+ and Wi-Fi into a single unit, but these are apparently proving tricky as the carrier appears to be in no rush to hustle the MSM devices out of the lab and into real-world deployments.

"It would be foolish to think less than a year" for the MSM deployments, Mansfield told Light Reading Mobile, but he added the rollout effort probably will not take two years either.

Speaking at the Citi Global Internet, Media & Communications Conference held during January in Las Vegas, John Donovan, senior executive vice president of AT&T technology and network operations, emphasized the importance of multi-standard small cells in the operator's network plans. "Our objective for 2014 is that we won't do any small cell or in-building systems that don't include Wi-Fi," he said.

AT&T announced last November that it intends to deploy more than 40,000 small cells over the next two years as part of its expansive Project Velocity IP (or VIP). The project also will entail the rollout of 10,000 new macrocells and 1,000 distributed antenna systems (DAS) throughout its service footprint.

During AT&T's Innovation Showcase in New York last week, Mansfield indicated that the end-of-2015 target for 40,000 small cells still seems quite feasible. "At this point I see no reason to believe that we won't hit that number...and we could revise it next year," he said.

Wireless Backhaul and Vendor Landscape

As mentioned earlier, backhaul is one of the biggest challenges for Small Cells Deployment. A recent article in Maravedis Rethink stated the following:

While some people forecast that as many as 80 or 90% of outdoor metrocells will be connected by wireless backhaul, Maravedis-Rethink believes we'll see something closer to today's split in macrocells - about 55% wireless and 45% fiber. Operators will use fiber wherever possible and install short range wireless in the gaps.

In some countries, the availability of fiber is far higher than in others, for example in South Korea, China and Japan. Even in the US, where there is plenty of copper, my guess is that operators will try to reuse existing copper lines to reach the nearest fibre point of presence. As an analyst, it would be quite easy to be aggressive with high wireless backhaul forecasts, but we have to consider that in reality most operators are very conservative about adopting new technology.

So wireless backhaul may be more important for metrocells than for macrocells, but not excessively so.The most important issue for a metrocell is to offload traffic from the macro network. Location is fundamental – the NGMN (Next Generation Mobile Network) Alliance has indicated that cells need to be located within 10 meters of each traffic hotspot – so there really needs to be far more flexibility in backhaul. This is where wireless backhaul becomes more significant.

The role that third party players offering ‘small cells as a service’ such as Virgin and Colt can play is also important. The value of street furniture will increase in the coming years. Those who deployed city Wi-Fi in the past (and failed through lack of monetization) have now realised they were getting access to valuable infrastructure. If you get permission for public Wi-Fi and small cell deployment then that could make the service provider Wi-Fi business more interesting. This gives intermediate players like Virgin, who can deal directly with building, real estate and council owners, an important role to isolate network operators from many/multiple negotiations with location owners. This would make it much more convenient for operators to contract through intermediate players than directly themselves. 

More than 5 Million Metrocells to be shipped in 2017

From the Microwave Journal:

Mobile Experts has released a new Small Cell Market Forecast, predicting more than 5 million metrocells shipped in 2017.

Based on weak shipment data during 2012, Mobile Experts predicts slow growth for residential femtocells, at only 12 percent per year. Faster growth will come from capacity upgrades, as mobile operators are pushing hard for high-capacity small cells. The new Mobile Experts forecast predicts that, taken together, outdoor metrocells and indoor capacity nodes will overtake residential femtocell shipments in the 2016 time frame.