Tuesday 14 September 2010

Femtocell Interference Management in real life

Couple of years back we blogged about the Femtocell Inteference in Macro network. Since then things have moved on a long way. There are commercial rollouts happening with Vodafone leading the way. Yesterday, I was reading Prof. Simon Saunders article on Femtocell and the following struck me.

A major technical challenge that femtocell designers initially faced was the need to manage potential interference. It takes up to two years to install conventional base stations, during which time radio engineers meticulously plan a station’s position and radio characteristics to avoid interference. However, such an approach is not viable in the case of femtocells, deployed potentially in their millions at random. Automating a process conducted by radio engineers was no mean feat and simply would not have been possible a few years ago.

Fortunately, the fact that the walls of buildings keep 3G signals out and keep the femtocell’s signals in provides strong inherent interference mitigation for indoor femtocells. Extensive studies have shown that proper implementation of a few key techniques to reduce interference can take advantage of this attenuation in an intelligent manner. Such techniques include frequent monitoring of the cell’s surrounding radio environment combined with adaptive power control. Indoor users gain faster data rates, as do outdoor users who now operate on less congested cells, while it costs less for operators to deliver higher overall network capacity. Large-scale, real-world deployments are demonstrating that these techniques work in practice and even allow new approaches, such as operating 3G networks in the same spectrum as 2G networks.

AT&T has deployed femtocells on the same frequencies as both the hopping channels for GSM macrocells and with UMTS macrocells. They have tested thousands of femtocells, and found that the mitigation techniques implemented successfully minimise and avoid interference. The more femtocells are deployed, the more uplink interference is reduced.

It is very interesting to see that the interference is not causing any problems in real life.


Back in Feb, Femto Forum released a new report on "Interference Management in UMTS Femtocells". A similar report was released in Dec. 08. Then in March they released a similar report for OFDMA (covering both LTE and WiMAX) femtocells. They are interesting reading for those who are interested in this area.


European Union is having a similar program called FREEDOM (Femtocell-based network enhancement by interference management and coordination of information for seamless connectivity ). FREEDOM focuses on:
  • Advanced interference-aware cooperative PHY techniques,
  • Improvement of the control plane procedures for seamless connectivity, and
  • System-level evaluation and hardware demonstrator of the proposed femto-based network architecture.

More info on their website (http://www.ict-freedom.eu/). You can see their scenario document that shows different interference scenarios and also compares different approaches including those of Femto Forum, 3GPP and WiMAX.

Friday 10 September 2010

Selected IP Traffic Offload (SIPTO)

The industry is developing a new standard called Selected IP Traffic Offload (SIPTO). SIPTO allows internet traffic to flow from the femtocell directly to the internet, bypassing the operator’s core network, as shown in Figure 8 below.


More information on LIPA and SIPTO can be obtained from:
1. 3GPP TR 23.829: Local IP Access and Selected IP Traffic Offload (http://www.3gpp1.eu/ftp/Specs/archive/23_series/23.829/)

Thursday 9 September 2010

Local IP Access (LIPA) for Femtocells

I blogged about data offload earlier, for Femtocells. This traffic offload can be done via a feature called Local IP Access (LIPA). If you have LIPA support in your Home NodeB (HNB) or Home eNodeB (HeNB) then once you have camped on your Femtocell then you can access your local network as well as the network's IP network.

This would mean that you can directly print from your mobile to the local printer or access other PC's on your LAN. Note that I am also referring to access via Dongle as Mobile access though in practice I dont see much point of people just using dongles when they are in their Home Zone. Every laptop/notebook/netbook is now Wifi enabled so this situation doesnt benefit much for the dongle access.

I am sure there are quite a few unresolved issues with regards to the Security of the data, the IP address allocation, QoS, etc.

Continuous computing have a white paper on LIPA available that can be obtained by registering here. Anyway, enough information is available even without getting the PDF.

There is also a small presentation here that gives a bit of idea on LIPA.
As usual any comments, insights and references welcome.

Friday 3 September 2010

Wireless Power Consortium (WPC) launches Qi



The WPC has chosen the Qi logo as the international symbol of wireless charging compatibility. Qi—pronounced “chee”, meaning “vital energy” in Asian philosophy—represents an intangible flow of power. Qi is the sign of interoperability between power transmitters and power receivers. All Qi receivers will work with any Qi transmitter. Every electronic device bearing the Qi symbol can be charged on any charging pad or surface marked with the same Qi logo.


In a post last year I mentioned about the wireless chargers. There were few that were released but they are expensive and not sure about the reliability.

The following is from eWeek:

The Wireless Power Consortium (WPC) has launched version 1.0 of its specification for charging handsets and other devices wirelessly, to be marketed under the name “Qi”, and has certified initial products for Blackberry and iPhone devices.

The product announcements come a year after the consortium announced version .95 of the spec. The products, including chargers for iPhone and BlackBerry devices, are to be demonstrated at a WPC meeting later this month.

Qi is based on inductive power transmission, already used in products such as the Touchstone charging dock used by the Palm Pre and the charging station for the Wii gaming console remote control. Such chargers allow a device to charge when placed on a flat surface or in a sleeve or dock. They eliminate the need for the connection of a metal contact connection, such as is found in standard cordless phone chargers.

The consortium, which includes Samsung, Sanyo, Olympus, Philips and Texas Instruments, aims to standardise inductive power charging technology so that chargers can be used with any device bearing the Qi logo. The specification is suitable for devices using up to 5 Watts of power, which the WPC said should cover “the majority of handheld mobile devices”.

“Qi can now be integrated into products. All ingredients for growing the market are now on the table,” said WPC chair Menno Treffers, in a statement.

Initial Qi-certified products are to include a charging sleeve for the iPhone 3GS and 3G and a charger for the Blackberry Curve 8900, both to be launched by Energizer this autumn. Sanyo, ST-Ericsson, National Semiconductor and others said they are working on Qi products.

Prototypes are to be demonstrated at a WPC meeting in Eindhoven, Belgium, from 15 to 16 September. The WPC said it has now begun work on a wireless charging specification for devices requiring more power, including netbooks, laptops, tablet computers and power tools.

The consortium said it chose the brand Qi (pronounced “chee”) to refer to the concept of energy flow in traditional Chinese medicine, not the cult quiz show QI (for “quite interesting”) hosted by Stephen Fry on British TV.

The technology is less ambitious than the system demonstrated this summer by Witricity, which operates at a distance of a few metres, using resonance, which the company claims has green benefits through replacing disposable batteries


From ZDNet:

"It took us only 18 months to develop the Qi standard, and less than one month to see the first products certified. Qi is now the industry's choice for wireless power," said Menno Treffers, chairman of the WPC, in a statement.

Three sets of specifications — for interface definition, performance requirements and test procedure — were handed over to consortium members in July. The only standard released publicly as Qi 1.0 is the interface definition, with the others being restricted to consortium members. The WPC has grown from 27 members in July to over 55 members, including Nokia, LG, Research In Motion, Duracell, Energiser and Texas Instruments.

Wireless charging has great potential to make charging easier for consumers", said Petri Vuori, Nokia's director of mobile solutions research, in the WPC announcement statement. "For full user benefit, a standard ensuring cross-compatibility between different manufacturers' products is required. Qi low-power standard specification release 1.0 is a significant milestone into this direction."

The Qi standard uses inductive charging to transfer up to 5W of power between devices and chargers. There are already products on the market that support inductive charging, but these are tied to particular products, rather than being universal.

The WPC said that it now plans to begin work on a wireless power standard for medium power devices such as netbooks, laptops, tablet computers and power tools.

The group expects the technology to boost the market for wireless battery charging from 100,000 units to 100,000,000 units annually. "Qi can now be integrated into products. All ingredients for growing the market are now on the table." said Treffers.


You may also be interested in the video below:

Wednesday 1 September 2010

On Twitter!

I am finally on twitter @zahidtg

There are so many news, etc which are worth sharing but don't deserve a separate post so I am going to tweet them.

You are most welcome to follow me on twitter or alternatively a widget displaying the latest tweets are on the left hand side of this blog. Please feel free to check them out and feel free to share your feedback or opinions.

Tuesday 31 August 2010

EDGE evolution to REDHOT


EDGE is more than three times as efficient as GSM/GPRS in handling packet-switched data. Using EDGE, operators can support 3x more subscribers than GPRS, either by increasing the data rate per subscriber to 300 kbps, according to network & device capabilities, or adding voice capacity. EDGE uses the same TDMA frame structure, logic channel and 200 kHz carrier as GSM; existing cell plans remain intact. No change is needed in the core network. Neither new spectrum nor a new operating licence is needed. EDGE is a mature, mainstream global technology which allows operators to compete, to protect investments/assets, and stimulate growth of mobile multimedia services. Upgrading to EDGE is a natural step for operators to offer high performance mobile data services over GSM.

The performance of EDGE has improved steadily since its introduction in the market in 2003, and today offers users the possibility of data speeds up to 250kbps, with a latency of less than 150ms. This is sufficient for any current data service to be attractive to customers. According to GSA’s latest EDGE Fact Sheet (August 19, 2010 and available as a free download from www.gsacom.com) over 80% of GSM/GPRS operators globally have committed to deploying EDGE in their networks. 531 GSM/EDGE networks are in commercial service in 196 countries, and thousands of EDGE-capable user devices are launched.

A key part of the evolution is the opportunity to deploy more than a single RF carrier. Downlink Dual Carrier (DLDC) is the first step in evolving EDGE, doubling data rates to 592 kbps on existing EDGE-capable networks.

Downlink speed quadrupled:
up to 1.2 Mbps per user initially
(the standard enables up to 1.9 Mbps per user)
• Dual Carrier first phase implementation 10 timeslots per user; standard enables up to 16 timeslots per user
• EGPRS-2 DL (REDHOT) level B maximum 118.4 kbps per timeslot

Uplink speed up to 474 kbps per user
(the standard enables up to 947 kbps per user)
• EGPRS-2 UL (HUGE) level B with maximum 118.4 kbps per timeslot
• Peak implementation today 4 timeslots per user (standard enables up to 8 timeslots per user)

The EGPRS-2 feature is expected in the market in 2012.

More information is available in the GSA Report 'EDGE Evolution' released on Aug 23 2010. Available to download from GSACOM here.

Monday 30 August 2010

100+ LTE Commitments, 22 commercial networks planned for 2010


The Global mobile Suppliers Association (GSA) has published an update to its Evolution to LTE report which confirms that 101 firm LTE network deployments are in progress or planned in 41 countries. The number of network commitments is 71% higher than GSA reported in a similar survey six months ago.

This figure includes three LTE systems which have launched commercial service – in Sweden, Norway, and Uzbekistan. GSA anticipates up to 22 LTE networks will be in commercial service by end 2010.

Another 31 operators are engaged in various LTE pilot trials and technology tests (these are referred to as pre-commitment trials). Taken together, it means that 132 operators are now investing in LTE in 56 countries.

The GSA Evolution to LTE report covers both LTE FDD and LTE TDD modes, and provides a summary of the market situation in each country, including operator activities and plans, spectrum requirements and developments, information on the growing eco-system including device and platforms availability, performance and interoperability trials results, key industry trends and forecasts.

LTE networks are now being deployed for commercial service or planned in Armenia, Australia, Austria, Bahrain, Brazil, Canada, Chile, China, Denmark, Estonia, Finland, France, Germany, Hong Kong, Hungary, India, Ireland, Italy, Japan, Jordan, Kazakhstan, Kuwait, Latvia, Libya, Netherlands, New Zealand, Norway, Portugal, Russia, Saudi Arabia, Singapore, South Africa, South Korea, Sweden, Switzerland, Taiwan, The Philippines, UAE, UK, USA, and Uzbekistan.

Governments around the world are preparing the way to ensure the availability of spectrum to support delivery of next generation mobile broadband services for the mass market, by allocating or preparing for the release of new spectrum such as 2.6 GHz, and in the digital dividend (700 MHz, 800 MHz) bands, or re-farming existing spectrum e.g. 900 MHz, 1800 MHz, etc. or facilitating a combination of new and re-farmed bands. The report notes that several trials licenses have been granted in many countries to allow operators to familiarize with the technology, capabilities and performance aspects. A number of tenders for spectrum licenses have been announced or confirmed in recent weeks for the granting of spectrum suitable for LTE deployments, including in Australia, Brazil, Chile, Poland, and the UK. Several auctions are scheduled for completion in the next few months.

LTE is the next generation mobile broadband technology of choice and the natural evolutionary step for GSM/WCDMA-HSPA operators and also for many leading CDMA operators around the world. A leading WiMAX operator has also recently announced the company has decided to shift to LTE.

While the majority of LTE deployments today are using the FDD mode, the report confirms significant operator interest in the TDD mode. LTE FDD and LTE TDD are complementary technologies and standardized by 3GPP. A number of key technology milestones have been demonstrated in recent weeks which confirm how the LTE TDD system is maturing towards commercialization. The recently concluded BWA spectrum auction in India has paved the way for early and large scale introduction of TDD LTE into the world’s fastest developing market.

Alan Hadden, President, GSA said: “Our latest Evolution to LTE report shows how the pace towards LTE has quickened, which is easy to see from the increasing numbers of operator trials and announcements, and positive actions by several regulatory bodies around the world”.

The GSA Evolution to LTE report (August 26, 2010) is available as a free download to registered site users at http://www.gsacom.com/gsm_3g/info_papers.php4 and is embedded below