Posts Tagged ‘Carrier Aggregation’

LTE-Advanced deployments – Tracking the fastest wireless networks globally

In an earlier article written on this site in May 2013 (LTE Advanced – Key features and differentiators), I had discussed technical details of LTE-A. Sometimes called 4.5G, the technology was in testing stages at that time. Commercial deployment took off in different parts of the world about an year ago. The promise of LTE-Advanced is live and real as we head into 2015. Let us look at 10 operators that have taken the lead on LTE-A. For the sake of variety, only one operator has been taken from a particular country. Their region of operation, spectrum bands and top download speeds under ideal conditions are also listed. Only a few devices support LTE-A technology so far although many more are in the offing. If a device supporting LTE-A is available on a particular network, that would be included in this post too. Readers could refer to the earlier article on this blog for an explanation of technical terminologies.

SK Telecom, South Korea – Korean operators maintained their global telecom lead when SK Telecom unveiled LTE-A services in Seoul in June 2013. Its plan is to cover the whole country by the beginning of next year. SK Telecom used the Samsung Galaxy S5 to show speeds of 225 Mbps on the LTE-A network by combining 20 MHz spectrum from 800 MHz and 10 MHz spectrum from 1800 MHz band. Advanced techniques like Coordinated Multi Point (CoMP) transmission and Enhanced Inter-Cell Interference Coordination (eICIC) are also being put to use by the telco. Evolving to combine more bands, SK Telecom has announced the capability to aggregate total 40 MHz of bandwidth from 800 MHz, 1800 MHz and 2100 MHz, thus making download speeds of up to 300 Mbps a reality. Data rate as high as 450 Mbps was also tested recently by the operator.

MegaFon, Russia – During the Sochi Winter Olympics in February this year, MegaFon demonstrated its LTE-Advanced network clocking download speeds near 300 Mbps. The deployment was done in 2600 MHz by using 20 MHz of MegaFon’s and 20 MHz of its subsidiary Scartel’s spectrum. First commercially launched in Moscow, LTE-A was recently deployed in St. Petersburg with more Russian cities expected to be covered soon. Samsung Galaxy Note Edge was MegaFon’s first device for LTE-Advanced.

STC, Saudi Arabia – STC is one of the biggest service providers’ in the Middle-East. It launched LTE-Advanced in the kingdom in February 2014. The network is unique in the sense that it combines two 20 MHz LTE-TDD airwaves in the 2300 MHz band to achieve a speed of 225 Mbps. Recently, the carrier also demonstrated TDD-FDD carrier aggregation using 1800 MHz and 2300 MHz spectrum. Not much information is available about the current coverage or device support for STC’s network.

AT&T, USA – In March this year, Ma Bell declared the launch of LTE-Advanced in Chicago. AT&T claims speeds of up to 110 Mbps by aggregating a total of 15 MHz bandwidth from its 700 MHz and 2100 MHz AWS band. Rumors are that New York, San Francisco, Dallas and Washington DC are all ready for LTE-A. But consumers’ ability to experience such speeds is limited by device availability. AT&T’s Unite hotspot is the only device that supports LTE-A but much more action is expected on the phone front next year.

SingTel, Singapore – SingTel first showed off its LTE-A network in May this year. Commercial launch followed in summer and more than half of island has been covered already. Nationwide coverage is expected by next spring. SingTel claims top data rate of 300 Mbps. The operator has combined 20 MHz of bandwidth each from 1800 MHz and 2600 MHz bands. Huawei E5786 MiFi hotspot was the first compatible device. Subsequently, Samsung delivered the Galaxy S5 4G+ version of their flagship phone that took full advantage of SingTel’s fastest data speeds.

Swisscom, Switzerland – Swisscom rolled out LTE-Advanced in June this year starting from Berne and Lausanne stations. It was extended to cover the whole city of Berne and a few other urban areas in July. LTE-A will also be available in Zurich, Geneva and Lucerne soon. Like other carriers, Swisscom too went for carrier aggregation with 40 MHz total bandwidth from 1800 MHz and 2600 MHz bands. This resulted in speeds of about 300 Mbps. The telco pushed the limits further achieving data rates of 450 Mbps by combining 3 bands. It also declared that such superfast networks would be available in dense areas of this beautiful country by the end of next year. Compatible devices are also expected to be launched around that time only.

Bouygues Telecom, France – The third largest French mobile operator announced LTE-A or 4G+ services in June 2014. Lyon, Bordeaux and many other cities were covered by the end of summer. Speeds up to 220 Mbps have been achieved by Bouygues. Spectrum in 1800 MHz and 2600 MHz was aggregated for the LTE-Advanced network. The operator has also tested speeds of 300 Mbps by adding spectrum from 800 MHz to the above two bands for a total bandwidth of 45 MHz. Huawei’s 4G+ gateway and Bbox Nomad 4G+ hotspot are the first devices that support LTE-A on Bouygues’ network.

Vodafone, Spain – In October this year, Vodafone announced the deployment of LTE-Advanced in the Spanish cities of Madrid, Barcelona and Valencia. More cities are coming soon. By combining 20 MHz spectrum each from 1800 MHz and 2600 MHz, the operator was able to tout speeds of around 300 Mbps. Vodafone also plans to add the 800 MHz and 2600 MHz TDD spectrum to the above mix for LTE-A that could boost the data speed to 500 Mbps. Special version of Samsung Galaxy S5 will take advantage of Vodafone Spain’s superfast network.

Rogers Wireless, Canada – Canada’s largest carrier, Rogers declared the launch of its LTE-Advanced network with theoretical speeds of 150 Mbps couple of months ago. The service provider combined airwaves from its 700 MHz and 2100 MHz AWS holdings. Vancouver, Toronto, Calgary and many other cities were included in the launch. The latest iPhone 6 and Samsung Galaxy Note 4 with software updates will work on Rogers’ LTE-A network.

EE, United Kingdom – Britain’s EE went live with its LTE-Advanced network in October in the Central London area. Early next year, this 4G+ service will be extended to whole of London city apart from Birmingham, Liverpool and Manchester. Peak speeds of 300 Mbps have been delivered by aggregating 20 MHz spectrum each from 1800 MHz and 2600 MHz bands. Samsung Galaxy Note 4 and Samsung Galaxy Alpha will be compatible with the LTE-A network on EE.

Few other operators around the world that are deploying LTE-Advanced are Sprint USA, Vodafone Netherlands, Ooredoo Qatar, Telecom Italia and CSL Hong Kong. Carrier Aggregation still remains the most deployed feature of LTE-A. Higher order MIMO, eICIC and CoMP are expected over the next year or so. Deutsche Telekom in Germany demonstrated that carrier aggregation along with 4×4 MIMO can achieve speeds nearing 600 Mbps. Verizon Wireless in US plans to launch multi-feature LTE-Advanced in 2015. Not only will it aggregate 10 MHz airwaves from 700 MHz band with 20 MHz airwaves from AWS band, it will also deploy 4×4 MIMO and eICIC for an even faster LTE-A network. Now there is the argument that the telcos are jumping ahead of themselves when it comes to higher data rates. Do we need them and what about the supporting devices? However, there is always a need for speed and phones will arrive with time. Another interesting observation here is that Europe seems to be catching up and in some ways surpassing the LTE leader USA when it comes to LTE-Advanced. Asia is running along with Europe in terms of wireless data speeds. The wireless communications space keeps on getting more and more competitive. There is no scope for complacency or inertia.


Tracking the progress of LTE in Asia

About a year ago, I wrote a blog post about LTE developments across Europe. In the current article, the focus would be on Asia, the continent that is home to 60% of the world’s population. The dynamics of the telecom market in Asia are different from those in US and Europe. Most countries are developing economies where the majority of revenue still comes from voice. Much of the mobile market is untapped and even voice penetration is nowhere near 100% in most Asian nations. But contrast is noticeable all over the continent. On one hand, there is South Korea that leads the world in implementation of mobile technologies like LTE-Advanced, and on the other hand there is Myanmar where mobile penetration remains extremely low and market liberalization is a recent phenomenon. 3G is still in developmental stages and LTE is a far-fetched dream in many countries. Consequently, the average customer is not yet addicted to his/her smartphone or tablet.

In order to discuss the progress of LTE in Asia, I have focused on 10 most populous nations in the continent that either already have or will soon have at least one operational LTE network. So if a highly populated country in Asia does not feature in this status update, that’s because it has not gained much LTE momentum yet. LTE progress will be tracked on 3 parameters – Deployment timelines, spectrum and LTE flavor (FDD or TDD).

China – The world’s biggest operator by subscriber count, China Mobile is deploying LTE TDD primarily in the 2.6 GHz band and a full scale commercial launch is expected later in 2013. In some areas, 1900 MHz and 2.3 GHz frequencies will also be utilized by the operator. For the past 2 years, technology trials have been run in various cities. The initial launch is expected to cover about 500 million people in some 100 cities. The country’s next two big telcos, China Unicom and China Telecom are still testing LTE with no fixed time frame yet for commercial rollout. Both are aiming for a hybrid FDD-TDD LTE network with 1800 MHz and 2.1 GHz expected to be the spectrum for the FDD form.

Hong Kong saw its first LTE network in November 2010 deployed by CSL Limited in 1800 MHz and 2.6 GHz bands. Two other mobile service proivders in Hong Kong, PCCW and Hutchinson 3, launched LTE in May 2012 under the ‘Genius’ brand using the same frequencies. SmarTone announced LTE service in August last year in the 1800 MHz band. All these networks are FDD. China Mobile Hong Kong started LTE FDD service in April 2012 in the 2.6 GHz band. That was followed by LTE TDD service in December 2012 in the 2.3 GHz band.

India – World’s second largest mobile market by subscribers saw its first LTE network in TDD form launched by Bharti Airtel in the 2.3 GHz band in April 2012. This mobile broadband LTE service is so far available in 4 cities – Kolkata, Bangalore, Pune and Chandigarh, although Delhi and Mumbai are expected to join that group in the next few months. Reliance Jio Infocomm is the only Indian operator which has nationwide BWA licenses in 2.3 GHz band. It intends to launch LTE TDD network in select cities next year. Tikona Digital Networks is looking to rollout a similar LTE service in the same band in early 2014 in 5 circles (telecom zones). Aircel won BWA (2.3 GHz) licenses in 8 circles but the company is heavily under debt. Unconfirmed reports stated earlier this year that the telco might sell its BWA licenses. Videocon has announced plans to deploy LTE FDD in 1800 MHz by next year in 6 circles. It could be the only Indian cellular service provider whose LTE service is more aligned with many other operators in the world. India’s adoption of LTE will be slow, since 3G has only recently gained some real momentum.

Japan – Japan’s NTT DoCoMo was an early adopter of LTE when it started offering the technology to its customers in December 2010. NTT uses LTE FDD in the 2.1 GHz band and reached 15 million LTE subscribers in the recent past. Last year, the service provider added LTE capacity in the 1500 MHz band. KDDI’s LTE FDD service under their ‘au’ brand went commercial in September 2012 in the 2.1 GHz band. They added 800 MHz and 1500 MHz frequencies in November that year. Softbank, the No. 3 mobile service provider of Japan, launched LTE TDD in 2.5 GHz band in February 2012. Then in last September, the FDD version was launched in the 2.1 GHz band. Softbank’s eMobile brand has an LTE FDD service since March 2012 in 1800 MHz band. All Japanese telcos are also looking to utilize frequencies in the 700 MHz range for LTE services by 2015.

Philippines – Smart Communications commenced full scale LTE service in the Philippines in August 2012. Initial deployment was done in the 2.1 GHz band but later that year, the network added 850 MHz and 1800 MHz bands. The service has been extended to about 115 cities in the country. Another provider, Globe Telecom launched its LTE network in September 2012 in the 1800 MHz band. Both service providers have used the FDD version.

Thailand – Thailand’s first LTE network was launched in May this year by True Move H using FDD in the 2.1 GHz band. That remains the only operational LTE deployment in the country so far. Network partners TOT & AIS are expected to rollout LTE TDD service this year in the 2.3 GHz band for mobile broadband customers. DTAC and CAT Telecom are two other Thai operators that are looking to deploy LTE FDD in the 1800 MHz band with no defined timeline for a commercial launch.

South Korea – Korea’s SK Telecom has been a harbinger of LTE technology. Their first LTE network went into operation in July 2011. 850 MHz frequencies were used for this service which went nationwide by April 2012. Femtocells were added to the network in December 2011, making it one of the first heterogeneous networks in the world. Thereafter in another global first, VoLTE was launched by SK Telecom about a year ago and the operator notched up about 4.5 million VoLTE subscribers in 11 months. The telco also deployed Carrier Aggregation, an LTE-Advanced feature, on their network in June 2013. 10 MHz spectrum each from 850 MHz and 1800 MHz bands was combined to create an effective bandwidth of 20 MHz. Another Korean service provider, LG Uplus launched a similar LTE service simultaneously with SK Telecom in the same band. They again matched SK Telecom’s calendar for nationwide LTE and VoLTE rollout. A couple of months ago, LG U+ also started using 2.1 GHz spectrum for LTE and combined it with 800 MHz airwaves to enable Carrier Aggregation. Both SK Telecom and LG U+ will be deploying more LTE-Advanced features like CoMP and eICIC in 2014. (For more on these technologies, look at this post). Not to be left behind, the country’s third big telco, KT rolled out LTE in January last year using the 1800 MHz band. Recently, KT also started employing 900 MHz spectrum for LTE. With the service provider acquiring another chunk of airwaves in the 1800 MHz band in a recent auction, it announced the capability to provide LTE-Advanced this month. All Korean deployments have used LTE FDD.

Iraq – Despite all the troubles that Iraq has faced in the recent past, the country has made progress in telecommunications. Regional Telecom launched the country’s first LTE FDD service in the 2.6 GHz band in June 2013 under the Fastlink brand for mobile broadband subscribers. MaxyTel in Iraq has been in planning stages of an LTE TDD network.

Malaysia – Many service providers in Malaysia have launched LTE services in 2013 in the 2.6 GHz band using FDD. Maxis/REDTone did it in January, Celcom/Axiata in April, and DiGi launched it in July. In April 2013, Maxis and Celcom added 1800 MHz spectrum to their LTE networks. Packet One and Asiaspace are two WiMAX mobile broadband operators in 2.3 GHz that are planning to convert to LTE TDD. U Mobile is another Malaysian operator looking to launch LTE FDD later this year in the 2.6 GHz band.

Uzbekistan – MTS commenced LTE service in Uzbekistan in July 2010 but the company later went bankrupt. TeliaSonera’s UCell rolled out LTE FDD in the 700 MHz and 2.6 GHz bands in August 2010. Another telco, Unitel under the Beeline brand, has been testing the same technology in 2.6 GHz band since February 2012 although not much information is available about a market launch.

Saudi Arabia – Three major Saudi operators simultaneously launched LTE in September 2011. Etisalat’s Mobily deployed LTE TDD network in the 2.6 GHz band. Saudi Telecom Company (STC) deployed 2.3 GHz spectrum for the same service. In February this year, the operator commenced LTE FDD service in the 1800 MHz band. Zain Saudi Arabia launched LTE FDD in the 2.6 GHz band in September 2011 and added 1800 MHz spectrum to the service in June 2012.

Many other Asian countries have made impressive strides in LTE deployments. But it was not possible to discuss all such countries in one post, thus only 10 of them have been covered. Looking at the analysis above, it is obvious that multiple spectrum bands have been used although 1800 MHz and 2.6 GHz are the most popular ones. The time division form of LTE is popular in Asia more than any other continent. LTE device ecosystem is still in nascent stages in Asia and that prevents the full scale use of this technology. There are many nations yet to jump on the LTE bandwagon, but by the end of the decade, most mobile wireless communications would be happening over LTE networks not just in Asia, but all over the world.

LTE Advanced – Key features and differentiators

As a wireless technology, LTE is still in early stages of deployment in various countries outside US. But that has not prevented the wireless operators from talking about its next version, LTE Advanced (LTE-A). Technology Inflation has become the nature of wireless industry. The next big thing is always around the corner. In their attempt to lure customers away from their competitors, many service providers love to declare their adoption of the latest and fastest wireless standard. As long as this latest technology presents a substantial data rate improvement over the previous version, it is labeled as a new generation. This is also what is happening with LTE Advanced. A superior form of the already velocious LTE, some call it the actual 4G. For others it could be 4.5G. Without getting into the generation debate, I will keep referring to this technology as LTE Advanced throughout this article. According to the 3GPP group, LTE-A networks should support a downlink data speed of 3 Gbps and uplink speed of 1.5 Gbps. Let us understand the primary features of LTE Advanced that would propel LTE towards achieving those speeds. Most of these were formalized as part of 3GPP Release 10 –

  • Carrier Aggregation – One of the most popular aspects of LTE-A is that it allows a combination of up to five component carriers of varying bandwidth to aggregate and form a cumulative bandwidth of maximum 100 MHz. In comparison, contemporary LTE networks support only a single channel with a maximum bandwidth of 20 MHz. Carrier aggregation can be achieved within the same band using contiguous or non-contiguous stream of channels or between channels from two different bands. It offers an ideal solution to operators who do not own a contiguous chunk of 100 MHz spectrum. The technique can be applied to both FDD and TDD versions of LTE. Carrier aggregation will perhaps be the first attribute of LTE Advanced that goes into live action. For more details on carrier aggregation, refer to an earlier article on this blog here.
  • Higher order MIMO – Multiple Input Multiple Output (MIMO) increases the bitrate by using multiple transmission and receiver antennas. While LTE can support 4×4 MIMO configuration with 2×2 being the most common, LTE-A will have the capability to run 8×8 configurations in downlink and 4×4 in the uplink. Higher order MIMO directly improves spectral efficiency and throughput. Theoretically, 8 spatial streams can achieve speeds which are about 8x faster than a single input single output system.
  • Relay nodes and Heterogeneous networks – Relay nodes are deployed to provide better coverage and capacity at cell edges. Such nodes are low power base stations that act as repeaters to enhance the signal quality and rebroadcast the signal. They connect with eNodeB via wireless interface and offer substantial cost savings as compared to a new eNodeB installation. The concept of relay nodes directly ties into the idea of a heterogeneous network (HetNet). As I discussed here, HetNets enable wireless networks of varying cell sizes, output power and radio access technologies to work together towards the goal of boosting network coverage and capacity. With many wireless operators believing that small cells would be an essential part of their future strategy, there is a big industry push towards HetNets. LTE Advanced will further drive the deployment and adoption of heterogeneous networks.
  • Enhanced Inter-Cell Interference Coordination – eICIC will be the primary interference management and mitigation procedure adopted in the LTE-A network. It is typically used in a heterogeneous network where both macro and pico cells transmit and receive data at the same time. The weaker signal from the smaller cell can be easily overpowered by the stronger signal from the larger cell. In eICIC, certain subframes are transmitted by the macro cell without any data. These almost blank subframes (ABS) are low power control channels. The users in the pico cell area then communicate with their base station during such blank subframes. This minimizes the interference between the macro and pico cell on both traffic and control channels. Advanced interference mitigation schemes have been used in LTE networks, but with the increasingly high density of wireless network cells, more sophisticated schemes like eICIC are required.
  • Coordinated Multipoint (CoMP) Transmission – Formalized in 3GPP Release 11, CoMP would be another key characteristic of a true LTE Advanced network. In a Coordinated multipoint transmission and reception scenario, multiple eNodeBs work with each other dynamically to avoid interference with other transmission signals. This leads to a better utilization of system resources and an enhancement of both network coverage and quality for cell edge users.

Above five functionalities are generally considered to be the vital differentiating factors which will separate LTE-A from its predecessors. There are plenty of other evolutionary technology proposals which have been suggested for LTE-A. Here are some of them –

  • Enhanced Self-Organizing Networks – SONs are self-configuring, optimizing and healing mobile networks. As the name suggests, self-configuration applies to newly deployed eNodeBs, self-optimization is performed by active base stations to regulate parameters in synchronization with the overall network situation and self-healing features automatic detection and compensation of network outages. The concept of SONs will be implemented in LTE Advanced networks.
  • Further Evolved Multimedia Broadcast Multicast Control – eMBMS ensures an economical mechanism for the operator to deliver broadcast and multicast services. First defined for LTE, eMBMS has been further refined and enhanced for LTE Advanced. It offers more carrier configuration flexibility, higher video resolution services because of higher LTE bit rates and a dynamic reservation/release of network resources.
  • Cognitive Radio – Cognitive radios are designed to understand their environment and modify their own parameters like frequency, power, and modulation in such a way so as to utilize the unused spectrum dynamically in order to maximize spectral efficiency and minimize interference. While not explicitly defined within the LTE-A proposals, cognitive radios have been a prime area of interest for such networks because they can solve the spectrum scarcity problem.

One has to take into account that a real LTE-A network could have many more cutting-edge attributes and not every LTE Advanced network will sport all the above features. LTE-A is actually a collection of technologies. Consequently, we have to be careful about the marketing strategies that the network operators will follow. They could implement just one or two of above technologies and called their network LTE Advanced as long as it doubles or triples the current data rates. Few operators already claim that they are on the path to LTE Advanced. Last fall, Russian service provider Yota announced the world’s first LTE-A in Moscow with speeds up to 300 Mbps on consumer devices. Of course there are no LTE-A capable devices available yet. Korea’s SK Telecom has recently advertised its plans to launch LTE Advanced network by September of this year. They claim to have applied carrier aggregation, CoMP, femtocells and self-organizing network capability to their network. In US, T-Mobile has been happily declaring that since they were last to the LTE party and thus have the latest hardware, their transition to LTE-A would be faster and smoother. AT&T, Verizon and Sprint have been deploying small cells and advanced MIMO as part of their future LTE Advanced strategy. China Mobile and Vodafone New Zealand have tested the technology while achieving peak downlink speeds of 300 Mbps. Australia’s Telstra is also using carrier aggregation to launch LTE-A services later this year. Hardware manufacturers are not far behind. Qualcomm, Broadcom, Agilent, Ericsson and many others are already out with their LTE Advanced capable chipsets and network equipment.

Again, all above claims must be taken with a grain of salt. Wireless service providers are in a tightly competitive market and it is their business to tout the deployment of state of the art technologies. But it is for the consumers to decide that how much speed is good enough for them. Industry analysts like us can help them in separating truth from hype. Yes, LTE Advanced, whenever it gets here would be very awesome, but will not arrive in its true form before 2015.

Carrier Aggregation as a solution to spectrum woes

Many wireless carriers all over the world are talking about the looming spectrum shortage. This is especially true for carriers in the US where mobile data usage is high. Acquiring spectrum has also become one of the primary motives behind any merger and acquisition in the wireless telecom industry. The only other way to buy spectrum is through government controlled spectrum auctions. As I have written in a previous post here, spectrum scarcity will be a real concern in the next few years but the situation is definitely not as bad as the service providers are projecting it. There are multiple ways to utilize the available spectrum more efficiently. One such solution which many operators are looking at and some are already implementing is carrier aggregation. Carrier aggregation is a salient feature of LTE-Advanced (3GPP Release 10). Simply put, carrier aggregation delivers high traffic data rates by combining disparate contiguous and non-contiguous spectrum bands into a single logical channel. So if a mobile service provider has 20 MHz of spectrum in the 1900 MHz band and 10 MHz of spectrum in the 800 MHz band, then it can combine both of those into a 30 MHz carrier bandwidth channel. According to the specifications, the upper limit of such aggregated spectrum is 100 MHz. The benefit is primarily in downlink due to the asymmetrical nature of data flows. Carrier Aggregation combined with advanced MIMO and interference management techniques, has the capability to achieve the targets set by the IMT-Advanced standard (the original ‘4G’) i.e. 1 Gbps downlink speed to stationary users and 100 Mbps to highly mobile users. Note that I am not claiming that the networks will actually achieve that speed, but technologies like carrier aggregation have the potential to take the wireless networks in that direction.

There are 3 different ways in which LTE component carriers can be aggregated. Carrier arrangements can be intra-band contiguous, intra-band non-contiguous and inter-band corresponding to immediately adjacent carriers, non-adjacent carriers within the same band and carriers in different operating band. For the next few years, aggregation of only contiguous frequencies is expected. There is still time before the concept of non-contiguous and inter-band aggregation is standardized but it will happen eventually. When using carrier aggregation, the total bandwidth available would be referred to as aggregated channel bandwidth and the mobile equipment would be classified based on carrier bandwidth class. This class would depend on the aggregated channel bandwidth and the number of component carriers. Efforts are currently in progress so that the move from LTE to LTE-Advanced with carrier aggregation can be achieved using only software upgrades.

In the context of the US wireless industry, carrier aggregation can play an important role. Sprint Nextel’s imminent LTE network will utilize 5×5 MHz channel in the 1900 MHz PCS band. While the company plans to use the 800 MHz spectrum (after switching off iDEN) for CDMA, eventually, it will combine the two frequency bands into a 10×10 MHz channel using carrier aggregation to provide much faster LTE speeds. Sprint’s LTE network is considered LTE Advanced-ready. T-Mobile is gearing up for the nationwide LTE launch in 2013 and they have stated that the network would be Release 10 compatible. The operator is already using dual carrier technology for its HSPA+ service. Clearwire’s CTO recently said that their network would be LTE Advanced-ready next year with the capability to provide theoretical peak speeds of up to 168 Mbps by 2014. Using time division version of LTE, better known as TD-LTE, Clearwire would initially use 20 MHz channel and then migrate to 40 MHz carrier bandwidth as the LTE-Advanced ecosystem develops. AT&T has also made its intentions clear about carrier aggregation. Their plan is to combine the 700 MHz spectrum acquired from Qualcomm with their spectrum in the 850 or 1900 MHz band. This will provide them with an immense boost in the markets where their LTE network is on a 5 MHz channel as carrier aggregation will upgrade their total bandwidth to 10 MHz in each direction. Verizon could potentially blend their 700 MHz holdings with the AWS spectrum once its acquisition of airwaves from the cable companies is approved. Outside the US, SK Telecom in South Korea has committed to utilize carrier aggregation in 2013 by combining its spectrum in 800 MHz and 1.8 GHz to achieve 40 MHz of bandwidth for providing LTE services. Japan’s NTT DOCOMO has been doing LTE-Advanced trials in its quest to achieve the 1 Gbps downlink data rate. At the 2012 Mobile World Congress, Vodafone demonstrated carrier aggregation by combining 10 MHz of spectrum from 800 MHz with 20 MHz of spectrum from 2.6 GHz to achieve downlink data speeds of up to 230 Mbps.

Of course one could ask that why do we need anything greater than 10 or 20 Mbps of speed on a mobile phone? A wireless service is deemed good if it can provide hundreds of users with speeds of 10 Mbps, rather than providing a handful of users with a speed of 1 Gbps in a single cell. Carrier Aggregation is a logical step in that direction, but the technology in itself is not the magical wand in resolving the shortage of spectrum and capacity issues. A big challenge with the implementation of carrier aggregation would be the user equipment hardware complexity. While the simplest form of carrier aggregation with intra-band contiguous carriers might not require a very complex chipset inside the phone or mobile terminal, intra-band non-contiguous and inter-band aggregated channels will necessitate the use of multiple transceivers inside the user terminal. This would have substantial impact on cost, power and performance. The commercial deployment of LTE Advanced on a major scale will not happen before the later half of this decade, but wireless network operators are hoping that carrier aggregation would solve their spectrum woes partially if not completely.