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Saturday, January 4, 2014

Could Radio Technologies be Converging Towards LTE?

The huge popularity of smartphones and tablet computers has pushed the need for mobile broadband networks. Users find increasing value in mobile devices combined with a wireless broadband connection. Users and new applications need faster access speeds and lower latency while operators need more capacity and higher efficiency. LTE is all about fulfilling these requirements. GSM made voice go wireless, HSPA made initial set of data connections go wireless and now LTE offers massive capabilities for the mobile broadband applications.

The first set of LTE specifications were completed in 3GPP in March 2009. The first commercial LTE network opened in December 2009. There were approximately 50 commercial LTE networks by the end of 2011 and over 100 networks are expected by the end of 2012. The first LTE smartphones were introduced in 2011 and a wide selection of devices hit the market during 2012.

Overall, LTE technology deployment has been a success story. LTE shows attractive performance in the field in terms of data rates and latency and the technology acceptance has been very fast. The underlying technology capabilities evolve further which allows pushing also LTE technology to even higher data rates, higher base station densities and higher efficiencies.

The history of mobile communications has seen many competing radio standards for voice and for data. LTE changes the landscape because all the existing radios converge towards LTE. LTE is the evolution of not only GSM/HSPA operators but also CDMA and WiMAX operators. Therefore, LTE can achieve the largest possible ecosystem. LTE co-exists smoothly with the current radio networks. Most GSM/HSPA operators keep their existing GSM and HSPA radio networks running for long time together with LTE, and they also keep enhancing the existing networks with GSM and HSPA evolutions. The LTE terminals are multimode capable supporting also GSM and HSPA. The radio network solution is based on multi-radio base station which is able to run simultaneously all three radios. Many operators introduce multi-radio products to their networks together with LTE rollouts to simplify the network management and to modernize the existing networks.

The starting point for CDMA andWiMAX operators is different since there is no real evolution for those radio technologies happening. Therefore, CDMA and WiMAX operators tend to have the most aggressive plans for LTE rollouts to get quickly to the main stream 3GPP radio technology to enjoy the LTE radio performance and to get access to the world market terminals.

LTE Capabilities...........

Practical LTE data rates in many cases are higher than the available data rates in fixed Asymmetric Digital Subscriber Lines (ADSL). LTE has been deployed using number of different bandwidths: most networks use bandwidth from 5 to 20MHz. If the LTE bandwidth is smaller than 20MHz, the data rates scale down correspondingly. LTE has been rolled out both with Frequency Division Duplex (FDD) and Time Division Duplex) TDD variants. LTE has the benefit that both the FDD and TDD modes are highly harmonized in standardization.
The end user performance is also enhanced by low latency: the LTE networks can offer round trip times of 10–20 ms. The LTE connections support full mobility including seamless intra-frequency LTE handovers and inter-RAT (Radio Access Technology) mobility between LTE and legacy radio networks. The terminal power consumption is optimized by using discontinuous reception and transmission (DRX/DTX).

LTE also offers benefits for the operators in terms of simple network deployment. The flat architecture reduces the number of network elements and the interfaces. Self-Organizing Network (SON) has made the network configuration and optimization simpler enabling faster and more efficient network rollout.

LTE supports large number of different frequency bands to cater the needs of all global operators. The large number of RF bands makes it challenging to make universal LTE devices. The practical solution is to have several different device variants for the different markets. The roaming cases are handled mainly by legacy radios.

Initial LTE smartphones have a few different solutions for voice: Circuit Switched Fallback (CSFB) handover from LTE to legacy radio (GSM, HSPA, CDMA) or dual radio CDMAรพLTE radio. Both options use the legacy circuit switched network for voice and LTE network for data. The Voice over LTE (VoLTE) solution with Voice over IP (VoIP) also started during 2012.

Radio technology Evolution...................

The radio technology improvements need to be supported by the evolution of the underlying technologies. The technology components – including mass storage, baseband, RF and batteries – keep evolving and help the radio improvements to materialize. The size of the mass
storage is expected to have fastest growth during the next ten years which allows for storing more data on the device and which may fuel data download over the radio. The memory size can increase from tens of Gigabytes to several Terabytes. Also the digital processing has its strong evolution. The digital processing power has improved according to Moore’s law for several decades. The evolution of the integration level will not be as easy as in earlier times, especially when we need to minimize the device power consumption. Still, the digital processing capabilities will improve during the 2010s, which allows for processing of higher data rates and more powerful interference cancellation techniques. Another area of improvement is the RF bandwidth which increases mainly because of innovations in digital front end processing.

The terminal power consumption remains one of the challenges because the battery capacity is expected to have relatively slow evolution. Therefore, power saving features in the devices will still be needed.

The technology evolution is illustrated below;

With all the above said,  Could Radio Technologies be Convergencing Towards LTE?

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