LTE Advanced

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The Ruling 4G Wireless technology

LTE-Advanced will be one of the 4G buzzwords of 2013 as carriers around the world star t to upgrade and deploy the next evolution in networks. Here’s what you need to know:
LTE-Advanced is laid out in the 3rd Generation Partnership Project (3GPP) release 10 of the LTE specification. The updated specification focuses on using technology and tweaks at the basestation and handset to increase the transmission speeds and spectral efficiency of 4G.
The spec is aiming for maximum download rates of 3Gbit/s and uploads of 1.5Gbit/s. These speeds will be less, however, when deployed on real networks outside of the lab.
LTE-Advanced will offer a data speed increase over current LTE networks by deploying upgrades at the radio access network (RAN) and handset. These include “carrier aggregation” techniques that bond together two or more separate radio channels to get faster data speeds, two-by-two smart antenna arrays [also known as 2×2 (or more) multiple input, multiple output (MIMO)] for faster uplink and downlinks. Relay nodes — low power radios that will provide improved coverage and capacity at the cell edge — will help speed up the network, too. Some of these upgrades will help boost speeds on existing LTE devices. Taking full advantage of LTE- Advanced will, however, require a new device with more antennas onboard.
“LTE-Advanced is the next-generation mobile communications standard offering faster speeds than today’s LTE by using the carrier aggregation function. Increasing sales of smart phones, low cost data devices & demand – interest of data centric are creating pressure on service providers to roll out latest technology to meet customers demand, increase customer satisfaction, Improve user experience etc. All these factors are leading to search of new technology or upgrade of existing technology. This road leads to LTE-Advanced”, says Mr. Madhukar Tripathi, Manager-Telecom Segment, Anritsu Pte Ltd India.
According to Mr. Nitin Sharma, Strategic Marketing Manager of Wireless Infrastructure, Analog Devices, “LTE Advanced is the next step in the evolution to 4G networks and offers considerably higher data rates than initial releases of LTE. It promises peak data rates of 3Gbps on the downlink and 1.5Gbps on the uplink path providing average user throughout that are 3x that of LTE. The standard enables higher spectrum efficiency by utilizing techniques such as 8×8 MIMO (Multiple Input Multiple Output) on the downlink and 4×4 MIMO on the uplink reaching efficiencies of 30bps/Hz and 16bps/Hz respectively. In addition spectrum management schemes like Carrier Aggregation are planned to make efficient use of the available bandwidth which in many cases is fragmented. Other features include improvements in cell edge throughput via the use of relay node base stations and techniques such as CoMP (Coordinated MultiPoint) transmission and reception. A combination of these features will enable LTE-A to satiate the throughput and data demand of the future”.

LTE Advanced –A True 4G Technology

LTE Advanced is an official “4G” standard. It’s defined by the ITU as delivering 100 Mbps (mobile) and 1 Gbps (fixed).
The ITU (International Telecommunications Union) in the month of January 2012 agreed on which technologies qualify for the IMT-Advanced specification. The ITU finalized LTE-Advanced and WirelessMAN-Advanced (commonly known as WiMAX 2) both qualify and are officially designated as IMT-Advanced technologies.
IMT-Advanced was the original set of specifications that determined whether a technology could be considered to be “4G” by the ITU (who owns the global trademark for “4G”).
IMT-Advanced defines true fourth generation (4G) mobile technology, succeeding the IMT-2000 standard for 3G mobile technology. The ITU’s decision regarding IMT-Advanced allows organizations like the 3rd Generation Partnership Project (3GPP) to finalize specifications for migration from 3G to 4G. It allows equipment manufacturers to move forward with development of technology with the required functionality, and wireless providers to plan the deployment of new services.
The ITU determined that two platforms under development, LTE-Advanced and WirelessMAN- Advanced (WiMax 2), are capable of meeting the IMT-Advanced standard. These IMT-Advanced technologies will operate on a digital packet- switched network that is IPv6 compatible, with sustained data rates of 100 Mb/s for mobile services and 1 Gb/s for fixed service. Networks will have automatic resource reorganization on demand, enabling them to adjust to changing conditions, and will have scalable frequency bandwidths up to at least 40 MHz. The specification also calls for seamless, smooth call handover among cells and networks, especially for global roaming, and for support of high-quality, high-definition multimedia services.
What consumers currently think of as 4G LTE is actually a pre-4G technology, defined by 3GPP Release 8 and 9 standards. Release 8 introduced LTE technology with three key features. The first is very low latency achieved through shortening the setup time, transfer delay, handover latency, and interruption time. Second, it supports variable bandwidths including 1.4, 3.5, 5, 10, 15, and 20 MHz. Finally, it achieves spectral efficiency through multiple antenna application, a multipath resistant OFDM downlink compatible with MIMO and frequency domain channel-dependent scheduling, and low peak-to-average ratio DFTS-OFDM in uplink, know as a single-carrier FDMA scheme. Release 9 of the standard provides additional higher-layer network enhancements. In terms of performance, millions of current 3G subscribers experience real-world download speeds of 0.5 to
1.5 Mb/s, and those who have made the leap to LTE achieve downloads at least 15 Mb/s.
LTE- Advanced, defined by 3GPP Release 10, will increase both network speed and capacity through wider bandwidths of up to 100 MHz and advanced 8×8 multiple-input multiple-output (MIMO) techniques. Reaching theoretical speeds of 1 Gb/s will be difficult, requiring at least 40 MHz of bandwidth and advanced MIMO. Service providers will have to continue acquiring new bandwidth for LTE-Advanced to reach its full potential. Other features like heterogeneous network and enhanced inter- cell interference coordination, and coordinated multipoint transmission and reception, are intended to improve cell-edge throughput and coverage, while support for relay sites will improve coverage areas.
Now that the IMT-Advanced standards have been approved, U.S. service providers will continue current deployments of LTE while telecom and handset manufacturers integrate release 10 features into basestation equipment and smartphones, to make LTE-Advanced a reality. Next-generation deployments could begin in
2013, but acquiring the necessary spectrum may determine how quickly LTE-Advanced networks reach maximum speed and capacity.
Mr. Mombasawala Mohmedsaeed, General Manager – Applications, EMG, Agilent Technologies India Pvt. Ltd.
”The driving force to further develop LTE towards LTE–Advanced – LTE Release10 is set to provide higher bitrates in a cost efficient way and, at the same time, completely fulfill the requirements set by ITU for IMT Advanced, also referred to as 4G:.
Key Radio Aspects which are proposed in LTE- Advanced Release -10 are:
Enhanced Uplink:
• Clustered SC-FDMA
• Simultaneous PUCCH and PUSCH MIMO
Carrier Aggregation:
• Contiguous and non-contiguous spectrum allocations
• Uplink and downlink signals

Carrier aggregation

Carrier aggregation (CA) is one of the key features of LTE-Advanced and is likely to be one of the earliest deployed technologies of LTE-Advanced. The basis of CA is to extend the maximum transmission bandwidth to up to 100 MHz, and that is done by aggregating up to 5 LTE carriers. When carriers are aggregated, each carrier is referred to as a component carrier. Two or more component carriers are aggregated in order to support wider transmission bandwidths up to 100 MHz to meet peak data rate targets which are – 1Gbps in the downlink and 500 Mbps in the uplink.

LTE-Advanced-The Hope Beyond the Hype

Wireless has always been a game of one- upmanship, as operators and vendors look to leapfrog competitors by rolling out a next- generation technology. For example, although most operators have barely begun building Long Term Evolution (LTE) networks, a few are planning to launch commercial LTE-Advanced (LTE-A) as early as the first quarter of 2013.
Also known as Release 10 of the 3rd Generation Partnership Project (3GPP R10) family of standards, LTE-A achieves fast throughput largely by combining carriers – meaning frequencies, not operators – to deliver higher speeds than a single carrier can handle. The more carriers that are combined, the higher the theoretical and real- world speeds. (R10 supports up to five carriers and a total of 100 MHz.) As a result, an LTE-A operator’s competitive position is closely linked to its spectrum holdings, because the more it has, the more carriers it can bond together.
Unlike LTE, LTE-A doesn’t require network-wide forklift upgrades and wholesale architectural changes. So, in that regard, LTE-A will provide an incremental boost to infrastructure spending through the end of this decade. That’s not to say that LTE-A is a small-revenue opportunity. Just the opposite: Eventually the entire mobile ecosystem will migrate to LTE-A.
Although the first commercial networks will launch in 2013, LTE-A is still a few more years from being a major player in the telecom market.

Test equipment on target for LTE- Advanced

Carrier aggregation is one of the new features that were introduced in 3GPP Release 10 to augment the existing LTE standard and allow it to meet or exceed the ITU targets for IMS-Advanced, aimed at raising the peak data rate to 1Gbps and beyond. Carrier aggregation—the ability to combine multiple carriers scattered around the spectrum—will be used to achieve the wider effective bandwidth,typically up to 100MHz, that will be required to achieve this data rate.
Carrier aggregation of contiguous and non- contiguous bands has been identified as one of the most
crucial aspects in the evolution towards LTE – Advanced. It has also been recognized as presenting a major challenge to the design of user equipment.
Some possible designchallenges in UE in supporting LTE-Advanced discussed by Mr. Mombasawala Mohmedsaeed, General Manager– Applications, Electronics Measurement Group, Agilent Technologies India Pvt. Ltd.
“Carrier aggregation has several implications for the RF characteristics. From RF perspective, intra- band contiguous aggregated carriers have similar properties as a corresponding wider carrier being transmitted and received. However the output power dynamics are impacted by the UE architecture, which may be based on single or multiple PAs. When considering the PA configuration, one must take into account additional back-off requirements that may exist due to combination of carrier aggregation and the other new UL features such as clustering introduced in Release 10 which requires more stringent linearity requirements on the PA than was the case for Release 8/9. When using multiple component carriers, the maximum output power of a UE must be reduced in order to keep the amplifier in the linear region. UE maximum output power is a critical parameter that limits the UL coverage of a network so reduced transmission power means limited UL coverage. So for a UE, increasing the bandwidth does not always result in an increase of the user performance. Because of that, use of multiple uplink carriers needs to be an option that is only used for cases where UEs are not at the cell edge, thus ensuring that the cell-edge data rate is not reduced.
The other test challenge is to analyze the multiple
transmit and receive chains simultaneously. When an eNB transmits multiple component carriers to a UE, the multiple component carriers must arrive at the receiver at the same time, time alignment error of 1.3 µs for inter-band and 130 ns for intra-band are specified for downlink. This requires simultaneous demodulation of the multiple component carriers.Higher order MIMO will increase the need for simultaneous transceivers in a manner similar to carrier aggregation. However, MIMO has an additional challenge in that the number of antennas will multiply, and the MIMO antennas will have to be de-correlated. It will be especially difficult to design multiband, MIMO antennas with good de-correlation to operate in the small space of a 4G UE. Conducted testing of higher order MIMO terminals will no longer be usable for predicting actual radiated performance in an operational network. The introduction of clustered SC-FDMA in the uplink allows frequency selective scheduling within a component carrier for better link performance, and the PUCCH and PUSCH can be scheduled together to reduce latency. However, clustered SC-FDMA increases peak to average power ratio (PAR) by several dB, adding to transmitter linearity issues. Simultaneous PUCCH and PUSCH also increase PAR. Both features create multi-carrier signals within the channel bandwidth and increase the opportunity for in-channel and adjacent channel spur generation. Test tools will need to be enhanced with capability for signal generation and analysis of multicarrier signals in 4G power amplifiers”.

Agilent Solutions to Design and Test:

1) Agilent LTE-Advanced library as a part of ADS, The industry’s first commercial design support for the physical layer of 3GPP Release 10. It enables system and algorithm developers to explore their new designs against the new standard. They can directly download test vectors to instruments for early and continuous hardware validation, accelerating design maturity. And the MIMO Channel Builder and Digital Pre-distortion applications also support Release 10.
2) LTE-Advanced signal generation and signal analysis tools, enabling design engineers to start testing LTE- Advanced physical layer implementations today. They include the flexible and easy-to-use Signal Studio that runs on all the Agilent signal generation hardware platforms including the PXB and the 89600B vector signal analysis (VSA) software that runs on signal analyzers, scopes and logic analyzers.

Anritsu Test Solutions

Anritsu is global leader for LTE testing solution. Anritsu offers a complete line of LTE test equipment to ensure the performance and quality of your LTE equipment and networks. Our MD8430A signalling tester is the first complete LTE Base Station Emulator. Couple the MF6900A Fading Simulator with the MD8430A Base Station Emulator to provide a reproducible fading environment that is essential for evaluating LTE. Our high-performance MS269xA Signal Analyzer provides complete LTE uplink and downlink analysis in a one-box platform that includes signal analysis and signal generation. Our MG3700A Vector Signal Generator produces realistic and reproducible LTE signals and our LTE IQProducer software provides a graphical interface that lets the user easily generate LTE-compliant waveforms.
Anritsu has developed world-first MD8430A-085 Carrier Aggregation option for its MD8430A base station simulator to help testing of LTE-Advanced terminals and chipsets. This will help chip – terminal manufacturers to design, test devices and make them available to market as soon as possible Installing MD8430A-085 option in the MD8430A allows it to operate as an LTE-Advanced base station simulator supporting the coding/decoding, protocol and throughput performance tests required by carrier aggregation function tests.
Rapid Test Designer (RTD) The Rapid Test Designer (RTD) is a revolutionary new tool that significantly speeds up the development and deployment of modern wireless user equipment (UE) by greatly simplifying the way in which tests are created, executed, and analyzed. This is achieved by using a graphical flow-chart interface and many innovative tools within the RTD environment. Users can concentrate on testing specific functions and protocols within the UE without having to be expert on all the 3GPP protocol layers.
Anritsu ME7834 Mobile Device Test Platform is Carrier Acceptance Test solution for LTE Advanced.

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