W H I T E P A P E R Arnon Friedmann Ph.D. and Sandeep Kumar Communications Infrastructure Group arnon@ti.com skumar@ti.com LTE emerges as early leader in 4G technologies Introduction Given recent commitments on the part of most major service providers, LTE is shaping up as the early leader in 4G deployments. LTE is the Long Term Evolution (LTE) of the Global System for Mobile Communication (GSM) and Universal Mobile Telecommunications System (UMTS) cell phone network. For the last several years, the LTE specification has been developed under the auspices of the Third Generation Partnership Programme (www.3gpp.org). In December of 2008 the LTE specification was accepted by 3GPP and finalized. LTE, like other 4G technologies, represents a departure from the analog circuit switched voice network and a transition toward an alldata packet network based on the Internet Protocol (IP). As such, voice traffic over an LTE network will be handled as Voice-over-IP (VoIP), which transforms voice into packetized data. In addition, the goal of 4G technologies like LTE is to achieve high-speed data rates over the cellular network, over 100 Mbps (more and 10x faster than typical broadband connections), so that consumers can use their mobile phone as the access method of choice for the Internet. With TI s multicore TMS320TCI6487 digital signal processor (DSP) technology, manufacturers have been able to develop not only LTE demonstration platforms and prototypes, but also deploy the TCI6487 in 3G and 3.5G equipment, resulting in a greatly simplified migration to 4G and an accelerated deployment of LTE. TI s second generation of the TCI6487, based on three 1.2 GHz DSP cores, further enhances the ability of equipment manufacturers to add features and functionality to better highlight the full capabilities of LTE. Digital End-to-End LTE has been developed with an eye toward the future requirements for wireless communications systems. LTE is intended to increase the wireless network s capacity and data rates to accommodate service enhancements and new multimedia applications such as interactive video, real-time gaming and other applications that demand tremendous processing power as well as network bandwidth. Current 3G and 3.5G wireless technologies, such as Wideband CDMA (WCDMA), were developed for a mixture of voice and data communications over the same wireless network. Improvements to the data-handling aspects of WCDMA in the form of high-speed packet access (HSPA) technology, and recently HSPA+, have increased the data communications rates of the 3G network to peak speeds of 28.8 megabits per second (Mbps) for downlinks and 5.76 Mbps for uplinks. In all likelihood, this will extend the life of HSPA base station systems somewhat, creating a period of time when both 3G HSPA and 4G LTE networks will be functioning. This sort of scenario points out the critical need for programmable solutions which support multiple standards, such as those embodied in TI s communications infrastructure DSPs.
2 Texas Instruments Even with the faster speeds of HSPA+, the data rate targets for LTE will be significantly higher, reaching peak speeds in the range of 100 Mbps for downlinks and 50 Mbps for uplinks. Field trials of LTE equipment are already underway in several parts of the world. Several aggressive carriers are projecting deployments of LTE in 2010, but the bulk of the deployments will likely transpire in the 2012/2013 timeframe. Faster, Flatter, Cheaper As with many modern post-internet networks, the architecture of an LTE network will transition from the more traditional hierarchical, vertically-oriented structure to a horizontal, egalitarian configuration of peers. This flattening of LTE networks is brought about by distributing intelligence and the functionality of the radio network controller (RNC) throughout the network to various nodes that previously were not equipped with this functionality, such as base stations, media gateways, switching stations and other nodes. Ultimately, this will lower much of the overhead inherent in hierarchical network architectures. Another major change in LTE is the use of orthogonal frequency division multiple access (OFDMA) instead of code division multiple access (CDMA) as the modulation technique. More specifically, the uplink will use OFDMA and the downlink will use single-carrier frequency division multiple access (SC-FDMA). Both frequency division techniques employ Fast Fourier Transforms (FFTs) to segment the allocated bandwidth into smaller units which can be shared among users. SC-FDMA reduces power consumption in handsets because the peak-to-average power ratio of SC-FDMA is lower than that of OFDMA.
Texas Instruments 3 From a computational standpoint, frequency division techniques scale more easily with bandwidth than code division systems. As a result, higher bandwidth CDMA systems require much more computational power than OFDMA systems. In addition, the use of different sized FFTs support implementation across multiple bandwidth allocations including 1.25 MHz, 1.6 MHz, 2.5 MHz, 5 MHz, 10 MHz, 15 MHz, and 20 MHz. This, and the ability to use either paired or un-paired spectrum allocations, allows operators to be much more flexible in the roll-out of LTE systems because LTE can be deployed in different sized bands, depending on the spectrum that is available to the operator. Another benefit of the new modulation is the possibility of higher spectral efficiencies through multiple antenna signal processing (commonly referred to as multiple input/multiple output (MIMO) or beamforming) which is easier to implement in OFDMA systems than in CDMA systems (where the noise is more uniformly spread). Combined with the other physical layer changes, significant increases in spectral efficiencies should be achieved with the transition from CDMA to OFDMA. The flatter and distributed network architecture of LTE and its reduced overhead costs as well as the increased spectral efficiencies inherent in LTE s modulation schemes both reduce the costs of transferring data over an LTE network. The current explosive growth of data communications over 3G and 3.5G networks is expected to continue for the foreseeable future. Consequently, the reduced cost-per-bit of data communicated over LTE will be critical to operators as they attempt to gain market share and meet consumer expectations for flat rates. UMTS and LTE: architecture Circuit Switch Core Network UMTS RNC2 lub interface lur lu-cs interface lu-ps interface MSC Packet Switch Core Network Node B RNC1 SGSN LTE X2 enode B Evolved Packet Core Network S1 interface enode B
4 Texas Instruments The Move to LTE is On Certainly migrating from 3G and 3.5G to 4G, and from one type of wireless technology like HSPDA to another such as LTE can be fraught with unexpected difficulties. TI s LTE solutions give manufacturers the tools they need to navigate through the issues and seize a leading position as a supplier to the LTE marketplace. The following are several examples of how TI s solutions will be able to avoid the risks that are inherent in any migration to a new technology. Multi-technology platforms TI s three-core TCI6487 DSP is well suited for LTE but it also has been effectively deployed in HSPA and WiMAX systems. As a result, the TCI6487 can enable a multi-technology platform supporting all three technologies. Equipment manufacturers can deploy TCI6487-based HSPA channel cards and with software changes have an LTE channel card as well. In addition, the c64x+ DSP core is compatible with prior generations of DSPs such as the TCI6482. This compatibility allows many of the common functions in 3G and 3.5G WCDMA protocols to be migrated seamlessly to LTE systems featuring the TCI6487. And the software development tools used on other TI DSPs, such as Code Composer Studio, are also available on the TCI6487, offering developers a familiar and efficient set of software development tools. Headroom for processing-intense applications The recent introduction of a new faster version of the TCI6487 incorporating three 1.2 GHz DSP cores gives developers additional processing headroom with which more LTE features and functionality can be implemented. Considering the types of processing-intense applications that are expected on LTE networks, the higher processing speeds of the new TCI6487 will undoubtedly be put to good use. Robust software support A critical part of a successful LTE development and deployment program is the system s software environment. Combining the simple programmability of TI s DSPs with a fully functional software platform reduces development time significantly. The LTE release 3 software library for the TCI6487 is comprised of ready-toimplement and fully-tested LTE software modules including all of the LTE PHY functions, such as modulation mapping, scrambling, channel equalization, RACH processing and others. Providing solid software tools and a robust programming platform allows for a flexible implementation, which is important for initial LTE field trials and deployments.
Texas Instruments 5 Fast time-to-market Because of the flexibility and scalability of TI technology as well as the portability of the software and firmware running on it, many equipment suppliers will be able to migrate quickly from their current platforms to LTE products. Indeed, TI has consistently demonstrated the value to manufacturers of code transportability from one technology node to the next. Much of the same can be expected again as wireless infrastructure equipment moves toward LTE. TI technology also allows service providers to deploy LTE systems early in the adoption phase and be assured upgrades and enhancements can be effectively accomplished later. For example, after an initial deployment of an LTE network has been completed, consumer demand may dictate features and functions that had not been included in field trials. With TI technology, the equipment deployed in early trials can be readily reprogrammed or otherwise updated to accommodate alterations or additions to the standard or to implement follow-on enhancements. World-class VoIP quality-of-service Since voice will be another packetized application on the LTE network, it is imperative that carriers have a very high level of confidence in the quality of the Voice over IP (VoIP) capabilities of their LTE systems. Without carrier-grade or better voice quality, subscribers will quickly become disenchanted with the service, increasing churn among subscribers. TI s VoIP capabilities are unsurpassed in the industry. From VoIP phones and throughout the infrastructure, TI s advanced hardware-based processing technologies, including the most powerful and low-power DSPs, and its industry-leading Telogy Software for VoIP are already supporting the most extensive and highest-quality VoIP applications. In addition, TI s PIQUA quality management technology is able to gather pertinent operational data in real time, giving operators the information needed to assure high quality VoIP services.
6 Texas Instruments New Services, New Revenues The very high data rates and other advanced capabilities of LTE will open opportunities for many compelling and exciting applications that will generate additional revenue streams for service providers. Interactive video applications, for example, are well suited to LTE. With a lower cost per gigabyte of data transferred and increased performance, simple applications that are often taken for granted on laptops and PCs, such as browsing or downloading music, should see a significant boost in mobile devices with the advent of LTE. Unlike the limited one-way wireless broadcast and multicast services such as DVB-H and Media-FLO, the high throughput rates of LTE will support both video services and user interactivity over the same network. This creates the possibility of video content that is much more participative than unidirectional broadcast video services. Video conferencing and high-quality multi-player gaming platforms should benefit from LTE as well. Now that the LTE standard has been completed, equipment manufacturers and service providers can clearly see the advantages and opportunities that this multi-faceted technology holds. With the support of TI s innovative technologies, the transition to LTE can be accomplished both quickly and efficiently. In the end, subscribers will be attracted to a plethora of compelling applications utilizing the higher bandwidth and other advanced capabilities of LTE. Important Notice: The products and services of Texas Instruments Incorporated and its subsidiaries described herein are sold subject to TI s standard terms and conditions of sale. Customers are advised to obtain the most current and complete information about TI products and services before placing orders. TI assumes no liability for applications assistance, customer s applications or product designs, software performance, or infringement of patents. The publication of information regarding any other company s products or services does not constitute TI s approval, warranty or endorsement thereof. The platform bar, Telogy Software and PIQUA are trademarks of Texas Instruments. All other trademarks are the property of their respective owners. B010208 2009 Texas Instruments Incorporated SPRY124