Wireless Systems Design

IP Network To Replace Circuit-Switch, Boost Data Rates In Handhelds

LTE could be the answer to keep designers in stride with app influx in cell phones

The mobile phone has evolved to do much more than place a call. Common desktop applications such as e-mail access, Web browsing, and downloading music and videos are becoming common on handsets. Uploading clips to YouTube along with direct video sharing merely hint at what is to come. Clearly the market is receptive to new ideas and services, and network operators are anxious to widen their palette of offerings and tap into new revenue streams. To do so, though, they need higher bandwidths with equally high reliability and handsets that can process such compute-intensive applications.

The answer lies in Long Term Evolution (LTE), an all-digital wireless scheme that will enable rich multimedia applications. The move to LTE means upgrading the wireless infrastructure along with capable terminal devices. Developing them will require significant investments to develop the ecosystem that allows equipment manufacturers to get both infrastructure and end-user products to market quickly.

LTE represents a fundamental change in thinking. Current 3G wireless technologies such as Wideband CDMA (W-CDMA) and High Speed Packet Access (HSPA) handle data and voice communications on circuit-switched networks. They reach speeds of 14.4-Mbps for downlinks to a terminal device and 5.76-Mbps for uplinks. An LTE network, in contrast, uses the Internet Protocol (IP) network to support data and voice traffic. Initial implementations should reach 100-Mbps downlink and 50-Mbps uplink.

As futuristic as LTE sounds, we are not far away. Prototype infrastructure systems are expected at the end of this year, and field trials could be underway in late 2008. As in any market, the first suppliers to provide attractive services will have a huge competitive advantage. Network operators are looking for partners who can help them get LTE systems online quickly. Even though the LTE standard specs are not finalized, equipment manufacturers can begin creating the necessary infrastructure and handsets by working with flexible technology that can adapt to spec revisions.

Implementing LTE systems is a major undertaking. For instance, there are significant changes to the physical layer compared to 3G systems. Instead of CDMA, LTE uses orthogonal frequency division multiple access (OFDMA) for the downlink and single-carrier frequency division multiple access (SC-FDMA) for the uplink, both of which support higher spectral efficiencies leading to faster data rates. In addition, the use of advanced antenna processing technologies such as multiple-in, multiple-out (MIMO) leads to better user capacity over the entire cell and a further increase in data rates.

In setting up new systems for LTE, network operators, network equipment vendors, and handset manufacturers require systems that are scalable to handle future capacity needs, that are upgradeable to adapt to improvements in the standards, and that can seamlessly bridge between current and future services. They’re therefore looking for knowledgeable technology providers who offer development ecosystems that mitigate any downside potential with the early development and deployment of LTE. Such an ecosystem includes:

High performance, flexible processors

Digital signal processing (DSP) engines are particularly well suited to handle the high-performance, low-latency requirements of LTE base stations. Here DSPs with on-board accelerators are preferred over general-purpose RISC processors that lack the needed performance or over ASIC/ FPGA combinations with insufficient programmability. On the handset side, multicore devices must have low power consumption, and dedicated cores will facilitate applications for imaging, video acceleration, or graphics for gaming.

Development platforms

Example systems can give engineers a large head start during product development. On the infrastructure side, many customers have ATCA test systems that accept Advanced Mezzanine Cards (AMC), and they look for prototype cards in that format. Handset manufacturers prefer partners experienced in the wireless sector who can guide them through the product-development cycle.


Developers want to work with productized software that includes well-tested and optimized libraries that implement all the new features and algorithms in LTE. Using this software in their product platforms lowers development time and cost and lets them focus R&D efforts on new end-user applications.


Equipment manufactures want to deal with suppliers that have experience at all levels of the new technology: From helping develop the standards, to designing optimized silicon and software libraries, to working with third parties to quickly bring out reference hardware platforms.

In addition, the increased complexity of the handset system will require equal expertise in design. Operators must deploy platform-optimized applications in order for the handset ecosystem to deliver the highest-level user experience. For example, game developers can potentially deliver console-quality products, or video processing that allows viewing in HD can facilitate vivid, seamless video sharing, or YouTube users can upload and download videos on any device whether it is a PC, laptop, PDA, or handset.

The LTE infrastructure is being put into place, and service providers are beginning to focus on end-user appliances. Forward-looking companies are getting involved with LTE early so they can offer an end-to-end product line and system-level solutions. But they need the help of firms such as TI, technology leaders who understand the demands of the applications and the impact of the transition to digital broadband on the services being provided. Further, TI’s network of third-party development partners have a proven track record of systems integration, application development and sophisticated mobile-device reference designs that feature the flexibility manufacturers need to quickly bring products to market.

TAGS: Mobile
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