Steve Caliguri is the Vice President - Telecom at Acorn Technologies Inc.; he has over 25 years of experience in the telecom and technology sectors and has led Acorn Technologies telecom division since its inception. Previously, he was a founder and senior executive officer of Leap Wireless, Inc., which began as a spin-off of Qualcomm. Mr Caliguri was also responsible for Leap’s Chilean Wireless operating company investment, SMARTCOM PCS. Prior to Leap Wireless, Mr Caliguri was Senior Director of Product Management for the CDMA Infrastructure Division of QUALCOMM where he focused on the development of products for system-level applications, including WLL, mobility systems, data systems, and advanced network solutions. Steve Caliguri received his Bachelor of Science degree in physics from Boston College and an MSEE from Northeastern University. He also attended Boston College’s MBA program.
Developing nations need 4G wireless networks to provide both voice and high-speed data connectivity, but the technology is so expensive that building a solid business case is difficult in many regions of the world. Low cost handsets are needed, but traditional ways to improve equipment performance are expensive. Today, innovative chips exist that improve network throughput by over 60 per cent and significantly reduce both handset and network deployment costs, so mobile operators can profitably deploy and market lower-priced 4G services.
We have come to expect from all of the media coverage that the roll out of 4G networks in developed nations will bring with it blazing multimedia performance, zero-lag voice communications and thousands of mobile apps, which in turn will boost economic performance and productivity. Developed nations therefore expect an optimized wireless infrastructure supporting sophisticated smart devices. Developing nations, on the other hand, do not have the benefit of a comprehensive wired online experience. Furthermore, usage of wireless networks is typically limited to a small proportion of the population and is used for fundamental communication needs. Wireless devices must be low cost to address the majority of the population. Smartphones are not in this category. The cost pressures in many developing nations can be among the most extreme of any world market, although 4G networks can provide excellent costs/benefit ratios; 4G market penetration will be quite low unless the high cost of LTE/WiMAX handsets is controlled. Much of the cost is due to handsets designed with high-cost features aimed at established markets like the United States, Japan and Europe where smartphones with large multimedia-capable displays are becoming the norm. Nevertheless, even if we strip away the large displays and the bells and whistles, the core handset is still too expensive for base of the pyramid markets. Changes at the core of the handsets’ physical design - the core of the handset’s physical layer, the so-called ‘PHY’ –. are needed to reduce their costs and match their performance to the needs of developing markets. These design changes can also improve these phones’ high-speed performance, so they can even help drive short-term financial gains in developed markets. In developed markets, 4G data rates in excess of 100Mbps are a reasonable objective. Wireless channels, however, impose fundamental range and data rate limits that make this a significant challenge. OFDM (orthogonal frequency-division multiplexing - the basis for LTE and WiMAX 4G) is inherently vulnerable to Doppler frequency shifts that result when the handset is in motion - say, in a car - even at moderate speeds. OFDM is also sensitive to interference from other base stations - a serious problem in dense urban deployments. These vulnerabilities reduce data and voice rates, and seriously hamper the ability of these networks to bring high-speed, cost-effective, communications to developing regions. In any market deployment, wireless operators and device manufacturers need to manage the trade-off between performance and system cost. Since the effective capacity of any given bandwidth allocation is degraded by multiple sources of interference, several techniques are available on the market to restore as much performance as possible. However these solutions - additional antennas and amplifiers, for example - make the handsets significantly more costly without significantly improving throughput. With wireless broadband, for example, multiple input multiple output (MIMO) schemes for both base stations and handsets are often used to counteract interference. These solutions increase network capacity compared to current single antenna solutions, but the handsets tend to be complex and expensive, due to the miniaturization and compact configurations required. Handset technology now exists - chip-level, IP core receivers for OFDM-based 4G wireless networks - that provide gains in spectral efficiency of over 60 per cent. With these capacity increases and bandwidth efficiencies, mobile operators can deliver higher data rates and wider coverage to end-users. This sort of capacity greatly improves the business case for deploying LTE or WiMAX networks in data-hungry markets - even, as in developing markets, if they are only focused on basic services. These chips make it possible to economically manufacture high performance single-antenna user handsets that rival the performance of devices with two antennas. Reducing the complexity and eliminating a second transceiver can reduce the cost of handsets considerably and makes it easier to miniaturise the device. The advanced PHY IP core (the chip’s ‘physical layer’) mitigates noise and interference by leveraging an extremely evolved mathematical algorithm pioneered in the 1950s for physics applications. With far lower complexity and occupying less than one-half of a square millimetre of chip space, these algorithms demonstrably, both in simulations and in commercial hardware, offer upwards of 10dB packet error rate (PER) improvement under standards-defined conditions and environments. It is also particularly effective at reducing Doppler-related and co-channel interference performance degradations. Increasing overall receiver performance, by whatever means, provides capacity improvements under challenging mobile channel conditions; co-channel interference, inter-carrier interference, and multipath interference no longer have to be the drains upon capacity that they are today. Compared to other solutions, the advanced PHY chip circuitry provides some of the highest spectral gain per dollar, while retaining critically low implementation complexity. Moreover, it can be easily integrated into any 4G-chipset solution with minimal impact. Perhaps best of all, the advanced PHY can work with a single antenna or as an improvement to MIMO receivers. All things considered, service providers can deploy fewer base stations and still deliver a better user experience; the cost reduction could be critical to deployments in developing nations. The advanced PHY can boost existing MIMO performance and, in some instances, eliminate the need for, and cost of, advanced MIMO. In fact, simulations have shown the advanced PHY, in a single antenna (SISO) configuration, can perform better than certain MIMO implementations specified in current standards. This advanced PHY also helps in DSL (digital subscriber line) fixed-wire and HD digital TV broadcast applications. That is, it is widely applicable in any communication system with multi-tone (e.g., OFDM) schemes, regardless of the standard employed. Simulations suggest that the algorithm can potentially double effective spectrum capacity over current PHY designs at significantly lower costs than the proposed alternatives. The race to 4G is currently a consumer-driven competition mostly focused on developed nations. Growth in data consumption requires higher connection speeds and efficient spectrum use. Although developing nations have less need for extremely high-speed data traffic, wireless operators and device manufacturers still seek cost-effective methods that let both consumers and service providers in these regions get the most out of 4G networks. Simply put, advanced PHY gives 4G operators and manufacturers an explosive return on investment and offers greatly needed cost advantages for developing markets.