Editor’s Note: Welcome to our weekly Reader Forum section. In an attempt to broaden our interaction with our readers we have created this forum for those with something meaningful to say to the wireless industry. We want to keep this as open as possible, but maintain some editorial control so as to keep it free of commercials or attacks. Please send along submissions for this section to our editors at: [email protected]
There’s a lot of excitement in the mobile industry about the business case for rolling out 4G networks in developing markets. The chance to be the first to provide blazing multimedia performance, zero-lag voice communications and thousands of mobile apps to huge, previously underserved populations seems economically hard to resist. But unfortunately, it’s just not that simple.
In fact, terms like “blazing multimedia,” “zero-lag” and “apps” represent values in performance and productivity that are necessarily born from first-world modes of modern life. The truth is, the culture of touch-screens and video chat will remain financially out of reach for developing markets well after their 4G networks are in place. The eagerly anticipated opportunity to boost developing markets’ economic performance and productivity is, in reality, a deferred one. However, clever technological planning and correct early implementation can help ensure the future that so many of us can clearly see.
In general, developing nations presently do not have the benefit of a comprehensive wired online experience. Furthermore, access to wireless networks is typically limited to a small proportion of the population and its usage is limited to basic communication needs. Wireless devices must be low cost to address any significant fraction of the population. Smart phones are not in this category. The cost pressures in many developing nations can be the most extreme of any world market, and while the 4G network topology can provide excellent costs/benefits, market penetration will not be realized if the relatively high cost of LTE/WiMAX handsets is not addressed and solved.
Much of the handset cost can be attributed to the desires and competitive requirements of established markets like the United States and parts of Asia and Europe where smartphones with large multimedia-capable displays are becoming the norm. However, even when we strip away the large displays and other non-essential features, from a developing nation perspective, we are still left with a core handset that is too expensive.
To effectively address developing markets, key cost innovations need to make their way into the core of the handset’s physical layer – the so-called PHY – to reduce handset costs. These same innovations can also have a positive impact on high-speed performance in wireless devices in developed markets is an important plus.
In developed markets, 4G data rates in excess of 100 Mbps are a reasonable objective. Wireless channels, however, impose fundamental range and data rate limits that make this a significant challenge. OFDM is inherently vulnerable to Doppler frequency shifts that result from moderate mobility speeds. OFDM is also sensitive to interference caused by other base station transmissions, which in dense urban deployments, such as occur in much of the developing world, becomes increasingly problematic. These conditions also have a significant effect on lower data rates and voice, which are likely the first requirements for developing nations and markets.
In all market deployments, wireless operators and device manufacturers constantly 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, there are several approaches to restore as much performance as possible. In the wireless broadband space, for example, the current approach to counteracting interference is Multiple Input Multiple Output (MIMO) schemes in base stations and handsets. These MIMO solutions result in a significantly higher handset cost due to additional antennas and RF amplifiers. While these solutions succeed in achieving a network capacity increase over current single antenna solutions, they tend to be complex and the required hardware is expensive, especially in user terminals due to miniaturization and compact configuration requirements.
Fortunately, breakthrough technology has been recently developed and introduced in the form of chip-level, IP core receiver solutions (Advanced PHY) for OFDM-based 4G wireless networks that can offer more than 65% gain in spectral efficiency. Through these types of capacity increases and bandwidth efficiencies, mobile operators can deliver higher data rates and wider coverage to end-users, greatly improving the business case for deploying LTE or WiMAX networks in data-hungry markets, and this is just as applicable to deployments focused on basic services. More importantly, this level of performance improvement can allow user terminals to be deployed with single-antenna solutions while retaining the very high performance that approaches the level of devices with two antennas. Reducing the complexity and eliminating a second transceiver considerably reduces the cost of handsets and provides a much better approach to miniaturization.
The Advanced PHY IP core mitigates noise and interference by leveraging a highly evolved mathematical algorithm first pioneered in the 1950s for physics applications. With far lower complexity and occupying less than one half of a square millimeter of chip space, these algorithms have been demonstrated both in simulations and in commercial hardware to offer upwards of 10dB Packet Error Rate (PER) improvement under real world conditions and environments. Advanced PHY is also particularly effective at reducing Doppler-related and co-channel interference performance degradations.
Increasing overall receiver performance provides capacity improvements under challenging mobile channel conditions. Co-channel interference, inter-carrier interference, and multipath interference no longer have to be the drains on capacity they are today. Compared to other solutions, the Advanced PHY provides some of the highest spectral gain/dollar, while retaining critically low implementation complexity. Moreover, it can be easily integrated into any 4G-chipset solution. Perhaps best of all, Advanced PHY can work with a single antenna or as a significant improvement to MIMO receivers. All things considered, service providers can deploy fewer base stations and at the same time deliver a better user experience. This reduction in cost is critical to handset deployments in developing nations.
Thus, Advanced PHY can boost existing MIMO performance and potentially eliminate the need for advanced MIMO in some instances that may be significantly cost-sensitive. In fact, simulations have shown that the Advanced PHY, in a single antenna (SISO) configuration, performs above 2×2 MIMO implementations in current standards. Advanced PHY also helps in DSL fixed-wire and HD digital TV broadcast applications and It is widely applicable to any communication system with multi-tone (e.g., OFDM) schemes, regardless of the standard. Simulations show that the Advanced PHY algorithm can improve effective spectrum capacity over current PHY designs by a larger margin at significantly lower costs compared to any proposed alternatives.
The race to 4G is currently a consumer-driven competition with a huge additional opportunity in developed nationsand the relentless growth in data consumption necessitates higher connection speeds and very efficient use of spectrum. While the need for high-speed data traffic in developing nations is today less important, wireless operators and device manufacturers must consider the unique benefits 4G in
these environments can provide. Advanced PHY accelerat
es the 4G ascent, giving operators and manufacturers’ explosive return on investment and providing essential cost advantages for developing markets.
Steve Caliguri is VP of Business Development at Acorn Technologies. www.acorntech.com
