Tackling complex signal-processing tasks for 3G LTE May 1, 2007 12:00 PM
By Ashok Bindra
With a significant boost in data rates coupled with much wider channel
bandwidths, 3G LTE specs will require complex signal-processing techniques
such as MIMOs, OFDMA and MC-CDMA. This report investigates solutions
that are being readied even before the standard is ratified. While semiconductor
suppliers are readying their DSPs and FPGAs, as well as front-end data
converters and RF power amplifiers, test gear providers are unveiling their
test strategies.
As 3G wireless technologies continue to make progress worldwide, developers at the Third Generation Partner-ship Project (3GPP) are looking beyond the current 3G wireless technologies, such as wideband CDMA (W-CDMA), which were developed for a mixture of voice and data communications over the same wireless network. Recent enhancements to W-CDMA, such as the high-speed packet access (HSPA), both on the uplink and downlink, are not enough. In fact, according to experts, significant further improvements are required if 3G must continue to dominate the global cellular market. Toward that goal, 3GPP has taken an initiative, resulting in long-term evolution (LTE) or 3G LTE. Some also refer to it as 4G. With competitive pressure building from mobile WiMAX and ultramobile broadband (UMB), a parallel effort of CDMA, developers are pushing the evolution in 3G LTE. As a result, initial standards are expected in the fourth quarter of this year. As per the timeline shown in Figure 1, prototype systems are expected in late 2007. Field trials may get under way toward the end of 2008 with real-world network deployments seen as early as 2010. According to a new study from ABI Research, network operators will invest almost $18 billion in LTE capital infrastructure over the period to 2014.
Aiming to achieve broadband-class data rates over the cellular network, LTE is intended to significantly increase the wireless network's capacity and data rates so that it can accommodate service enhancements and new multimedia applications such asinteractive video. Hence, by comparison, packet-based LTE is planning to significantly boost data rates by achieving speeds in the range of 100 Mbps for downlinks and 50 Mbps for uplinks. Presently, circuit switched 3G networks deliver speeds of 14.4 Mbps downlink and 5.76 Mbps uplink. According to the developers, one change that helps enable these increased speeds is the transformation of the network into an all-data network, which uses VoIP for voice traffic.
