Powering Wireless Communications

The recent increased demand for 3G smart phones and wireless-enabled PDA-type devices will continue to drive the increase of mobile data traffic in the enterprise and consumer market spaces. The requirement for more data consumption for a richer multimedia experience will encourage service providers to add higher capacity 3.5G and 4G base stations to their existing wireless infrastructure mix, be they WiMAX or 3G LTE. In 3.5G and 4G base station architectures, the increasing data rate and the push for a higher capacity of users per base station led to increasing backplane speeds between radio and baseband cards. This overall bandwidth increase, in turn, requires more multi-core digital signal processors (DSPs) interconnected in a standard cluster configuration on the baseband card with FPGAs and embedded processors in a peer-to-peer networking cluster. Multi-core DSPs now offer architectures with three to six cores, operating in the Gigahertz-per-core range. Data rates between processing elements and the back plane can range from 1 gigabit to as high as 10Gbps, all of which are supported by semiconductors that use the RapidIO 1.3 standard. Continued demands for greater bandwidth have resulted in a market need for higher data rates between processing elements, while at the same time, maintaining low latency, deterministic reliable packet delivery plus an easy-to-manage memory map. All of these are attributes supported by RapidIO 1.3 The above market drivers led to the Serial RapidIO® 2.1 standard. Leading wireless infrastructure equipment providers are adopting this technology in their next-generation platform designs to increase overall system performance and support more subscribers per base station with more revenue-generating, real-time multimedia features. But Serial RapidIO 2.1 is not limited to the rollout of new platforms or upgrades of base stations to 4G standards. In some cases, Serial RapidIO 2.1 is ideal for cost-reduction and power-saving measures in legacy platform updates because Serial RapidIO 2.1 can support more bandwidth per serial link, doubling the baud rate on a link from 3.125Gbaud in Serial RapidIO 1.3 to 6.25Gbaud in Serial RapidIO 2.1. Moreover, it can be transmitted up to 100cm over two connectors, making it ideal for cascading multiple chassis co-located in one physical rack, immediately expanding the processing capacity of a base station. Serial RapidIO 2.1 also adds support for Virtual Channels (VCs) and Virtual Output Queuing (VOQs), improving overall traffic management and allowing OEMs to support more bandwidth in the network with differentiated classes of service, ideal for 4G networks being developed today. Improvements to Quality of Service (QoS) will appeal to carrier-grade communications applications. Within the physical layer, the new standard additions receive equalization capabilities that will allow it to support extended long-reach (100cm) traces at the full data rate. This can even be done with conventional FR4-based PC board materials. In embedded systems, all of the above features are only supported by RapidIO. While 10 Gigabit Ethernet offers some of the attributes that RapidIO 2.1 offers, given that it originates from the LAN/WAN networks, using it in multiprocessor embedded systems for peer-to-peer processing can be difficult due to its higher latency, non-deterministic packet delivery, large packets sizes (causing system-level congestion) and large processor overhead in terminating the protocol, reducing processor cycles for application implementation. The 10 Gigabit Ethernet raw data rate is only half of what is available with Serial RapidIO 2.1. Wireless system OEMs, as well as those in other embedded markets, have chosen to continue from their existing RapidIO 1.3 investments and are moving forward with Serial RapidIO 2.1. The continuous advances in the wireless infrastructure create the need for significant increases in system capability and bandwidth. The industry has responded with the evolution of its most successful interface standard to meet the needs for more bandwidth, more flexibility and better quality of service. Serial RapidIO 2.1 addresses all of these needs and maintains backward compatibility with the previous versions of the specification — helping to keep the installed infrastructure base from becoming obsolete. www.idt.com