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Wireless base stations are an ideal application for the Serial RapidIO® protocol. The systems are typically composed of a variety of cards enclosed in either a standard (ATCA® or MicroTCA™) or custom chassis. These cards can typically consist of: - RF Cards
- Baseband Cards
- Control Card
- Switch Cards
- Network Interface Cards
An example of a MicroTCA based system with a variety of cards is shown below. Some or all of these cards can use the Serial RapidIO protocol. 
Baseband cards require a large amount of signal processing split between ASICs FPGAs and Digital Signal Processors (DSPs). Such a cluster of processing elements needs to be linked together, Tundra RapidIO switches are the ideal solution for implementing these processing element clusters.
Some of the requirements of baseband cards include: An example of a baseband card for UMTS is shown below with Serial RapidIO for local interconnect and GbE for connection to the backplane containing a merged control and data plane over Ethernet: 
The advantages of this implementation include:
- FPGA allows flexible rate approach for evolving air protocols
- Clean partitioning between chip rate and symbol rate
- Switch allows for scalable approach to architecture and add DSPs as required
- Dynamically adjust power/bandwidth as required
- Switch is cost effective and low-power
- DSP implementation allows flexible approach to symbol rate as well as chip rate assist
- This same architecture can be applied to UMTS or other air protocols
- Ease of migration with respect to upgrading baseband cards while maintaining a legacy GbE backplane
Shown below is an example of a baseband card for 3G Long Term Evolution (LTE) with Serial RapidIO for local interconnect and data backplane while maintaining GbE for the control plane. 
WiMAX Baseband Card
For WiMAX (Worldwide interoperability for Microwave Access) applications, the data processing load becomes much more intensive than tradition 2G and 3G networks. Serial RapidIO addresses all of the challenges associated with WiMAX deployment including:
- More bits per dollar than 3G
- Higher data rates than UMTS, requiring larger DSP clusters and more switching bandwidth
- Designed from the ground up for IP applications, not designed on top of circuit switched technology
- Real Mobile Data with 802.16e
- Desire to support maximum number of subscribers per line card with higher data rate per subscriber than UMTS
- Low and deterministic latency to ensure quality of service for voice and video over data infrastructure
Typically there is Orthogonal Frequency Division Multiplexing (OFDM) processing in an FPGA or ASIC and Turbo decoding assist. The WiMAX application also has a higher data rate in the backplane than conventional 3G systems due to the high data rate. Often GigE backplanes are insufficient. Migrating to a Serial RapidIO backplane with up to 10 Gbps of data rate offers a solution that provides sufficient bandwidth to support the needs of WiMAX. 
The above diagram highlights a WiMAX application showing:
- Only 1 FPGA
- FPGA interface to Antenna
- Antenna Combiner function in FPGA if multiple antennae used
- One Serial RapidIO endpoint in FPGA saving Logical Elements
- Include Turbo decode assist in FPGA
- One DSP per antenna sector, but can scale by adding two DSPs per sector
- Control plane can remain Ethernet to gracefully transition software and also leverage Serial RapidIO backplane for high bandwidth data plane
- Low power Serial RapidIO switch with 120-200mW per port
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