Essential Elements of Wireless Physical Layer Design
Each PHY implementation is a unique embedded system. Delivering superior baseband performance requires a range of elements to come together in a unified design. The technical foundation for successfully designing and delivering wireless PHY solutions is more than an ability to study industry specifications and generate digital signal processing code. ArrayComm has expertise in the skills that are essential in delivering a commerical PHY:
Real-Time Framework — The data processing demands for a wireless PHY are extremely challenging and must be addressed by a real-time combination of silicon, PHY software, performance requirements, and the interface to Layer 2 and beyond. A successful implementation accounts for all the data flows at the outset of the program, troubleshooting the choke points and breakdowns before they occur in downstream system tests.
Hardware–Software Partitioning — Virtually all Layer 1 designs require the most intensive signal processing routines to be rendered in hardware accelerators rather than DSP software, formerly on FPGAs and now with on-chip function engines. The remaining signal processing routines will be spread across a multicore hierarchy of DSP and MCU processors, caches, buses, and shared memories. Optimizing the task assignments across these resources is key to attaining the best combination of cost, design risk, and time to market.
Code Optimization — Each hardware platform presents a combination of strengths and challenges as a software platform because the software compilers and multicore operating systems affect the ability to use the hardware. Architecting the PHY algorithms and software to make the most efficient use of the available tools, operating systems, and processing engines will assure maximum performance and design headroom.
Standards Knowledge — An in-depth understanding of the practical application of the PHY air interface standard assures that the product will be successful in the market, with rapid time to market and efficient use of project resources. Knowing which protocol permutations will be crucial for success in the field, as well as those which have lower or no priority, will focus the design on the proper critical success factors.
Testing Expertise and Environment — Roughly half of the total effort in a PHY development program is invested in testing at multiple points in the delivery process. Practical knowledge of what to test, how to test, and the equipment it takes to be successful is just as important as the research and coding that support the actual PHY design.
System Integration — Integrating a PHY with the MAC scheduler and radio resource management requires overall system expertise and careful testing in a lab environment. The bring-up process should include functional, corner case, and stress testing using digital vectors as well as RF test equipment. Including appropriate metrics and diagnostics in the PHY design provides more visibility to the upper layers, and extends this debug capability into the field deployment.
RF Knowledge — Layer 1 processing is by definition the translation of an RF signal to the digital data realm and vice versa. An in-depth understanding of the radio propagation and interference characteristics of the specific standard and frequency range to be supported assures a practical design that maximizes real-world performance.
ArrayComm’s extensive experience in all aspects of wireless baseband design and development provides us with a strong foundation from which to deliver best-in-class wireless PHY products. Take a moment to scan our BasePort PHY for LTE and WiMAX product page to see how we can fit into your wireless equipment designs.