From Algorithm to Bit-True Design
– by Ming-Luen Liou and Tzi-Dar Chiueh
In modern receivers, signal processing algorithms are usually executed in fixed-point arithmetic to save hardware costs as well as power consumption. Designers need to make compromises among cost, performance and hardware constraints of building blocks to obtain acceptable designs meeting the overall system performance specifications.
8.1 Design Flow Overview
System design is a series of mapping processes. As Figure 8.1 depicts, during these processes, a design starts from a clear system specification, and then descends gradually from higher levels to lower levels with more details. Checked points are specified between successive design phases to make sure that design consistency is always maintained and target specifications are met. If an intermediate design fails to meet the target functional/performance specifications or the system behaviors are not consistent with those from higher-level models, designers should revise the design for a better solution.
During the initial design phase, system algorithm is developed by constructing a floating-point functional model that meets the system specifications in both performance and functionalities. For receiver algorithm exploration, it is also necessary to analyze and model the channel effects, non-ideal characteristics and impairments. Even with functional models for all modules, the design is still inadequate because hardware-related information such as ...