Flexible and efficient architecture design for MIMO MMSE-IC linear turbo-equalization

Abstract

International audienceThe variety of wireless communication standards and their corresponding applications requires more and more flexible, yet efficient, implementations. The emerging flexibility need induces a new challenge when added to the ever increasing requirements in terms of high throughput and low complexity. This paper presents a design of an application-specific processor dedicated for a minimum mean square error interference cancellation (MMSE-IC) linear equalizer (LE) used in iterative multi-input multi-output (MIMO) turbo receiver. The explored design approach applies static scheduling of datapath control signals. The proposed architecture supports the requirements of flexibility for different MIMO system configurations concerning channel time selectivity and transmission diversity. In order to evaluate the efficiency of the adopted architecture model for this kind of applications and requirements, a fair comparison is conducted with a state-of-the-art application specific instruction-set processor (ASIP) implementation. The obtained results illustrate a significant performance improvement in terms of execution time and implementation area while using identical computational resources and supporting same flexibility parameters

Efficient quantization and fixed-point representation for MIMO turbo-detection and turbo-demapping

“…The multiplicand and multiplies are represented in Q [ 10] . [ 6] and Q [ 5] . [ 11] , respectively, whereas, the product is represented in Q [ 6] .…”

“…It supports iterative demodulation and its flexibility is not restricted to certain types of modulation and/or mapping styles. Similarly, another flexible application-specific processor dedicated for minimum mean-squared error (MMSE) linear equalizer has been proposed in [6]. Its flexibility is extracted from the following requirements: (1) the capability to support different MIMO schemes reaching to 4× 4 antenna dimension, (2) the ability to maintain efficient use of hardware resources for different time diversity channel types (fast fading, quasi-static, and block fading) and (3) the possibility to execute in an iterative or non-iterative modes.…”

“…In fact, the techniques which were found to be effective in combating ISI are often extended to the context of MIMO detection [7,8]. Therefore, the designed MMSE equalizer in [6] is used for iterative MIMO detection. In the remainder of this paper, iterative MIMO detection based on MMSE linear equalization is referred to as turbo-equalization.…”

“…In the designed architectures for Max-Log-MAP demapping [5] and MMSE equalization [6], fixed-point arithmetic has been adopted. In addition, the input data, the output data, and the intermediate computational values have been quantized according to defined precisions.…”

“…The purpose of this paper is to present the efficient data quantization and fixed-point representation that are devised for the architectures of MMSE turbo-equalizer [6] and Max-Log-Map turbo-demapper [5]. Moreover, their influence on the receiver error-rate performance is evaluated for multitude configurations.…”