Efficient DSP and Circuit Architectures for Massive MIMO: State-of-the-Art and Future Directions

Massive MIMO is a compelling wireless access concept that relies on the use of an excess number of base-station antennas, relative to the number of active terminals. This technology is a main component of 5G New Radio (NR) and addresses all important requirements of future wireless standards: a great capacity increase, the support of many simultaneous users, and improvement in energy efficiency. Massive MIMO requires the simultaneous processing of signals from many antenna chains, and computational operations on large matrices. The complexity of the digital processing has been viewed as a fundamental obstacle to the feasibility of Massive MIMO in the past. Recent advances on system-algorithm-hardware co-design have led to extremely energy-efficient implementations. These exploit opportunities in deeply-scaled silicon technologies and perform partly distributed processing to cope with the bottlenecks encountered in the interconnection of many signals. For example, prototype ASIC implementations have demonstrated zero-forcing precoding in real time at a 55 mW power consumption (20 MHz bandwidth, 128 antennas, multiplexing of 8 terminals). Coarse and even error-prone digital processing in the antenna paths permits a reduction of consumption with a factor of 2 to 5. This article summarizes the fundamental technical contributions to efficient digital signal processing for Massive MIMO. The opportunities and constraints on operating on low-complexity RF and analog hardware chains are clarified. It illustrates how terminals can benefit from improved energy efficiency. The status of technology and real-life prototypes discussed. Open challenges and directions for future research are suggested.Comment: submitted to IEEE transactions on signal processin

A real-time FPGA-based implementation of a high-performance MIMO-OFDM mobile WiMAX transmitter

The Multiple Input Multiple Output (MIMO)-Orthogonal Frequency Division Multiplexing (OFDM) is considered a key technology in modern wireless-access communication systems. The IEEE 802.16e standard, also denoted as mobile WiMAX, utilizes the MIMO-OFDM technology and it was one of the first initiatives towards the roadmap of fourth generation systems. This paper presents the PHY-layer design, implementation and validation of a high-performance real-time 2x2 MIMO mobile WiMAX transmitter that accounts for low-level deployment issues and signal impairments. The focus is mainly laid on the impact of the selected high bandwidth, which scales the implementation complexity of the baseband signal processing algorithms. The latter also requires an advanced pipelined memory architecture to timely address the datapath operations that involve high memory utilization. We present in this paper a first evaluation of the extracted results that demonstrate the performance of the system using a 2x2 MIMO channel emulation.Postprint (published version

Design, implementation and testing of a real-time mobile WiMAX testbed featuring MIMO technology

Postprint (author’s final draft

A taxonomy and evaluation for developing 802.11‐based wireless mesh network testbeds

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/92433/1/dac1299.pd

Dynamic Federations for 6G Cell-Free Networking: Concepts and Terminology

Cell-Free networking is one of the prime candidates for 6G networks. Despite being capable of providing the 6G needs, practical limitations and considerations are often neglected in current research. In this work, we introduce the concept of federations to dynamically scale and select the best set of resources, e.g., antennas, computing and data resources, to serve a given application. Next to communication, 6G systems are expected to provide also wireless powering, positioning and sensing, further increasing the complexity of such systems. Therefore, each federation is self-managing and is distributed over the area in a cell-free manner. Next to the dynamic federations, new accompanying terminology is proposed to design cell-free systems taking into account practical limitations such as time synchronization and distributed processing. We conclude with an illustration with four federations, serving distinct applications, and introduce two new testbeds to study these architectures and concepts

Dynamic Federations for 6G Cell-Free Networking: Concepts and Terminology

Cell-Free networking is one of the prime candidatesfor 6G networks. Despite being capable of providing the 6Gneeds, practical limitations and considerations are often neglectedin current research. In this work, we introduce the conceptof federations to dynamically scale and select the best set ofresources, e.g., antennas, computing and data resources, to servea given application. Next to communication, 6G systems are expected to provide also wireless powering, positioning and sensing,further increasing the complexity of such systems. Therefore,each federation is self-managing and is distributed over thearea in a cell-free manner. Next to the dynamic federations,new accompanying terminology is proposed to design cell-freesystems taking into account practical limitations such as timesynchronization and distributed processing. We conclude withan illustration with four federations, serving distinct applications,and introduce two new testbeds to study these architectures andconcepts