The fifth generation (5G) wireless communication networks is currently attracting extensive research interest from both industry and academia. It is widely agreed that in contrast to 4G, 5G should achieve 1000 times the system capacity, 10 times the spectral efficiency, higher data rates (i.e., the peak data rate of 10 Gb/s and the user experienced rate of 1Gb/s), 25 times the average cell throughput, 5 times reduction in E2E latency and 100 times connectivity density. Among them, thousand-fold increase in capacity becomes the most important requirement for 5G.

To achieve above gains for 5G, three symbiotic technological directions are independently emerging: Firstly, the increased network density achieved by the small cell technique helps to improve the frequency reuse for substantially increased spectral efficiency; Secondly, spectrum extension especially in the millimeter wave (mmWave) band can provide much larger bandwidth for improved capacity. Lastly, Massive multiple-input multiple-output (MIMO) using a large number of antennas at the base station to accommodate more users is able to substantially increase the spectral and energy efficiency simultaneously.

Separately, each of above technologies could offer an order of magnitude increase in wireless capacity compared to current broadband systems. By the combination of them together, one can envision achieving the approximate thousand-fold increase in capacity for 5G that will be needed in the coming decades. An encouraging factor is the apparent symbiosis between these three concepts: smaller cell sizes are attractive for the mmWave communications where RF path loss increases with frequency, the large beamforming gains achievable with Massive MIMO can conversely extend coverage at longer ranges to help overcome the high mmWave path loss, the reduction in channel coherence time at mmWave frequencies is offset by the lower mobility and hence the higher channel coherence bandwidth due to operation in small cells, and the shorter wavelength associated with higher frequencies is appealing for Massive MIMO transceiver design since the physical dimensions of the antenna array and associated electronics are reduced in size. Therefore, mmWave Massive MIMO provides a judicious solution that naturally integrates these three concepts in an elegant way to achieve the goal of thousand-fold increase in capacity for future 5G wireless communications.

This Workshop, inspired by the recent advances in mmWave Massive MIMO towards 5G research initiative, envisions contributions including different aspects ranging from the physical layer signal processing techniques, and the medium access control (MAC) design, to the networking protocols. This special issue will bring together academic and industrial researchers to identify and discuss technical challenges and recent results related to mmWave Massive MIMO communications. Specific topics include, but are not limited to:

• Information theoretic issues of mmWave Massive MIMO

• Novel waveform for mmWave Massive MIMO

• 3D Models for mmWave Massive MIMO Networks

• Channel Estimation techniques for mmWave Massive MIMO

• Coherent and non-coherent detection for mmWave Massive MIMO

• Modulation and Energy Efficiency for mmWave Massive MIMO

• MAC layer design for mmWave Massive MIMO

• Interference Management for mmWave Massive MIMO

• New Correlation sources for MmWave Massive MIMO Networks

• Mobility Management in mmWave Massive MIMO Networks

• Random matrix theory and mmWave Massive MIMO analysis of wireless communication systems

• Beamforming, precoding and space-time coding schemes

• Backhaul Transmissions for mmWave Massive MIMO

• System-Level Modeling in mmWave Massive MIMO Cellular Networks

• Antenna and RF Transceiver

• Architecture Experimental demonstrations, tests and performance characterization of large-scale wireless systems

• Standardization and Business model for mmWave Massive MIMO