Millimeter-Wave Enhanced Local Area Systems: A High-Data-Rate Approach for Future Wireless Networks

Wireless data traffic is projected to skyrocket 10 000 fold within the next 20 years. To tackle this incredible increase in wireless data traffic, a first approach is to further improve spectrally efficient systems such as 4G LTE in bands below 6 GHz by using more advanced spectral efficiency techniques. However, the required substantial increase in system complexity along with fundamental limits on hardware implementation and channel conditions may limit the viability of this approach. Furthermore, the end result would be an extremely spectrally efficient system with little room for future improvement to meet the ever-growing wireless data usage. The second approach is to move up in frequency, into an unused nontraditional spectrum where enormous bandwidths are available, such as at millimeter wave (mmWave). The mmWave option enables the use of simple air interfaces since large bandwidths can be exploited (e.g., 2 GHz) to achieve high data rates rather than relying on highly complex techniques originally aimed at achieving a high spectral efficiency with smaller bandwidths. In addition, mmWave systems will easily evolve to even higher system capacities, because there will be plenty of margin to improve the spectral efficiency as data demands further increase. In this paper, a case is made for using mmWave for a fifth generation (5G) wireless system for ultradense networks by presenting an overview of enhanced local area (eLA) technology at mmWave with emphasis on 5G requirements, spectrum considerations, propagation and channel modeling, air-interface and multiantenna design, and network architecture solutions.

I. Introduction

WIRELESS data traffic is projected to increase by 1000 fold by the year 2020 [1] and is likely to grow by more than 10 000 fold by the year 2030 [2]. To meet this incredible projected increase in traffic demand, the throughput per square meter in wireless networks must be increased by either shrinking cell sizes (with associated interference mitigation), greatly increasing spectral efficiency, acquiring additional spectrum, or doing some combination of these three. In other words, the 10 000 fold increase in network capacity could be achieved through an increase in performance, spectrum availability and massive densification of small cells as illustrated in Fig. 1. Fig. 1.

Achieving 10 000 capacity.