Suddenly 2017 rather than 2020 looks possible for Massive MIMO and beamforming. Verizon told Wall Street they were close to trials. Nokia next quarter will test Antonio Forenza's pCells, with similar features. Verizon's Lowell McAdam also briefed the street on a plan for "Staying ~two years ahead of competitors in network performance." (Paul de Sa.) They can't reach that goal without pulling up technologies that most thought were five years away.
"Go Massive" is the conclusion of Robert Heath, at The University of Texas at Austin.
Texas is a primary center for the future of wireless. Heath has played an important role. His MIMO testbeds confirmed theoretical ideas with practical demonstrations. With Ted Rappaport, now at NYU, he co-authored the textbook, Millimeter Wave Wireless Communications.
Delivered wireless performance can increase two to ten times over the next few years using arrays of thirty-five to hundreds of antennas. In a simple model, performance doubles as the number of antennas double. The world isn't "simple" but the improvements should be enormous. Ten times wouldn't surprise any of the researchers. Until this week, almost everyone thought that unlikely until 2020 and 5G.
pCell already has a 35 antenna 5'x2'x2' hub. Tower, working with UCSD, has a 256 antenna transmitter that looks aimed at expensive military systems. Henry Samueli at Broadcom mentioned last year they were working on a chip for 50 antennas or more although they haven't released any details.
Last year, Stanford's Arogyaswami Paulraj told me that Massive MIMO was close to ready. Paul nearly twenty years ago forecast speed improvements of 100x one day. 1997 processors probably couldn't control that many signals for a long time but Moore's Law would likely solve that. Jennie and I were interviewing Paul for his Marconi Award, the $100,000 prize that anoints the top communications engineers. I asked what role MIMO could play Australia's NBN in rural areas. "They should look at Massive and MU-MIMO," he replied.
Paulraj trained Heath (Stanford Ph.D 2001,) who in turn trained Forenza (Ph.D. Texas 2009.) Heath, Rappaport & Tom Marzetta of Bell Labs were among the first true believers in this technology. Their research and near-ubiquitous presentations persuaded many. At the Marconi Awards, Marzetta outlined what was coming but research would hold things up. Verizon and Nokia now intend to prove him wrong. AT&T is also watching this closely. I met AT&T's John Stankey at NYU Wireless' 5G conference where AT&T is a supporter. (Friends of Ted will be glad to know he's back at work and sent over a new paper which I wrote up as 14,000 Tests Support Indoor High Frequencies for 5G.)
Massive and other forms of MIMO are at the heart of 5G plans but may come sooner.
Heath and Marzetta are among the authors of the IEEE paper, Five Disruptive Technology Directions for 5G, with Federico Boccardi, Angel Lozano, and Petar Popovski. The Nokia and Verizon moves suggest some of this will be part of 4G. The naming is really marketing; the substance hasn't changed. Here's the abstract. The link is worth following if the topics are important to you.
New research directions will lead to fundamental changes in the design of future 5th generation (5G) cellular networks. This paper describes five technologies that could lead to both architectural and component disruptive design changes: device-centric architectures, millimeter Wave, Massive-MIMO, smarter devices, and native support to machine-2-machine. The key ideas for each technology are described, along with their potential impact on 5G and the research challenges that remain.
I. INTRODUCTION: 5G is coming.
What technologies will define it? Will 5G be just an evolution of 4G, or will emerging technologies cause a disruption requiring a wholesale rethinking of entrenched cellular principles? This paper focuses on potential disruptive technologies and their implications for 5G. We classify the impact of new technologies, leveraging the Henderson-Clark model , as follows:
- Minor changes at both the node and the architectural level, e.g., the introduction of codebooks and signaling support for a higher number of antennas. We refer to these as evolutions in the design.
- Disruptive changes in the design of a class of network nodes, e.g., the introduction of a new waveform. We refer to these as component changes.
- Disruptive changes in the system architecture, e.g., the introduction of new types of nodes or new functions in existing ones. We refer to these as architectural changes.
- Disruptive changes that have an impact at both the node and the architecture levels. We refer to these as radical changes. We focus on disruptive (component, architectural or radical) technologies, driven by our belief that the extremely higher aggregate data rates and the much lower latencies required by 5G cannot be achieved with a mere evolution of the status quo.
We believe that the following five potentially disruptive technologies could lead to both architectural and component design changes, as classified in Figure 1.
1. Device-centric architectures. The base-station-centric architecture of cellular systems may change in 5G. It may be time to reconsider the concepts of uplink and downlink, as well as control and data channels, to better route information flows with different priorities and purposes towards different sets of nodes within the network. We present device-centric architectures in Section II.
2. Millimeter Wave (mmWave). While spectrum has become scarce at microwave frequencies, it is plentiful in the mmWave realm. Such a spectrum ‘el Dorado’ has led to a mmWave ‘gold rush’ in which researchers with diverse backgrounds are studying different aspects of mmWave transmission. Although far from fully understood, mmWave technologies have already been standardized for short-range services (IEEE 802.11ad) and deployed for niche applications such as small-cell backhaul. In Section III, we discuss the potential of mmWave for a broader application in 5G.
3. Massive-MIMO. Massive-MIMO1 proposes utilizing a very high number of antennas to multiplex messages for several devices on each time-frequency resource, focusing the radiated energy towards the intended directions while minimizing intra- and inter-cell interference. Massive-MIMO may require major architectural changes, in particular in the design of macro base stations, and it may also lead to new types of deployments. We discuss massive-MIMO in Section IV.
4. Smarter devices. 2G-3G-4G cellular networks were built under the design premise of having complete control at the infrastructure side. We argue that 5G systems should drop this design assumption and exploit intelligence at the device side within different layers of the protocol stack, e.g., by allowing Device-to-Device (D2D) connectivity or by exploiting smart caching at the mobile side. While this design philosophy mainly requires a change at the node level (component change), it has also implications at the architectural level. We argue for smarter devices in Section V.
5. Native support for Machine-to-Machine (M2M) communication A native2 inclusion of M2M communication in 5G involves satisfying three fundamentally different requirements associated to different classes of low-data-rate services: support of a massive number of low-rate devices, sustainment of a minimal data rate in virtually all circumstances, and very-low-latency data transfer. Addressing these requirements in 5G requires new methods and ideas at both the component and architectural level, and such is the focus of Section VI.
Suddenly 2017 rather than 2020 looks possible. Verizon told Wall Street they were close to trials of massive MIMO and beamforming. Nokia next quarter will test Antonio Forenza's pCells, with similar features. Verizon's Lowell McAdam also briefed the street on a plan for "Staying ~two years ahead of competitors in network performance." (Paul de Sa.) They can't reach that goal without pulling up technologies that most thought were five years away.
elivered wireless performance can increase two to ten times over the next few years using arrays of thirty-five to hundreds of antennas. In a simple model, performance doubles as the number of antennas double. The world isn't "simple" but the improvements should be enormous. Ten times wouldn't surprise any of the researchers. Until this week, almost everyone thought that unlikely until 2020 and 5G.