08-10-2014, 09:42 AM
Millimeter-wave Mobile Broadband with Large Scale Spatial
Processing for 5G Mobile Communication
Millimeter-wave.pdf (Size: 1.05 MB / Downloads: 47)
Abstract—
The phenomenal growth in mobile data traffic calls
for a drastic increase in mobile network capacity beyond
current 3G/4G networks. In this paper, we propose a
millimeter wave mobile broadband (MMB) system for the next
generation mobile communication system (5G). MMB taps into
the vast spectrum in 3 – 300 GHz range to meet this growing
demand. We reason why the millimeter wave spectrum is
suitable for mobile broadband applications. We discuss the
unique advantages of millimeter waves such as spectrum
availability and large beamforming gain in small form factors.
We also describe a practical MMB system design capable of
providing Gb/s data rates at distances up to 500 meters and
supports mobility up to 350 km/h. By means of system
simulations, we show that a basic MMB system is capable of
delivering an average cell throughput and cell-edge throughput
performances that is 10 – 100 times better than the current 20-
MHz LTE-Advanced systems.
INTRODUCTION
Mobile communication has been one of the most
successful technology advancements in modern history. The
combination of technology breakthroughs and product
innovation has made mobile devices an indispensable part of
life for more than 5 billion people. The increasing popularity
of smart phones and tablet computers suggests that the
demand for mobile broadband will continue to grow in the
foreseeable future.
The current 4G LTE system uses advanced technologies
such as OFDM, MIMO, Turbo Code, Hybrid ARQ, and
sophisticated radio resource management algorithms. These
technologies are made possible by decades of extensive
research in wireless communication and systems. Still,
continuous improvements in air interface are being
considered by introducing new techniques such as carrier
aggregation, higher order MIMO, Coordinated Multi-Point
(CoMP) processing, etc. However, further improvements in
spectral efficiency appear extremely challenging [1-3].
Another possibility to increase capacity in a given area is to
increase frequency reuse by deploying smaller cells, e.g.
femto-cells. However, the number of cells that can be
deployed in a given area can be limited due to several cost
factors such as site-acquisition, equipment installation, and
backhaul provisioning. Therefore, small cells alone are not
expected to meet the orders of magnitude increase in mobile
data traffic demand in a cost effective and scalable manner.
LARGE SCALE SPATIAL PROCESSING
The antenna aperture size decreases with the square of the
carrier frequency. This means that a 100X more antennas
can be used at 20 GHz to capture the same energy as an
equivalent 2 GHz antenna. However, a single digital chain
per antenna is likely to be prohibitive for MMB systems due
to area, power and cost con n o uppo ng 100’ o
digital chains. Hence, a hybrid approach consisting of both
analog and digital spatial processing looks promising for
MMB systems and has been investigated in [17-20].
Figure 6 shows a possible architecture for hybrid large
scale spatial processing with Nt antennas, transmitting Ns
data streams to K users. To do so, the transmitter is equipped
with Ns < N
t
RF < Nt RF chains. The signal is first precoded
digitally by a baseband precoder, followed by a phase-only
per antenna RF precoder using phased antenna array
CONCLUSION
In this paper, we analyzed the millimeter-wave spectrum
(3 – 300 GHz) and discussed its suitability for mobile
broadband communication. We proposed a millimeter-wave
mobile broadband (MMB) system for 5G mobile