mmwave beamforming for 5G - Copy

MILLIMETER-WAVE BEAMFORMING FOR 5G CELLULAR COMMUNICATIONS

FEDERAL INSTITUTE OF SCIENCE AND TECHNOLOGY, M.TECH COMMUNICATION ENGINEERING 1

CHAPTER 1

INTRODUCTION

The rapid increase of mobile data growth and the use of smart phones are creating

unprecedented challenges for wireless service providers to overcome a global bandwidth

shortage. As today's cellular providers attempt to deliver high quality, low latency video

and multimedia applications for wireless devices, they are limited to a carrier frequency

spectrum ranging between 700 MHz and 2.6 GHz.

The global spectrum bandwidth allocation for all cellular technologies does not

exceed 780 MHz, where each major wireless provider has approximately 200 MHz across

all of the different cellular bands of spectrum available to them. Servicing legacy users

with older inefficient cell phones as well as customers with newer smart phones requires

simultaneous management of multiple technologies in the same band-limited spectrum.

Currently, allotted spectrum for operators is dissected into disjoint frequency bands, each

of which possesses different radio networks with different propagation characteristics and

building penetration losses. This means that base station designs must service many

different bands with different cell sites, where each site has multiple base stations (one

for each frequency or technology usage e.g. third generation (3G), fourth generation (4G),

and Long Term Evolution - Advanced (LTE-A)).

To obtain new spectrum, it can take a decade of administration through regulatory

bodies such as the International Telecommunication Union (ITU) and the U.S. Federal

Communications Commission (FCC). When spectrum is finally licensed, unavoidable

users must be moved off the spectrum, causing further delays and increasing costs.

The need for high-speed connectivity is a common denominator as we look ahead

to next generations of networks. Achieving 24x7 access to, and sharing of, all our stuff

requires that we continue on our current path: going far beyond simple voice and data

services, and moving to a future state of everything everywhere and always connected.

Today, as the provisioning and take-up of data services, and the types of connected

devices, on both fixed-line and mobile networks continues to increase exponentially, the

rules of network provisioning need to be re-written. Data services are by their nature



discontinuous. Moving to packet rather than circuit-based service delivery allows more

users to share the same resource even though the overhead associated with directing the

data becomes more complex. As fixed-line network infrastructures have moved from

copper to the virtually-limitless capacity of fiber, this packet delivery overhead has not

been an issue.

Successive advances in mobile network technology and system specifications

have provided higher cell capacity and consequent improvements in single user data rate.

The Increases in data rate have come courtesy of increased computing power, and

increased modulation density made possible by better components, particularly in the area

of digital receivers. In all this, there is one certainty that must be considered wireless

spectrum is limited. In the long run, this must mean only those connections which MUST

be mobile should be wireless. Were already seeing the rise of television and radio

services delivered over the internet, todays Wi-Fi offload becomes the starting point for

the norm of tomorrow, freeing up cellular system capacity to give mobile users the best

possible service.

In the mobile world, capacity gains come essentially from three variables: more

spectrum, better efficiency and better frequency re-use through progressively smaller cell

size. Freeing up frequency bands currently used for other systems will become a major

priority. Mobile broadband networks need to support ever-growing consumer data rate

demands and will need to tackle the exponential increase in the predicted traffic volumes.

An efficient radio access technology combined with more spectrum availability is

essential to achieve the ongoing demands faced by wireless carriers.

In this report, how millimeter wave beam forming can be used for 5G cellular is

presented & also the reasons why the wireless community should start looking at the 3 -

300 GHz spectrum for mobile broadband applications. Discusses propagation and device

technology challenges associated with this band as well as its unique advantages for

mobile communication. And introduce a millimeter-wave mobile broadband (MMB)

system as a candidate for next generation mobile communication system. And show the

feasibility for MMB to achieve gigabit-per-second data rates at a distance up to 1 km in

an urban mobile environment.



CHAPTER 2

LITERATURE SURVEY

To date, four generations of cellular communication systems have been adopted

worldwide with each new mobile generation emerging every 10 years or so since

around 1980: first generation analog FM cellular systems in 1981; second generation

digital technology in 1992, 3G in 2001, and 4G LTE-A in 2011.

Review of Previous Fourth Generations Systems:-

First-Generation Systems (1G):

The 1st generation was pioneered for voice service in early 1980s, where almost

all of them were analog systems using the frequency modulation technique for radio

transmission using frequency division multiple access (FDMA) with channel capacity of

30 KHz and frequency band was 824-894 MHz, which was based on a technology known

as Advance Mobile Phone Service (AMPS).

Second Generation Systems (2G):

The 2nd generation was accomplished in later 1990s. The 2G mobile

communication system is a digital system; this system is still mostly used in different

parts of the world. This generation mainly used for voice communication also offered

additional services such as SMS and e-mail. In this generation two digital modulation

schemes are used; one is time division multiple access (TDMA) and the 2nd is code

division multiple access (CDMA) and frequency band is 850-1900 MHzs. In 2G, GSM

technology uses eight channels per carrier with a gross data rate of 22.8 kbps (a net rate

of 13 kbps) in the full rate channel and a frame of 4.6 milliseconds (ms) duration .The

family of this generation includes of 2G, 2.5G and 2.75G.

Third Generation Systems (3G):

Third generation (3G) services combine high speed mobile access with Internet

Protocol (IP)-based services. The main features of 3G technology include wireless web

base access, multimedia services, email, and video conferencing. The 3G W-CDMA air

interface standard had been designed for always-on packet-based wireless service, so that

computer, entertainment devices and telephones may all share the same wireless network

and be connected internet anytime, anywhere.

3G systems offer high data rates up to 2 Mbps, over 5 MHz channel carrier width,

depending on mobility/velocity, and high spectrum efficiency. The data rate supported by



3G networks depends also on the environment the call is being made in; 144 kbps in

satellite and rural outdoor, 384 kbps in urban outdoor and 2Mbps in indoor and low range

outdoor. The frequency band is 1.8 - 2.5 GHz.

Fourth Generation Systems (4G):

4G usually refers to the successor of the 3G and 2G standards. In fact, the 3GPP

is recently standardizing LTE Advanced as future 4G standard. A 4G system may

upgrade existing communication networks and is expected to provide a comprehensive

and secure IP based solution where facilities such as voice, streamed multimedia and data

will be provided to users on an "Anytime, Anywhere" basis and at much higher data rates

compared to previous generations. Applications such as wireless broadband access,

Multimedia Messaging Service (MMS), video chat, mobile TV, HDTV content and

Digital Video Broadcasting (DVB) are being developed to use a 4G network.

4G-LTE advanced:

LTE also referred to as LTE-Advanced, is claimed to be the true 4G evolution

step. LTE is an orthogonal frequency-division multiplexing (OFDM)-based radio access

technology that supports a scalable transmission band width up to 20 MHz and advanced

multi-antenna transmission. As a key technology in supporting high data rates in 4G

systems, Multiple-Input Multiple-Output (MIMO) enables multi-stream transmission for

high spectrum efficiency, improved link quality, and adaptation of radiation patterns for

signal gain and interference mitigation via adaptive beam forming using antenna arrays .

The coalescence of HSPA and LTE will increase the peak mobile data rates of the two

systems, with data rates exceeding 100 Mbps, and will also allow for optimal dynamic

load balancing between the two technologies.

Earlier releases of LTE are included as integrated parts of LTE release 10,

providing a more straightforward backwards compatibility and support of legacy

terminals, for example. The main requirement specification for LTE advanced as

approved are:

Peak Downlink data rate: 1 Gbps, Peak Uplink data rate: 500 Mbps.

Transmission bandwidth: Wider than approximately 70 MHz in DL and 40

MHz in UL.

User throughput at cell edge 2 times higher than that in LTE.

Average user throughput is 3 times higher than that in LTE.

Spectrum efficiency 3 times higher than that in LTE; Peak spectrum



Efficiency downlink: 30 bps/Hz, Uplink: 15 bps/Hz.

Mobility: Same as that in LTE.

Coverage should be optimized or deployment in local areas/micro cell

Environments with Inter Site Distance (ISD) up to 1 km.

Fig.2.Evolution of wireless communication



CHAPTER 3

FIFTH GENERATION (5G) WIRELESS COMMUNICATION

As fifth generation (5G) is developed and implemented, we believe the main differences

compared to 4G will be the use of much greater spectrum allocations at untapped mm-

wave frequency bands, highly directional beam forming antennas at both the mobile

device and base station, longer battery life, lower outage probability, much higher bit

rates in larger portions of the coverage area, lower infrastructure costs, and higher

aggregate capacity for many simultaneous users in both licensed and unlicensed spectrum

(e.g. the convergence of Wi-Fi and cellular).

The backbone networks of 5G will move from copper and optic fiber to mm-wave

wireless connections, allowing rapid deployment and mesh-like connectivity with

cooperation between base stations.

5G technology has changed to use cell phones within very high bandwidth. 5G is

a packet switched wireless system with wide area coverage and high throughput. 5G

technologies use CDMA and millimeter wireless that enables speed greater than 100Mbps

at full mobility and higher than1Gbps at low mobility. The 5G technologies include all

types of advanced features which make 5G technology most powerful and in huge

demand in the near future. It is not amazing, such a huge collection of technology being

integrated into a small device. The 5G technology provides the mobile phone users more

features and efficiency. A user of mobile phone can easily hook their 5G technology

gadget with laptops or tablets to acquire broadband internet connectivity. Up till now

following features of the 5G technology have come to surface- High resolution is offered

by 5G for extreme mobile users, it also offers bidirectional huge bandwidth , higher data

rates and the finest Quality of Service (QOS) .

Now a day, all wireless and mobile networks are forwarding to all-IP principle,

that means all data and signaling will be transferred via IP (Internet Protocol) on network

layer. The purpose of the All-IP Network (AIPN) is to completely transform (to change

in composition or structure) the 100+ years of legacy network infrastructure into a

simplified and standardized network with a single common infrastructure for all services.

In order to implement 5G technology, Master Core technique is needed to apply

All-IP Network (AIPN) properly. Hence, the Master core is designed. The 5G Master

Core is a convergence of Parallel Multimode (PMM), Nanotechnology, Cloud



Computing, and All IP Platform also 5G-IU technology. These technologies have their

own impacts on existing wireless networks which make them into 5G.

5G wireless networks will support 1,000-fold gains in capacity, connections for

at least 100 billion devices, and a 10 Gbps individual user experience capable of

extremely low latency and response times. Deployment of these networks will emerge

between 2020 and 2030. 5G radio access will be built upon both new radio access

technologies (RAT) and evolved existing wireless technologies (LTE, HSPA, GSM and

Wi-Fi). Breakthroughs in wireless network innovation will also drive economic and

societal growth in entirely new ways. 5G will realize networks capable of providing zero-

distance connectivity between people and connected machines.

5G requirements are:-

Immersive experience: at least 1 Gbps or more data rates to support ultra-high

definition video and virtual reality applications.

Fiber-like user experience: 10 Gbps data rates to support mobile cloud service.

Zero latency and response times: less than one millisecond latency to support

real time mobile control and vehicle-to-vehicle applications and communications.

Zero second switching: max 10 millisecond switching time between different

radio access technologies to ensure a consistently seamless delivery of services.

Massive capacity and always on: current mobile network systems already

support 5 billion users; this will need to expand to also support several billions of

applications and hundreds of billions of machines.

Energy consumption: energy-per-bit usage should be reduced by a factor of

1,000 to improve upon connected device battery life.

Advantages of using 5G:-

5G technology will include spectral bandwidth more than 40 MHz on frequency

channel which is a larger range than all other wireless technology systems.

The artificial intelligence will be included in 5G technology through advance

wearable computer technology.

Massive Distributed with Multiple-input and multiple-output (MIMO) will be

provided by 5G which will help cut costs and make it energy-effective.



5G technologies may consume low battery power, provide a wide range of

coverage, cheap rate of network services and many other advantages.

4G technology provides speed up to 1 GBPS internet speed and so it is possible

that 5G technology will provide more than 1 GBPS speed.

They are more efficient, highly reliable, highly secured network.



CHAPTER 4

MILLIMETER (mm) WAVE TECHNOLOGY

MmWave is a promising technology for future cellular systems. Since limited spectrum

is available for commercial cellular systems, most research has focused on increasing

spectral efficiency by using OFDM, MIMO, efficient channel coding, and interference

coordination. Network densification has also been studied to increase area spectral

efficiency, including the use of heterogeneous infrastructure (macro-, Pico-, femto cells,

relays, distributed antennas) but increased spectral efficiency is not enough to guarantee

high user data rates. The alternative is more spectrum.

Millimeter wave (mmWave) cellular systems, operating in the 30-300GHz band,

above which electromagnetic radiation is considered to be low (or far) infrared light, also

referred to as terahertz radiation.

Fig 4. Millimeter wave frequency spectrum

Despite industrial research efforts to deploy the most efficient wireless

technologies possible, the wireless industry always eventually faces overwhelming

capacity demands for its currently deployed wireless technologies, brought on by the

continued advances and discoveries in computing and communications, and the

emergence of new customer handsets and use cases (such as the need to access the

internet).

This trend will occur in the coming years for 4G LTE, implying that at some point

around 2020; wireless networks will face congestion, as well as the need to implement



new technologies and architectures to properly serve the continuing demands of carriers

and customers.

The life cycle of every new generation of cellular technology is generally a decade

or less, due to the natural evolution of computer and communications technology. Our

work contemplates a wireless future where mobile data rates expand to the multi gigabit-

per-second range, made possible by the use of steerable antennas and mm-wave spectrum

that could simultaneously support mobile communications and backhaul, with the

possible convergence of cellular and Wi-Fi services.

Recent studies suggest that mm-wave frequencies could be used to augment the

currently saturated 700 MHz to 2.6 GHz radio spectrum bands for wireless

communications. The combination of cost-effective CMOS technology that can now

operate well into the mm-wave frequency bands, and high-gain, steerable antennas at the

mobile and base station, strengthens the viability of mm-wave wireless communications.

Further mm-wave carrier frequencies allow for larger bandwidth allocations, which

translate directly to higher data transfer rates.

Mm-wave spectrum would allow service providers to significantly expand the

channel bandwidths far beyond the present 20 MHz channels used by 4G customers. By

increasing the RF channel bandwidth for mobile radio channels, the data capacity is

greatly increased, while the latency for digital traffic is greatly decreased, thus supporting

much better internet based access and applications that require minimal latency. Mm-

wave frequencies, due to the much smaller wavelength, may exploit polarization and new

spatial processing techniques, such as massive MIMO and adaptive beam forming.

Given this significant jump in bandwidth and new capabilities offered by mm-

waves, the base station-to-device links, as well as backhaul links between base stations,

will be able to handle much greater capacity than today's 4G networks in highly populated

areas. Also, as operators continue to reduce cell coverage areas to exploit spatial reuse,

and implement new cooperative architectures such as cooperative MIMO, relays, and

interference mitigation between base stations, the cost per base station will drop as they

become more plentiful and more densely distributed in urban areas, making wireless

backhaul essential for flexibility, quick deployment, and reduced ongoing operating costs.

Finally, as opposed to the disjointed spectrum employed by many cellular operators

today, where the coverage distances of cell sites vary widely over three octaves of

frequency between 700 MHz and 2.6 GHz, the mm-wave spectrum will have spectral



allocations that are relatively much closer together, making the propagation

characteristics of different mm-wave bands much more comparable and ``homogenous''.

The 28 GHz and 38 GHz bands are currently available with spectrum allocations of over

1 GHz of band-width. Originally intended for Local Multipoint Distribution Service

(LMDS) use in the late 1990's, these licensees could be used for mobile cellular as well

as backhaul.

4.1 HISTORY OF mmWAVE

Though relatively new in the world of wireless communication, the history of millimeter

wave technology goes back to the 1890s when J.C. Bose was experimenting with

millimeter wave signals at just about the time when his contemporaries like Marconi were

Inventing radio communications.

Following Boses research, millimeter wave technology remained within the

confines of university and government laboratories for almost half a century. The

technology started so see its early applications in Radio Astronomy in the 1960s,

followed by applications in the military in the 70s. In the 80s, the development of

millimeter-wave integrated circuits created opportunities for mass manufacturing of

millimeter wave products for commercial applications.

In 1990s, the advent of automotive collision avoidance radar at 77 GHz marked

the first consumer oriented use of millimeter wave frequencies above 40 GHz. In 1995,

the FCC (US Federal Communications Commission) opened the spectrum between 59

and 64 GHz for unlicensed wireless communication, resulting in the development of a

plethora of broadband communication and radar equipment for commercial application.

In 2003, the FCC authorized the use of 71-76 GHz and 81-86 GHz for licensed point-to-

point communication, creating a fertile ground for new of industries developing products

and services in this band.



Fig 4.1.0 J.C. Bose demonstrating millimeter wave in 1897

4.2 BENEFITS OF mm-WAVE SPECTRUM

Bandwidth: - The main benefit that millimeter Wave technology has over RF

frequencies is the spectral bandwidth of 5GHz being available in these ranges,

resulting in current speeds of 1.25Gbps Full Duplex with potential throughput

speeds of up to 10Gbps Full Duplex being made possible. Service providers can

significantly expand channel band width way beyond 20 MHz

Beam Width Interference Resistance: - Millimeter wave signals transmit in

very narrow focused beams which allows for multiple deployments in close range

using the same frequency ranges. This allows Millimeter wave ideal for Point-to-

Point Mesh, Ring and dense Hub & Spoke network topologies where lower

frequency signals would not be able to cope before cross signal interference

would become a significant limiting factor. The beam width is approx. 2 degree

this benefit from increased interference protection and spectrum reuse. The

highly directional and narrow radiation pattern from millimeter wave allows

many transmitters to be positioned near each other without causing troublesome

interference even when they are using the same frequencies. Using cross-

polarization techniques allows even more radios to be deployed in an area, even

along the same path.



Security: - Since millimeter waves have a narrow beam width and are blocked

by many solid structures they also create an inherent level of security. In order to

sniff millimeter wave radiation a receiver would have to be setup very near, or in

the path of, the radio connection. The loss of data integrity caused by a sniffing

antenna provides a detection mechanism for networks under attack. Additional

measures, such as cryptographic algorithms can be used that allow a network to

be fully protected against attack.

Fig 4.2. Millimeter wave beam width

4.3 ANTENNAS:- Due to the recent advancements in VLSI technology it is possible to

develop circuits that work in millimeter wave frequency range. The choice of integrated

circuit (IC) technology depends on the implementation aspects and system requirements.

The former is related to the issues such as power consumption, efficiency, dynamic range,

linearity requirements, integration level, and so forth, while the later is related to the

transmission rate, cost and size, modulation scheme, transmit power, bandwidth, and so

forth.

Narrow beam is the key feature of millimeter wave because of this property we

can reduce fading, multipath and interference. The antenna geometry is at chip size

because they have to operate in high frequency rage.

The physical size of the antennas are so small, this becomes practical to build

complex smart antenna arrays that are steerable in nature. Further integrating them on

chip or PCB becomes more feasible. These smart array antennas are adaptive in nature.



Fig 4.3 Antenna array for highly directional MIMO transmission

4.4 PROPAGATION BEHAVIOUR

Millimeter wave transmission and reception is based on the principle of line of

sight (LOS) paths. Received signal strength is relatively stronger than other directions in

line of sight (LOS) path. Line of sight path correspond to the situations where the main

lobes of the transmitter and receiver pair are positioned in a way to capture the line of

sight.

Since the beam width is narrow and the distance covered by millimeter wave is

small (approx. 200 m). Even if there are obstacles usually large objects such as buildings blocks these LOS paths we can still use mm-wave by the principle of Non-line of sight

propagation.

Fig. 4.4.1.LOS and non-LOS links



Non-line of sight path propagation takes place through paths that contains a

single-reflected signal and multiple reflected signal which will yield the best signal

strength for the receiver.

Except for connections between fixed devices, such as a PC and its peripherals,

where non-LOS may be encountered permanently, but most cases involves portable

devices that should be able to have LOS connections because these devices can be moved

to adjust aiming.

These reflections can establish non-LOS links, but these will be still tens of dB

weaker than LOS signal, hence the data rates provided by these non-LOS links are quite

less compared to rates provided by LOS signal.

Fig. 4.4.2. Outdoor & indoor mesh

Path loss exponent for LOS path=2

Path loss exponent for non-LOS path =4

So, to improve the performance is

Incorporate directional beam forming.

Receiver and transmitter antenna should communicate via. Main lobes to

achieve higher array gain.



Self-steerable smart antenna is required such that it adjust automatically

to achieve higher gain, hence the data rate is increased.

Smart antenna is required to distinguish between LOS and non LOS paths

Fig 4.4.2 Performance improvements



CHAPTER 5

mm-WAVE CHANNEL PROPAGATION

5.1 THEORY AND MEASUREMENTS

There have been concerns about utilizing mm Wave frequency bands for mobile cellular

communications. Some of these concerns regarding the propagation characteristics at

higher frequencies such as higher penetration, precipitation, and foliage losses are

reasonable even though the actual amounts of additional propagation losses vary

depending on the material of the building, the strength of rain, or the thickness of foliage.

The most common misunderstanding, however, of the propagation characteristics at

higher frequencies is that they always incur a much higher Propagation loss even in free

space compared to lower frequencies, and thus are not adequate for long-range

communications. To clarify this misunderstanding, let us start with the Friis transmission

equation, given by Eq. (5.1)

(5.1)

Where Pr is the receive power in unobstructed free space, Pt is the transmit power,

Gt and Gr are the transmit and receive antenna gains, R is the distance between the

transmitter and receiver in meters, f is the carrier frequency, c is the speed of light.

The received power can easily be seen as inversely proportional to the frequency

squared when an ideal isotropic radiator (Gt = 1) and an ideal isotropic receiver (Gr = 1)

are used at each end. In reality, however, antennas or an array of antennas with antenna

gains of Gt and Gr greater than unity are typically employed at both ends, and the antenna

gains are proportional to the frequency squared given a fixed physical aperture size. Given

the same physical aperture size, therefore, transmit and receive antennas at higher

frequencies, in fact, send and receive more energy through narrower directed beams,

which is not commonly recognized . In order to verify this, measurements have been



conducted in an anechoic chamber using two antennas supporting 3 and 30 GHz,

respectively, as shown in Fig. 5.1.

Fig.5.1 Results of verification measurements of propogation loss predicted by

Friis equation

A patch antenna at 3 GHz and an array antenna at 30 GHz of the same physical

size were designed for this measurement and placed within an anechoic chamber at each

communication ends. The results in Fig. 5.1 show the same amount of propagation loss

regardless of the operating frequency when an array antenna of the same physical aperture

size is used at the 30 GHz receiving end. In addition, when array antennas are used at

both transmitting and receiving ends at 30 GHz, the measured receive power is 20 dB

higher than that of the 3GHz patch antenna case.

Along with the above-mentioned laboratory measurements , there have been

recent studies regarding the outdoor channel propagation characteristics that have shown

the potential for utilizing higher frequency bands for cellular communications, outdoor

channel measurements were carried out at 38and 28 GHz, respectively, on the campus of

the University of Texas at Austin. Another channel measurement campaign was

conducted at 28GHz to produce measurement data for a suburban environment at the

Samsung Electronics site in Suwon, Korea . In addition, investigation of the channel

characteristics in a dense urban environment was done in Manhattan, New York. All these



channel measurements were carried out at 38 and 28 GHz instead of 60GHz and E-Band,

with many aspects considered including regional regulatory status and availability of

significant amount of licensed spectrum. These study results reveal that the key

parameters characterizing the propagation properties of the mm Wave bands, such as the

path loss exponent, are comparable to those of typical cellular frequency bands when

transmit and receive antennas are used to produce beam forming gains. Transmission

links were established for a distance of up to 200300 m with path loss exponents in the

range of 3.24.58 for NLoS and 1.682.3 for LoS environments, which are similar to

those measured in the traditional cellular bands. Path loss exponents below 2 are

frequently observed due to constructive addition of the reflected and direct paths in street

corridors or tunnels in LoS environments.

While more extensive measurement campaigns are currently being carried out in

Korea and in the United States to build a comprehensive statistical mmWave channel

propagation model, it is evident that the mmWave bands have strong potential as

candidate bands for next generation cellular services. After the verification of the channel

feasibility, the next step is to develop underlying core technologies to most efficiently

utilize the abundant spectrum in the mmWave bands and prove commercial viability.



CHAPTER 6

mm-WAVE BEAMFORMING ALGORITHM

An appropriate beam forming scheme focus the transmitted and/or received signal in a

desired direction in order to overcome the unfavourable path loss is one of the key

enablers for cellular communications at mm Wave frequency bands. The small

wavelengths of mm Wave frequencies facilitate the use of a large number of antenna

elements in a compact form factor to synthesize highly directional beams corresponding

to large array gains.

Depending on the beamforming architecture, the beam forming weights required

to form the directive beam could be applied in the digital or analog domain. When

combined with an orthogonal frequency-division multiplexing (OFDM) system, digital

beamforming is carried out on a subcarrier basis before the inverse fast Fourier transform

(IFFT) operation at the transmitter and after the FFT operation at the receiver, whereas

analog beamforming is performed in the time domain after the IFFT operation at the

transmitter and before the FFT operation at the receiver

Digital Beamforming

Digital beamforming is done in the form of digital precoding that multiplies a

particular coefficient to the modulated baseband signal per RF chain.

Higher degree of freedom

Better performance

Highly flexible

Support for data multiplexing

increased complexity & cost

separate FFT/IFFT blocks , DACs, ADCs required / each RF chain

Analog Beamforming

For analog beamforming, complex coefficients are applied to manipulate the RF

signals by means of controlling phase shifters and/or variable gain amplifiers (VGAs).



Simple

Beam forming with scalar complex weights

Effective method to generate high beamforming gains from large number

of antennas

Reduce costs & complexity and power consumption

less flexible

It is this trade-off between flexibility/performance and simplicity that drives the

need for hybrid beamforming architectures, especially when a multitude of antennas is

required as in the mmWave bands.

Hybrid Beamforming Architecture

A hybrid beamforming architecture applied at both the transmitter and receiver is

illustrated in fig. In this architecture, the sharp beams formed with analog beamforming

(phase shifters) compensate for the large path loss at mm Wave bands, and digital

beamforming provides the necessary flexibility to perform advanced multi-antenna

techniques such as multi-beam MIMO.

Fig.6.Block diagram of Hybrid Beamforming Architecture



In hybrid analog-digital transceiver architecture, full spatial processing at RF

frontend is to divide spatial processing on both RF-frontend and baseband processing

units. The target of this hybrid multi-beam beamforming architecture is provide support

for data multiplexing with reduced power consumptions and costs. Similarly to analog

beamforming architecture, phase shifters in RF beamformers are controlled digitally to

form narrow beams. The target of RF phase-shifters is to enable adaptive analog beam

steering. The purpose of digital domain spatial processing is to perform actual precoding

according to certain optimization criteria, e.g. zero-forcing, minimum mean square error

(MMSE). The simulated performance of the hybrid beamforming architecture in mm

Wave bands are presented in , where link- and system-level simulation results are

provided with various numbers of transmit/receive antennas and RF chains. Using a 500

MHz bandwidth at 28 GHz, presents some notable results for the hybrid beamforming

system including an 8 dB gain over the conventional spatial multiplexing scheme and 8

Gb/s average sector throughput with 16antennas with 4 RF chains at the base station and

8 antennas with a single RF chain at the mobile station.



CHAPTER 7

PROPOSED mm-WAVE BEAMFORMING

PROTOTYPE

The main purposes of the mm Wave prototype are to check the feasibility of mm Wave

bands for sufficiently large geographical coverage for cellular services and support for

mobility even in NLoS environments. The mm Wave beamforming prototype developed

and tested at the DMC R&D Centre, Samsung Electronics, Korea, including system

configuration, key parameters, and capabilities are described here. This prototype

includes RF units, array antennas, baseband modems, and a diagnostic monitor (DM), as

shown in Fig.7.1

Fig.7.1 Configuration of mmWave beamforming prototype

It is the worlds first mmwave mobile technology. Adaptive array transceiver

technology operating in the millimeterwave frequency bands for outdoor cellular

systems includes

RF units

array antennas

baseband modems

diagnostic monitor (DM)



Fig.7.2 Prototype setup model

Both transmit and receive array antennas have two channels.

Each comprises 32 antenna elements arranged in the form of a uniform planar

array (UPA) with 8 horizontal and 4 vertical elements, confined within an area of

60 mm 30 mm. This small footprint was made possible by the short wavelength

of the carrier frequency at 27.925 GHz.

Two channels at the transmit and receive array antennas are designed to support

various multi-antenna schemes such as MIMO and diversity.

The array antenna is connected to the RF unit, which contains a set of phase

shifters, mixers, and related RF circuitry.

The set of phase shifters control the phases of the signals sent to the antennas to

form a desired beam pattern. Therefore, by setting the phase shifter values to a

particular set, transmit and receive array antennas are capable of forming a sharp

beam pattern in the intended horizontal(azimuth) and vertical (elevation) angles.

To reduce the hardware complexity, a sub-array architecture was employed to

group8 antennas into a sub-array, thus requiring only4 RF units per channel

instead of 32.

The reduction in the number of RF paths results in a reduction of antenna gain at

the desired angle(except antenna bore sight), a reduction of beam scanning ranges,

and an increase in side lobe levels, but still meets the overall beamforming

requirements.



The resulting full width at half maximum (FWHM) of the beam at the antenna

bore sight is approximately 10 horizontally and20 vertically with an overall

beamforming gain of 18 dBi.

In addition, a set of beam patterns is predefined to reduce the feedback overhead

required for the adaptive beamforming operation between the transmitter and the

receiver, where the overlapped beam patterns cover the intended service area with

a unique beam identifier (ID) for each beam.

These beam IDs are used by the baseband modem to control the phase shifter

weights and to feed back the preferred transmission beam information to the

transmitter.

The baseband modem shown in Fig. 7.1 was designed and implemented for real-

time operation with commercial off-the-shelf signal processing units including

Xilinx Virtex-6 field programmable gate arrays (FPGAs), and an ADC and a

DAC each with up to 1 Gs/s conversion rate.

The analog signal ports of the modem analog front-end (AFE) are connected to

the RF/antenna input (output) port to transmit (receive) the complex analog

baseband signal.

The baseband modem is linked to a DM program developed to visualize the

operational status of the system and collect system statistics including data

throughput, packet error rates, transmit/receive beam IDs, received signal

constellations, and signal strengths.

Two sets of the mm Wave beamforming prototypes as specified above were built,

playing the roles of a base station and a mobile station, and various laboratory

and field tests in both indoor and outdoor environments were performed.

For the downlink transmission, the base station periodically transmits a sequence

of beam measurement signals in predefined beams so that the mobile station can

carry out, also in predefined receive beams, channel quality measurements of the

transmit-receive beam pairs and thus select the best beam pair for data

transmissions.

The selected base station transmit beam ID is fed back to the base station for the

subsequent downlink transmission until the next update incident.



In this fashion, the base and mobile stations quickly establish the wireless

communications link and adaptively sustain the link even in high mobility

conditions.

The communications link setup for the uplink is done in an analogous way where

the roles of the base station and mobile stations are interchanged.

The developed mm Wave beamforming prototype was designed to complete the

search for the best transmit and receive beam pair within 45 ms.

Table 1 lists key system parameters of the implemented prototype.

Fig.7.3.Key system parameters of the mmWave beamforming prototype



CHAPTER 8

PROTOTYPE TEST RESULTS

Using the mmWave adaptive beamforming prototype, comprehensive indoor and outdoor

field tests were carried out at the campus of Samsung Electronics headquarters in Suwon,

Korea in early 2013.An aggregated peak data rate of 1.056 Gb/s was achieved in the

laboratory with negligible packet error using two channels at the base station supporting

two stationary mobile stations with 528 Mb/s each.

Outdoor coverage tests

- To demonstrate the service availability in a typical outdoor environment for both

LoS and NLoS sites.

- The tests were performed at sites surrounded by tall buildings where various

channel propagation effects such as reflection, diffraction, or penetration are

expected to take place, as shown in Fig. 8.3.

Fig.8.1.Outdoor coverage test results of mmwave beamforming prototype



Outdoor LineofSight (LoS) Range Test

- Error free communications possible at 1.7 Km LoS with > 10dB TX power

headroom

- Pencil BF both at TX and RX supporting long range communications.

Fig.8.2 Outdoor LineofSight (LoS) Range Test

Outdoor NonLineofSight (NLoS) Mobility Tests

- Fast Joint Beamforming & Tracking Supports 8 km/h Mobility in NLOS

- Mobility support up to 8 Km/h at outdoor NLoS environments

- 16QAM (528Mbps) : BLER 0~0.5%

- QPSK (264Mbps) : Error Free

Fig.8.3 Outdoor NonLineofSight (NLoS) Mobility Tests



As can be seen from the test results in Fig.8.3, satisfactory communications links were

discovered even in NLoS sites more than 200 m away, mostly due to reflections off

neighbouring buildings. On the other hand, there were a few locations where a proper link

could not be established (i.e., coverage holes), which necessitate solutions for coverage

improvement such as optimized cell deployment, intercell coordination, relays, or

repeaters. Considering one of the important operation scenarios in practical cellular

networks, communication between an outdoor base station and an indoor mobile station

was also investigated. The above test results present link qualities between an outdoor

base station to an indoor mobile station placed inside a typical modern office building

with heavily tinted glass at more than 150 m separation. These types of buildings are

representative of presenting highly unfavourable propagation (penetration) conditions

even for current cellular frequency bands below 6 GHz. Surprisingly amicable indoor

coverage results were obtained with only the totally obstructed, farthest side of the

building resulting in lost connections. While the spots showing BLERs around 10~20

percent can be improved with conventional error correction schemes such as hybrid

automatic repeat request (HARQ) and modulation/coding adaptation schemes, remaining

coverage holes would need to be covered with other alternative schemes, such as repeaters

and indoor femto cells, as in traditional cellular systems.

Building Penetration Test

- Outdoortoindoor penetration made through tinted glasses and doors

- Most Signals Successfully Received at Indoor MS from Outdoor BS

Fig.8.4 Building Penetration Test



The test results were extremely encouraging and resulted in error-free transmission at

264 Mb/s and less than 1 percent BLER at 528 Mb/s transmissions due to the fast adaptive

beamforming algorithm running at both communications ends. The design capability of

the adaptive joint beam searching and switching algorithms implemented in our prototype

could easily support mobility higher than 8 km/h. The ensuing results will provide a firm

ground for the development of mm Wave-beam forming-based 5G cellular networks.



CHAPTER 9

CONCLUSION

An overview of using Millimeter wave Mobile Communication for 5G Cellular is

presented in this paper, and how 5G Cellular systems can overcome the issues related to

the previous generations of Communication systems and evolved to be the most

promising System.

As the additional availability of spectrum for cellular usage in the lower

frequencies becomes scarce, the significant amount of underutilized spectrum in the

mmWave bands could potentially provide the answer to the very large bandwidth

requirements for 5G.The large bandwidth available at millimeter wave frequencies results

in very high data transmission rate; also helps to minimize the amount of time that a node

needs to stay in transmission mode; and therefore, minimizes the possibility of its

transmission being detected. This article shows how these high frequencies exhibit them-

selves as strong candidates for cellular bands with recent channel measurement,

simulation, and prototype results.

The advanced hybrid beamforming algorithm described exploits both analog and

digital domain beamforming, which not only offers sharp beamforming to cope with the

propagation loss but also allows advanced digital domain processing such as multi-beam

MIMO with manageable complexity. The main portion of the article is dedicated to

presenting the results of recent mmWave prototype, which features a large system

bandwidth in excess of 500 MHz at 28 GHz and supports tens of antennas placed in planar

arrays at both ends of the communications. The prototype incorporates a real-time

baseband modem, full mmWave RF circuitry, and relevant software. The advanced

adaptive beamforming system successfully demonstrates that the mmWave frequency

band is capable of supporting a few-hundred-meter radius of outdoor and indoor coverage

with more than 500 Mb/s data rate with support for mobility as high as 8 km/h even in

NLoS environments. The security and reliability provided is quite huge. Hence

considering all the factors given above these millimeter wave frequencies is going to serve

the future generations of wireless communications enabling the ALL IP features and

providing good quality of service (QOS).



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[2]. T. Rappaport et al., Millimeter Wave Mobile Communications for 5G

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[3]. Z. Pi and F. Khan, `An introduction to millimeter-wave mobile broadband

systems,'' IEEE Commun. Mag., vol. 49, no. 6, pp. 101_107, Jun. 2011.

[4]. S. Rangan, T. S. Rappaport, and E. Erkip, Millimeter-Wave Cellular

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