Smart antennas (presented by ali & aibad)

1. Presented By:
Aibad Ahmed & Ali Habib

2. HOW SMART ANTENNAS EVOLVED?
 In the first cellular radio systems deployed, each base
station was equipped with an omnidirectional antenna
with a typical amplitude pattern.
 Because only a small percentage of the total energy
reached the desired user, the remaining energy was
radiated in undesired directions.

3.  As the number of users increased, also interference
increases, thereby reducing capacity.
 An immediate solution to this problem was to subdivide
a cell into smaller cells, this technique is referred to as cell
splitting

4. CELL SPLITTING
 It subdivides a congested cell into smaller cells called
microcells, each with its own base station.
 The disadvantages of cell splitting are costs incurred from
the installation of new base stations.
 The increase in the number of handoffs

5. SECTORIZED SYSTEMS
 The number of frequencies assigned to a cell eventually
became insufficient.
 A cellular design technique that provide more frequencies
per coverage area is knawn as Cell Sectoring.
 In this technique single omnidirectional antenna is
replaced at the base station with several directional
antennas.
 Typically, a cell is sectorized into thre sectors of 120◦
each.

6. SECTORIZED ANTENNAS
 Cell sectoring did not provide the adequate solution
needed for the capacity problem.
 Therefore, a system required that could dynamically
sectorize a cell.

7. SMART ANTENNAS
“Smart Antennas are arrays of antenna elements that
change their antenna pattern dynamically to adjust to
the noise, interference in the channel that effects on the
signal of interest.”
 Smart antennas are not smart, it is the digital signal
processing, along with the antennas, which makes the
system smart.
 Smart-antenna systems are basically an extension of cell
sectoring in which the sector coverage is composed of
multiple beams.

8. SMART ANTENNAS ANALOGY WITH HUMAN
 The functionality of many engineering systems is readily
understood when it is related to our human body system.

9. TYPES OF SMART ANTENNAS
Smart Antenna systems are of two types:
 Switched Beam Antenna System
 Adaptive Array Antenna System

10. SWITCHED BEAM ANTENNA SYSTEMS
 It is an extension of cell sectoring as each sector is
subdivided into smaller sectors.
 As the mobile unit moves throughout the cell, the switched-
beam system detects the signal strength and continually
switches the beams as necessary.
 The overall goal of the switched-beam system is to increase
the gain according to the location of the user.

11.  If there is an interferer near the center of the active
beam, it may be enhanced more than the desired user.

12. ADAPTIVE ARRAY ANTENNA SYSTEMS
 They can direct the main beam toward the SOI(Signal Of
Interest) while suppressing the antenna pattern in the
direction of the interferers or SNOIs.
 Adaptive array systems can customize an appropriate radiation
pattern for each individual user.
 Adaptive array systems can locate and track signals (users
and interferers)
 Dynamically adjust the antenna pattern to enhance reception
while minimizing or fully rejecting interference using signal-
processing algorithms.

13. Switched Beam & Adaptive Array Antenna
Radiation Pattern

14. BLOCK DIAGRAM OF ADAPTIVE ARRAY ANTENNA

15. Comparison of Switched Beam Antenna &
Adaptive Arrays
CRITERIA SWITCHED BEAM ADAPTIVE ARRAYS
INTEGERATION • Easy to implement • Transceiver complexity
• Low cost • High cost
RANGE/COVERAGE • More coverage •More coverage compared
compared to to switched beam system
conventional systems
• Less coverage compared
to adaptive array
INTERFERENCE •Difficulty in • Focusing is narrower.
REJECTION distinguishing between
desired signal and • Capable of nulling
interferer . interfering signals
• Does not react to the
movement of nterferers.

16. Smart Antenna Receiver

17. Smart Antenna Transmitter

18. SDMA
 SDMA (Space Division Multiple Access) is the most-
sophisticated utilization of smart-antenna technology.
 This means that more than one user can be allocated to
the same physicalcommunication channel in the same cell
simultaneously, with only an angle separation.

19. SDMA

20. Smart Antenna’s Benefits
 The primary reason for the growing interest in smart-
antenna systems is the capacity increase.
 Smart-antenna systems provides increase of range.
because smart antennas are more directional than
omnidirectional and sectorized antennas.
 Another added advantage of smart-antenna systems is
security.

21.  Smart antennas make it more difficult to tap a
connection because the intruder must be positioned in
the same direction as the user.
 They can be used to locate humans in emergencies.

22. Smart Antenna’s Drawbacks
 Their transceivers are much more complex than
traditional base station transceivers.
 To have pattern-adaptive capabilities and reasonable
gain, an array of antenna elements is necessary.
 Smart-antenna base stations must be equipped with very
powerful digital signal processors. This tends to increase
the system costs in the short term.

23. Smart Antennas on Mobile Handsets
RESEARCH
 A single base station often serves hundreds to thousands
of mobile stations. It is more economical to add
equipment to BTS rather than at each MS.
 Adaptive beamforming is a practical and effective
technique for reducing the effect of multipath fading, it is
rarely used at a MS due to cost, size and available power
of the MS.
 With 3G systems increasing growth of mobile phone
users has created a need for even higher capacity in
cellular network .

24. Two Types OF Mobile Handset Adaptive Antennas
 The Intelligent Quadrifilar Helix Antenna was invented in the
University of Surrey by A. A. Agius, S. M. Leach, P. Suvannapattana
and S. R. Saunders.
Specifications of the antenna are listed in the following :
 The QHA consists of four twisted wires in a form of a helix
 It permits reception inside the buildings where signals are too weak
to be picked up by standard antennas
 Designed to improve performance and minimize radiation into the
human head.

25.  The signal is produced through use of a torch beam which
means that instead of radiation going in all directions, it will
use a narrow beam traveling towards the nearest base station.
 It makes batteries last longer

26. The solid state antenna
Specifications of the antenna are listed in the following:
 Surface mounted to motherboard
 Approximately one tenth size of conventional copper
antenna
 The antenna is steerable
 Life of the battery is increased as the handset only points
in the direction of the base station so more efficient
transmission is achieved

27.  Minimizes RF health issue by directing the RF emissions
away from the head or body.