Frequency reuse .

• frequency reuse

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Digital Enhanced Cordless Telecommunications Radio links

1 If frequency-hopping is avoided, each base station can provide up to 120

channels in the DECT spectrum before frequency reuse


Cellular network Frequency reuse

1 The key characteristic of a cellular network is the ability to re-use frequencies to increase both coverage and capacity. As described above, adjacent cells must use different frequencies, however there is no

problem with two cells sufficiently far apart operating on the same frequency. The elements that determine frequency

reuse are the reuse distance and the reuse factor.



1 The frequency reuse factor is the rate at which the same frequency

can be used in the network. It is 1/K (or K according to some books)

where K is the number of cells which cannot use the same frequencies for transmission. Common values for the frequency reuse factor are 1/3, 1/4,

1/7, 1/9 and 1/12 (or 3, 4, 7, 9 and 12 depending on notation).



1 Code division multiple access-based systems use a wider frequency band

to achieve the same rate of transmission as FDMA, but this is

compensated for by the ability to use a frequency reuse factor of 1, for

example using a reuse pattern of 1/1



1 Recently also orthogonal frequency-division multiple access based systems such as LTE are being

deployed with a frequency reuse of 1


Code division multiple access Spread-spectrum characteristics of CDMA

1 Frequency reuse is the ability to reuse the same radio channel

frequency at other cell sites within a cellular system


Microwave

1 Microwaves are especially suitable for this use since they are more easily

focused into narrow beams than radio waves, allowing frequency reuse; their comparatively higher frequencies allow

broad bandwidth and high data transmission rates, and antenna sizes are smaller than at lower frequencies

because antenna size is inversely proportional to transmitted frequency


History of mobile phones - Cellular concepts

1 The concepts of frequency reuse and handoff, as well as a number of other

concepts that formed the basis of modern cell phone technology, were

described in the late 1960s, in papers by Frenkiel and Porter


Digital radio - Two-way digital radio standards

1 The key breakthrough or key feature in digital radio transmission systems is that they allow lower transmission power, they can provide robustness

to noise and cross-talk and other forms of interference, and thus allow

the same radio frequency to be frequency reuse|reused at shorter

distance


CDMA - Spread-spectrum characteristics of CDMA

1 Frequency reuse is the ability to reuse the same radio channel

frequency at other cell sites within a cellular system


Greenfield project - Cellular networks

1 They were developed with no regard for future capacity considerations or frequency

reuse


Extremely high frequency

1 The small wavelength allows modest size antennas to have a small beam width, further increasing frequency

reuse potential.


Extremely high frequency - Propagation

1 Millimeter waves travel solely by line-of-sight propagation|line-of-sight, and are

blocked by building walls and attenuated by foliage. The high free space loss and

atmospheric absorption limits propagation to a few kilometers. Thus they are useful

for densely packed communications networks such as personal area networks that improve spectrum utilization through

frequency reuse.


Spectral efficiency comparison table - Link spectral efficiency

1 This can allow for much denser geographical frequency reuse that

compensates for the lower link spectral efficiency, resulting in

approximately the same capacity (the same number of simultaneous

phone calls) over the same bandwidth, using the same number

of base station transmitters


Spectral efficiency comparison table - System spectral efficiency or area spectral efficiency

1 :'Example 8:' In a cellular system based on frequency-division multiple access (FDMA) with a fixed channel

allocation (FCA) cellplan using a frequency reuse factor of 4, each

base station has access to 1/4 of the total available frequency spectrum


Spectral efficiency comparison table - System spectral efficiency or area spectral efficiency

1 Spread spectrum makes it possible to have as low a frequency reuse factor as 1, if each base station is divided

into 3 cells by means of 3 directional sector antennas


Cell site - Channel reuse

1 To overcome this limitation, it is necessary to repeat and frequency reuse|reuse the same channels at

different locations


DECT - Radio links

1 If frequency-hopping is avoided, each base station can provide up to 120

channels in the DECT spectrum before frequency reuse


Cellular networks - Frequency reuse

1 The key characteristic of a cellular network is the ability to re-use frequencies to increase both coverage and capacity. As described above, adjacent cells must

use different frequencies, however there is no problem with two cells sufficiently far apart operating on the same frequency. The elements that determine frequency

reuse are the reuse distance and the reuse factor.


Cellular networks - Frequency reuse

1 Recently also orthogonal frequency-division multiple access based

systems such as 3GPP Long Term Evolution|LTE are being deployed with a frequency reuse of 1. Since such systems do not spread the

signal across the frequency band,


Licensed spectrum - Governments and spectrum management

1 Unlike these, however, frequency reuse|RF is reusable


Frequency allocation

1 * Only the licensed user of that band may transmit: the licensing body may give the same frequency to

several users as a form of frequency reuse if they cannot interfere

because their coverage map areas never overlap.


Digital Audio Broadcasting - Use of frequency spectrum and transmitter sites

1 The frequency reuse factor for local programmes and multi-frequency

broadcasting networks (Multi-frequency network|MFN) is typically 4 or 5, resulting in 1 / 4 / (0.26MHz) = 0.96 programmes/transmitter/MHz


Super high frequency - Propagation

1 Such high gain antennas allow

frequency reuse by nearby transmitters


Super high frequency - Utilization

1 They are the lowest frequency band where radio waves can be directed in narrow beams by conveniently sized

antennas so they do not interfere with nearby transmitters on the

same frequency, allowing frequency reuse


Saorsat - Overview

1 The spot beam with frequency reuse means reception in most of Britain

and continental Europe is not possible


Microwaves - Microwave uses

1 Microwaves are especially suitable for this use since they are more easily focused into narrower beams than radio waves, allowing

frequency reuse; their comparatively higher frequencies allow broad Bandwidth

(signal processing)|bandwidth and high data transmission rates, and antenna sizes

are smaller than at lower frequencies because antenna size is inversely

proportional to transmitted frequency


Spectrum allocation

1 * Only the licensed user of that band may transmit: the licensing body may give the same frequency or

band to several users as a form of frequency reuse if they cannot

interfere because their coverage map areas never overlap. Amateur

radio frequency allocations also devoted only for licensed users with listen before talk contention-based

protocol.https://store.theartofservice.com/the-frequency-reuse-toolkit.html

Radio resource management

1 RRM is especially important in systems limited by co-channel

interference rather than by noise, for example cellular systems and

broadcast networks homogeneously covering large areas, and wireless

networks consisting of many adjacent Wireless access point|

access points that may frequency reuse|reuse the same channel

frequencies.https://store.theartofservice.com/the-frequency-reuse-toolkit.html

Radio resource management

1 In cellular networks, this means that the fractional frequency reuse in the GSM standard has been replaced by a universal frequency reuse in LTE (telecommunication)|LTE standard.


Radio resource management - Dynamic radio resource management

1 Dynamic RRM schemes adaptively adjust the radio network parameters to the traffic load, user positions, user mobility, quality

of service requirements, base station density, etc. Dynamic RRM schemes are

considered in the design of wireless systems, in view to minimize expensive

manual cell planning and achieve tighter frequency reuse patterns, resulting in improved system spectral efficiency.


Radio resource management - Inter-cell radio resource management

1 Future networks like the LTE (telecommunication)|LTE standard

(defined by 3GPP) are designed for a frequency reuse of one


Spectrum management - Governments and spectrum management

1 Unlike these, however, frequency reuse|RF is

reusable.[http://ssrn.com/abstract=793526 Radio spectrum as natural resource] The purpose of spectrum management is to mitigate radio spectrum pollution and maximize the benefit of usable radio

spectrum.[http://ssrn.com/abstract=556673 Application of the Public-Trust Doctrine and Principles of Natural Resource Management

to Electromagnetic Spectrum]https://store.theartofservice.com/the-frequency-reuse-toolkit.html

Polarisation division multiple access

1 Each corresponding ground station antenna needs to be polarized in the same way as its counterpart in the satellite. This

is generally accomplished by providing each participating ground station with an antenna that has dual polarization. The

frequency band allocated to each antenna beam can be identical because the uplink signals are orthogonal in polarization. This

technique allows frequency reuse.


Spectrum efficiency - System spectral efficiency or area spectral efficiency

1 :'Example 8:' In a cellular system based on frequency-division multiple access (FDMA) with a fixed channel

allocation (FCA) cellplan using a frequency reuse factor of 1/4, each

base station has access to 1/4 of the total available frequency spectrum


Tooway - Technology

1 Smaller beams allow more efficient use of satellite power on the forward link and improved G/T (Link budget|

Gain-over-Temperature) on the return link. Smaller beams draw smaller cells on ground (beam footprint)

which also permits more cells in a given service area, increasing

frequency reuse.


Ultra Mobile Broadband - Features

1 **Dynamic fractional frequency

reuse


Power control - Benefits

1 Even in FDMA systems such as GSM where each user in a cell uses a

different frequency, interference is still present between different cells

and reduces the amount of frequency reuse the network can support


Co-channel interference

1 The co-channel interference arises in the cellular mobile networks owing to this phenomenon of Cellular network|

Frequency reuse


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