TRANSMISSION

References Informative references Attention is drawn to the following places, which may be of interest for search: Transmission systems for measured values, control or similar signals G08C Speech analysis or synthesis G10L Coding, decoding or code conversion H03M Broadcast communication H04H Multiplex communication H04J Secret communication H04K Transmission of digital information H04L Telephonic communication H04M Pictorial communication H04N Wireless communication networks H04W


Informative references
Attention is drawn to the following places, which may be of interest for search: {Placing the antenna at a place where the noise level is low and using a noisefree transmission line between the antenna and the receivers (screened aerials H01Q 7/04; feeders for aerials H01Q 9/00)}

Informative references
Attention is drawn to the following places, which may be of interest for search:

Limiting references
This place does not cover: Using adaptive balancing or compensation means H04B 1/123 Narrow band interference reduction in spread spectrum systems H04B 1/71

Informative references
Attention is drawn to the following places, which may be of interest for search: Filter circuits H03H

Limiting references
This place does not cover: Reduction of multipath noise by equalising H04B 7/005 H04B 1/109 {by improving strong signal performance of the receiver when strong unwanted signals are present at the receiver input}

Glossary of terms
In this place, the following terms or expressions are used with the meaning indicated: Unwanted signal signals outside the wanted signal bandwidth H04B 1/12 Neutralising, balancing, or compensation arrangements

Informative references
Attention is drawn to the following places, which may be of interest for search: Balancing ripple filters H04B 15/005, H02M 1/143

Informative references
Attention is drawn to the following places, which may be of interest for search: Adaptive filter circuits and algorithms H03H H04B 1/126 {having multiple inputs, e.g. auxiliary antenna for receiving interfering signal (aerials in general H01Q)}

Informative references
Attention is drawn to the following places, which may be of interest for search: Aerials in general H01Q

Informative references
Attention is drawn to the following places, which may be of interest for search:

Informative references
Attention is drawn to the following places, which may be of interest for search: Volume compression or expansion in amplifiers H03G 7/00 H04B 1/20 for coupling gramophone pick-up, recorder output, or microphone to receiver

Informative references
Attention is drawn to the following places, which may be of interest for search: Constructional details for associated working of receivers and recording devices G11B 31/003 For television signals only H04N 5/00

Informative references
Attention is drawn to the following places, which may be of interest for search: Remote controllers G08C

Limiting references
This place does not cover: With control bus for exchanging commands H04B 1/205 H04B 1/24 the receiver comprising at least one semiconductor device having three or more electrodes

Limiting references
This place does not cover: Older documents covering circuits with vacuum tubes H04B 1/22 H04B 1/28 the receiver comprising at least one semiconductor device having three or more electrodes

Limiting references
This place does not cover: Older documents covering circuits with vacuum tubes H04B 1/28

Glossary of terms
In this place, the following terms or expressions are used with the meaning indicated: Superheterodyne receiver A receiver in which the frequency of the incoming signal is reduced in a mixer or frequency changer by heterodyning with another frequency at the local oscillator. (Heterodyning: combining two sinusoidal frequencies radio frequency waves in a non-linear device resulting in sum and difference frequencies).

If Intermediate Frequency
Lo local oscillator

H04B 1/30 for homodyne or synchrodyne receivers (demodulator circuits H03D 1/22) Definition statement
This place covers: Additionally, super-regenerative receivers can be found in this group

Glossary of terms
In this place, the following terms or expressions are used with the meaning indicated: Homodyne receiver A receiver which involves multiplying the modulated received signal by a local oscillator which has the same frequency as that associated with the received signal, so that the received signal will be directly converted into the baseband.
Synchrodyne receiver A receiver in which a mixing carrier signal is inserted in exact synchronism with the original carrier at the transmitter. Used for the selective detection of signals coded in a certain way.

Informative references
Attention is drawn to the following places, which may be of interest for search:

Informative references
Attention is drawn to the following places, which may be of interest for search:

Informative references
Attention is drawn to the following places, which may be of interest for search: Light transmission systems H04B 10/00

Informative references
Attention is drawn to the following places, which may be of interest for search: Relay systems H04B 7/14 H04B 1/62 for providing a predistortion of the signal in the transmitter and corresponding correction in the receiver, e.g. for improving the signal/noise ratio

Informative references
Attention is drawn to the following places, which may be of interest for search: Spread spectrum techniques representing methods by which communication energy generated in a particular bandwidth is deliberately spread in the frequency domain, resulting in a signal with a wider bandwidth.

Relationships with other classification places
With regard to code multiplexing, the borderline between H04B 1/69 and H04J 13/00 should be determined based on whether the features relevant for classification are focused on the code multiplexing aspects or the implementation of the spread-spectrum technique (e.g. details of how the signals are physically transmitted, received and processed).

Informative references
Attention is drawn to the following places, which may be of interest for search:

Special rules of classification
Classification of invention and additional information: The invention information (main focus of the document) is classified in CPC groups and is compulsory.
Additional information is classified in Indexing Codes corresponding to the CPC groups. Classification of additional information is compulsory.
Indexing Codes which have no corresponding CPC group are used to classify invention information (compulsory) or additional information (compulsory). When classifying invention information, the most appropriate CPC group must also be assigned. When classifying in this group, any aspect of code division multiplexing, which is considered to represent information of interest for search, may also be classified in group H04J 13/00.

Glossary of terms
In this place, the following terms or expressions are used with the meaning indicated: Direct-sequence spread-spectrum techniques which directly modulate the data being transmitted by a spreading code whose frequency (chip rate) is much higher than the modulated bandwidth of the data signal (symbol rate).

Limiting references
This place does not cover: Aspects relating to the codes e.g. types of codes, code generation and code allocation H04J 13/00 Carrier synchronization per se H04L 7/06 H04B 1/713 using frequency hopping

Definition statement
This place covers: Frequency-hopping spread spectrum techniques which involve transmitting radio signals by switching a carrier among many frequency channels, using a hopping sequence known to both transmitter and receiver.

Definition statement
This place covers: Impulse radio spread spectrum which involve an ultra-wideband (UWB) communication system that transmits baseband pulses of very short duration (typically of the order of a nanosecond) with bandwidths that span from near dc to several GHz.

Limiting references
This place does not cover: Non-pulse systems which meet the requirements of the FCC mask for UWB communication (e.g. UWB OFDM systems) H04J 11/00 , H04L 27/26 or H04L 5/00

Special rules of classification
From 01/04/2011 documents relating to pulse-related aspects are classified in H04B 1/717 and the backlog for such documents is continuously being reclassified from H04B 1/7163.

Informative references
Attention is drawn to the following places, which may be of interest for search:

Limiting references
This place does not cover: Near-field transmission system H04B 5/00

Informative references
Attention is drawn to the following places, which may be of interest for search:

Informative references
Attention is drawn to the following places, which may be of interest for search: Hybrid junctions of the waveguide type H01P 5/16

Informative references
Attention is drawn to the following places, which may be of interest for search:

Control of amplification in general H03G
CPC -H04B -2020.08

H04B 3/26
Improving frequency characteristic by the use of loading coils

Informative references
Attention is drawn to the following places, which may be of interest for search: Loading coils per se H01F 17/08

Limiting references
This place does not cover:

Informative references
Attention is drawn to the following places, which may be of interest for search:

Informative references
Attention is drawn to the following places, which may be of interest for search: Amplifiers therefor H03F

Definition statement
This place covers: Transmission systems of a limited range wherein the information signal transmission is inductive or capacitive, rather than electromagnetic, e.g. inductive loop type Transmission systems operating in the low frequency and high frequency bands with reduced range and relatively short reading distances well within the radian sphere defined by λ/2π (wherein λ corresponds to the wavelength of the transmission signal). Near field communication systems are asymmetrical systems which do not allow a duplex communication initiated at both ends. The transmission of power is also inductive or capacitive, rather than electromagnetic.

Glossary of terms
In this place, the following terms or expressions are used with the meaning indicated: Nfc near field communication

Definition statement
This place covers: Only data transfer

Informative references
Attention is drawn to the following places, which may be of interest for search: Data and power transfer H04B 5/0037

Informative references
Attention is drawn to the following places, which may be of interest for search: Data and power transfer H04B 5/0037

Limiting references
This place does not cover: Record carriers for railways B61L 3/12

Glossary of terms
In this place, the following terms or expressions are used with the meaning indicated:

Limiting references
This place does not cover: Transformers or inductances adapted for inductive coupling H01F 38/14

Definition statement
This place covers: Radio transmission systems wherein the information signal transmission is by electromagnetic waves other than light or infra-red.

Limiting references
This place does not cover: Near-field transmission systems, e.g. inductive loop type H04B 5/00 Transmission systems employing beams of corpuscular radiation, or electromagnetic waves other than radio waves, e.g. light, infra-red H04B 10/00 Suppression or limitation of noise or interference H04B 15/00

Informative references
Attention is drawn to the following places, which may be of interest for search: Diversity systems specially adapted for direction finding G01S 3/72 Systems using reradiation of radio waves, e.g. secondary radar systems; Analogous systems G01S 13/74

Aerials H01Q
Selecting arrangements to which subscribers are connected via radio links H04W

Synonyms and Keywords
In patent documents, the following abbreviations are often used:

Definition statement
This place covers: • the use of one or more antennas to transmit or receive signals, characterised by separation in time, phase, frequency, polarisation, angle or spacing; the improvement thereby being of channel quality and reliability; • aspects of diversity, beamforming and antenna weighting; • the generation of antenna weights for multiple antennas; • the feedback of information in order to assign weights for multiple antennas; • the transmission through multiple beams, for single or multiple users; • the combination or selection of signals from one or more fading channels by using characteristics thereof or correlation.
Aspects related to diversity, beamforming and antenna weighting: • when the signal has diverse possibilities of being transmitted/ received through one or several antennas with different characteristics (including time, frequency, space, polarization, angle, phase...); "diverse possibilities" means the signal does not always have to be transmitted by more than one antenna. The diversity in this case would be achieved in the channel between the transmitter and receiver. This channel diversity is aimed to increase quality and reliability at the receiver; • exploiting gain of one or more fading channels either uncorrelated or correlated (such as single beamforming and pre-coding); • transmission through multiple beams for single user and multiple user; • feedback of information in order to assign weights and improve reliability of the signal in transmission/ reception;

H04B 7/02 (continued)
Definition statement CPC -H04B -2020.08 • generation of antenna weights for multiple antennas; • transmission of a plurality of different signals from different antennas, wherein at least one of said signals is transmitted (potentially weighted) from more than one antenna; for example MIMO transmission for N different streams via M different antennas, where M linear combinations of the N streams are transmitted, each linear combination being transmitted from each antenna.

Relationships with other classification places
Antenna redundancy, namely the inclusion of spare antennas for the easy replacement of malfunctioning antennas, is not considered to be a multi-antenna system and therefore is not covered by this group. Details of transmission systems for increasing reliability, e.g. using redundancy, are covered by group H04B 1/74.

Limiting references
This place does not cover: Reducing multipath interference in spread spectrum systems H04B 1/7115

Informative references
Attention is drawn to the following places, which may be of interest for search:

Limiting references
This place does not cover: Site diversity or macro-diversity using two or more spaced independent antennas H04B 7/04

Informative references
Attention is drawn to the following places, which may be of interest for search: Multicasting of data during hand-off to several target access points H04W 36/026

Glossary of terms
In this place, the following terms or expressions are used with the meaning indicated: Site diversity The technique of linking two or more ground stations receiving the same signal. This way, if the signal is heavily attenuated in one area, other ground stations can compensate.

Macro-diversity
In the field of wireless communication, macro-diversity is a kind of spatial diversity scheme using several antennas to transmit or receive wireless signals, wherein the distance between the antennas is much longer than the wavelength in use. This diversity technique limits the effects of fading in radio communications. The terms 'macro-diversity' and 'site diversity', are sometimes used synonymously in the art.

H04B 7/024
Co-operative use of antennas of several sites, e.g. in co-ordinated multipoint or co-operative multiple-input multiple-output [MIMO] systems

Definition statement
This place covers: Example of documents classified here: see US2010034146 (figure 7):

H04B 7/026
Co-operative diversity, e.g. using fixed or mobile stations as relays

Limiting references
This place does not cover: Example of documents classified in this group: see e.g. US2011070840 (abstract): "... The antenna(s) are spatially translated in an arbitrary trajectory. As the antenna(s) is being spatially translated, a data processing means samples the incoming signal at set intervals based on a clock signal provided by a system clock. By sampling the incoming signal at different times at different spatial locations on the arbitrary trajectory, the system acts as a synthetic antenna array. The different samplings of the incoming signal at different times and positions provide signal diversity gain as well as different readings which can be used to estimate and/or calculate various parameters of the incoming signal.".
H04B 7/04 using two or more spaced independent antennas

Definition statement
This place covers: Plurality of spaced independent aerials, both correlated (beamforming) or non-correlated (diversity) at transmitter or receiver or both, either using simultaneous transmission/reception (e.g. for beamforming) or successive transmission/reception (antenna switching/selection).

Definition statement
This place covers: Example of documents classified here: see WO2009046409 (figures 4, 7)

Informative references
Attention is drawn to the following places, which may be of interest for search:

Special rules of classification
This group takes precedence over the transmit/receive diversity groups H04B 7/06 and H04B 7/08.

Synonyms and Keywords
In patent documents, the following abbreviations are often used: Example of document classified here: see e.g. US2008004016 (abstract): "A base station for establishing a picocell is configured so as to provide multiple sectors, with spatial diversity between sectors. The combination of the multiple sectors and the spatial diversity reduces signal power requirements in the air interface within a confined space and provides improvements in quality of service."

Definition statement
This place covers: Plurality of spaced independent aerials at the transmitter (correlated or uncorrelated)

Limiting references
This place does not cover: H04B 7/08 at the receiving station

Definition statement
This place covers: Plurality of spaced independent aerials at the receiver (correlated or uncorrelated).

Limiting references
A passive relay is a relay on which a signal is only reflected.
Active relay systems are used by communication arrangements to receive, to process and to retransmit signals between devices separated by air or space.
Mobility is possible between the devices of the active relay system and the transmission can be unidirectional or bidirectional.
The processing within the relay is of a wide range. For instance the relay processing covers the following issues. The signals relayed can be a multiplex of a plurality of signals. The processing minimizes the interference between the signal received and retransmitted. Signal are regenerated, signals are switched in the relay before retransmission. Further processing details are indicated in the subgroups of H04B 7/15. Moreover, as indicated below, the active relay systems are further subdivided into ground based relay stations, airborne relay stations and space based relay station (satellites). A passive relay is a relay on which a signal is only reflected. No processing is done by such a relay. A passive relay is used to scatter a signal.

Relationships with other classification places
Radio waves, below a certain frequency, are reflected by the ionosphere. This allows propagation beyond the horizon.
Meteor burst communication or meteor scatter communication uses the ionized trail of a meteor for radio wave reflection.
Two antennas linked by a waveguide assure radio relaying. This is used for example to allow reception in a tunnel.
Reflection can be achieved by the use of a passive airborne platform.
To enable radio wave transmission in buildings, passive antennas, material transparent to radio waves … are used.

Limiting references
This place does not cover: Construction of passive reflectors G01S 13/75

Definition statement
This place covers: Relays are used for range extension, to cover shadowed regions, to allow communication with the inside of a building, to transmit signals over long distances.
Microwaves relays working from 2 to 5 GHz with fixed stations in line of sight allow point to point high data rate transmission for telephony or broadcasting signals.
Shortwave relay are used for broadcasting.
Relays are used in a wireless network for radio cell extension.
Cooperative relays are used for signals diversity.

Limiting references
This place does not cover: Multiple access H04B 7/204

Informative references
Attention is drawn to the following places, which may be of interest for search:

Definition statement
This place covers: The stations are navigating in the stratosphere (below 50 km).
The airborne station is an unmanned airborne device or an aircraft covering a region (for example in case of an emergency situation when communications are disrupted during a catastrophically event). The relay is a lighter than air device, a balloon, a dirigible, a device called HALE (High Altitude Low Expenditure), HAAP (High Altitude Atmospheric Platform), SHARP (Stationary High Altitude Relay Platform) or an unmanned aerial vehicle (UAV).
The airborne station works alone or is part of a network of other stations. The communications can then be handed over to another platform. A satellite can be part of the network. The technical characteristics of these devices, their trajectory are adapted for communication. The relays are drifting in the sky or they are stabilized in position and altitude.

This place covers:
Communications with or from an aircraft without relaying through a satellite.
The system are communication systems for commercial aircrafts and used for transmission between the passengers and the ground for voice or data communication. The systems are as well for communications between the cockpit and earth control stations for air traffic control, for aircraft short messages service … Such systems are as well used for transport devices like a bus or ship.
The communications are multiplexed on the up and down link and must be demultiplexed. Antenna aspects in such systems.
A network of ground stations is necessary to follow the aircraft. A call is handed over between ground stations.

Definition statement
This place covers: All aspects relating to communications in uplink and downlink in a satellite system such as:

Definition statement
This place covers: Equipment on board of the satellite. Telecommunication payload, bus and platform equipments.
All equipment on-board involved in transmission such as: transponder, amplifier, multiplexer, demultiplexer, on-board digital processors, antennas.

Definition statement
This place covers: All equipments used in earth-based stations.
These stations can be: a hub station, a control station, a gateway, a user terminal, a Small Aperture Terminal.

Definition statement
This place covers: Spare satellite. Replacement satellite. Backup satellite. Reconfiguration of a satellite.
Measuring performance of a system. Calibration of a system. Reception quality. Fault diagnostic.
Satellite attitude and orbital control to optimize communication performance.

Definition statement
This place covers: The link between satellites can be radio or optical.
Constellation of satellites with inter-satellite links to route a communication through the network of satellites.

Limiting references
This place does not cover:

Definition statement
This place covers: Simulcast (simultaneous broadcasting). Multicasting (transmission to a group of users). Geocast (transmission to geographic areas).
Feedback from the user (thru satellite or thru terrestrial network) for interactive system.
On-board transponders. Transport of data or signalling messages. Transport of voice channels.

Relationships with other classification places
Traffic channels, dedicated control channels, broadcast channels, paging channels, beacon signal, pilot channels, synchronisation channels.

Definition statement
This place covers: In particular for diversity used to increase link quality.
Resources seamlessly added or subtracted.
Transmission with multidirectional antennas from the base station to achieve diversity.

Definition statement
This place covers: Shadowing due to blockage of signals. Use of an additional terrestrial relay or other techniques.

H04B 7/18539
{Arrangements for managing radio, resources, i.e. for establishing or releasing a connection}

Definition statement
This place covers: Allocation of radio resources for establishing or releasing a connection.
Resource allocation for load balancing.
Determination and dissemination of information through the network of gateway for resource planning.
Frequency planning.
Frequency attributed according to need, to a reuse pattern, to limit interference.
Power control in real and non real time.
Time slot allocation.

This place covers:
A communication is handed over from one satellite to another according to the satellites rotations.
Handoff beam to beam, satellite to satellite, frequency to frequency.
Network controlled handover, mobile controlled handover, mobile assisted handover.

H04B 7/18543
{for adaptation of transmission parameters, e.g. power control (for detecting or preventing errors in the information received H04L 1/00)}

Limiting references
This place does not cover: Detecting or preventing errors in the information received H04L 1/00

Definition statement
This place covers: Terminal registration process. Local or global registration.
Location update of terminal.
Registration in a local and global database with user identification and position.
Re-registration. Periodic registration of a mobile, registration after loss of a signal (outage), terminal unavailability.

Definition statement
This place covers: Geolocalisation of a user for radio localisation, call barring, call billing, synchronisation.

Limiting references
This place does not cover: Position fixing by direction or distance determination G01S 5/00

Definition statement
This place covers: Measure of propagation delay variation, Doppler frequency variation, power variation, beam identification.
Measure of time delay satellite-user.

Limiting references
This place does not cover: Determining absolute distances from a plurality of spaced points of known location G01S 5/14

Definition statement
This place covers: Routing through terrestrial network with only node-satellite-terminal links.
Mobile to mobile call.
Mobile to fixed, fixed to mobile call.
Routing tables used are changed according to network topology (link usage, congestion, failure, shutdown).
Optimization of transmission path (minimum hop route, packet delay).
Satellite in relation with more than one node for control.

Definition statement
This place covers: Use of a terrestrial and a satellite system (dual mode).
Protocol conversion between different satellites, terrestrial systems.
Use of a terminal adapted for the two systems. Characteristics differ: antenna used (orientation), power transmitted (higher for a satellite system, user head protection).

Definition statement
This place covers: Description of the transmission equipments of the system. Satellite, terminal and control station. Description of the transport of the information. Modulation, demodulation, antenna, radio link between earth and satellite, bit synchronisation.

H04B 7/18582
{Arrangements for data linking, i.e. for data framing, for error recovery, for multiple access}

H04B 7/18586
{Arrangements for data transporting, e.g. for an end to end data transport or check}

Definition statement
This place covers: Segmentation and reassembly.
Connection oriented, connectionless communication. Establishment of the physical links.
Transport of bits, bytes, packets.
Multiplexing, demultiplexing on a single link.
Congestion control. Flow control.
Fiability of the transport.
Error detection and recovery (forward error correction, repetition, automatic repetition).

H04B 7/18593
{Arrangements for preventing unauthorised access or for providing user protection (arrangements for secret or secure communication H04L 9/00)}

Definition statement
This place covers: Encryption. Decryption. Use of SIM card. Adaptor card or conditional access. Scrambling, descrambling. Billing.

Limiting references
This place does not cover: Arrangements for secret or secure communication H04L 9/00

Definition statement
This place covers: The satellite is on a geostationary, an equatorial, a geosynchronous orbit or semi-synchronous orbit.
Description of the constellation of satellites, of the orbital parameters.

Definition statement
This place covers: The orbits are low earth orbit (LEO), medium earth orbit (MEO) or high earth orbit (HEO) according to the altitude of the satellite. Mixed constellation.

Definition statement
This place covers: On board of a satellite.

Special rules of classification
Group for consultation only. Documents are classified in H04B 7/18515.

Definition statement
This place covers: On board of a satellite.

Special rules of classification
Group for consultation only. Documents are classified in H04B 7/18515.

Definition statement
This place covers: On board of a satellite.

Informative references
Attention is drawn to the following places, which may be of interest for search: Spread spectrum techniques in general H04B 1/69

Special rules of classification
Group for consultation only. Documents are classified in H04B 7/18515.

Definition statement
This place covers: Use of ionosphere, troposphere reflexion or meteor scatter.
In such systems, the radio propagation is not a line of sight propagation between two devices. The signals are reflected, refracted or scattered by natural components of the earth atmosphere. A network using such reflexions and the radio link between the divers network components are described.
Passive relay are described in H04B 7/145. Radio waves are refracted by the ionized layers of the upper atmosphere. These layers are influenced by the sun. Such communications are used for amateur radio, marine and aircraft communications, shortwave broadcast.
Tropospheric scatter is a method of communication in which signals at particular frequencies are randomly scattered by the upper layers of the troposphere allowing the transmission of signals on a distance of hundred of kilometres. Only a small amount of the transmitted power is received. A narrow frequency band is generally used.
A meteor burst communication system uses the ionized meteor trails as radio reflector between two stations. These trails exit at an altitude of approximately 100 km and allow a long range, low data rate intermittent communication of a few seconds on a distance of 2000 km.
Auroral ionization, rain, lightning can create scattering.

Limiting references
This place does not cover: Relay systems H04B 7/14

Informative references
Attention is drawn to the following places, which may be of interest for search: Passive relay systems H04B 7/145

Definition statement
This place covers: In a communication network, the physical link and the signals transmitted between the divers network components are described. The link can be wired or wireless, the network components are fixed in this head group, mobile in the different sub-groups.

Definition statement
This place covers: In a wireless communication network, the radio link, called air interface, between the divers network components is described.
Different mobile systems exist. For example: cordless telephony is a short range system.
The mobile telephony has evolved toward cellular telecommunication systems for voice, narrowband or broadband data transmission.

Relationships with other classification places
The physical channel, channel access procedures and multiple access are the lower levels of the transmission system linking users and are the object of these groups. The higher levels control the flow of messages between the network components and allow the building up of a communication and are the subject of H04W in general.

Definition statement
This place covers: The signals transmitted on the air interface and the apparatuses therefore are described.
The frequency band or time interval allocated is separated in physical wireless channels.
Definition of the physical and logical channels, mapping of the logical channels on the physical channels. Logical channels for traffic of voice or data. Logical channels for control: dedicated control channels, broadcast channels, paging channels, access grant logical channels, random access channels, pilot channels, synchronisation channels ... Frequencies, time slots used, number of bits, format, overhead bits, preamble, guard periods ...

H04B 7/2606 {Arrangements for base station coverage control, e.g. by using relays in tunnels} Definition statement
This place covers: Relays are used for linking a user equipment with a base station.
Relays for lightening dark zones. Use of relays in tunnels, in buildings, in closed environments.

Roadway communication systems.
Fixed relay, mobile relay.
Relays for cell extension.

Multiplicity of relays.
Relay selection.
Use of multiple antennas. Antenna characteristics, antenna patterns, spacing of antennas.
Relay functionality and design. Half-duplex, full duplex repeater. TDD (Time Division Duplex), frequency change, frequency selective repeaters, amplify and forward, decode and forward repeaters. Loop-back interference cancellation. Signal delay. Link with the base station, link with a user equipment. Protocols implemented in the relay.

Definition statement
This place covers: Allocation of a physical layer transmission capacity.
Transport channels for carrying the logical channels.
Channel access control mechanisms.

Definition statement
This place covers: OFDM (Orthogonal Frequency Multiplexing).

Definition statement
This place covers: Using a common frequency.
Single frequency network.
A network of stations broadcasting on a single frequency for example.

Definition statement
This place covers: Divers types of spread spectrum systems:
• Near far problem, power control.
• Code synchronization, acquisition and tracking.

Definition statement
This place covers: Transmission of information on a plurality of parallel channels. Superframes, frames, time slots.
Formats used for the frames and the time slots. Description of the burst, the information in the time slot.
Guard bands to avoid overlapping of the signals.

Special rules of classification
Group used for consultation only. Documents are classified in H04W 56/00.

Special rules of classification
Group used for consultation only. Documents are classified in H04W 56/00.

Special rules of classification
Group used for consultation only. Documents are classified in H04W 56/00.

Definition statement
This place covers: • electromagnetic waves in the optical spectrum, e.g. visible, infrared, ultraviolet • optical corpuscular radiation, i.e. photons • non-optical electromagnetic waves other than radio-waves, e.g. low-frequency Terahertz waves • non-optical corpuscular radiation, i.e. beams of atomic or subatomic discrete particles

Relationships with other classification places
H04B 10/00 deals with the physical layer of an optical communication system, i.e. dealing with the physical properties of the optical data signal, e.g., power, distortion, optical-electrical and electricoptical conversion of data.
H04J 14/00 deals with the optical multiplexing layer, e.g. dealing with the optical signals as channels necessary for data transfer, e.g. routing, allocation, add-dropping, WDM networks, WDM protection.
Light guide arrangements as components or modules per se are classified in G02B 6/00, e.g. modules based on light guides for coupling, splitting, mixing, switching and dispersion compensation Lasers and fibre amplifiers per se are classified in H01S and H01S 3/067 Optical devices per se for changing the optical properties of the signals based on a change in refractive index, e.g. modulators are classified in G02F.

Informative references
Attention is drawn to the following places, which may be of interest for search:

Glossary of terms
In this place, the following terms or expressions are used with the meaning indicated: Corpuscular radiation the beams of atomic or subatomic discrete particles, e.g. photon, alpha particle, neutron, fission fragment or fissionable isotope

Synonyms and Keywords
In patent documents, the following abbreviations are often used: Subject matter wherein at least one communication parameter is determined by information from a signal reflected from a location in the communication network.

Definition statement
This place covers: Subject matter wherein the operational condition of an optical communication network or its component is tested or evaluated using an external stimulus signal while the system is not in operation.

H04B 10/11
Arrangements specific to free-space transmission, i.e. transmission through air or vacuum

Definition statement
This place covers: Subject matter wherein a signal-carrying optical beam is propagated such that the beam is transmitted through air or a vacuum and not spatially confined in any optical component or medium.

Informative references
Attention is drawn to the following places, which may be of interest for search: Light signal transmission through water H04B 10/80

H04B 10/112
Line-of-sight transmission over an extended range

Definition statement
This place covers: Subject matter wherein the optical beam is transmitted in a straight line to the receiver across longer distances outdoors, e.g. between buildings.

Definition statement
This place covers: Subject matter wherein one central station is communicating wirelessly with a plurality of terminal stations. Even if the document focuses on one such connection, but it is clear from the description and drawings it is for a network, the document should be classified here.

H04B 10/114
Indoor or close-range type systems

Definition statement
This place covers: Subject matter wherein the optical beam is propagated between nearby apparatuses or elements within an indoor space, directly or via diffuse communication.

Definition statement
This place covers: Subject-matter wherein two devices are communicating only one-way, e.g. remote controllers.

Informative references
Attention is drawn to the following places, which may be of interest for search: Subject matter wherein the optical beam is propagated to or from an Earth-orbiting object.

Definition statement
This place covers: Subject matter including one or more transparent elongated structures (e.g., rods, fibers, or pipes) which are used to transmit light waves from one point to another within the confines of their outer surface by means of internal reflections or modal transmission.

Informative references
Attention is drawn to the following places, which may be of interest for search: Optical waveguides per se G02B 6/00 H04B 10/2507 for the reduction or elimination of distortion or dispersion

Definition statement
This place covers: Subject matter comprises means for correcting or reducing distortion induced by (1) scattering in a light beam as it travels along the fiber or (2) overlapping of a light signal on one wavelength onto different wavelengths because of reflected rays and different refractive indices of the optical fiber material.

Definition statement
This place covers: Subject matter comprising means for correcting or reducing distortion that is caused by the broadening of the signal as it travels the length of the fiber.

Informative references
Attention is drawn to the following places, which may be of interest for search: Optical dispersion compensators involving optical fibres per se G02B 6/293 H04B 10/2519 using Bragg gratings

Definition statement
This place covers: Subject matter comprising means for correcting or reducing distortion caused by chromatic dispersion using a fiber Bragg grating.

Informative references
Attention is drawn to the following places, which may be of interest for search: Subject matter wherein over the whole fibre span a combination of different fibres are used to compensate for the dispersion of the span (does not cover a combination of fibres within a device)

Informative references
Attention is drawn to the following places, which may be of interest for search: Devices with different kinds of fibres for dispersion compensation per se G02B 6/29374 H04B 10/2531 using spectral inversion

Definition statement
This place covers: Subject-matter wherein dispersion is compensated through mid-span spectrum inversion.

Definition statement
This place covers: Subject matter comprising means for correcting or reducing distortion caused by the interaction of the signal with molecules in the fiber.

Definition statement
This place covers: Subject matter comprising means for correcting or reducing distortion caused by variations in the optical properties of the fiber, e.g. due to the Kerr effect.

Definition statement
This place covers: Subject matter comprising means for compensating for Self-phase modulation. SPM is caused by the Kerr effect which produces a variation in the refractive index of the fibre. This variation in refractive index will produce a phase shift in the pulse, leading to a change of the pulse's frequency spectrum.

This place covers:
Subject matter comprising means for compensating for Cross-phase modulation. XFM is caused by the Kerr effect which produces a variation in the refractive index of the fibre. This leads to one wavelength of light potentially affecting the phase of another wavelength of light.

This place covers:
Subject matter comprising means for compensating for Four-wave mixing. FWM is an intermodulation phenomenon in optical systems; when three wavelengths interact in a nonlinear medium, they give rise to a fourth wavelength.

This place covers:
Subject matter which comprises means for correcting or reducing distortion caused by modal dispersion where two different polarizations of light in a waveguide, which normally travel at the same speed, travel at different speeds due to random imperfections and asymmetries, causing random spreading of optical pulses.

Definition statement
This place covers: RF-over-Fiber architecture, wherein a data-carrying RF (Radio Frequency) signal with a high frequency is imposed on a lightwave signal before being transported over the optical link. Wireless signals are optically distributed to base stations directly at high frequencies and converted from the optical to the electrical domain at the base stations before being amplified and radiated by an antenna.

Definition statement
This place covers: Subject matter wherein the light source in a first station is used to transmit an optical data signal to at least a second station and the second station modulates the received light to transmit an optical data signal to the first station. The at least second station does not comprise a local light source.

Definition statement
This place covers: Subject matter wherein an optical communication system is comprised of a specific arrangement of interconnections.

Definition statement
This place covers: Subject matter in which the regeneration is provided using a single device that retransmits both upstream and downstream signals. The single device may contain different devices that interact with each other. A single fibre is used for upstream and downstream signals, the regeneration device can however comprise separate amplifiers for upstream and downstream signals.

Definition statement
This place covers: Subject matter in which the shape and/or timing of the signal is processed prior to regeneration, e.g. 3R amplifiers.

Definition statement
This place covers: Subject matter wherein an optical transmitter and a receiver are at a common location for transmission and reception of separate optical signals in such a manner that an optical signal is transmitted using some of the same equipment used for the reception of another optical signal. The optical transmitter and receiver are usually confined to a common housing in a transceiver and termed "a station".
Simultaneously operating transmitter and receiver elements that are completely separated physically are excluded from this subclass.
H04B 10/43 using a single component as both light source and receiver, e.g. using a photoemitter as a photoreceiver

Definition statement
This place covers: Subject matter wherein a same diode element is used both to transmit or receive signals depending on how it is biased.

Definition statement
This place covers: Subject matter including an opto-electric circuit for converting an information signal into a modulated optical signal suitable for propagation through or along a transmission medium. The opto-electric H04B 10/50 (continued) Definition statement CPC -H04B -2020.08 circuit includes, for example, opto-electronic light sources such as LEDs, laser diode, incandescent bulbs, an optical modulator and other elements associated with fiber optic or infrared transmission system required to communicate an information signal from one location to another via an optical beam.

Informative references
Attention is drawn to the following places, which may be of interest for search: WDM systems in general H04J 14/02 H04B 10/508 Pulse generation, e.g. generation of solitons

Definition statement
This place covers: Subject matter comprising details of a process in which the optical energy is transformed into pulses having a particular characteristic before information signal coding or modulation is applied to the optical energy.

H04B 10/516
Details of coding or modulation

Definition statement
This place covers: Subject matter comprising details of a process in which information signal is coded into beams of optical energy by use of a carrier wave.

Definition statement
This place covers: Subject matter in which modulation is produced by modulating a carrier light wave by a series of digital pulses and varying a non-amplitude attribute of the pulses (e.g., position, width) to represent information in the optical beam.

Definition statement
This place covers: Subject matter in which the polarization of the carrier light wave is controlled to represent information

Informative references
Attention is drawn to the following places, which may be of interest for search: Polarisation multiplexed systems H04J 14/06

Definition statement
This place covers: Subject matter in which modulation is produced by varying the amplitude of a carrier light wave as a function of the information signal.

Definition statement
This place covers: Subject matter in which angle modulation is produced by proportionally varying the instantaneous phase angle of a sine wave carrier with the instantaneous value of an amplitude of a modulating signal, or by causing the instantaneous frequency of a sine wave carrier to depart from a carrier frequency an amount that is proportional to the instantaneous value of a modulating signal.

Definition statement
This place covers: Subject matter in which the modulation is produced by creating discrete variations of the phase or frequency of the optical signal.

Definition statement
This place covers: Subject matter comprising details of regulating the energy level output from the transmitting laser or light emitter.

Definition statement
This place covers: Subject matter comprising details of regulating the wavelength output from the transmitting laser or light emitter. Regulating the wavelength output may include wavelength tuning or wavelength stabilization.

Informative references
Attention is drawn to the following places, which may be of interest for search: Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation H01S 3/10 Arrangements for controlling the laser output parameters H01S 5/06

Definition statement
This place covers: Subject matter wherein at least one output of the opto-electric circuit is modified to be an approximately linear function of its inputs. (techniques for making the output of the transmitter into a linear output)

Definition statement
This place covers: Subject matter including particular details of varying the output of at least one laser diode element using another element outside of the laser diode to provide the optically transmitted signal.

Definition statement
This place covers: Subject matter including an opto-electric circuit for retrieving information from a modulated optical signal propagated through or along a transmission medium.

H04B 10/63
Homodyne {, i.e. coherent receivers where the local oscillator is locked in frequency and phase to the carrier signal}

Definition statement
This place covers: A receiver that demodulates the received signal by mixing it with a local oscillator signal synchronized in frequency and phase to the carrier of the received signal.

This place covers:
A receiver that demodulates the received signal by mixing it with a local oscillator signal having a different frequency than the carrier of the received signal.

Definition statement
This place covers: Subject matter in which the data signal is directly converted from optical to electrical without the use of an oscillator.

H04B 10/67
Optical arrangements in the receiver

Definition statement
This place covers: Subject matter in which the detection of the signal is enhanced by an optical arrangement in the receiver that is provided in addition to the photodetection means.

H04B 10/69
Electrical arrangements in the receiver

Definition statement
This place covers: Subject matter in which the detection of the signal is enhanced by an electrical arrangement within the receiver that is provided in addition to the photodetection means.

Definition statement
This place covers: Transmission systems where the medium for transmission is more pertinent than the type of signal.

This place covers:
Transmission systems where the medium is the human body.

H04B 13/02
Transmission systems in which the medium consists of the earth or a large mass of water thereon, e.g. earth telegraphy

This place covers:
Transmission systems where the medium is the earth or a large mass of water.

H04B 14/00
Transmission systems not characterised by the medium used for transmission (details thereof H04B 1/00)

Definition statement
This place covers: Transmission systems characterised by the use of a carrier modulation; Transmission systems characterised by the use of pulse modulation, differential modulation or subcarrier modulation.