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MULTIPLEX COMMUNICATION (transmission in general H04B; peculiar to transmission of digital information H04L 5/00 ; systems for the simultaneous or sequential transmission of more than one television signal H04N 7/08 ; in exchanges H04Q 11/00 ; stereophonic systems H04S)
Definition statement
This subclass covers:

Multiplex Communication having circuits or apparatus for combining or dividing signals for the purpose of transmitting the signals simultaneously or sequentially over the same transmission path, and monitoring arrangements therefor.

Relationship between large subject matter areas

Class H04 Electric communication technique covers electrical communication systems with propagation paths employing beams of corpuscular radiation, acoustic waves or electromagnetic waves. Subclass H04J refers to multiplex communication in general. If the multiplex communication is specially adapted for particular applications classification is made in other subclasses of class H04.

References relevant to classification in this subclass
This subclass does not cover:

Optical monitoring arrangements, independent of the multiplexing method

H04B10/08

Selecting arrangements for multiplex systems

Examples of places where the subject matter of this class is covered when specially adapted, used for a particular purpose, or incorporated in a larger system:

Use of multiplexing in transmission systems for measured values, control or similar signals

Arrangements for transmission of digital information affording multiple use of the transmission path

Systems for the simultaneous or sequential transmission of more than one television signal

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

Optical elements, systems or apparatus

Addressing or transmission in computers

Electronic switching or gating

Transmission in general

Relay systems

Broadcast communication

Data switching networks

Modulated-carrier systems

Telephonic Communication

Selecting techniques

Stereophonic systems

Wireless communication networks

Frequency-division multiplex systems (H04J 14/00 takes precedence)
Definition statement
This group covers:

Frequency Division Multiplexing, FDM, by multiplexing two or more data sources. Covers particularly hierarchical multiplexing electrical frequencies in stages of power of 2, e.g. 8kHz, 64Khz.

References relevant to classification in this group
This group does not cover:

OFDM

FDM in satellite systems

FDM in radio system

OFDM synchronization

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

SCM

FDM in CATV or HFC networks

Hybrid TDM/FDM

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

FDM

Frequency Division Multiplexing

OFDM

Orthogonal Frequency Division Multiplexing

SCM

Multiplexing of electrical subcarriers on an optical wavelength

CATV

CAble Television Systems

HFC

Hybrid Fiber Coax

TDM

Time Division Multiplex

Frequency-transposition arrangements {(modulation with carrier or side-band suppression H03C 1/52 , H03C 1/60 ; single-band suppression H04B 1/00 , H04B 15/00 ; telegraphic communication H04L 27/02 , H04L 25/49 ; transference of modulation from one carrier to another, e.g. frequency- changing H03D 7/00 ; demodulation or transference of modulation of modulated electromagnetic waves H03D 9/00)}
Definition statement
This subgroup covers:

Systems for transposing frequency channels carrying information onto frequency carriers Covers also FDM multiplexers, demultiplexers

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

TDM/FDM conversion of transmultiplexing

Special rules of classification within this group

H04J 1/08 takes precedence

using digital techniques
Definition statement
This subgroup covers:

Frequency translators, FDM multiplexers, demultiplexers, operating with digital techniques

References relevant to classification in this group
This subgroup does not cover:

Group modulators /demodulators used for transmultiplexing FDM TDM

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

Digital Filters

Special rules of classification within this group

H04J 1/08 takes precedence

Arrangements for supplying the carrier waves {Arrangements for supplying synchronisation signals (carrier supply H04L 5/10 ; frequency multiplication H03B 19/00 , H03B 21/00 ; mixing H03D 7/00 , H03D 9/00 ; synchronisation in general H03B)}
References relevant to classification in this group
This subgroup does not cover:

- Channel allocation

Arrangements for combining channels {(branching filters H01P 1/213 , H03H 7/46)}
References relevant to classification in this group
This subgroup does not cover:

Branching filters

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

Discrete frequency-selective devices, e.g. stubs, waveguides, directional filters

Intermediate station arrangements, e.g. for branching, for tapping-off {(repeater circuits H04B 3/36 , H04B 3/58 ; two-way amplifiers H03F 3/62)}
Informative references
Attention is drawn to the following places, which may be of interest for search:

Two way amplifiers

Repeater circuits

Arrangements for reducing cross-talk between channels {(in line transmission systems H04B 3/32 ; in cables or lines H04B 3/26 to H04B 3/30)}
Definition statement
This subgroup covers:

Frequency allocation, including by demand or to reduce intermodulation;

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

In line transmission

In baseband systems

Time-division multiplex systems (H04J 14/00 takes precedence; relay systems H04B 7/14 ; selecting techniques H04Q)
Definition statement
This group covers:

Hierarchical frame structures, the structure repeats continuously at a fixed rate. Typically these are standard TDM frame structures at 8kHz rate like PDH, SDH or OTN. Other fixed rates frames should also be classified here and related fields.

  • fixed length Ethernet (H04L 12/40)
  • Digital audio transmission in fixed length formats ( H04H, H04R).

Synchronization of TDM Frames

Packet transmission is classified for some specific applications:

Transmission of synchronous services like voice via packets, e.g. VoIP, is classified in H04J 3/0632, when the source clock is recovered.

Alignment of packets using packet flags should be in H04J 3/0602 for fixed line systems and in H04L 7/04 in wireless, satellite or radio systems.

Ranging of packets in an uplink in systems with a TDM frame defined in the downlink, see H04J 3/0682.

Note 1: Ranging or time alignment of a radio/wireless channel preferably in H04W 56/00. For radio/wireless systems data transmitted via a fixed network, e.g. connections between Mobile Switching Centre (MSC) and Base Station (BS) or between several Access Points (AP), documents referring to specific data of the radio/wireless channel are in H04W 56/00, e.g. alignment for handover.

Allocation of packets within a TDM frame, e.g. Ethernet in OTN payload, see H04J 3/16 or lower.

Allocation of packets in an uplink of a systems with a TDM frame defined above in the downlink, H04J 3/1694.

Note 1 : This group refers to the allocation of the bandwidth.

Note 2 : Allocation in wireless systems, see H04W or H04B 7/00;

Note 3 : Allocation of timeslots in PON, H04Q 11/0001 takes precedence

Synchronization of TDMA or packets in the meaning of time alignment, the minimum entity of detection or correction is a bit. Smaller sub-bit values refer to bit synchronization of H04L 7/00

References relevant to classification in this group
This group does not cover:

Recording

Selecting techniques

Alignment of parallel data transmission

Frame structures of OFDM

Frame structures of wireless systems

H04B4/26

Relay systems

Synchronization of digital video, e.g. STC or PCR timestamps

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

Digital audio for loudspeakers

Simulcast or Single Frequency Networks

Packet networks

Internet protocol

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

SDH

Synchronous Digital Hierarchy

SONET

Synchronous Optical NETwork

OTN

Optical Transport Network

MulDex

Multiplexer/Demultiplexer

Details (electronic switching or gating H03K 17/00)
References relevant to classification in this group
This subgroup does not cover:

Electronic switching or gating

Distributors combined with modulators or demodulators {(pulse distributors in general H03K 5/15 ; pulse counters H03K 21/00 to H03K 29/06 ; for telegraphy H04L 5/22 , H04L 13/00 to H04L 23/00 , H04L 25/45 ; for telephony H04Q 11/04)}
Informative references
Attention is drawn to the following places, which may be of interest for search:

Pulse counters

Pulse distributors in general

SerDes not adapted for data communication of telecommunication

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

SerDes

Serializer / Deserializer

{Distributors with CRT}
Glossary of terms
In this subgroup, the following terms (or expressions) are used with the meaning indicated:

CRT

Cathode Ray tubes

{Distributors with transistors or integrated circuits}
Definition statement
This subgroup covers:

Details of multiplexing or demultiplexing of bits or bytes in arrangements specially adapted for time multiplexing.

Distributors with transistors or integrated circuits

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

Details of discrete elements, e.g. transistors

Timing and clocking in MulDex

Higher level of abstraction of hierarchical PDH MulDex

Special rules of classification within this group

Details of bit and byte multiplexers or demultiplexers per se, e.g. 2:1 pulse multiplexers and tree structures thereof, H03M 9/00 takes precedence.

Synchronising arrangements {(for television systems H04N 5/04 ; bit-synchronisation H04L 7/00)}
Definition statement
This subgroup covers:

Synchronization of TDM networks and some specific synchronization arrangements in TDMA or packet networks.

Synchronization of TDM networks covers:

Detection of FAW and alignment of frames, H04J 3/0602;

Absorbing of phase or frequency differences by buffers, H04J 3/062;

Distribution of synchronization information and organisation of the synchronization network, H04J 3/0635.

Specific synchronization arrangement of packet or TDMA networks are:

Distribution of synchronization information and organisation of the synchronization network, H04J 3/0635

Source clock recovery over packet or ATM networks, e.g. VoIP, H04J 3/0632.

Relationship between large subject matter areas

Synchronization of wireless network when mobility of radio channel is relevant, H04W 56/00.

References relevant to classification in this group
This subgroup does not cover:

Smaller, sub-bit, values refer to bit synchronization

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

Synchronization in computer networks, e.g. Time of Day

Buffers between clock domains

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

FAW

Frame Alignment Word

{Systems characterised by the synchronising information used}
Definition statement
This subgroup covers:

A FAW is used as synchronising information for a TDM frame.

References relevant to classification in this group
This subgroup does not cover:

Specific FAW

Details of the FAW detector

Detection of packet headers, e.g. HDLC flag

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

Special synchronization information, e.g. for packet or mobile transmission

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

FAW

Frame Alignment Word

{Special codes used as synchronising signal}
Definition statement
This subgroup covers:

Design rules of constructing FAW.

variable FAW, e.g. for low rate signalling, depending on the synchronization state.

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

Signalling in TDM

Special rules of classification within this group

FAW of standardized frames, e.g. T1, SONET, SDH or OTN are known per se are not classified here. Their detection is classified in H04J 3/0608.

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

FAW

Frame Alignment Word

UW

Unique Word

{Detectors therefor, e.g. correlators, state machines}
Definition statement
This subgroup covers:

Detection of FAW by correlators, state machines, forward or backward protection.

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

Digital correlators

Detectors of UW for packet detection or symbol synchronisation

{PN codes (H04J 3/0608 takes precedence)}
Definition statement
This subgroup covers:

PN codes used for synchronisation, if the PN synchronisation signals is varying during transmission, e.g. by a feedback Shift-register. Fixed synchronisation signals, e.g. unique words or FAW signals, are not to be classified in this group. This also applies even if the synchronisation signal can be presented as a state of such a PN-code generator. Only if the generator shifts, then the document is classified here.

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

PN codes used for synchronization in other transmission systems, e.g. packet or mobile

Special rules of classification within this group

H04J 3/0608 takes precedence for detection

Synonyms and Keywords

In patent documents the following abbreviations are often used:

PN code

Pseudo-Noise or Pseudorandom code

{Synchronisation of signals having the same nominal but fluctuating bit rates, e.g. using buffers (pulse-stuffing H04J 3/07 ; asynchronous-synchronous conversion H04L 5/24 ; speed conversion H04L 25/05 ; speed conversion in computers G06F 5/06)}
Definition statement
This subgroup covers:

Rate differences are compensated in a lossless way, e.g. by an elastic buffer or FIFO

References relevant to classification in this group
This subgroup does not cover:

Speed conversion in computers

Pulse stuffing

Speed conversion, e.g. 8 kHz to 9,2 kHz

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

FIFO

First In First Out buffer

{Synchronous multiplexing systems, e.g. synchronous digital hierarchy/synchronous optical network (SDH/SONET), synchronisation with a pointer process}
Definition statement
This subgroup covers:

Compensation of fluctuating rates in SDH/SONET or OTN

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

PDH/SDH interfaces, e.g. desynchronizers

Synonyms and Keywords

In patent documents the following abbreviations are often used:

OTN

Optical Transport Network

{plesiochronous multiplexing systems, e.g. plesiochronous digital hierarchy [PDH], jitter attenuators}
Informative references
Attention is drawn to the following places, which may be of interest for search:

PDH/SDH interfaces, e.g. desynchronizers

Slot or bandwidth allocation in PDH

Synonyms and Keywords

In patent documents the following abbreviations are often used:

PDH

Plesiochronous Digital Hierarchy

{Synchronisation of packets and cells, e.g. transmission of voice via a packet network, circuit emulation service [CES]}
Definition statement
This subgroup covers:

Recovery of source clock of Continuous Bit Rate (CBO) service, e.g. VoIP. The invention is located at the edge of the packet network and the output is a stream of bits.

References relevant to classification in this group
This subgroup does not cover:

Queuing arrangement in packet networks, e.g. Flow control

Synchronization of video or multimedia, e.g. use of MPEG PCR or STC

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

Multimedia packet transmission and protocols

Synonyms and Keywords

In patent documents the following abbreviations are often used:

FIFO

First In First Out buffer or elastic buffer

SRTS, RTS, SFE

Residual time stamps signalling a source clock offset compared to the network clock

CES

Circuit Emulating Switching

{Clock or time synchronisation among nodes; Internode synchronisation (synchronization for ring networks H04L 12/422 ; data switching networks with synchronous transmission H04L 12/43)}
Definition statement
This subgroup covers:

Distribution of synchronisation information among nodes, e.g. master/slave signalling or SSM.

TOD synchronization.

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

Clock synchronization in Computer Networks, e.g. TOD

Clock synchronization path among nodes of more than two levels

In combination with delay compensation using timestamp to determine RTD

Synchronisation of Ring Networks

Data switching networks with synchronous transmission

Synonyms and Keywords

In patent documents the following abbreviations are often used:

SSM

Synchronization Status Message

RTD

Round Trip Delay

NTP

Network Time Protocol

PTP

Precision Time Protocol

TOD

Time Of Day

{Change of the master or reference, e.g. take-over or failure of the master}
Definition statement
This subgroup covers:

Signalling to prevent or recover from a failure in the synchronization network.

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

Fail safe arrangements within the node

Monitoring and fail safe arrangements in general

Fail safe arrangements for synchronizers in general

Synonyms and Keywords

In patent documents the following abbreviations are often used:

APS

Automatic Protection Switching

{Synchronisation among time division multiple access [TDMA] nodes, e.g. time triggered protocol [TTP] (bus network with centralized control in which slots are of a TDMA packet structure H04L 12/4035)}
Informative references
Attention is drawn to the following places, which may be of interest for search:

Bus network with centralized control in which slots are of a TDMA packet structure

Synonyms and Keywords

In patent documents the following abbreviations are often used:

TTP

Time Triggered Protocol

{Bidirectional timestamps, e.g. NTP or PTP for compensation of clock drift and for compensation of propagation delays (monitoring or testing of delay in data switching networks H04L 12/2657)}
Informative references
Attention is drawn to the following places, which may be of interest for search:

Synchronization in computer networks, e.g. Time of Day

Delay compensation for other types of time multiplexing, e.g. TDM/TDMA in a star configuration

Timestamps used in protocols

Timestamps for delay measurement for network management

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

NTP

Network Time Protocol

PTP

Precision Time Protocol

{using intermediate nodes, e.g. modification of a received timestamp before further transmission to the next packet node, e.g. including internal delay time or residence time into the packet}
Definition statement
This subgroup covers:

Adding or modification of delay information, e.g. residence time in PTP

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

Interconnection of networks

Synonyms and Keywords

In patent documents the following abbreviations are often used:

PTP

Precision Time Protocol

{Mutual}
Definition statement
This subgroup covers:

Exchange of synchronization information, e.g. buffer fill.Coupling clocks, e.g. by adding weighted signals of clock or phase errors.

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

Clock selection in a TDM node

{by determining clock distribution path in a network}
Definition statement
This subgroup covers:

Determination or initialisation of clock distribution path among more than two levels of nodes according to parameters, e.g. priority, path length, number of hops, clock quality, statistics.Avoidance of clock loops or timing islands.

Synonyms and Keywords

In patent documents the following abbreviations are often used:

HMS

Hierarchical Master Slave

PAMS

Pre-Assigned Master Slave

SSM

Synchronisation Status Message

{by delay compensation, e.g. by compensation of propagation delay or variations thereof, by ranging}
Definition statement
This subgroup covers:

RTD measurement in TDM or TDMA networks for the purpose of timing adjustment, clock correction or time alignment.

References relevant to classification in this group
This subgroup does not cover:

Bidirectional timestamps, e.g. NTP or PTP for compensation of clock drift and for compensation of propagation delays

Synchronization in mobile networks

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

RTD measurement and compensation in satellite systems

RTD measurement for network management or monitoring

PON in general

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

PON

Passive Optical Network

CATV

CAble TeleVision

RTD

Round Trip Delay

{Change of the master or reference, e.g. take-over or failure of the master}
Informative references
Attention is drawn to the following places, which may be of interest for search:

Fail safe arrangements of PLL

Monitoring and fail safe arrangements in general

Fail safe arrangements for synchronizers in general

Synonyms and Keywords

In patent documents the following abbreviations are often used:

APS

Automatic Protection Switching

{Synchronisation in a TDMA node, e.g. TTP}
Synonyms and Keywords

In patent documents the following abbreviations are often used:

TTP

Time Triggered Protocol

{Synchronisation in a packet node}
Synonyms and Keywords

In patent documents the following abbreviations are often used:

PTP

Precision Time Protocol

using pulse stuffing for systems with different or fluctuating information rates {or bit rates}
Definition statement
This subgroup covers:

Variable length stuffing; self marking stuff indications

This subgroup does not refer to stuffing of packet flags as line coding to interrupt a long sequence of identical bit values.

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

Line coding

Packet headers or flags

Fill bit or bits in non-TDM formats,

Synonyms and Keywords

In patent documents the following abbreviations are often used:

WTJ

Waiting Time Jitter

STM

Stuff Threshold Modulation

In patent documents the following words "justification" and "stuffing" are often used as synonyms

{Bit stuffing, e.g. PDH}
Informative references
Attention is drawn to the following places, which may be of interest for search:

PDH buffering

PDH framing formats and slot allocation

{Bit and byte stuffing, e.g. SDH/PDH desynchronisers, bit-leaking}
Definition statement
This subgroup covers:

Stuffing in OTN

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

Buffer arrangements for synchronization in SDH/SONET or OTN

Synonyms and Keywords

In patent documents the following abbreviations are often used:

OTN

Optical Transport Network

Intermediate station arrangements, e.g. for branching, for tapping-off
Definition statement
This subgroup covers:

ADM Add Drop Multiplexers

Synonyms and Keywords

In patent documents the following abbreviations are often used:

ADM

Add Drop Multiplexer

{for ring networks, e.g. SDH/SONET rings, self-healing rings, meashed SDH/SONET networks}
Definition statement
This subgroup covers:

Protection in TDM ring networks

References relevant to classification in this group
This subgroup does not cover:

Protection in TDM networks in general

Protection in optical ring networks

Protection in packet ring networks, e.g. RPR

Synonyms and Keywords

In patent documents the following abbreviations are often used:

CW

Clockwise

CCW

Counter Clockwise

UPSR

Unidirectional Protection Switched Ring

BLSR

Bidirectional Line Switched Ring

{One of the channel pulses or the synchronisation pulse is also used for transmitting monitoring or supervisory signals}
Definition statement
This subgroup covers:

Bit stealing for signalling, e.g. winking in PDH T1.

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

LSB bit dropping for making bandwidth available for user payload

Monitoring arrangements {(for SDH/SONET rings H04J 3/085)}
Definition statement
This subgroup covers:

Protection Switching; Testing of TDM systems.

References relevant to classification in this group
This subgroup does not cover:

Monitoring or Protection Switching of TDM rings

Protection switching of SDH/SONET or OTN

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

Network management

in which the time allocation to individual channels within a transmission cycle is variable, e.g. to accommodate varying complexity of signals, to vary number of channels transmitted (H04J 3/17 , H04J 3/24 take precedence)
Definition statement
This subgroup covers:

Covering variable time slot allocation.

H04J 3/1605 fixed standard frame structures.

H04J 3/1682 statistical multiplexers, allocation changes per frame cycle

H04J 3/1694 distributed multiplexers, e.g. access multiplexer

Relationship between large subject matter areas

For specific applications, e.g. video H04N 7/00; or physical medium, e.g. radio H04B 7/00, see more specialized classes

{Synchronous digital hierarchy [SDH] or SONET (H04J 3/1664 takes precedence for interactions with OTN)}
Definition statement
This subgroup covers:

Refers to systems according to ITU recommendations G.707 - G.709 in the versions of 1990 (SDH/SONET)

Radio, satellite and microwave transmission according to the standards mentioned above.

Covers switches, nodes and Cross-connects and respective internal or proprietary formats

References relevant to classification in this group
This subgroup does not cover:

Interactions with OTN

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

SDH/SONET or OTN ring networks

Synonyms and Keywords

In patent documents the following abbreviations are often used:

SPE

Synchronous Payload Envelope

{carrying packets or ATM cells}
Definition statement
This subgroup covers:

SPE carries ATM cells or payload data packets

Relationship between large subject matter areas

H04J 2203/0082 Services, Interaction of SDH with non-ATM protocols

H04J 2203/0083 Support of the IP protocol

H04J 2203/0085 Support of Ethernet

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

Stuffing, destuffing and desynchronization

SDH/SONET or OTN ring networks

Packet networks in general

Data networks and protocols

Synonyms and Keywords

In patent documents the following abbreviations are often used:

PoS

Packet over SONET

GFP

Generic Framing Procedure

SPE

Synchronous Payload Envelope

{Plesiochronous digital hierarchy [PDH]}
Definition statement
This subgroup covers:

Covers switches, nodes and Cross-connects and respective internal or proprietary formats.

Also covers transport of packets via a plesiochronous network, e.g. "ATM over E1".

{Format building algorithm}
Definition statement
This subgroup covers:

Time slot allocation according to rules, e.g. to evenly distributed slots to various users while minimizing the distance to ideal evenly distributed slot allocation for a single user.

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

Splitting time slots to smaller entities or concatenating time slots to larger entities

Time slot allocation according the instantaneous needs of the sources to be multiplexed

{Format conversion, e.g. CEPT/US}
Definition statement
This subgroup covers:

Format conversion of PDH frames of different standards, e.g. ETSI and ANSI

{Hierarchical systems}
Definition statement
This subgroup covers:

DS0, DS1, DS3 or European PDH, PCM30/32, E1 to E4 according to ITU recommendation G.703. Covers the hardware structure of programmable TDM multiplexer, e.g. internal construction by bus, as described in ITU recommendation G.797.

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

Electronic details of multiplexers or demultiplexers, e.g. multiplexing of bits or bytes

Synonyms and Keywords

In patent documents the following abbreviations are often used:

MULDEX

Multiplexer Demultiplexer

{Subrate or multislot multiplexing}
Definition statement
This subgroup covers:

Variable allocation of elementary units like time slots, subslots or fragments. The allocation can be modified by splitting elementary units or by combining elementary units to units of larger bandwidth. The overall frame length remains constant.

{Optical Transport Network [OTN]}
Definition statement
This subgroup covers:

Refers to systems according to ITU recommendation G.707 - G.709 in the versions of 2000.

Covers radio and microwave transmission according to the standards mentioned above.

Covers switches, nodes and Cross-connects and respective internal or proprietary formats.

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

SDH/SONET or OTN ring networks

SDH/SONET as preceding technology to OTN

Optical wavelength networks

Synonyms and Keywords

In patent documents the following abbreviations are often used:

SPE

Synchronous Payload Envelope

{carrying packets or ATM cells; H04J 3/1664 takes precedence for payloads with different packet types}
Special rules of classification within this group

H04J 3/1664 takes precedence for payloads with different packet types

{interaction with SDH/SONET, e.g. carrying SDH/SONET frames, interfacing with SDH/SONET (H04J 3/1664 takes precedence)}
Special rules of classification within this group

H04J 3/1664 takes precedence

{Time-division multiplex with pulse-position, pulse-interval, or pulse-width modulation}
Informative references
Attention is drawn to the following places, which may be of interest for search:

Fee space optical transmission with PPM or PWM

General PPM or PWM transmission

PPM or PWM modulation

{Allocation of channels according to the instantaneous demands of the users, e.g. concentrated multiplexers, statistical multiplexers}
Definition statement
This subgroup covers:

Allocation of bandwidth changes instantaneously, e.g. on demand or according to buffer fill.

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

Distributed multiplexers, e.g. access multiplexers

Packet multiplexing in general

Hybrid switching, e.g. moveable boundary between CS and PS

Voice over Date multiplexing for a single user

Statistical multiplexing for video or multimedia

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

CS

Circuit Switched service

PS

Packet Switched service

{the demands of the users being taken into account after redundancy removal, e.g. by predictive coding, by variable sampling (reducing bandwidth of signals in general H04B 1/66 ; in PCM-systems H04B 14/046 ; removal of redundancy in telegraph communication H03M 7/30)}
References relevant to classification in this group
This subgroup does not cover:

Reducing bandwidth of signals in general

Reducing bandwidth of signals in PCM-systems

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

LSB dropping of bit stealing for transporting signalling

Digital Speech Interpolation (DSI)

Digital Circuit Multiplication (DCM)

{Allocation of channels in TDM/TDMA networks, e.g. distributed multiplexers (Passive Optical Networks H04Q 11/0062)}
References relevant to classification in this group
This subgroup does not cover:

Time slot allocation in Passive Optical Networks

Time slot allocation in wireless networks

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

Time slot allocation in computer networks via CATV or HFC

Synonyms and Keywords

In patent documents the following abbreviations are often used:

CATV

CAble TeleVision

HFC

Hybrid Fibre Coax

in which the transmission channel allotted to a first user may be taken away and re-allotted to a second user if the first user becomes inactive, e.g. TASI {(speech analysis or identification G10L)}
References relevant to classification in this group
This subgroup does not cover:

DTX in wireless networks for power saving

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

Speech analysis

Distributed multiplexers, e.g. access multiplexers

Silence suppression in packet networks

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

DTX

Discontinuous Transmission

Comfort Noise

Introduction of noise signal to have a more comfortable audio signal during speech pauses

Synonyms and Keywords

In patent documents the following abbreviations are often used:

TASI

Time Assignment Speech Interpolation

DSI

Digital Speech Interpolation

{Digital speech interpolation, i.e. DSI}
References relevant to classification in this group
This subgroup does not cover:

PRMA (Packet Reservation Multiple Access),

{Speech activity or inactivity detectors (echo suppressors H04B 3/20)}
Informative references
Attention is drawn to the following places, which may be of interest for search:

VAD

G10L11/02

Instant speaker`s algorithm in telephony systems

Synonyms and Keywords

In patent documents the following abbreviations are often used:

VAD

Voice Activity Detection

using frequency compression and subsequent expansion of the individual signals
Informative references
Attention is drawn to the following places, which may be of interest for search:

Frame conversion

in which the sources have different rates or codes {(simultaneous speech and digital data or video transmission H04M 11/06 ; see provisional also H04J 3/16)}
Definition statement
This subgroup covers:

Different symbol rates in the slots of the TDM frame.

Relationship between large subject matter areas

Different or variable user rates or source rates are classified under H04J 3/1605 or sub-groups.

in which the allocation is indicated by an address {the different channels being transmitted sequentially}(H04J 3/17 takes precedence; in computers G06F 12/00 , G06F 13/00{ code multiplex systems H04J 13/00 ; selecting techniques H04Q ; relay systems H04B 7/14})
Special rules of classification within this group

CDMA and Spread-spectrum communication, H04J 13/00 takes precedence.

{the frames being of variable length}
References relevant to classification in this group
This subgroup does not cover:

Variable length frames or packets to avoid errors

{ATM or packet multiplexing}
Definition statement
This subgroup covers:

Generic packet or ATM multiplexing

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

Packet multiplexing in general

in which the information and the address are simultaneously transmitted
Definition statement
This subgroup covers:

Time frequency encoded transmission. The combination of time and frequency is determined by the receiver address and the transmitted information.

Transmission of address by Pulse Position Modulation (PPM).

Random sampling of analog sources

Synonyms and Keywords

In patent documents the following abbreviations are often used:

RADA

Random Access Discrete Address

Combined time-division and frequency-division multiplex systems (H04J 13/00 takes precedence; { data transmission H04L 5/26 ; telemetry G08C 15/00})
References relevant to classification in this group
This group does not cover:

Time and Frequency allocation of OFDM systems

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

Allocation of time/frequency in radio systems

Synonyms and Keywords

In patent documents the following abbreviations are often used:

OFDM

Orthogonal Frequency Division Multiplexing

{Transmultiplexing}
Definition statement
This subgroup covers:

Translation of TDM into FDM and vice versa.

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

Satellite systems

Group demodulation

Multiplex systems in which the amplitudes or durations of the signals in individual channels are characteristic of those channels
Definition statement
This group covers:

Simultaneous transmission of analog and digital, e.g. by overmodulation

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

FAW having a special amplitude

Multiple use of the transmission path the signals being represented by different amplitude or polarities, e.g. quadriplex

Synchronization signal having a special amplitude

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

FAW

Frame Alignment Word of a TDM frame

Multiplex systems in which each channel is represented by a different type of modulation of the carrier
References relevant to classification in this group
This group does not cover:

Modification of modulation constellation

Orthogonal multiplex systems, {e.g. using WALSH codes}(H04J 13/00 takes precedence)
Definition statement
This group covers:

Orthogonal multiplex systems at the physical layer, techniques relating to problems arising from the multiplexing of users / base stations. Aspects that are covered include

cell search, i.e. how a mobile phone finds the identity of base stations;

interference handling and cancellation, at the transmitter, the receiver or both, especially

subtractive interference cancellation

intercell interference cancellation at the physical layer.

Examples of orthogonal multiplexing techniques are OFDMA [Orthogonal Frequency Division Multiple Access ], SC-FDMA [ Single Carrier Frequency Division Multiple Access ].

Examples of systems using orthogonal multiplexing are LTE [ Long Term Evolution ], LTE-advanced.

Relationship between large subject matter areas

Code multiplexing techniques, orthogonal or not, are classified in H04J 13/00 if the focus is on the code multiplexing aspects and in H04B 1/69 if the focus is on the implementation of the spread-spectrum technique (e.g. details of how the signals are physically transmitted, received and processed).

References relevant to classification in this group
This group does not cover:

Narrowband interference reduction

Direct sequence spread spectrum

Frequency Hopping

Spatial processing techniques

Allocation of channels of OFDM systems

Details of Linear Filters and Decision Feedback Equalisers

Sequence estimation techniques, including multi user sequence estimation

Correlative coding in synchronous or start-stop systems

OFDM modulation techniques

OFDM frequency synchronisation techniques

Power management

Local resource allocation of wireless systems

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

Cell search in CDMA systems

Interference aspects in CDMA systems

Broadcast communication

Modulated-carrier systems

Telephonic Communication

Processing access restriction or access information

Discovery of network devices for network data management

Special rules of classification within this group

Additional information is classified with the corresponding CPC codes. Classification of additional information is compulsory.

Code division multiplex systems (for frequency hopping H04B 1/713)
Definition statement
This group covers:

Code division multiplexing techniques which are related to the division of the communication medium according to codes.

Aspects that are covered include types of codes, generation of codes and allocation of codes to channels.

Relationship between large subject matter areas

With regard to spread-spectrum techniques, the borderline between H04J 13/00 and H04B 1/69 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).

Documents classified in H04J 13/00 containing aspects of spectral spreading of interest for search, may also be classified in group H04B 1/69.

With regard to systems that use frequency hopping as a means to divide the communication medium, it has been agreed that that frequency hopping is excluded from H04J 13/00 even if it is used within the context of multiple access. Because the concepts dealt with in H04J 13/00 do not have relevance for FH-CDMA even though frequency hopping can be used for CDMA (i.e. FH-CDMA), this subject-matter is exclusively classified in H04B 1/713.

References relevant to classification in this group
This group does not cover:

Details of the signal processing which are covered by systems that use frequency hopping as a means to divide the communication medium

MC-CDMA

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

Implementation of the spread-spectrum technique

Special rules of classification within this group

Additional information is classified with the corresponding CPC codes. Classification of additional information is compulsory.

When classifying in this group, any aspect of spread spectrum techniques not specific to frequency hopping, and which is considered to represent information of interest for search, may also be classified in group H04B 1/69.

Synonyms and Keywords

In patent documents the following abbreviations are often used:

CDMA

Code Division Multiple Access

MC-CDMA

Multi-carrier Code Division Multiple Access

OVSF

Orthogonal variable spreading factor

Optical multiplex systems (optical coupling, mixing or splitting, per se G02B)
References relevant to classification in this group
This group does not cover:

Optical devices per se

Laser, amplifier per se

Electrical multiplex systems

Optical switching per se

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

Optical coupling devices, e.g. optical fibres, optical gratings

Optical integrated multiplexers and demultiplexers devices, e.g. AWG, optical interferometers

Optical coupling with wavelength selective means

Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating, or modulating; Non-linear optics

Demodulating light; Transferring the modulation of modulated light; Frequency-changing of light

Optical Transmission

Electrical Time-division multiplex systems

{Coherencemultiplexing}
Definition statement
This subgroup covers:

Coherence Multiplex for data transmission

References relevant to classification in this group
This subgroup does not cover:

Sensor systems

Coherent homodyne or heterodyne systems

{Optical Code Multiplex}
Definition statement
This subgroup covers:

Optical code division multiplexing systems

References relevant to classification in this group
This subgroup does not cover:

Electrical code division multiplexing

{Orthogonal Optical Code Multiplex}
Definition statement
This subgroup covers:

Orthogonal optical code division multiplexing systems

References relevant to classification in this group
This subgroup does not cover:

Electrical orthogonal multiplexing systems

Wavelength-division multiplex systems
Definition statement
This subgroup covers:

Wavelength division multiplex systems, in general, as well as WDM equipment terminal, e.g. WDM sources and WDM receivers.

{Add-and-drop multiplexing}
Definition statement
This subgroup covers:

Optical add and drop multiplexing systems for WDM systems

Synonyms and Keywords

In patent documents the following abbreviations are often used:

OADM

Optical Add and Drop multiplexing

{Arrangements therefor}
Definition statement
This subgroup covers:

Internal arrangements details of OADM for WDM systems

{Broadcast and select arrangements, e.g. with an optical splitter at the input before adding or dropping}
Definition statement
This subgroup covers:

OADM arrangements that first broadcast the input signals, typically implemented with an optical splitter at the input of the OADM, and then select among the signals before they are output.

{Select and combine arrangements, e.g. with an optical combiner at the output after adding or dropping}
Definition statement
This subgroup covers:

OADM arrangements that first selects among the input signals at the input of the OADM and then combines the signals before they are output, typically implemented with an optical combiner at the output of the OADM

{Express channels arrangements}
Definition statement
This subgroup covers:

OADM arrangements that allow express channels to be directly brought from the input of the OADM to the input of the OADM, typically for minimising the insertion losses incurred by those channels.

{Interleaved arrangements}
Definition statement
This subgroup covers:

OADM arrangements that include multiplexing and/or demultiplexing using interleavers, e.g. processing the odd and even WDM channels separately.

{Multi-stage arrangements, e.g. by cascading multiplexers or demultiplexers}
Definition statement
This subgroup covers:

OADM arrangements where multiplexing and/or demultiplexing are implemented by a cascading of multiple stages.

{Reconfigurable arrangements, e.g. reconfigurable optical add/drop multiplexers [ROADM] or tunable optical add/drop multiplexers [TOADM]}
Definition statement
This subgroup covers:

Reconfigurable or tuneable OADM arrangements where the optical channels that are actually added or dropped can be changed during the operation of the OADM.

{using optical switches or wavelength selective switches [WSS]}
Definition statement
This subgroup covers:

OADM arrangements where the reconfiguration is accomplish by using optical switches or wavelength selective switches.

{Groups of channels or wave bands arrangements}
Definition statement
This subgroup covers:

OADM arrangements where the groups of channel or wave bands are processed together.

{Architecture aspects}
Definition statement
This subgroup covers:

Architectures aspects of OADM in WDM systems in terms of how they relate to the WDM networks where they are in.

{Bidirectional architectures}
Definition statement
This subgroup covers:

OADM architectures that are prepared to be used in bidirectional networks, meaning that the ports of the OADM are input and output ports at the same time and consequently the fibres connected at those ports transmit optical WDM signals in both directions.

{Multi-degree architectures, e.g. having a connection degree greater than two}
Definition statement
This subgroup covers:

OADM architectures that have more than one input and/or more than one output (the degree of a node in a network is defined as the number of input plus output ports of such node).

{Modular or upgradable architectures}
Definition statement
This subgroup covers:

OADM architectures constituted by modules that are repeated to increase the capabilities of the node, typically to upgrade the number of channels that can be added or dropped.

{For interconnection of WDM optical networks}
Definition statement
This subgroup covers:

OADM architectures that are used for interconnecting different WDM networks, e.g. interconnected rings.

{Power control, e.g. to keep the total optical power constant}
Definition statement
This subgroup covers:

Power control in a WDM system. Subject covers equalizing power of the different wavelengths, e.g. to keep the total optical power constant or to control the optical power per channel in a WDM system so as to maintain constant a particular performance related characteristic. Also covers control of power transients due to add and drop wavelengths, wavelength switching, e.g. caused by protection switching, or wavelength re-allocation.

{Conversion to or from optical TDM}
Definition statement
This subgroup covers:

Conversion from WDM signals into OTDM or vice versa to facilitate the multiplexing or demultiplexing of optical channels.

{Irregular wavelength spacing, e.g. to accomodate interference to all wavelengths}
Definition statement
This subgroup covers:

WDM irregular allocation plans, typically to overcome non-linear effects or to accommodate optical channels of different bit rate. This group covers also regular schemes in which carriers remain unused, e.g. to avoid interference.

{Fixed carrier allocation, e.g. according to service}
Definition statement
This subgroup covers:

Fixed carrier allocation according to service or for a particular use, e.g. dummy channels to keep the power constant.

{Operation, administration, maintenance or provisioning [OAMP] of WDM networks, e.g. media access, routing or wavelength allocation}
Definition statement
This subgroup covers:

Wavelength allocation and assignment for WDM and the application of management to WDM networks. It covers routing, e.g. use of tables for wavelength routing, and wavelength allocation algorithms, dynamic allocation of wavelengths and use of a dedicated wavelength for OAM, e.g. optical service channel, and pilot tones for OAM. It also covers optical channel and optical multiplex identification and labelling, optical signalling in WDM networks and WDM networks restoration (in network restoration, as opposed to network protection, all available resources in the network are considered when looking for a new path to be established).

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

Monitoring of optical transmission parameters in general

{WDM optical network architectures}
Definition statement
This subgroup covers:

WDM optical networks defined by the type of interconnection between WDM nodes

{WDM point-to-point architectures}
Definition statement
This subgroup covers:

WDM systems using a point to point network connection between two WDM nodes.

{WDM bus architectures}
Definition statement
This subgroup covers:

Multiple WDM nodes connected to two adjacent WDM nodes, except for the two nodes constituting the bus head-end, and using a common optical fibre supporting a WDM signal.

{WDM tree architectures}
Definition statement
This subgroup covers:

A common WDM node is connected via multiple fibres to a multiplicity of other WDM nodes. It also covers the case of star networks, where multiple WDM nodes are interconnected to other WDM nodes using multiple optical fibres each supporting a WDM signal, typically using a star coupler.

{WDM ring architectures}
Definition statement
This subgroup covers:

WDM architecture where all WDM nodes are connected to two adjacent nodes using a common optical fibre supporting a WDM signal.

{WDM mesh architectures}
Definition statement
This subgroup covers:

WDM architecture where each WDM node is typically connected to every other node using multiple optical fibres, each supporting a WDM signal.

{WDM hierarchical architectures}
Definition statement
This subgroup covers:

WDM networks where different layers of interconnection between the different WDM nodes. Each layer can be of the same type of network architecture or of different types.

{Protection in WDM systems}
Definition statement
This subgroup covers:

Protection aspects in WDM systems, typically switching from a protected resource to a protection resource when a failure occurs. As opposed to network restoration, network protection considers only resources that have a priori been labelled as protection resources.

{Optical multiplex section protection}
Definition statement
This subgroup covers:

Protection is carried out at the level of the whole WDM multiplex.

{Dedicated protection at the optical multiplex section (1+1)}
Definition statement
This subgroup covers:

A WDM multiplex is duplicated and transmitted simultaneously using two WDM multiplex signals. The selection of which WDM signal to receive is done at the WDM level and at the receiver end, typically without considering any specific signalling from the transmitter end.

{Shared protection at the optical multiplex section (1:1, n:m)}
Definition statement
This subgroup covers:

A WDM multiplex is transmitted using working resources and in case that a failure occurs, then the WDM multiplex is switched to the protection resource, typically shared by different nodes. At the receiver end the WDM signal coming via the protection resource is selected, typically this mechanism involves switching or bridging at both transmitter and receiver ends at the WDM multiplex level any requires some signalling between transmitter and receiver ends. The protection WDM multiplex can be used by low priority traffic until protection takes place.

{Dedicated protection at the optical channel (1+1)}
Definition statement
This subgroup covers:

A WDM channel is duplicated and transmitted simultaneously using two WDM channels. The selection of which WDM channel to receive is done at the channel level and at the receiver end, typically without considering any specific messaging from the transmitter end.

{Shared protection at the optical channel (1:1, n:m)}
Definition statement
This subgroup covers:

WDM channels are transmitted using working resources and in case that a failure occurs, then the WDM channel is switched to the protection resource, typically shared by different WDM channels. At the receiver end the WDM signal coming via the protection resource is selected, typically this mechanism involves switching or bridging at both transmitter and receiver ends at the channel level any requires some signalling between transmitter and receiver ends. The protection channels can be used by low priority traffic until protection takes place.

{Optical equipment protection}
Definition statement
This subgroup covers:

WDM is duplicated to protect the equipment against internal faults.

{with sub-carrier multiplexing [SCM]}
Definition statement
This subgroup covers:

Sub-carrier multiplexing system, e.g. for CATV.

Mode multiplex systems
Definition statement
This subgroup covers:

Systems where the different modes of transmission in the optical fibres are used to multiplex different channels of information.

Polarisation multiplex systems
Definition statement
This subgroup covers:

System where the different states of polarisation of the light are used to multiplex different channels of information.

Time-division multiplex systems
Definition statement
This subgroup covers:

Systems using optical time division multiplexing (OTDM). Time multiplexing of optical pulses.

References relevant to classification in this group
This subgroup does not cover:

Optical synchronisation

{Add and drop multiplexing}
Definition statement
This subgroup covers:

Optical add and drop multiplexing systems for OTDM systems.

{Medium access (H04J 3/16 takes precedence)}
Definition statement
This subgroup covers:

Medium access in OTDM systems.

Special rules of classification within this group

H04J 3/16 takes precedence

This page is owned by Office of Patent Classification.
Last Modified: 10/11/2013