Transmission of signals having been supplied in digital form, e.g. data transmission, telegraphic communication, or methods or arrangements for monitoring.

As the scope of H04L covers a diversity of subject matter, the user is referred to the definitions for the main groups of H04L. The following list is intended to assist the user.

Systems:

Arrangements of general application:

Codes for error detection or error correction, i.e. theoretical code construction and coding circuit architecture designs are classified in H04M 13/00; the application of such codes in transmission systems is covered by H04L 1/00 subgroups.

Classification into the main group H04L 1/00 itself should be avoided and instead its relevant subgroups should be used by identifying the particular error technique used. If no other group can be assigned for error control applicable to transmission systems, then it may be assigned to this main group.

In addition an Indexing Code can be given under H04L 2001/0092 for network topology, which is of interest to H04L 1/00.

General link adaptation techniques, including power control for non-radio links, and handshaking procedures involving link adaptation.

Adaptive techniques are covered by specific subgroups under H04L 1/0001 unless they are other aspects, e.g. frequency hopping, adaptive slew rate, adaptive interleaving, DSL power back-off.

ARQ adaptive retransmission aspects should be classified mainly under the H04L 1/16, H04L 1/18 subgroups.

The end raw rate at which bits are transmitted through the channel, e.g. after encoding.

Also adaptive CDMA and direct sequence spread spectrum is covered by this subgroup.

Adaptation of modulation is classified in H04L 1/0003 even if line bitrate remains constant, e.g. switch-over from 8-QAM to 8-PSK.

Adaptation of modulation and coding schemes (MCS/AMR) are classifed also under H04L 1/0009.

Particular ARQ physical mapping aspects should be classified mainly under the H04L 1/1893 or H04L 1/1861.

If the adaptation concerns both control and payload then only H04L 1/0003 is used.

If the adaptation concerns both control and payload then only H04L 1/0003 is used.

This group covers adaptive formatting aspects, e.g. adaptive slot allocation, or adaptive packet formats other than coding.

Frame or packet length adaptation at lower OSI layers.

Also switching between uncoded and coded modes.

ARQ redundancy schemes are classified under the subgroups of H04L 1/1812.

Repetition coding per se is classified also in H04L 1/08; other types of codes under the subgroups of H04L 1/004.

Adaptation of space-time coded transmissions, in particular modification of the space-time matrix is classified under the subgroups of H04L 1/0618.

Adaptation of modulation and coding schemes (MCS) are classified also under H04L 1/0003.

If the adaptation concerns both control and payload then only H04L 1/0009 is used.

If the adaptation concerns both control and payload then only H04L 1/0009 is used.

The coding rate must be adapted in rate matching operations for link adaptation.

Use of multiple puncturing patterns is covered by H04L 1/0068; general rate matching without regard to link quality is covered H04L 1/0067.

This class is used for special adaptation strategies for adopting a transmission mode, e.g. select an MCS mode, which do not fall within its subclasses. For example, use of special utility or cost functions is classified here.

This class is used for uncommon memory structures, e.g. switching tables, look-up tables and the like.

Guarantee of QoS and interaction of QoS parameters of higher layers and of the physical and data link layers. Adaptation takes into account types of data, e.g. real-time data.

Latency aspects per se should be classified only here and not in any higher subgroups.

Special statistical approaches for mode-switching including future system or channel conditions mode-switching decision, e.g. calculation of confidence intervals or sequential testing for early decisions.

Algorithms explicitly using Markov chains.

Algorithms in which the adaptation thresholds themselves are adapted according to e.g. state of transmitter or receiver.

E.g. during the negotiation phase.

Signaling conveying adaptation commands or channel quality indicators, scheduling and formatting aspects thereof.

The appropriate sub-group should be assigned and the main sub-class be avoided.

Signal quality per se is classified in H04L 1/20.

Both for forward and reverse direction.

How the actual signaling is conveyed.

The appropriate sub-group should be assigned and the main sub-class be avoided. Mere error control coding of signaling is not assigned by this class.

Protection of CQI (channel quality indicator) or TFCI (or transport format combination indicator) with error control is classified in H04L 1/0072.

The class should not be assigned if the commands include an acknowledgement indication.

Piggybacked acknowledgements or transmission of command with acknowledgement indication is classified in H04L 1/1664 , H04L 1/1671 .

Implicit signaling is not classified here either but in relevant subgroups under H04L 1/0033, H04L 1/0036.

Specific parameters of transmitter aspects, i.e. circuit or computer-based implementation, e.g. amplifying circuit, etc. according to channel quality.

The class should be assigned only if its subclass is not relevant.

Mode switching based on ACK/NACK indications (ACK/NACKs are used as derivative channel quality indicators).

Specific parameters of receiver aspects, i.e. circuit or computer-based implementation, e.g. demodulator, etc. according to channel quality.

The class should be assigned only if any subclass is not relevant.

Code rate detection of code type detection are classified in H04L 1/0046.

Application of FEC codes in transmission systems.

Adaptive FEC is classified in H04L 1/0009.

Space-time/frequency coding/decoding is classified in H04L 1/0618, H04L 1/0606

Repetition coding is classified in H04L 1/08.

Hybrid ARQ redundancy schemes (ARQ combined with FEC) are classified under the subgroups of H04L 1/1812.

Hardware circuit design or functional computer-implemented arrangements.

The FEC encoding operation is specifically designed by taking into account other signal generation operations (e.g. properties of the modulator or local oscillator).

Classes H04L 1/0058, H04L 1/006, H04L 1/0067 are considered first before giving the above subclass.

Hardware circuit design or functional computer-implemented arrangements.

Adaptive code rate or code type detection is classified in H04L 1/0038.

Packet format detection is classified in H04L 1/0091.

The FEC encoding operation is specifically designed by taking into account other signal generation operations (e.g. properties of the demodulator, sensitivity to errors of later signal processing stages).

Repetition coding is classified in H04L 1/08.

Block codes such as Reed-Solomon codes, LDPC codes, etc.

Classes H04L 1/0061 and H04L 1/0064 take precedence.

Adaptive rate matching according to link quality is covered by H04L 1/0013.

Repetition coding is covered by H04L 1/08.

Puncturing patterns (adaptive and non-adaptive).

Unequal error protection formatting arrangements is covered by H04L 1/0086.

General aspects of UEP is covered by old Indexing Code H04L 2001/0098.

Use of interleavers, which interchange data elements in the time domain in transmission systems.

Diversity arrangements, see H04L 1/02.

Turbo coding interleavers are not classified here since they are considered integral part of the turbo coder.

Non-adaptive formatting arrangements is covered by H04L 1/0086.

Adaptive FEC for control data is covered by H04L 1/001.

Details of FEC of feedback such as CQI, ACK.

ACK/NACK repetition coding is covered by H04L 1/1858.

Details concerning transmission of FEC related parameters related to signaling information.

Transmission of signaling for adaptation purposes is covered by H04L 1/0023.

Details of error control at intermediate node, e.g. exclusive OR signal coding or stronger re-encoding arrangements at relay.

Coding in both space and time is covered by H04L 1/0618.

Topology aspect is covered by H04L 2001/0097.

Adaptive formatting is covered by H04L 1/0006.

FEC coding, e.g. CRC is covered by H04L 1/004.

Acknowledgement formats is covered by H04L 1/16 and H04L 1/1607.

Arrangements for preventing errors in the return channel, e.g. handshaking are covered by Indexing Code H04L 2001/125.

UEP for coding is covered by H04L 1/007.

General aspects of UEP is covered by old Indexing Code H04L 2001/0098.

Hardware circuit design or functional computer-implemented functions.

Hardware circuit design or functional computer-implemented functions.

Code rate detection is covered by H04L 1/0046.

Space-time coding techniques (i.e. for radio) are classified beneath, see relevant subclasses.

In addition, non-radio diversity arrangements involving redundant, simultaneous signal transmission.

The class should be assigned only if any subclass is not applicable.

Arrangements with constellation plane partitioning taking space-time diversity into account in equivalence to trellis coded modulation in non-diversity schemes.

Hardware circuit design or functional computer-implemented arrangement.

Hardware circuit design or functional computer-implemented arrangement.

Transmitted space-time matrices that are considered each as one block coded entity.

For symbol block coding prior to space-time matrix transmission H04L 1/0057.

For symbol convolutional coding prior to space-time matrix transmission H04L 1/0059.

Semi-orthogonal space-time matrix arrangements to increase the transmission rate.

Signaling pertaining to the space-time matrix.

For normal adaptive transmissions H04L 1/0001.

Arrangements for preventing errors in the return channel, e.g. handshaking are covered also by Indexing Code H04L 2001/125.

Explicit indications of ranges of acknowledged data packets, e.g. sequence numbers SN:5 to 16, 23 to 25. Rules may be involved to further compress the sequence number or other signaling.

Bitmaps where list acknowledgements appear as 0s and 1s are in H04L 1/1614.

Constellation / mapping rearrangements due to retransmissions, and mapping of receiver-initiated transmissions to resource blocks.

Acknowledgement signaling per se is classified in H04L 1/1607.

Constellation / mapping rearrangements due to retransmissions, and mapping of transmitter-initiated transmissions to resource blocks.

Frame indication per se H04L 1/0082.

E.g. redundant stand-by links.

Testing correct operation.

Echo systems are in H04L 1/14.

Arrangements for dividing a transmission path, for allocating sub-channels, signalling for multiple channel indication and duplex/half-duplex systems.

This group works at the physical layer, for wireless or line communications (ADSL).

The arrangements for dividing the transmission path involve multiple access techniques capable of supporting multiple users by sharing the available system resources. Examples of such multiple-access techniques include Frequency Division Multiple Access (FDMA) systems, Orthogonal FDMA (OFDMA) systems, multicarrier Code Division Multiple Access (multicarrier CDMA) systems, i.e. any combination of multicarrier signals and a code division.

An OFDM system may implement a radio technology such as Evolved UTRA (E-UTRA), Ultra Mobile Broadband (UMB), IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMax), IEEE 802.20, Flash-OFDM, etc.

3GPP Long Term Evolution (LTE) is a release of UMTS that uses E-UTRA, which employs OFDM on the downlink and SC-FDMA on the uplink.

When the multiple access scheme relies on the use of multicarrier signals, and if what is important is how the signal is modulated/demodulated, or "hardware" aspects in the transmitter or the receiver to produce or recover (like synchronisation) such signal or aspects related to the peak power reduction, then the classes under H04L 27/2601 are relevant. Otherwise, to indicate that the signal involved is, for example, an OFDM signal, then the class under H04L 5/0007 is used instead.

Subgroups H04L 5/22, H04L 5/225, H04L 5/24, H04L 5/245, H04L 5/26 are inactive. The classification should be done in H04J 3/00.

This group answers the question "How is the transmission path split up?". Since the signals are digital, it is considered that there is always a time dimension, and thus, the minimum number of dimensions is two.

The case of an access method allowing multiple users to share the same frequency band by subdividing the band into orthogonal frequency channels. If the frequencies are not orthogonal then the group H04L 5/0005 should be given instead.

Frequency hopping for multicarrier signals, SC-FDMA and IFDMA are also covered by H04L 5/0007.

This group should contain the cases of spreading codes in the time domain, where chips of the code are applied in sequence, once at a time, to each of the subcarriers.

This group should contain the cases of spreading codes in the time domain, where each frequency sees the same spreading code (for example, multicarrier DS-CDMA).

This group should contain the cases of spreading codes in the frequency domain. Each chip of the spreading code is transmitted through a different subcarrier.

The combination OFDM and MIMO; or frequency reuse.

Changes from time-frequency to time-frequency-space, for example.

Sub-channels are what the path is split up into according to H04L 5/0001.

This group answers the question of "Who makes the allocation?". Cooperative allocation (for example in CoMP systems or cognitive radio systems or when dealing with ICIC, Inter-cell Interference Cancellation) is classified under H04L 5/0032, which implies a plurality of base stations that cooperates or exchanges information to perform the allocation.

The allocation for plurality of users, thus, to indicate which user gets what.

Single user case, what a single user does with its resources.

Allocation of payload or data in the available subchannels.

The case of having different modulations in the different subcarriers.

Pilot or reference signal patterns.

Where (for example, in the time-frequency grid) to send ACK/NacK signals, CQI (Channel Quality Indicator) signals and in general any control signalling which is not a known signal to the receiver (pilots, sounding reference symbols, SRS, or synchronisation signals are known to the receiver and they are classified under H04L 5/0048). In order words, which physical resources are used for signalling.

According to QoS (Quality of Service) is also classified here.

The subgroups answer the question "How often the allocation is updated?". For Persistent allocation (if the update is due to channel conditions change, then H04L 5/0085), fixed allocation (H04L 5/008).

How the channel is divided, for instance, for indicating that the whole frequency band is divided into a certain number of subcarriers, or that the base station informs the mobile how according to H04L 5/0001 the channel is divided. Both uplink or downlink.

The signalling of the Content of the allocation. For example, which carriers are allocated, how many bits are allocated to each subcarrier, etc. Both uplink or downlink.

FDM. Different data signals for transmission on a single communications channel are multiplexed, whereby each signal (single carrier) is assigned a non-overlapping frequency range within the main channel.

ADSL systems. FDD systems.

For example, Zipper (a time-synchronised frequency division duplex implementation of discrete multi-tone, DMT, modulation).

Bit or symbol synchronization of digital receivers.

Synchronization of packets or bursts in radio or optical transmission.

Bit or symbol synchronization of digital recording system, if this system is not specially adapted to recording.

Bit or symbol synchronization of in a memory system, if the system is not specially adapted to memorizing.

Calibration of synchronizers.

H04L 7/0075 and H04L 7/10 take precedence.

Source synchronous systems.

Transmission of clock on a dedicated channel, line or link.

Clockwise and counterclockwise clock distribution.

Clock distributed as sinus or standing wave

The received clock is compared with a local clock of the receiver. The comparison controls the synchronisation.

Synchronization of received clock and local clock by PLL or DLL, H03L 7/00 takes precedence.

Correction of the synchronisation error in receiver or transmitter

Applies also to clock interpolation in the transmitter for the purpose of synchronisation.

If clock interpolation for synchronization is performed at the transmitter, also H04L 7/0091 should be applied.

Covers interpolation of received clock of source synchronous systems.

Covers interpolation of local, e.g. interpolation among several local phase shifted clocks.

Delay of other signals than clock or information data, e.g. delay of additional signalling among transmitter and receiver

Delay of a received clock signal, e.g. a clock signal received by via a clock line. Delay of a clock signal in the receiver or in the transmitter

Delay of a received data signal.

Delay of the data signal in the transmitter, e.g. the transmitter receiver an information regarding the synchronisation error.

An elastic buffer or FIFO is used to compensate the synchronisation error

Synchronization by sample processing, e.g. Wave-Difference-Method.

Determination of gradients.

Synchronization by determining maximum of first derivation of sampled waveform as estimate of zero or threshold crossing: H04L 7/0334 takes precedence.

Synchronization by determining zero of the second derivation of the sampled waveform: H04L 7/007 takes precedence.

Detection of error by monitoring of equalizer taps, e.g. center tap tracking.

Error of the data decision, e.g. subtracting input from output of the decision device, to control synchronisation.

Timing Function: Combining of the error with input signals or not decided symbols.

Synchronization using properties of line codes like Manchester, PPM or RZ. Synchronization using properties of block codes as 4b/5b.

Also covers violations of such coding rules to transmit synch information.

Covers SCCL detectors, Sample Correlate Choose Largest.

This group covers clock synchronisation using at least one optical device that is essential for the functioning of the synchronizer. A synchronizer used in an optical transmission system but using exclusively electrical means for synchronization has to be classified in the other respective groups of H04L 7/00.

Details in the construction of the synchronizer in the receiver, e.g. adaption of signals among various parts of the receiver; constructional details

This class can be applied additionally to any other class in H04L 7/00

The transmitter is adapted to the synchronisation process, e.g. the receiver provides signalling concerning the synchronisation error to the transmitter.

The error is based on the received code signal.

Synchronisation is achieved by intermediate buffering, multiple phases and/or intermediate clocks. Synchronisation of interfaces or among equipments having different clock phases or clock domains

A spectral line at clock rate of NRZ data can be generated, e.g. by squaring or differentiating and subsequent filtering, e.g. SAW filter or FFT.

Covers detection of synchronization error by measuring a spectral property of a known code signal, e.g. UW or dotting.

PLL with edge detectors, and at least partial analog loop elements, e.g. VCO;

Edge detectors like HOGGE type or ALEXANDER type.

The term "control" does not limit the scope to "tracking" or "closed loop" but includes also feed-forward control.

Initialization of the PLL is further classified in H04L 7/0004.

Special adaptions for preventing loss of synchronization or loss of lock are also classified in H04L 7/0083

This group also covers detection of the synchronization error by measuring the length of the received bits, e.g. by oversampling and sample processing of binary samples.

Covers correction of the synchronization error by add/subtract logic.

Digital implementation of DTTL.

H04L 7/0337 takes precedence

For the pulse length measurement is done by analogue means, e.g. integrate/dump, H04L 7/0332 takes precedence.

Analogue techniques of determining the synchronization error by measuring a pulse length esp. for line codes with a transition in the bit cell like Manchester coding or NRZI.

Analogue implementation of DTTL.

Samples processed of more than binary values, if the processing evaluates a symbol transition.

First and also higher order derivatives of the sampled waveform, if a transition is detected.

Statistical analysis of the samples, e.g. histogram.

The selected phase is looped back into the phase error detection.

Comparison of the actually selected phase with a previously selected phase is not feed backward under this definition. Such a comparison functions as a filter, e.g. for reducing large phase jumps or jitter.

Phase aligners in switches of communication networks or packet receivers.

Phase aligners for electronic displays, e.g. DVI or HDMI interfaces, if the invention is not specially adapted to such a display, e.g. using special signals.

Synchronization by phase picking.

Covers also interpolation among different clock phases.

Selection in an open loop control: H04L 7/0338 takes precedence.

Documents that only refer to the use of a synchronisation signal, e.g. UW, without further specifying their structure or the way it is detected.

Comma free codes.

Forbidden code words.

Synchronization signals in TDM frames: H04J 3/0602.

Special synchronisation signals, e.g. midambles or variable UW: H04L 7/041.

Code construction.

Theory of codes used for synchronization.

Training sequences or midambles.

Variable Synchronization codes, e.g. according to synchronization state or for transmission of low rate data like signalling.

Cross-correlation or auto-correlation.

Peak detection, threshold control at the output of the correlator.

Windowing around expected location of the synchronization information, H04L 7/08 takes precedence.

Synchronization state machines or diagrams for acquisition, search, verify or lock, H04L 7/10 takes precedence.

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, 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 is active and shifts, then the document is classified here.

Synchronization by using a start bit or start/stop bit, incl. the use of the transition of the stop bit to the adjacent start bit.

Covers single synch pulses with differing length from information pulse length.

Complex phase reversals used for symbol synchronization in digital demodulators.

Use of Error Correcting or detecting codes for alignment of packets or ATM cells.

H04L as such is directed to transmission of digital signals, meaninig the information is transmitted in binary form. Synchronisation signals classified here have a different form than the information signal, e.g. a higher amplitude, a longer pulse width.

Synchronisation information is not transmitted in series with the information signals, i.e. as this is the case for packet headers. Instead, a synchronisation signal is provided by modulation of the information signal, e.g. by an amplitude modulation using a low modulation index

Detection by windowing around the expected recurring location of the synchronization information.

Variable synchronization information for initialisation.

During initialisation, variable means of the detector, e.g. low detection threshold and increasing threshold when synchronisation information is detected.

Signalling or handshaking for initialisation.

Other means for synchronisation, H04L 7/0004 takes precedence.

Start/Stop bit detection, H04L 7/044 takes precedence.

Dotting detection, H04L 7/046 takes precedence.

Cryptographic mechanisms including cryptographic protocols and cryptographic algorithms, whereby a cryptographic protocol is a distributed cryptographic algorithm defined by a sequence of steps precisely specifying the actions required of two or more entities to achieve specific security objectives (e.g. cryptographic protocol for key agreement), and whereby a cryptographic algorithm is specifying the steps followed by a single entity to achieve specific security objectives (e.g. cryptographic algorithm for symmetric key encryption).

H04L 9/00 focuses on cryptographic mechanisms such as encryption schemes, digital signatures, hash functions, random number generation, key management, said cryptographic mechanisms providing information security such as privacy or confidentiality, data integrity, message authentication, entity authentication, authorization, validation, certification, time-stamping.

H04L 9/00 covers also Financial cryptography.

H04L 9/00 covers also countermeasures against attacks on cryptographic mechanisms.

H04L 63/00 Networking architectures and network communication protocols for securing the traffic flowing through data packet networks and providing secure exchanges among applications communicating through data packet networks.

H04L 63/00 covers specifically network architectures and network communication protocols for supporting:

H04L 63/00 focuses on network architectures (i.e. network entities involved, roles played by these entities) and network communication protocols (i.e. how these network entities communicate) regardless of the specifics of the cryptographic mechanism used.

G06F 21/00 Security arrangements for protecting computers or computer systems against unauthorised activity, where the cryptographic mechanisms are not relevant.

The classification of additional information is not seen as mandatory; it will be up to the classifier to decide whether the additional information should be classified or not (is pertinent or not). If considered pertinent, it should be classified.

Indexing Codes are to be used as orthogonal cross.

Invention may be assign more than one code if necessary.

Subject-matter directed to protection and enhancement of cryptographic mechanisms against cryptographic attacks as replay, brute force or birthday attacks.

Subject-matter directed to authentication infrastructures based on public-key cryptography.

Subject-matter directed to homomorphic cryptographic mechanisms.

Subject-matter directed to symmetric-key encryption as DES, (i.e. same keys are used for encryption and decryption), hash functions as MD5, stream ciphers as RC4 or pseudorandom sequence generation.

Encrypting groups of characters of a plain text message using a fixed encryption transformation.

Subject-matter directed to cryptographic mechanisms as Feistel based algorithms, DES, FEAL, IDEA or KASUMI algorithms.

Ciphers composed of a number of stages/rounds each involving linear or nonlinear transformations, as AES algorithm.

Subject-matter directed to modes of operation for block ciphers, as CBC (cipher block chaining), CFB (cipher feedback) or OFB (output feedback).

The design, structure or function of cryptographic hash functions, as message authentication codes (MAC) or modification detection codes (MDC).

Subject-matter directed to synchronous or asynchronous stream ciphers (i.e. encrypting individual characters of a plaintext message one at a time, using an encryption transformation which varies with time), and to key-stream generation.

Subject-matter directed to encryption (combination) of data with (pseudo)random key-stream.

Subject-matter directed to the design, structure, functionality or mechanism of pseudorandom sequence generators.

Subject-matter directed to the design, structure, functionality or mechanism of pseudorandom sequence generators using non-linear functions.

Subject-matter directed to management of secret material including generation, distribution, sharing, updating of cryptographic keys or passwords.

Subject-matter directed to processes or cryptographic protocols whereby a secret (as cryptographic key, password) becomes available to two or more parties, for subsequent cryptographic use.

Subject-matter directed to key establishment techniques where one party creates or otherwise obtains a secret value, and securely transfers it to other(s).

Subject-matter directed to managing (e.g. transport, distribute) cryptographic keys for securing information by using key encryption keys. Before transmission/distribution the cryptographic keys are encrypted with the key encryption keys. Passwords may be also used as cryptographic keys for encryption.

Subject-matter directed to managing (e.g. transport, distribute) cryptographic keys for securing information by using public key encryption. The cryptographic key is either encrypted with a private key (i.e. signature) and decrypted with the corresponding public key, or it is encrypted with a public key and decrypted with the corresponding private key. A public key infrastructure (PKI) may be also used wherein the public keys are certified.

Subject-matter directed to exchanging/distributing cryptographic keys between communication partners by using distinctive intermediate devices or communication paths/channels. The paths/channels may be out-of-band channels or virtual paths.

Subject-matter directed to centralized key units as key distribution center (KDC), trusted third party (TTP) or key translation center (KTC) that are used for cryptographic key management.

Examples: "Handbook of Applied Cryptography" by A.J. Menezes, P.C. van Oorschot, S. A. Vanstone, 5th Edition, June 2001, Pages 546-549.

Subject-matter directed to secure mechanisms for distributing cryptographic group keys to different communication entities. To ensure the security of a multi-party communication, the multi-party communication messages are transmitted in encrypted form. The group key used for encrypting and decrypting the multi-party communication messages are only known to the group members, so as to ensure that the encrypted messages may be interpreted only by the group members.

Subject-matter directed to mechanisms for distributing cryptographic conference or group keys to different communication entities involving tree or hierarchical structures wherein the central key unit is the root and the group members are the leafs.

Subject-matter directed to key establishment techniques in which a shared key is derived by parties as a function of information contributed by, or associated with, each of these, ideally such that no party can predetermine the resulting value.

Subject-matter directed to key agreement protocols that allow users or entities to exchange public key values and from these values and knowledge of their own corresponding private keys, securely compute a shared key, allowing for further secure communication.

Examples: "Handbook of Applied Cryptography" by A.J. Menezes, P.C. van Oorschot, S. A. Vanstone, 5th Edition, June 2001, Pages 515-516.

Subject-matter directed to key agreement protocols providing user authentication or key authentication, to schemes as ElGamal, MTI, MQV or related protocols, to key agreement protocols using implicitly-certified keys, or to password-authenticated key agreement mechanisms as PAKE (password-authenticated key exchange), EKE (encrypted key exchange) or SPEKE (simple password exponential key exchange).

Examples: "Handbook of Applied Cryptography" by A.J. Menezes, P.C. van Oorschot, S. A. Vanstone, 5th Edition, June 2001, Pages 517-523.

Subject-matter directed to key agreement protocols involving IBE schemes (the public key of a user is the binary sequence corresponding to information identifying him in a non-ambiguous way).

Examples: "Handbook of Applied Cryptography" by A.J. Menezes, P.C. van Oorschot, S. A. Vanstone, 5th Edition, June 2001, Pages 561-562.

Subject-matter directed to distribution of a secret amongst a group of participants, each of which is allocated a share of the secret; the secret can be reconstructed only when a sufficient number of shares are combined together; individual shares are of no use on their own (threshold schemes).

Subject-matter directed to quantum key distribution (QKD), i.e. the process of using quantum communication to establish a shared key between two parties without a third party learning anything about that key, even if said third party can eavesdrop on all communication between said two parties.

Subject-matter directed to QKD involving additional nodes as quantum relays, repeaters, intermediate or remote nodes.

Subject-matter directed to reconciliation, error correction, privacy amplification, polarisation or phase coding for QKD systems.

Subject-matter directed to generation, derivation, calculation or extraction of cryptographic keys or passwords.

Subject-matter directed to derivation or generation of encryption keys from passwords.

Subject-matter directed to cryptographic key derivation or extraction involving user or device identifiers as serial number of a device, measurable physical characteristics provided by a device like a PUF (physical unclonable function), or biometrical information of a user.

Subject-matter directed to cryptographic mechanisms for cryptographic keys generation involving random numbers or seeds.

Subject-matter directed to cryptographic key derivation/generation using data regarding geographical position, time, relative or proximity position to other entities.

Subject-matter directed to mechanisms for cryptographic key generation / derivation using channel characteristics.

Subject-matter directed to cryptographic keys generation using secure crypto-processors as trusted platform modules, smartcards or hardware security modules.

Subject-matter relating to cryptographic techniques (as control vectors, key notarization) for restricting cryptographic keys to pre-authorized uses, to crypto-periods of keys (long-term, short-term, ephemeral keys), or to controlling encryption strength (export regulation for cryptographic algorithms).

Subject-matter relating to cryptographic keys revocation (compromised keys have to be revoked) or updating (old key is replaced by new key).

Subject-matter directed to cryptographic mechanisms for secret key escrow (user traffic is encrypted such that the session keys used for the encryption are available to properly authorized third parties under special circumstances), for secret key recovery (encrypted data have to be recovered following loss or destruction of keying material due to equipment failure or malicious activities), or for storing/restoring of secret keys (as backups).

Subject-matter directed to involving additional (portable) units (as TPM, smartcards) in the cryptographic mechanisms for escrow, recovery or storing of secret information.

Subject-matter directed to cryptographic mechanisms using a plurality of keys or algorithms (as hybrid encryption, i.e. combination of symmetric and public-key encryption) for providing information security.

Subject-matter directed to cryptographic mechanisms using a plurality of keys or algorithms changing dynamically or during operation.

Subject-matter directed to asymmetric-key or public key cryptography.

Subject-matter directed to the interaction between the intractability of several computational problems (as the quadratic residuosity problem) and the security of public-key cryptosystems, or to details relating to public-key parameters (as generators and elements of high order).

Subject-matter directed to public-key schemes based on the discrete logarithm problem.

Subject-matter directed to public-key schemes based on the integer factorization problem.

Subject-matter directed to polynomials generation in public-key schemes.

Subject-matter directed to pseudo-prime or prime number generation in public-key schemes.

Subject-matter directed to public-key schemes involving error correction codes.

Subject-matter directed to details of the algebraic or abelian varieties used in the public-key cryptographic schemes, as algebraic groups, rings, fields or elliptic curves.

Subject-matter directed to public-key schemes involving pairings or mappings, as identity based encryption (IBE) schemes.

Subject-matter directed to public-key schemes involving Lattices (e.g. vector spaces) or polynomial equations.

Subject-matter directed to cryptographic mechanisms for authentication or identification, including mechanisms (involving cryptographic primitives or data structures as signatures, certificates, credentials) for authorization, entity authentication, message authentication, data integrity, key authentication, non-repudiation, verification or proof of knowledge.

Subject-matter directed to cryptographic mechanisms for authentication between two devices involving a third device.

Subject-matter directed to cryptographic mechanisms for authentication using tickets or tokens (as Kerberos authentication protocols).

Examples: "Handbook of Applied Cryptography" by A.J. Menezes, P.C. van Oorschot, S. A. Vanstone, 5th Edition, June 2001, Pages 501-502.

Subject-matter directed to authentication involving the use of a plurality of channels, as for example the use of a wire channel and a wireless channel.

Subject-matter directed to identification mechanisms using knowledge proofs, as (NIZKP) non-interactive zero-knowledge proofs (Fiat-Shamir, Schnorr protocols).

Subject-matter directed to identification mechanisms using interactive zero-knowledge proofs.

Subject-matter directed to cryptographic mechanisms for authentication or authorization using predetermined codes as passwords, passphrases, personal identification numbers (PIN).

Subject-matter directed to authentication or authorization using predetermined codes, said predetermined codes comprising information which is sent for every authentication or authorization, as one-time-password, one-time-token or one-time-key.

Subject-matter directed to cryptographic mechanisms for identification or verification of an individual using biometrical data as fingerprint, voice or retina.

Subject-matter directed to cryptographic mechanisms for authentication or authorization involving hardware tokens like trusted platform module (TPM), smartcard, USB or software tokens.

Subject-matter directed to authentication mechanisms using cryptographic hash functions.

Subject-matter directed to authentication mechanisms involving modification detection codes (MDC's) as MD5, SHA or RIPEMD, also called non-keyed hash functions.

Subject-matter directed to authentication mechanisms involving message authentication codes (MAC's) as CBC-MAC or HMAC, also called keyed hash functions.

Subject-matter directed to authentication mechanisms involving digital signatures.

Subject-matter directed to authentication mechanisms involving RSA or related signature schemes, as the Rabin signature scheme.

Examples: "Handbook of Applied Cryptography" by A.J. Menezes, P.C. van Oorschot, S. A. Vanstone, 5th Edition, June 2001, Pages 433-447.

Subject-matter directed to authentication mechanisms involving DSA or related signature schemes, as elliptic curve digital signature algorithm ECDSA or ElGamal signature scheme.

Examples: "Handbook of Applied Cryptography" by A.J. Menezes, P.C. van Oorschot, S. A. Vanstone, 5th Edition, June 2001, Pages 452-462.

Subject-matter directed to authentication mechanisms using digital signatures where signers can establish groups such that each member of the group can produce signatures anonymously on behalf of the group.

Subject-matter directed to authentication mechanisms using signatures schemes in which the content of a message is disguised before it is signed.

Examples: "Handbook of Applied Cryptography" by A.J. Menezes, P.C. van Oorschot, S. A. Vanstone, 5th Edition, June 2001, Page 475.

Subject-matter directed to cryptographic mechanisms involving digital certificates as public key certificates or attribute certificates, or to public key infrastructure (PKI) based authentication/verification using certificates.

Examples: "Handbook of Applied Cryptography" by A.J. Menezes, P.C. van Oorschot, S. A. Vanstone, 5th Edition, June 2001, Pages 559-561.

Subject-matter directed to authentication mechanisms involving multiple certification authorities (CA) in public-key systems. Trust relationships between the CA's determine how certificates issued by one CA may be utilized or verified by entities certified by distinct CA's. Hierarchical trust models for certification and cross-certificates are also covered by this subgroup.

Examples: "Handbook of Applied Cryptography" by A.J. Menezes, P.C. van Oorschot, S. A. Vanstone, 5th Edition, June 2001, Pages 572-575.

Subject-matter directed to cryptographic mechanisms involving certificate generation, validation, registration, distribution (pull, push model) or revocation (certificate revocation list CRL).

Examples: "Handbook of Applied Cryptography" by A.J. Menezes, P.C. van Oorschot, S. A. Vanstone, 5th Edition, June 2001, Pages 576-577.

Subject-matter directed to cryptographic mechanisms comprising protocols where a verifier sends a claimant a challenge (usually a random value or a nonce) that the claimant combines with a shared secret (often by hashing the challenge and secret together) to generate a response that is sent to the verifier. The verifier knows the shared secret and can independently compute the response and compare it with the response generated by the claimant.

Examples: "Handbook of Applied Cryptography" by A.J. Menezes, P.C. van Oorschot, S. A. Vanstone, 5th Edition, June 2001, Pages 397-405.

Subject-matter directed to authentication between parties that may corroborate their identities to the other.

Subject-matter directed to authentication using PUF.

Subject-matter directed to cryptographic mechanisms for authentication involving time stamps or generation of timestamps.

Examples: "Handbook of Applied Cryptography" by A.J. Menezes, P.C. van Oorschot, S. A. Vanstone, 5th Edition, June 2001, Pages 581-583.

Subject-matter directed to cryptographic mechanisms involving interchanging in time bits or block of bits of the message.

Subject-matter directed to cryptographic mechanisms involving means for detecting characters not meant for transmission.

Subject-matter directed to cryptographic mechanisms involving encryption effected by mechanical apparatus, as rotating cams, switches or key-tape punchers.

Transfer of information having been supplied in digital form in data switching networks, e.g.

Systems characterised by network topology;

Systems in which paths are physically permanent during the communication, e.g. connection oriented communication, virtual circuits;

Systems in which the path identification data is included in each information unit, e.g. connectionless communication, datagram;

Hybrid switching systems;

Arrangements for connecting networks having different types of switching systems;

Topology management and discovery;

Local area networks and interworking arrangements there between;

Flow control and congestion control. Traffic scheduling and balancing;

Routing, pathfinding;

Access control and network resource allocation;

Asynchronous transfer mode networks.

Devices for a human operator manually and/or physically routing or switching communications between source and destination.

This groups contains documents dealing with different ways to supply power to terminals connected to a network.

It covers activation or deactivation of terminals or nodes connected to a network. Sometimes, a power on/off is involved, while other documents deal more with logical (de-)activations.

Aspects of billing, charging, accounting, tariffing for the transport of data packets in wireless or wireline data networks, including data sub networks of voice networks.

G06Q: systems or methods specially adapted for administrative, commercial, financial, managerial or supervisory purposes.

H04M: telephonic communication.

H04W: wireless communications networks.

Features for which there is no matching subgroup under H04L 12/14 should be classified under H04M 15/00 or H04M 17/00 if appropriate subgroups are provided there.

This group is used for features related to the interrelation between network nodes, addition of new network nodes, software downloaded to user, self-billing, sampling, backup of billing data, etc. for charging purposes.

Charging aspects of the Policy and Charging Rules Function / Policy Charging Rules Node, or Policy and Charging Control architectures.

If flow control or admission control aspects are relevant, this is classified in H04L 47/20 , H04L 47/70 or H04W 28/10.

If network maintenance or administration aspects are relevant, this is classified in H04L 41/0893.

Advice of charge (AoC) during a communication.

Advice of charge (AoC) with a threshold, e.g. user indicating maximum cost.

This includes e.g. providing the user a preview of estimated costs before he/she starts a communication, for example before start of a file transfer.

Special fields, for example in IP-headers of SIP-headers, used for charging or billing.

This group is used for metric aspects whereby the charging is based neither on volume nor on time, for instance based on distance / number of hops, or the use of more complicated formulas for determining the charging.

This group is used for exceptional volume based charging, for instance only charging for volume of useful data, not overhead data (overhead data being for example: session set-up / tear down, retransmission of erroneous packets).

This group is used for exceptional time based charging, for example only charging for actual transmission time, or time based charging where this would otherwise be uncommon.

This includes for example: clearing of revenue, format conversion, meta format for billing.

This includes for example the exchanges for trading the capacity, or selecting operators / routes based on tariff.

Aspects of payment or settlement of charges involving interaction with the data transmission network, see the subgroups below.

Payment using e-cash, credit units, tokens, points.

Features related to prepayment accounts are classified here.

The on-line / real-time metering / charging aspects are additionally classified under "Architecture" by tagging with the subgroup code H04L 12/1403.

More detailed features are classified under H04M 17/00.

Cost splitting involving a third party, such as an advertiser, a sponsor.

This could include a discount to the user based on the acceptance of an advertisement where e.g. the advertiser pays the remaining amount.

Even when the third party bears the full cost, this is still classified here.

Cost splitting involving only the communication parties, e.g. the "A" party and the "B" party in a standard two-party communication, or additional parties in case of teleconferencing.

This includes e.g. the use of call detail record CDR, or the Intelligent Network infrastructure.

This includes variable tariff dependent on subscription-contract, time-of day, flow, QoS/diffserv, bandwidth usage.

Aspects related to network maintenance or administration with service quality level based billing are also classified under H04L 41/5029.

This includes variable tariffs dependent on congestion, i.e. congestion pricing.

This includes negotiation of the tariff, between the user and the provider, or between providers. Also automatic negotiation by algorithms, i.e. without user involvement, is classified here.

Discounts on the overall charge where only one communication party, typically the "A" party, pays the cost.

If another communication party is involved, this is classified under H04L 12/1475 .

It is a subgroup of H04L 12/00 and hence contains only documents with broadcast, multicast or conference arrangements in data switching networks, and where there is a disclosure of subject-matter relevant for the broadcast, multicast or conference per se.

This subgroup is not active and contains networks adapted for stock quotations. Computer supported buying and selling of stocks without network aspects is classified in G06Q 40/04 .

This subgroup is not active and contains networks specifically adapted for auctions. Computer supported auctioneering such as Internet auctions without network aspects is classified in G06Q 30/08 .

This subgroup includes documents regarding data exchange in real-time between a group of user equipment connected to a data-switching network. The documents provide solutions suitable for groups of more than two pieces of user equipment but do not exclude two users in a degenerate situation.

Instant messaging is classified in H04L 51/04.

This subgroup contains documents related to conference administration arrangements for setting up and starting a conference. It covers aspects related to events before the actual conference takes place.

This subgroup contains documents related to conference administration arrangements during the conference itself.

Examples of documents classified here: US2007274460, US7408890, US7426540.

This subgroup contains documents directed to solving problems such as transmission errors and/or delays, and terminals with limited capabilities.

Examples of documents classified here: EP1876755, WO2004008336

This subgroup contains documents directed to the recording of conference content, participant activities and/or behaviour, etc. for later retrieval.

This subgroup contains documents where not all the receivers of the broadcast or multicast data are connected through the same kind of networks, which influences the broadcast/multicast service.

This subgroup contains documents where not all the receivers have the same capabilities, which influences the broadcast/multicast service.

Layered encoding of data as such is classified in H04N 19/00.

The size of the location is not relevant; the data transmission can take place within a room, a building, a city, or a nation etc. (location of the user terminal in data switching networks H04L 67/52; services specially adapted for wireless communication networks making use of the location of users or terminals H04W 4/02)

This subgroup contains inter alia documents related to the IGMP or MLD protocols for joining and leaving a multicast group.

It also contains documents dealing with changes to the multicast service as the result of a node failure or a member joining or leaving the group.

Routing tree calculation is classified in H04L 45/48 .

This subgroup contains documents dealing with systems where the data forwarding to every receiver is also the responsibility of the receivers themselves, e.g. application layer multicast.

This subgroup covers documents where the multicast or broadcast aspect is relevant for the push service, such as pushing common data to a group of users. Pushed-based network services H04L 67/55.

Push systems in relation to Internet retrieval, see G06F 16/951.

This subgroup contains documents dealing with the problem of how to make sure that each receiver has received the data and what to do when this is not the case.

This subgroup contains documents dealing with any action (e.g. verifications, increased resources, alternative paths, etc.) taken prior to transmission in order to ensure network reliability. Arrangements for detecting or preventing errors in received information in general, see H04L 1/00.

This subgroup contains documents concerning the transmission order of multicast and/or broadcast data packets onto the network, e.g. vis-à-vis unicast data.

The restrictions are for instance applied to avoid flooding of data by dividing the recipients into multicast groups or using subnets or subdomains.

This subgroup only contains documents dealing with multicast or broadcast problems that are a result of (at least some) network links being wireless, e.g. intermittent connectivity or bandwidth constraints.

Documents concerned with the wireless part of the network for broadcast or multicast services such as MBMS are classified in H04W 4/06, e.g. radio channel allocation.

This subgroup contains documents where real-time information is unidirectionally communicated to a group of recipients.

H04H: Broadcast communication in broadcast networks, e.g. radio or television networks.

H04N: Pictorial communication, e.g. television.

The rule for classification in this group is "multiple places, no priority". This means that a document should be classified in all the subgroups that are appropriate for the document.

This subgroup was initially used to classify network security aspects, which are now classified in:

Header group accommodating those networks whose topology respond to regular LAN topologies (bus, ring or star). His head group contains also WAN and MAN topologies. Documents dealing with very generic network topologies on Layer 2 should be classified here.