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1b7280b3698ef65a56ab482a869194d4 | 103 636-1 | 1 Scope | The present document provides an overview on DECT-2020 NR including layers, system and network architectures envisioned for this release. Further it provides an overview to ETSI TS 103 636-2 [1], ETSI TS 103 636-3 [2], ETSI TS 103 636-4 [3], ETSI TS 103 636-5 [4] and their interrelation. |
1b7280b3698ef65a56ab482a869194d4 | 103 636-1 | 2 References | |
1b7280b3698ef65a56ab482a869194d4 | 103 636-1 | 2.1 Normative references | References are either specific (identified by date of publication and/or edition number or version number) or non-specific. For specific references, only the cited version applies. For non-specific references, the latest version of the referenced document (including any amendments) applies. Referenced documents which a... |
1b7280b3698ef65a56ab482a869194d4 | 103 636-1 | 2.2 Informative references | References are either specific (identified by date of publication and/or edition number or version number) or non-specific. For specific references, only the cited version applies. For non-specific references, the latest version of the referenced document (including any amendments) applies. NOTE: While any hyperlinks i... |
1b7280b3698ef65a56ab482a869194d4 | 103 636-1 | 3 Definition of terms, symbols and abbreviations | |
1b7280b3698ef65a56ab482a869194d4 | 103 636-1 | 3.1 Terms | For the purposes of the present document, the following terms apply: Fixed Termination point (FT): operational mode of RD where RD initiates coordinates local radio resources, provides information how other RDs may connect and communicate with it operating channel: single continuous part of radio spectrum with a define... |
1b7280b3698ef65a56ab482a869194d4 | 103 636-1 | 3.2 Symbols | For the purposes of the present document, the following symbols apply: RDFT RD operating in FT mode RDFT,PT RD operating in both FT and PT mode RDPT RD operating in PT mode |
1b7280b3698ef65a56ab482a869194d4 | 103 636-1 | 3.3 Abbreviations | For the purposes of the present document, the following abbreviations apply: 3GPP 3rd Generation Partnership Project 5G 5th Generation ARQ Automatic Repeat reQuest BCC Broadcast Control BCCH Broadcast Control CHannel BLER BLock Error Ratio BPSK Binary Phase Shift Keying BSC Beacon Scanning Control CCC Connection Config... |
1b7280b3698ef65a56ab482a869194d4 | 103 636-1 | 4 General | |
1b7280b3698ef65a56ab482a869194d4 | 103 636-1 | 4.1 Introduction | DECT-2020 NR is a Radio Interface Technology (RIT) designed to provide a slim but powerful technology foundation for wireless applications deployed in various use cases and markets. This radio interface technology supports all kind of applications including, but not limited to Cordless Telephony, Audio Streaming Applic... |
1b7280b3698ef65a56ab482a869194d4 | 103 636-1 | 5 System and Network Architectures | |
1b7280b3698ef65a56ab482a869194d4 | 103 636-1 | 5.1 Wireless Point-to-Point and Point-to-Multipoint Links | Wireless Point-to-Point links involve two radio devices communicating with each other. A typical application is the cable replacement by a wireless link established between two radio devices requiring communicating with each other. Compared to wireline systems, wireless comes with the benefit that point to multipoint c... |
1b7280b3698ef65a56ab482a869194d4 | 103 636-1 | 5.3 Mesh network topology | |
1b7280b3698ef65a56ab482a869194d4 | 103 636-1 | 5.3.1 Introduction | In DECT-2020 mesh network devices can communicate directly to each other extending the range of network and increasing the reliability of communication. The mode of the involved radio devices may change autonomously depending on the context of the communication. Each radio device can act as a node transmitting a messag... |
1b7280b3698ef65a56ab482a869194d4 | 103 636-1 | 5.3.2 Mesh system operation | The mesh system operation is based on a clustered tree topology where each RD decides the next hop individually based available routes towards the RD providing the connection to the external internet in FT mode (RDFT). Each radio device has knowledge of the next uplink and downlink hop in the clustered tree and RDFT, o... |
1b7280b3698ef65a56ab482a869194d4 | 103 636-1 | 5.3.3 Uplink Routing | RD associates to the next hop RD based on received beacons quality attributes such as Received Signal Strength Indicator (RSSI) measurement from a beacon signal which assists it to determine the pathloss. If both DL pathloss and UL pathloss are such that connection can be established, the RD transmitting this beacon is... |
1b7280b3698ef65a56ab482a869194d4 | 103 636-1 | 5.3.4 Downlink Routing | DECT-2020 NR standard defines three tools for downlink routing: Selective Flooding, Selective Source Routing and Cached Downlink Routing. Each downlink routing method is based on the cluster tree topology basis explained in clauses 5.3.1 to 5.3.4. Selective Flooding is a basic mechanism to send downlink packets without... |
1b7280b3698ef65a56ab482a869194d4 | 103 636-1 | 5.3.5 Routing between RDs | Packet routing between RDs in cluster tree topology uses selective hop-limited flooding, where RD transmits data to only destination if there is association between RD and RD that is the destination of the packet. Otherwise, data is flooded in radio neighbourhood with a limited hop count defined by the originating RD. |
1b7280b3698ef65a56ab482a869194d4 | 103 636-1 | 5.3.6 Configuration data distribution | The configuration data distribution mechanism is used to provide an efficient and reliable way of distributing the data to the RDs in the DECT-2020 network. Each RD operating in FT mode shall store the configuration data and transfer this data to associated RDs based on RD request. The application sequence number is ad... |
1b7280b3698ef65a56ab482a869194d4 | 103 636-1 | 5.4 Interworking | The interworking with 3GPP 5G networks is supported by DECT-2020 NR via interworking profiles. DECT-2020 can be connected as untrusted non-3GPP access network to the 5G Core Network via a Non-3GPP Inter-Working-Function (N3IWF) or as a trusted non-3GPP access network via a Trusted Non-3GPP Gateway Function (TNGF). Figu... |
1b7280b3698ef65a56ab482a869194d4 | 103 636-1 | 5.5 Energy optimization features | |
1b7280b3698ef65a56ab482a869194d4 | 103 636-1 | 5.5.1 Data without association | The data transmission without association enables a radio device to transmit data to an FT without performing association with it. Based on the target address in routing PDU, the data can be routed to the backend as depicted in Figure 5.5.1-1 or to other RD in the network. The RD in FT mode enables this operation by in... |
1b7280b3698ef65a56ab482a869194d4 | 103 636-1 | 6 Overview on Radio technology | |
1b7280b3698ef65a56ab482a869194d4 | 103 636-1 | 6.1 Radio interface protocol architecture | Figure 6.1-1: Radio interface protocol architecture Figure 6.1-1 shows the DECT-2020 radio interface protocol architecture around the Physical layer (PHY). The physical layer interfaces the Medium Access Control (MAC) layer. The circles between different layer/sub-layers indicate Service Access Points (SAPs). The physi... |
1b7280b3698ef65a56ab482a869194d4 | 103 636-1 | 6.2 Physical Layer | |
1b7280b3698ef65a56ab482a869194d4 | 103 636-1 | 6.2.1 Physical Layer functions and capabilities | The DECT-2020 NR physical layer is in principle suitable to address frequency bands below 6 GHz. The physical layer employs Cyclic Prefix Orthogonal Frequency Division Multiplexing (CP-OFDM) combined with Time Division Multiple Access (TDMA) and Frequency Division Multiple Access (FDMA) in a Time Division Duplex (TDD) ... |
1b7280b3698ef65a56ab482a869194d4 | 103 636-1 | 6.2.2 Radio characteristics | Radio characteristics of DECT-2020 NR combined with the physical layer support nominal RF bandwidth from 1,728 MHz up to 221,184 MHz. The current release focuses on URLLC and mMTC use cases. The radio channel numbering scheme enables to assign channels from 450 MHz up to 5 875 MHz organized into 17 different operating ... |
1b7280b3698ef65a56ab482a869194d4 | 103 636-1 | 6.3 Medium Access Control Layer | |
1b7280b3698ef65a56ab482a869194d4 | 103 636-1 | 6.3.1 Introduction | The objective of this clause is to provide an overview on the MAC protocol layer architecture, the used identities, the used transport channels and the mapping of the MAC PDU into the physical layer packet. The descriptions provided are a model of the MAC layer i.e. it does not specify or restrict implementations. |
1b7280b3698ef65a56ab482a869194d4 | 103 636-1 | 6.3.2 MAC Structure | The overall MAC structure is depicted in Figure 6.3.2-1. The MAC layer provides DTCH and MTCH logical channels for transferring higher layer data. The flow of the higher layer data and MAC internal messages to physical channels is depicted with black solid lines. The grey dashed line corresponds to MAC internal control... |
1b7280b3698ef65a56ab482a869194d4 | 103 636-1 | 6.3.3 Identities | Network ID The Network ID has a length of 32 bits, and first 24 MSB bits are used to identify a DECT-2020 network uniquely from other DECT-2020 networks. The 8 LSB bits of the network ID are selected locally to minimize collision with other networks. The network ID is transmitted periodically in a beacon frame as plain... |
1b7280b3698ef65a56ab482a869194d4 | 103 636-1 | 6.3.4 Services | The MAC layer provides the following services to upper layers: β’ data transfer; β’ radio resource allocation. ETSI ETSI TS 103 636-1 V2.1.1 (2024-10) 24 Release 2 The MAC layer expects the following services from the physical layer: β’ data transfer services in physical layer packets; β’ measurements. |
1b7280b3698ef65a56ab482a869194d4 | 103 636-1 | 6.3.5 Functions | The MAC layer supports the following control functions in the MAC control entity: β’ Local Radio Control (LRC): This function is overall in charge of the radio resource in the local coordination area, when RD coordinates local radio resources, i.e. operates as FT. β’ Paging Transmission Control (PTC): This function contr... |
1b7280b3698ef65a56ab482a869194d4 | 103 636-1 | 6.3.6 Channel Structure | The MAC layer provides data transfer services on logical channels. To accommodate different kinds of data transfer services, multiple types of logical channels are defined i.e. each supporting transfer of a particular type of information. Each logical channel type is defined by what type of information is transferred. ... |
1b7280b3698ef65a56ab482a869194d4 | 103 636-1 | 6.4 Mobility and State Transitions | |
1b7280b3698ef65a56ab482a869194d4 | 103 636-1 | 6.4.1 Overview | The RDPT operates in the following states: non-associated and associated. The mobility support, i.e. handover, is applicable for an RD which is associated to one or more RDFT or RDFT,PT. The different handover procedures are introduced in clause 6.4.2, wherein the handover functionality is the same in both star and mes... |
1b7280b3698ef65a56ab482a869194d4 | 103 636-1 | 6.4.2 Intra DECT-2020 Mobility | The involved handover procedures may be intra-cell or inter cell. The intra-cell handover means RDPT or RDFT,PT changes its association from an instance (e.g. sector) of an RDFT or RDFT,PT into another instance of the same RDFT or RDFT,PT. The inter-cell handovers consider changing association from an RDFT or RDFT,PT i... |
1b7280b3698ef65a56ab482a869194d4 | 103 636-1 | 6.5 Data Link Control | |
1b7280b3698ef65a56ab482a869194d4 | 103 636-1 | 6.5.1 DLC Entities and Architecture | The DLC architecture is depicted in Figure 6.5.1-2. There is single routing service entity in each RD. There is a single DLC entity set for each radio link between an RD in PT mode and an RD in FT mode. For an RD operating in both FT and PT mode in mesh clustered three, the RD has: β’ One DLC entity set for the RD that ... |
1b7280b3698ef65a56ab482a869194d4 | 103 636-1 | 6.5.2 Routing services | Routing services support the following: β’ Packet Routing from RD to backend (uplink) with special unicast address reserved for backend. β’ Packet routing from backend (downlink) to RDs with unicast, multicast or broadcast address. β’ Packet Routing between RDs, with unicast, multicast or broadcast address with hop-limite... |
1b7280b3698ef65a56ab482a869194d4 | 103 636-1 | 6.6 Convergence Layer | |
1b7280b3698ef65a56ab482a869194d4 | 103 636-1 | 6.6.1 General | The CVG layer operates end-to-end between the terminal entities. Intermediate nodes in a mesh network do not process the CVG layer payload. The convergence layer provides the following services: β’ Multiplexing service: - Identification and multiplexing of higher layer data (see clause 6.6.3). β’ Transmission service: - ... |
1b7280b3698ef65a56ab482a869194d4 | 103 636-1 | 6.6.2 CVG Service types | The CVG layer's service types are related to the CVG procedures as defined in Table 6.6.2-1. However, the use of CVG Security, Multiplexing, Duplicate removal and Delivery order procedures are independent of the CVG service type. ETSI ETSI TS 103 636-1 V2.1.1 (2024-10) 29 Release 2 Table 6.6.2-1: CVG Service types & fe... |
1b7280b3698ef65a56ab482a869194d4 | 103 636-1 | 6.6.3 Data identification and multiplexing | Convergence layer provides identification and multiplexing of higher layer data using different CVG level multiplexing procedures: Endpoint (EP) multiplexing and Mux tag multiplexing. Endpoint multiplexing is based on using a 2-octet EP mux field. The EP mux address space is divided into different purposes, for free us... |
1b7280b3698ef65a56ab482a869194d4 | 103 636-1 | 6.7 Co-existence | |
1b7280b3698ef65a56ab482a869194d4 | 103 636-1 | 6.7.1 General | 6. |
1b7280b3698ef65a56ab482a869194d4 | 103 636-1 | 7.1 General | DECT-2020 NR supports several features enabling the co-existence of different DECT technologies in the 1 880 MHz to 1 900 MHz band and in other frequency bands DECT technologies can employ. In the design of DECT-2020 NR special attention has been given to enable co-existence between multiple DECT-2020 NR systems and sy... |
1b7280b3698ef65a56ab482a869194d4 | 103 636-1 | 6.7.2 Technical Features for Supporting Co-existence | For enabling co-existence between DECT-2020 NR systems and systems employing other DECT technologies (e.g. DECT, DECT evolution, DECT ULE) the following design choices were specifically made in DECT-2020 NR: β’ The smallest nominal channel bandwidth is the same as the nominal channel bandwidth in DECT systems, i.e. 1,72... |
1b7280b3698ef65a56ab482a869194d4 | 103 636-1 | 7 Security Architecture | 7.1 General DECT-2020 NR security architecture relies on two independent security layers operating at MAC and CVG protocol layers. The MAC security is a radio link specific operating between two RDs transmitting and receiving MAC PDUs, whereas the CVG layer security is end-to-end between two CVG endpoints entities send... |
1b7280b3698ef65a56ab482a869194d4 | 103 636-1 | 7.2 Secure Joining | Secure Joining enables communication for authentication and provisioning process including security key distribution between RD and the Provisioning Server for an RD that does not have valid MAC and/or CVG security credentials of the network. Secure Joining is enabled when needed by the network owner. It can be enabled... |
64c5405618784b24a18fe0e72433f605 | 103 634 | 1 Scope | The present document contains the specification of the Low Complexity Communication Codec plus (LC3plus). The specification includes a full algorithmic description of both the encoder and the decoder. It includes reference fixed-point and floating-point ANSI C source code and conformance test procedures. The codec has ... |
64c5405618784b24a18fe0e72433f605 | 103 634 | 2 References | |
64c5405618784b24a18fe0e72433f605 | 103 634 | 2.1 Normative references | References are either specific (identified by date of publication and/or edition number or version number) or non-specific. For specific references, only the cited version applies. For non-specific references, the latest version of the referenced document (including any amendments) applies. Referenced documents which a... |
64c5405618784b24a18fe0e72433f605 | 103 634 | 2.2 Informative references | References are either specific (identified by date of publication and/or edition number or version number) or non-specific. For specific references, only the cited version applies. For non-specific references, the latest version of the referenced document (including any amendments) applies. NOTE: While any hyperlinks i... |
64c5405618784b24a18fe0e72433f605 | 103 634 | 3 Definition of terms, symbols and abbreviations | |
64c5405618784b24a18fe0e72433f605 | 103 634 | 3.1 Terms | For the purposes of the present document, the following terms apply: codec redundancy: redundancy created by the LC3plus codec NOTE: The codec encodes two variants of a frame, one primary encoding and one secondary (or redundant) encoding. The primary encoding typically uses more bits than the secondary encoding. frame... |
64c5405618784b24a18fe0e72433f605 | 103 634 | 3.2 Symbols | |
64c5405618784b24a18fe0e72433f605 | 103 634 | 3.2.1 Mathematical symbols | For the purposes of the present document, the following mathematical symbols apply: Ξ Difference between two ODG values Algorithmic delay of the codec Delay due to the frame size Delay due to the MDCT look ahead Energy per band Sampling rate Band indices in dependency of sampling rate ... |
64c5405618784b24a18fe0e72433f605 | 103 634 | 3.2.2 Operator symbols | For the purposes of the present document, the following operator symbols apply: a mod b Modulo operator defined by β {x|condition(x)} Defines the quantity of x where x fulfils a certain condition , The transpose of vector x and matrix X respectively a | b Set construction operator with elements a such tha... |
64c5405618784b24a18fe0e72433f605 | 103 634 | 3.3 Abbreviations | For the purposes of the present document, the following abbreviations apply: AL-FEC Application Layer FEC ALU Arithmetic Logic Unit ANSI-C American National Standards Institute C ETSI ETSI TS 103 634 V1.4.1 (2023-03) 15 BEC Bit Error Condition BER Bit Error Rate BFI Bad Frame Indicator BS.1387-1 Method for Objective Me... |
64c5405618784b24a18fe0e72433f605 | 103 634 | 4 General description | |
64c5405618784b24a18fe0e72433f605 | 103 634 | 4.1 Overview | The LC3plus codec can operate at highly flexible modes. For regular operation mode, the codec supports coding of speech and audio for several audio bandwidths, using the sampling frequencies 8 kHz, 16 kHz, 24 kHz, 32 kHz or 48 kHz. The LC3plus codec may also be used for streaming audio and therefore also supports CD sa... |
64c5405618784b24a18fe0e72433f605 | 103 634 | 4.2 Transcoding functions | This clause provides a high-level overview of the operation of the LC3plus including the interfaces and configuration options. The following figures outline possible LC3plus configuration scenarios. The full technical details of the codec are provided in clause 5 of the present document. Figure 4.1: LC3plus operation f... |
64c5405618784b24a18fe0e72433f605 | 103 634 | 4.3 ANSI C-code | A reference ANSI C-code implementation of the LC3plus codec is available in archive ts_103634v010401p0.zip which accompanies the present document, see clause 6 for a more detailed description. The ANSI C-code implementation is available in fixed-point arithmetic for efficient implementation in fixed-point Digital Signa... |
64c5405618784b24a18fe0e72433f605 | 103 634 | 4.4 Conformance testing | Conformance tests are defined in clause 7, testing encoder, decoder and complete codec implementations of any kind of arithmetic, precision and platform. For that, the implementation under test is compared against the fix-point reference executable and the difference is evaluated using quality metrics such as Root Mean... |
64c5405618784b24a18fe0e72433f605 | 103 634 | 4.5 RTP payload format | An RTP payload format for transporting LC3plus encoded audio in IP/UDP/RTP is defined in Annex B. The RTP payload format supports all possible combinations of frame durations, audio bandwidths and bitrates the LC3plus codec may generate. The RTP payload format also defines configuration parameters that can be used to n... |
64c5405618784b24a18fe0e72433f605 | 103 634 | 4.6 Performance characterization | The LC3plus characterization is available in ETSI TR 103 633 [i.5]. ETSI ETSI TS 103 634 V1.4.1 (2023-03) 20 |
64c5405618784b24a18fe0e72433f605 | 103 634 | 5 Codec algorithm description | |
64c5405618784b24a18fe0e72433f605 | 103 634 | 5.1 General codec description | This clause describes the technical specification of the Low Complexity Communication Codec plus (LC3plus). The main features of LC3plus coding one audio channel are: Table 5.1: Feature summary Feature Supported Range Frame duration 2,5 ms, 5 ms and 10 ms (2,72 ms, 5,44 ms, 10,88 ms @ 44,1 kHz) Look ahead delay 2,5 ms ... |
64c5405618784b24a18fe0e72433f605 | 103 634 | 5.2 General codec parameters | |
64c5405618784b24a18fe0e72433f605 | 103 634 | 5.2.1 Audio channels | The algorithm describes only the coding of a single audio channel. Any stereo or multi-channel coding shall be supported by coding of multiple mono streams. |
64c5405618784b24a18fe0e72433f605 | 103 634 | 5.2.2 Sampling rates | The codec supports the sampling rates of 8 000 Hz, 16 000 Hz, 24 000 Hz, 32 000 Hz, 44 100 Hz and 48 000 Hz. Please note that for the 44 100 Hz mode, all configurations, e.g. frame size in number of samples, are identical to the 48 000 Hz mode. A sampling rate index is defined as follows: = min 4, 8 000 β1 1... |
64c5405618784b24a18fe0e72433f605 | 103 634 | 5.2.3 Bits per sample | The codec algorithm itself has the restriction that the sample resolution is limited to a maximum of 32 bits per audio sample of the input and output audio samples. Typical values are 16, 24 or 32 bits per audio sample. |
64c5405618784b24a18fe0e72433f605 | 103 634 | 5.2.4 Frame size and delay | The codec works at a frame duration of 2,5 ms, 5 ms and 10 ms resulting in a frame length = β β samples, where: = 48 000 44 100 , = 44 100 !" 1 , β . 2 The algorithmic delay of the codec consists of the delay due to frame length and the overlap of the MDCT . The delays in ... |
64c5405618784b24a18fe0e72433f605 | 103 634 | 5.2.5 Bit budget and bitrate | The number of bytes available in one frame is denoted . The number of bytes to use for encoding a single channel is a required external input to each single channel LC3plus encoder. The same number of bytes (now to be used for decoding) is also a required external input to each single channel LC3plus decoder. The... |
64c5405618784b24a18fe0e72433f605 | 103 634 | 5.2.6 Bandwidth | The parameter represents the audio bandwidth in Hz and is by default = min ( , 20 000) β . may be set externally to a lower value, which will limit the spectrum (clause 5.3.8) and deactivate the bandwidth detector (clause 5.3.5). The external value shall represent the supported audio bandwidths NB, WB, SS... |
64c5405618784b24a18fe0e72433f605 | 103 634 | 5.3 Encoding process | |
64c5405618784b24a18fe0e72433f605 | 103 634 | 5.3.1 Encoder modules | A high-level overview of the encoding modules is given in Figure 5.1. The coder is a spectral transform coder which converts a segment of the time domain into a spectral representation (using a LD-MDCT transform). The corresponding frequency components are processed by a Spectral Noise Shaping (SNS) module to reduce pe... |
64c5405618784b24a18fe0e72433f605 | 103 634 | 5.3.2 Input signal | The input signal of the current frame consists of audio samples, 0, β¦ , 1 where the newest one is located at 1. Audio samples of past frames are accessed by negative indexing, e.g. 1 is the most recent sample of the previous frame. The input signal is typically retrieved in Pulse-Code-... |
64c5405618784b24a18fe0e72433f605 | 103 634 | 5.3.3 Input signal scaling | The input signal is first scaled to the range [-32 768, 32 768] according to: β 2 3 ETSI ETSI TS 103 634 V1.4.1 (2023-03) 24 where is the smallest integer such that fits in this range. E.g. for integer PCM format equals the bit-depths and for floating point PCM format is equal to 1... |
64c5405618784b24a18fe0e72433f605 | 103 634 | 5.3.4 Low Delay MDCT analysis | |
64c5405618784b24a18fe0e72433f605 | 103 634 | 5.3.4.1 Overview | The Low Delay Modified Discrete Cosine Transform (LD-MDCT) converts the audio input time domain samples into spectral coefficients and corresponding energy values grouped into bands. Figure 5.2 outlines the processing blocks. Figure 5.2: Low delay MDCT overview |
64c5405618784b24a18fe0e72433f605 | 103 634 | 5.3.4.2 Update time buffer | The time input buffer for the MDCT shall be updated according to: = β + = 0 β¦ 2 β1 β 2 β + = 0 = 0 β¦ β1 5 where the latter initialization is typically jointly optimized with the subsequent time-frequency transformation. |
64c5405618784b24a18fe0e72433f605 | 103 634 | 5.3.4.3 Time-frequency transformation | A block of time samples is transformed to the frequency coefficients ( ) using equation (6): = 2 _() β cos ! " # + 1 2 + 2 $ # + 1 2$% = 0 β¦ β1 6 where _ is the Low Delay MDCT window chosen for the frame size and length. The window has been optimized for = 480 and all other versi... |
64c5405618784b24a18fe0e72433f605 | 103 634 | 5.3.4.4 Energy estimation per band | The energy per band ) is computed as follows: ) = * + 1 β* = 0 β¦ β1 8 where are the MDCT coefficients computed in clause 5.3.4.3, is the number of bands and * are the band indices given in clause 5.9.1. |
64c5405618784b24a18fe0e72433f605 | 103 634 | 5.3.4a Near Nyquist detector | The near Nyquist detector is used to identify signals with comparatively high energy in the range close to the Nyquist frequency. The near Nyquist detector is active only for sample rates <= 32,000 '(. The Aliasing-like structures in these signals can accidently trigger TNS and lead to distortions. To identify such s... |
64c5405618784b24a18fe0e72433f605 | 103 634 | 5.3.5 Bandwidth detector | |
64c5405618784b24a18fe0e72433f605 | 103 634 | 5.3.5.1 Algorithm | This tool detects bandlimited signals coded at higher sampling rates, e.g. NB telephone call coded at 8 kHz but upsampled to a higher sampling rate. The detector provides guidance to the TNS (see clauses 5.3.8 and 5.4.6) and noise filling tool (see clauses 5.3.13 and 5.4.4) in order to avoid any spreading or smearing o... |
64c5405618784b24a18fe0e72433f605 | 103 634 | 5.3.5.2 Parameters | Table 5.6 lists the used parameters to detect the active bandwidth for a given sampling rate and frame duration . Table 5.6: Parameter table bandwidth detector (Hz) Bandwidth ( ) 2,5 ms 8 000 0 - - {NB} 0 2,5 ms 16 000 1 {24, 0, 0, 0} {34, 0, 0, 0} {NB, WB} 1 2,5 ms 24 000 2 {24... |
64c5405618784b24a18fe0e72433f605 | 103 634 | 5.3.6 Time Domain Attack Detector | |
64c5405618784b24a18fe0e72433f605 | 103 634 | 5.3.6.1 Overview | 5.3. |
64c5405618784b24a18fe0e72433f605 | 103 634 | 6.1 Overview | The time domain attack detector is active only for higher bit-rates, sampling rates β₯32 000 '( and a frame duration of 10 ms. Specifically, transient detection is carried out when = 320, 80 < < 340 and = 10, or when = 480, 100 β€ < 340 and = 10. If active, the transient detector outputs a flag... |
64c5405618784b24a18fe0e72433f605 | 103 634 | 5.3.6.2 Downsampling and Filtering of Input Signal | The first step is a downsampling of the input signal , = 0 β¦ β1, which is performed as: "" = # 160 + <$ . = 0 β¦ 159 11 Next, the downsampled signal is high pass filtered according to: #) = 0,375 "" β0,5 "" β1 + 0,125 "" β2 , = 0 β¦ 159. 12 As in the case of t... |
64c5405618784b24a18fe0e72433f605 | 103 634 | 5.3.6.3 Energy Calculation | The attack detector operates on block wise energies on 4 blocks of 40 samples. )"" = #) , = 0 β¦ 3 - /0 - , 13 which are compared to a delayed long term temporal envelope which is inductively defined by: ="" = max >0,25 ="" β1 , )"" β1 ?, = 0 β¦ 3, 14 where the values at index -1... |
64c5405618784b24a18fe0e72433f605 | 103 634 | 5.3.6.4 Attack Detection | An attack is detected if: )"" > 8,5 ="" () 15 holds for any between 0 and 3. Furthermore, in this case the attack position ;""( ) is defined to be the largest n such that the inequality holds. Otherwise, ;""( ) is set to -1. The value ;""( β1) is defined to be -1. The attack flag for frame is computed as:... |
64c5405618784b24a18fe0e72433f605 | 103 634 | 5.3.7 Spectral Noise Shaping | |
64c5405618784b24a18fe0e72433f605 | 103 634 | 5.3.7.1 Overview | 5.3. |
64c5405618784b24a18fe0e72433f605 | 103 634 | 7.1 Overview | Spectral Noise Shaping (SNS) applies a set of scale factors to the MDCT spectrum. These scale factors shape the quantization noise introduced in the frequency domain by the spectral quantization. The noise shaping is performed in such a way that the quantization noise is minimally perceived by the human ear, maximizing... |
64c5405618784b24a18fe0e72433f605 | 103 634 | 5.3.7.2 SNS analysis | |
64c5405618784b24a18fe0e72433f605 | 103 634 | 5.3.7.2.1 Overview | In the first step of the SNS encoder, a set of 16 scale factors are estimated. These scale factors are derived from the 64 energies per band ) (see clause 5.3.4.4). In case, the codec is configured to operate on less than 64 bands , the given energy values are padded to get exactly 64 energies per band ) . |
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