Are you studying the Optical Communication?
Are you confused about so many terminologies?
Here I share you a cheat sheet of this knowledge. Keep it now!
- ADM Add Drop Multiplexer
Bandwidth switching is used to implement broadband management, which allows different VCs between two STM-N signals to be interconnected, and has various interface signals (PDH) specified by G.703 without tapping and terminating the overall signal. Or the STM-N signal (SDH) is connected to any branch in the STM-M.
- AON Active Optical Network
The active optical network is a point-to-multipoint optical communication system consisting of an ONU, an optical remote terminal OLT, and an optical fiber transmission line.
- APON ATM Passive Optical Network ATM
An ideal long-term solution that combines ATM multi-service multi-bitrate support and passive optical network transparent broadband transmission capabilities, represents the latest development direction of broadband access technology for the 21st century.
- ADSL Asymmetric Digital Subscriber Line
Asymmetric Digital Subscriber Line System ADSL is a digital subscriber line DSL system that uses discrete multi-tone DMT line codes.
- AA Adaptive Antenna
An antenna provides a beam that is directed at a target, such as an antenna of a mobile phone, capable of automatically adjusting power as the target moves, also known as a smart antenna (SMART ANTENNA).
- ADPCM Adaptive Differential Pulse Code Modulation
An encoding technique that reduces the number of bits of analog sampling from 8 bits to 3 to 4 bits to complete the compression of the transmitted signal. ITU-T recommends G.721 to define an algorithm for 32-bit ADPCM (8000 samples per second. Each sample is 4 bits long, and its transmission capacity is doubled compared to conventional PCM coding.
- ADFE Automatic Decree Feedback Equalizer
An equalizer technique that utilizes the determined signal as an input signal to the backward tap to eliminate the effects of noise on the backward tap signal.
- AMI Alternate Mark Inversion
A coding technique commonly used in digital transmission, with logic 0 represented by a null level and logic 1 represented by alternating positive and negative voltages.
- AON All Optical Net
That is, the signal channel between the network and the end user node still maintains the form of light, that is, the end-to-end all-optical path, and there is no photoelectric converter in the middle. In this way, there is no obstacle to photoelectric conversion in the flow of the optical signal in the network, and the information transmission process does not need to face the difficulty in processing the information rate of the electronic device.
- AOWC All Optical Wave Converter
A device that directly converts information from one wavelength of light to another without electrical domain processing.
- ASK Amplitude Shift Keying
A keying technique that corresponds to a binary modulated signal that switches between on and off, also known as ON-OFF keying.
- ATPC Automatic Transfer Power Control
The point of the technology is that the output power of the microwave transmitter changes in the ATPC control range by automatically tracking the change in the receiving level of the receiving means. It has the advantages of reducing interference to adjacent systems, reducing the upper attenuation problem, reducing DC power consumption, improving the residual error characteristics, and increasing the output power by an additional 2 dB under fading conditions.
- AWF All Wave Fiber
The water peak of the fiber at 1383 nm is eliminated, so that more than 120 new wavelengths (interval 100 GHz) can be added in the 1350-1450 nm band. It is very beneficial for users of the urban access network.
- AU Administrative Unit
It provides an information structure for the adaptation function between the higher-order channel layer and the multiplex section layer.
- AUG Administrative Unit Group
It consists of one or more management units that determine the location that occupy a fixed position in the STM-N payload.
- APD Avalanche Diode
A highly sensitive detector that utilizes an avalanche multiplication effect to multiply photocurrent.
- BA Booster(power) Amplifier
An optical amplifier that compensates for the loss of the optical multiplexer and increases the fiber input power.
- BBER Background Block Error Ratio
For a certain test time, the ratio of the number of BBEs present at the available time to the total number of blocks deducting the unavailable time and all blocks during the SES.
- BR Basic Rate Access
ITU-T defines an interface rate for narrowband ISDN, also known as 2B+D, B channel 64K is the bearer channel, and D channel 16K is the digital signaling channel.
It’s a wireless LAN standard that is jointly developed by equipment manufacturers and has a coverage of 10M, a working frequency band of 2.4G, and a transmission rate of approximately 1M.
- C Band C
That is, the operating wavelength is in the range of 1525 to 1560 nm, and the bandwidth is about 35 nm.
When the single longitudinal mode laser is operated in direct modulation, the change of the injection current causes a change in the carrier density, which in turn changes the refractive index of the active region, and as a result, the optical path length of the laser cavity changes accordingly. Causes the oscillation wavelength to drift with time. It is generally necessary to overcome it with an external modulation technique.
- C Container C
The information structure for loading various rate service signals is denoted as C-n (11, 12, 2, 3, 4).
- CSMA/CD Carrier Sense Multiple Access with Collision Detection
A multiple access technology applied to wired local area networks.
- CSMA/CA Carrier Sense Multiple Access with Collision Avoidance
Since wireless products are not easy to detect whether there is a conflict in the channel, 802.11 defines a new protocol, namely (CSMA/CA). On the one hand, carrier sensing–checking whether the channel is idle; on the other hand, avoiding collisions–the probability of signal collision occurring when the channel is not idle, waiting through random time until a new idle channel occurs, so that the signal collision occurs. Minimize to a minimum. Not only that, but to make the system more stable, 802.11 also provides CSMA/CA with acknowledgement frame ACK. A signal collision can occur in the event of other noise interference, or due to a failure of the interception, and this ACK working at the MAC layer can provide fast recovery capability at this time.
- CNR Carrier to Noise Ratio
The ratio of carrier level to noise level before any modulation is applied.
- CP Cross polarization
Two antenna systems use the same frequency but one uses horizontal polarization and the other uses vertical polarization to improve spectrum utilization.
- DCF Dispersion Compensating Fiber
It is a large negative dispersion fiber, which is a new type of fiber designed for the 1310nm design. A certain dispersion compensation fiber is added to the G.652 fiber to perform dispersion compensation to ensure that the total dispersion of the entire fiber line is zero.
- DFF Dispersion-flattened Fiber
A wide range of dispersions from 1.3um to 1.55um can be used to achieve very low, virtually zero-dispersion fibers.
- DR Diversity Receiver
Diversity reception is a measure to reduce the impact caused by fading by selecting or synthesizing two or more receiver outputs with less correlation (ie, simultaneous quality deterioration). Specifically, it can be divided into different ways such as spatial diversity, frequency diversity, polarization diversity, and angle diversity.
- DPT Dynamic Packet Transport
This is a new transmission method proposed by Cisco – IP-optimized optical transmission technology. This technology provides high efficiency in bandwidth usage, richness of service categories, and advanced self-healing capabilities of the network.
- ODM Optical Division ltiplexer
Multiple wavelengths are divided into individual fibers to separate the channels.
- DSF Dispersion-Shifted Fiber
Known as the best single-mode fiber at 1550 nm, this fiber is designed to match the fiber’s refractive index profile to zero-dispersion to the 1550 nm window, which matches the minimum window of the fiber, making ultra-high-speed and ultra-long-range transmission possible.
- DTM Dynamic Synchronous Transfer Mode
A new technology based on high speed circuit switching and dynamic time slot allocation. As the second layer of switching/transmission technology, DTM has stronger bandwidth management capabilities and adapts to the continuous expansion of fiber bandwidth.
- DWDM Dense Wavelength Division Multiplexing
Multiple optical multiplexing of the same low loss window, relative to coarse wavelength division multiplexing of optical multiplexing of different low loss windows.
- DLC Digital loop carrier
Active optical network for densely populated areas
- DXC Digital cross connect equipment
A device that has one or more quasi-synchronous digital hierarchy (G.702) or digital system (G.707) signal ports that can be controllably connected and reconnected between any port signal rate (and its sub-rates).
- EA Electricity Absorb Modulation
A loss modulator that operates at the wavelength of the absorption region of the modulator material. When the modulator is unbiased, the wavelength is in an on state. As the bias voltage on the modulator increases, the absorption coefficient at the original wavelength becomes larger, the modulator becomes off, and the on/off state of the modulator is the light intensity modulation.
- EB Error Block
The error performance for high bit rate channels in an SDH network is a “block”, a collection of consecutive bits transmitted in a channel. When an error occurs in any bit within a block, the block is said to be a block error.
- ECC Embedded Control Channel
The embedded control channel that transmits the network management information has a physical channel of DCC and adopts a seven-layer protocol stack required by ITU-T G.784.
- EDFA Erbium-doped Fiber Amplifier
When fabricating the fiber, a special process is used to incorporate a very small concentration of barium ions in the core layer deposition to produce a corresponding erbium-doped fiber. The doped ions in the fiber are excited to the metastable high-excited state after being excited by the pump light, and stimulated radiation is generated under the signal light to form a coherent amplification of the signal light. The EDFA works in the 1550 window. The commercial EDFA has low noise, good gain curve, large amplifier bandwidth, compatibility with wavelength division multiplexing (WDM) system, high pumping efficiency, stable working performance and mature technology, and is favored in modern long-distance high-speed optical communication systems. At present, “EDFA” + Dense Wavelength Division Multiplexing (DWDM) + Non-Zero Dispersive Fiber (NZDF) + Photonic Integration (PIC) is becoming the main technical direction of long-distance high-speed optical fiber communication lines in the world.
- EDFL Erbium-doped Fiber Laser
A type of fiber laser that emits light at a wavelength of 1550 nm and consists of a doped fiber and an optical pump and other related optical components, such as a wavelength selector, a polarization controller, an input/output coupler, etc., having a low threshold, and Compatible with fiber-optic communication systems. In particular, the tunable circular EDFL has a large tuning range and high output power, and becomes the mainstream of tunable lasers. The main types are polished tunable WDM devices, DFB type, fiber birefringence tuning type, and piezoelectric tuning fiber FP etalon. Type and so on. EDFL is suitable for high-capacity long-haul fiber-optic communications and WDM systems.
- ES Errored Second
When a certain one second has one or more error blocks, the second is called a block error second.
- ESR Errored Second Ratio
The ratio of the number of ESs present at the available time to the total number of seconds for a certain test time.
- FEC Forward Error Correction
It is a data encoding technology. The error detection during transmission is verified by the receiver, and if there is an error, the sender is notified to resend. It allows re-encoding from a low bit error encoded data to form a column of error free data streams.
- FWM Four-wave Mixing
Four-Wave Mixing (FWM), also known as four-phonon mixing, occurs when two or three light waves of different wavelengths interact to produce new light waves of so-called mixing products or sidebands at other wavelengths. These lights can affect normal communication. This nonlinear optical effect is called four-wave mixing.
- FDMA Frequency Division Multiple Access
The total frequency band of the communication system is divided into a number of equally spaced channels (or channels), and the channels are reassigned to different users. These channels do not overlap each other.
- FTTB Fiber to the Building
ONU is placed in the building
- FTTC Fiber to the Curb
ONU is placed on the roadside
- FTTH Fiber to the Home
ONU is at home
- FA Frequency agility
Refers to the ability of the transmitting system to automatically hop to adapt to the environment according to changes in external conditions.
- CSMF Common Single Mode Fiber
A single-mode fiber that meets the requirements of ITU-T.G.652, often referred to as a non-dispersion-shifted fiber, has a zero dispersion in the low-loss region of the 1.3um window and operates at a wavelength of 1310 nm (loss of 0.36 dB/km). With the successful advancement of the fiber optic cable industry and semiconductor laser technology, the operating wavelength of the fiber line can be transferred to a lower loss (0.22 dB/km) 1550 nm fiber window.
- DSF Dispersion-Shifted Fiber
A single-mode fiber that meets the requirements of ITU-T G.653 has a zero-dispersion wavelength shifted to a very low loss of 1550 nm.
- GE Gigabit Ethernet
The Gigabit Ethernet standard was officially launched in October 1997 with a maximum transfer rate of 1 Gbps and is backward compatible with Ethernet technology and Fast Ethernet technology.
- GIF Graded Index Fiber
Light travels in a sinusoidal shape with a bandwidth of 1-2 GHz.km, which is used for some LANs that are not too fast.
- GS-EDFA Gain Shifted Erbium-doped Fiber Amplifier
By controlling the degree of particle inversion of the doped fiber, the 1570-1600 nm band is amplified, and it can be combined with a common EDFA to obtain a broadband amplifier having a bandwidth of about 80 nm.
- GVD Group Velocity Dispersion
In high-speed and large-capacity optical fiber communication, the shape of the optical pulse envelope changes due to the nonlinearity of the optical fiber medium. This change affecting the reception of the optical signal is called group velocity dispersion, and the group velocity dispersion causes the transmission waveform. Broadening. G.654 Cut-off wavelength shifting single-mode fiber This focus of fiber design considerations is to reduce the rate of 1550nm. The zero dispersion point is around 1310nm, so the dispersion at 1550nm is higher, which can be greater than 18ps/(nm.km). A single longitudinal mode laser can be used to eliminate the effects of dispersion. It is mainly used for submarine communication fiber communication with a long regenerative distance.
- HPF High Pass Filter
It’s a filter that allows radio waves that exceed a certain frequency to pass almost without attenuation, while other waves below this frequency band are severely attenuated.
- HRDS Hypothetical Reference Digital Section
It is a degree model with a certain length and performance specification, which can be used as a reference model for indicator allocation. For the SDH number field, there are three lengths of 420km, 280km and 50km.
- IDLC Integrated DLC
Broadband active optical network, ie Integrated Digital Loop Carrier System (IDLC) is a transmission platform based on SDH or PDH, which can provide PSTN, ISDN, B-ISDN, DDN, LANE, Internet and digital video services for centralized user areas. Access is also an ideal way to integrate broadband access and has great potential for development.
- IDEN Integrated Digital Enhanced Networks
The iDEN system was introduced in Los Angeles in 1994. It is a digital cluster system proposed by Motorola. It works in the 800MHz frequency range. After about three years of promotion, it has been put into commercial application in 13 countries in North America, South America and Asia. Its main feature is that it can be compatible with GSM, suitable for large networks and more suitable for PAMR applications.
- IEEE 802.3
CSMA/CD LAN, the Ethernet standard.
- IEEE 802.11
The wireless LAN technology standard promulgated in 1997, the IEEE 802.11 specification defines three physical layer (PHY) options: infrared, direct sequence spread spectrum (DSSS), and frequency hopping spread spectrum (FHSS). Since the wireless LAN transmission medium (microwave, infrared) is very different from the wired medium, there are some new technical problems objectively. For this reason, the IEEE802.11 protocol specifies some crucial technical mechanisms such as CSMA/CA protocol, RTS/ CTS protocol, etc. In August 1999, the 802.11 standard was further refined and revised. Two new contents, 802.11a and 802.11b, were added, which expanded the standard physical layer and MAC layer specifications.
One of the important transmission characteristics of the SDH optical transmission network is defined as the short-term deviation of the effective moments of the digital signal from the theoretical specified time position.
- K Band K
10G-12G for satellite communications.
- Ku Band Ku
12G-14G for multi-satellite communication.
- LA Line Amplifier
An optical amplifier that compensates for fiber loss on the trunk line.
- LEAF Large Effective Area Fiber
Single-mode non-zero dispersion-shifted fiber, working in the 1550nm window; compared with the standard non-zero dispersion-shifted fiber, it has a larger “effective area” and the effective area is increased to 72um2 or more, thus a large power bearing capacity. For the use of high output power doped fiber amplifiers, namely EDFA and dense wavelength division multiplexing technology networks.
- LANE LAN Emulation
When ATM switching is exchanged with Ethernet, a simulation process for ATM cells is required.
- LMDS Local Multipoint Distribution Service
A very popular broadband wireless access system that utilizes spread spectrum and polarization techniques. The base station covers approximately 2-10 KM and can provide up to 4.8 G of bandwidth. Suitable for wireless access in densely populated areas.
- LOF Loss of Frame
After the frame out-of-synchronization state lasts for 3 ms, the SDH device should enter the frame loss state; and when the STM-N signal is continuously in the fixed frame state for at least 1 ms, the SDH device should exit the frame loss state.
- LOS Loss of Signal
When the received optical signal power is always below a certain threshold value Pd (Pd corresponds to BER ≥ 10-3) for a given time (10 us or longer), the device enters the LOS state.
- LOP Loss of Pointer
When no valid pointer is found for 8 consecutive frames, or 8 consecutive new data flags (NDF) are enabled, the device should enter the LOP state; and when 3 consecutive valid pointers or cascade indications with normal NDF are detected. This device should exit the LOP state.
- MI Modulation Instability
Modulation instability instantaneously breaks a continuous wave (CW) signal or a pulse, making them a modulated shape. A quasi-monochromatic signal spontaneously produces two symmetric frequency sidebands. This phenomenon may be observed in areas above the zero dispersion wavelength.
- MLCM Multi-Level Coded Modulation
A complex code modulation method can be regarded as a delete trellis coded 64QAM mode. The design idea is the same as TCM, which brings the redundancy generated by the error correction code to the most error-prone symbols to maximize the coding redundancy.
- MMF Multi Mode Fiber
Two or more modes of fiber can be propagated at the wavelengths considered.
- MMDS Multichannel Multipoint Distribution Service
Often referred to as a wireless cable, a wireless system is typically used to transmit image traffic.
- MVDS Multipoint Video Distribution Service
A wireless local loop technology developed by the UK, running at 40.5G to 42.5G, is very similar to LMDS, but is mainly used in video on demand services.
- MQAM Quadrature Amplitude Modulation
Multi-ary quadrature amplitude modulation is a carrier control method widely used in medium and large-capacity digital microwave communication systems. This method has a high spectrum utilization rate. When the modulation number is high, the distribution of the signal vector set is also reasonable, and it is also convenient to implement. At present, 64QAM, 128QAM, etc., which are widely used in large-capacity digital microwave communication systems such as SDH digital microwave and LMDS, belong to this modulation mode.
- MSOH Multiplex Section Overhead
Responsible for managing the multiplex section, which can only be accessed at the terminal device.
- MSP Multiplexer Section Protection
A protection method for SDH optical fiber communication, the service volume of protection is based on the multiplex section, and the switching is determined according to the merits of the multiplex section signal between each node. When the multiplex section fails, the multiplex section service signal between the entire nodes is turned to the protection section.
- MZ Mach-Zehnder
The modulator splits the input light into two equal signals into the two optical branches of the modulator. The materials used in these two optical branches are electro-optic materials whose refractive index varies with the magnitude of the externally applied electrical signal. Since the refractive index change of the optical branch causes a change in the phase of the signal, when the output ends of the two branch signal modulators are combined again, the synthesized optical signal will be an interference signal of varying intensity, equivalent to the electrical signal. The change is converted into a change in the optical signal, and the modulation of the light intensity is achieved.
- NA Numerical Aperture
It indicates the ability of the fiber to receive and transmit light. The larger the NA, the stronger the ability of the fiber to receive light, and the higher the coupling efficiency from the source to the fiber.
- NC Network Connection
Network connections are cascaded by subnet connections and/or link connections and can be seen as an abstract representation of this complex entity. It transparently delivers end-to-end information over a layer network, delimited by a terminal connection point (TCP).
- NEL Network Element Layer
The most basic management layer is responsible for the management of configuration, fault, and performance of a single network element.
- NML Network Management Layer
Manage, monitor, and control the network areas of different manufacturers.
- NE Network Element
The basic unit that constitutes the network.
- NZDSF Non Zero Dispersion Shifted Fiber
Single-mode fiber that meets ITU-TG655 requirements is a dispersion-shifted fiber, but the dispersion is not zero at 1550 nm (according to ITU-TG655, the dispersion value in the range of 1530-1565 nm is 0.1-6.0 ps/nm. Km) to balance nonlinear effects such as four-wave mixing. Commercial fibers are like TrueWave fiber from AT&T, Corning’s SMF-LS fiber (which has a zero-dispersion wavelength of 1567.5 nm, a typical zero dispersion of 0.07 ps/nm2.km) and Corning’s LEAF fiber.
- NNI Network Node Interface
It can be a simple node with only multiplexing functions, or a complex node with transmission, multiplexing, cross-connect, and switching functions.
- OADM Optical Add Drop Multiplexe
Its function is to select the optical signal from the transmission device to the local optical signal, and to send the optical signal of the local user to the user of another node without affecting the transmission of other wavelength channels, that is to say, the OADM is realized in the optical domain. The function of the electrical add/drop multiplexer in the traditional SDH device in the time domain.
- OA&M Operations, Administration and Maintenance
A set of network management features for network performance monitoring, failure detection, and system troubleshooting and protection.
- OFA Optical Fiber Amplifier
It refers to a new all-optical amplifier used in fiber-optic communication lines to achieve signal amplification. According to its position and role in the fiber line, it is generally divided into relay amplification, preamplification and power amplification.
- ODN Optical Distribution Network
Optical distribution network, consisting of passive optical components
- OAN Optical Access Network
Access network technology based on optical transmission
- OBD Optical Branching Device Optical Splitter
Passive optical power splitter (coupler) that distributes the downlink signal and couples the upstream signal
- OLT Optical Line Terminal
Provides an interface between the network side and the local switch, and connects one or more ODN/ODTs to communicate with the ONUs on the user side.
- ONU Optical Network Unit
Provides a user-side interface for the optical access network and is connected to one ODN/ODT.
- OFS Out of Frame Second
A second with one or more OOF events is called OFS.
- OM Optical Multiplex
Multiple wavelengths are multiplexed into one fiber for transmission.
- OMSP Optical Multiplex Section Protect
This technique only performs 1+1 protection on the optical path without protecting the terminal equipment. A 1×2 optical splitter or optical switch is used at the originating end and the receiving end respectively, and the combined optical signal is separated at the transmitting end, and the optical signal is selected at the receiving end. Optical multiplex section protection is only practical if implemented in two separate optical cables.
- OOF Out of Frame
When the position of the frame alignment byte in the input bit stream is not known, the STM-N signal is considered to be in a lost state.
- OSC Optical Supervisory Channel
Complete the transmission of network management, business calls and other information. Transmission is carried out using a single wavelength with a wavelength of 1510 nm.
- O-SNCP Optical Subnetwork Connection Protection
1+1 protection based on the optical channel layer, commonly known as dual-shot selection protection.
- OSNR Optical Signal to Noise Ratio
Optical signal-to-noise ratio is defined as the ratio of optical signal power to noise power over a light effective bandwidth of 0.1 nm. The power of the optical signal generally takes the peak-to-peak value, and the power of the noise generally takes the power level of the intermediate point of the two-phase approach path. Optical signal-to-noise ratio is a very important parameter and is of great significance to estimation and measurement systems.
- OTDM Optical Time Division Multiplexing
Refers to time division (de)multiplexing within the optical domain. Multiplexing is typically achieved using planar waveguide delay line arrays (or planar lightwave circuits PLC) or high-speed optical switches; while all-optical time domain demultiplexers are often based on four-wave mixing (FWM) or nonlinear fiber-optic ring mirrors ( NOLM) and so on.
- OTDR Optical Time Domain Reflectmeter
By analyzing the scattered signal returned by the optical transmission signal in the optical cable, judging the condition of the optical cable is a necessary equipment for maintenance of the optical cable.
- OTN Optical Transmission Net Optical Transport Network
The optical transport network is based on DWDM technology, and uses OADM, OXC and other network elements to connect point-to-point wavelength division multiplexing equipment. Transparent to the transmission rate, data format and modulation scheme, it can transmit ATM, SDH/Sonet and Gigabit Ethernet services with different bit rates.
- OMN Optical Transport Network
The management system of the optical transport network is a subnet of the TMN.
- OTU Optical Transform Unit
The optical signal from the SDH is converted into an optical signal that satisfies the requirements of the wavelength division multiplexing system.
- OXC Optical Cross Connect
It is the most important network component of the optical network. It mainly completes the cross-connect function of the optical channel and the local uplink and downlink functions in the optical transmission layer, and the redistribution of large bandwidth is formed in the network through the loop by the wavelength (Rerouting wavelength). When the cable is disconnected, the optical transport layer acts as a network restoration.
- PA Pre Amplifier
Increase the receiving level and increase the receiver sensitivity.
- PMR Private Mobile Radio
It refers to a professional mobile department, such as the public security, military, water conservancy, railway and other departments that are independently constructed and used only for their own use.
- PON Passive Optical Network
Passive optical networks mainly use passive optical power splitters (couplers) to send information to users. Since the optical power splitter is used to reduce the power, it is suitable for short-distance use.
- PAMR Public Access Mobile Radio
It refers to a mobile communication network where multiple professional departments share frequency, shared equipment, shared coverage area, share costs, and centrally manage and maintain. It can be used as a virtual communication platform for professional departments.
It is a bit that is really used for telecommunication services and stores the channel overhead that can be used for channel maintenance management.
- PCM Pulse Code Modulation
The sampled quantized values of the analog signals are transformed into codes.
- PDH Plesiochronous Digital Hierarchy
It is mainly designed for voice communication. There is no universal standard digital signal rate and frame structure, and international interconnection is difficult.
- PJE Pointer Justification Count
Indicates that the I bit or D bit of the pointer is inverted and mixed with an event of increasing or decreasing the value of the pointer.
- PMD Polarisation Mode Dispersion
Refers to the polarization dispersion in a single-mode fiber. The fundamental mode of the single-mode fiber contains two mutually perpendicular polarization modes. During the propagation of the fiber, the fiber is inevitably affected by external factors such as temperature and pressure. So that the two modes are coupled, and their propagation speeds are not the same, resulting in broadening of the light pulse, and the amount of broadening is also uncertain, which is equivalent to random dispersion. As the transmission rate increases, the effect of the dispersion on the communication system becomes more and more obvious, and it is increasingly impossible to underestimate. There is a literature giving the maximum distance of the system limited by PMD according to the formula: L maximum = 1000 / (PMD. bit rate) 2, where: L unit is (root) km, PMD unit is PS / KM, and bit rate The unit is Gb/s. Some international standards organizations, such as IEC, TIA and ITU, consider the development of statistical properties and corresponding test methods for such random dispersion.
- POS Packet Over SDH POS
It is a technical model of the network, and its network is mainly connected by high-capacity high-end routers via high-speed fiber transmission channels.
- POH Path Overhead
The channel overhead byte for channel maintenance management in the STM-N payload area.
- PON Passive Optical Network
Passive optical networks mainly use passive optical power splitters (couplers) to send information to users. Since the optical power splitter is used to reduce the power, it is suitable for short-distance use.
- PRC Primary Resource Clock
A high-precision, high-stability clock that is distributed to the following levels of clocks via a synchronous distribution network.
- QOS Quality of Service
An ATM performance parameter term describing transmission quality over a given virtual connection. These parameters include: CTD, CDV, CER, CLR, CMR and SECBR, ALL service classes, Qos Classes, traffic contract, traffic control.
- Raman Effect
When a monochromatic light of a frequency f is incident on a substance, scattered light of a frequency such as f±fR and f±2fR other than the frequency f appears in the scattered light, and this phenomenon is called a Raman effect.
- REG Regenerator
A regenerative, relaying device on the transmission line for overcoming waveform distortion caused by dispersion of signal damage, such as dispersion, in the optical path. REG can be divided into three types: 1R, 2R, and 3R.
- RSOH Regenerator Section Overhead
Responsible for managing the regeneration section, accessing the regenerator and terminal equipment.
- Radio channel
Radio channel. A sufficiently wide frequency band for radio communication.
- RTS/CTS Request to Send/ Clear to Send
It is equivalent to a handshake protocol and is mainly used to improve the efficiency when transferring large files. IEEE 802.11 provides the following solution: In the parameter configuration, if the RTS/CTS protocol is used, the access point and the subscriber station adapter simultaneously set the transmission upper limit byte number. The RTS/CTS handshake protocol is initiated once the data to be transmitted is greater than this upper limit.
- 3R Regenration, Reshaping, Retiming
Regeneration ensures that the output power point of each connection is equal enough to reach the next node. Re-shaping eliminates the pulse distortion caused by factors such as excellent dispersion. The retiming eliminates the time domain distortion of the digital pulse so that the downstream clock recovery circuit can accurately receive the signal. 3R eliminates the distortion that the optical signal accumulates in each subnet.
- SBS Stimulated Brillouin Scattering
When the signal light power injected into the fiber exceeds a certain value, a strong forward transmission signal light is converted into a backward transmission. SRS is related to the macroscopic elastic properties of the medium.
- SCP Service Control Point
Terminology used in SS7, in order to provide fast and reliable service, an SCP usually refers to a computer or advanced switch that contains a large database.
- SD Signal Degrade
Refers to the case where the signal has deteriorated beyond a predetermined limit.
- SDH Synchronous Digital Hierarchy
It is a standardized digital signal structure level for synchronous information transmission, multiplexing, add-drop and cross-connect, and transmits synchronous signals on transmission media (such as optical fiber, microwave, etc.).
- SHR Self-healing Hybrid Ring SDH
The SDH network can automatically recover the carried services from failures and failures in a very short period of time without human intervention, so that the user does not feel that the network has failed.
- SDM Space Division Multiplex
Using two optical fibers, the working mode is limited to the 1310 nm area.
- SDXC Synchronous Digital Cross Connector
DXC for SDH provides further controllable VC transparent connectivity and reconnection between ports.
- SES Severely Errored Second
When there is no less than 30% of the error block or at least one defect in a certain second, the second is considered to be a serious error block second.
- SESR Severely Errored Second
The ratio of the number of SESs present at the available time to the total number of seconds for a certain test time.
- SIF Step Index Fiber
The light propagates in a zigzag shape and propagates in the optical fiber. The pulse signal is distorted and has a bandwidth of only 10 MHz.km, which is usually used for short-distance transmission.
- SMF Single Mode Fibre
Only one mode of fiber can be propagated at the wavelength considered.
- SMN SDH Management Network
That is, a subset of TMNs that manage SDH network elements.
- SMS SDH Management Subnetwork SDH
It consists of a series of separate ECCs and associated intra-site data communication links and forms the organic part of the entire TMN. Multiple SMSs form the SMN.
In a discrete nonlinear medium, the envelope is pulsed. Under certain conditions, the envelope is not only transmitted without distortion, but also has the same characteristics as particles. Optical soliton communication can be realized by using the singular characteristics of optical soliton.
- STM Synchronous transfer mode
SDH standardized information structure level, called synchronous transfer module, the most basic module is STM-1, the rate is 155Mb / s.
- SNC Subnetwork Connection
A connection that spans a subnet is called a subnet connection. It can pass information transparently over the subnet, which can be delimited by subnet boundaries.
- SNI Service Network Interface
It is the interface between the wireless local loop system and the switch. It is a digital interface and should meet the access requirements of the PSTN. The interface is implemented in the fog using twisted pair, coaxial cable, microwave or fiber.
- SOH Section Overhead
The extra bytes necessary to ensure normal, flexible, and efficient transmission of information in the SDH frame structure.
- SONET Synchronous Optical Network
SDH’s North American Correspondence, which consists of a set of hierarchical standard digital transmission structures that are suitable for transmission on a variety of adapted payloads on physical media.
- SPM Self-healing Network
The instantaneous change in signal light intensity causes its own phase modulation. This effect is called self phase modulation.
- SRS Stimulated Raman Scattering
Stimulated Raman scattering is a broadband effect associated with the interaction between light and the vibrational modes of silicon atoms. Stimulated Raman scattering causes the signal wavelength to be like a Raman pump with a longer wavelength signal path or spontaneously scattered Raman shifted light. In any case, short-wavelength signals are always attenuated by this process, while long-wavelength signals are enhanced.
- SRP S pace Recycle Protocol
SRP is a stand-alone MAC layer protocol used to activate DPT functions in ring configuration. The SRP MAC layer provides basic functions such as addressing, packet discarding, and bandwidth management through the propagation of SRP-f a and ring-up control information.
- SRS Simulated Raman Scattering
It is an inelastic scattering where the frequency of the light wave is reduced or the energy of the photon is reduced. SRS is related to the optical properties of the medium.
- SPM Self-phase Modulation
In a coherent optical communication system, the refractive index of the fiber is related to the input optical power, which causes the spectrum of the optical pulse to be greatly broadened.
- TETRA Trans European Trunked Radio
The TETRA system is a new open digital trunking standard for both PMR and PAMR. It was officially confirmed by ETSI in 1995 and is widely used by many European manufacturers. It mainly works in the 400MHz band. Currently, only Maconi has launched commercial products for the 800MHz system.
- TCM Trellis Coded Modulation
An advanced coding modulation method that makes full use of the redundancy generated in convolutional coding and the memory effect of Viterbi decoding, so that the encoded signal sequence generated by cascading the encoder and the modulator has the largest Euclidean free distance. And its ideal decoding method should be implemented by Viterbi algorithm.
- TDM Time Division Multiplexing
It is a technique that uses a staggered arrangement of multiple low-speed analog or digital channels to transmit on a high-speed channel.
- TM Terminal Multiplexing
The low-speed branch electrical signal and the 155 Mb/s electrical signal are incorporated into the STM-1 frame structure and are electrically/photo-switched to the STM-1 optical line signal, which is reversed.
- TWF True Wave Fiber
The zero dispersion point is in the short wavelength region below 1530 nm. In the optical amplification region of 1530 to 1565 nm, the dispersion coefficient is 1.3 to 5.8 ps/nm.km. The system operates in the “positive region” of the dispersion of the fiber. In this region, the self-phase modulation effect SPM can compress the pulse width, thereby contributing to the reduction of the dispersion pressure.
- TU Tributary Unit
An information structure that provides an adaptation function between the lower-order channel layer and the higher-order channel layer.
- TUG Tributary Unit Group
Consists of one or more branch units that occupy a fixed, determined position in the high-order VC payload.
- VC Virtual Container
The information structure used to support the SDH channel layer connection is the information terminal of the SDH channel. The encapsulation rate of the virtual container is synchronized with the SDH network, that is, different VCs are synchronized.
Phase changes below 10 Hz are called wandering
- WDM Wavelength Division Multiplexing
The way in which optical signals of different wavelengths are multiplexed into one fiber for transmission (one TDM electrical signal per wavelength) is collectively referred to as wavelength division multiplexing.
- WLL Wireless Local Loop
The wireless access method designed for the access network generally uses frequencies of 1.8 GHz, 800 MHz, 450 MHz, and even 150 MHz, depending on the regional spectrum arrangement. It has the advantages of fast installation speed, flexible installation, low construction investment, low maintenance cost and good safety.
- WRS Wavelength Router Switch
It consists of a wavelength division multiplexer/demultiplexer and an optical switch matrix, which allows the selected optical channel to be directly connected through the optical transmission node or cross-connected with other links, or locally on or off the road.
- WXC Wavelength Cross Connect
A cross-connect device that can be used with a wavelength converter.
- XPIC Cross-polarisation Interference counteracter
A commonly used interference compensation technique in SDH digital microwave communication systems. In the case of SDH microwave transmission, in order to improve the spectrum utilization, it is often necessary to adopt the same channel or insert channel type cross-polarization frequency reuse method, so it is necessary to introduce interference compensation technology between cross-polarization waves. Its implementation is usually implemented in the baseband and IF bands.
- XPM Cross-phase Modulation
A nonlinear optical effect caused by the light field itself when two or more channels use different frequencies while propagating in the fiber.