Patent Application
20230327764
Various embodiments relate to wireless communications.
Optical transport networks (OTN) are commonly used in access nodes for fronthauling, that is, for communication between a centralized radio controller (or centralized baseband unit) of the access node and the remote radio head(s) of the access node. Typically, a small-form pluggable (SFP) module is used, in the centralized radio controller and in the remote radio head(s), for signal conversion from optical signals received via the OTN to electrical signals (and vice versa). The SFP module may also serve to tune the optical frequency (or equally optical wavelength) of signals transmitted over the OTN.
According to an aspect, there is provided the subject matter of the independent claims. Embodiments are defined in the dependent claims.
One or more examples of implementations are set forth in more detail in the accompanying drawings and the description below. Other features will be apparent from the description, drawings and the claims.
In the following, embodiments will be described in greater detail with reference to the attached drawings, in which
The following embodiments are only presented as examples. Although the specification may refer to “an”, “one”, or “some” embodiment(s) and/or example(s) in several locations of the text, this does not necessarily mean that each reference is made to the same embodiment(s) or example(s), or that a particular feature only applies to a single embodiment and/or example. Single features of different embodiments and/or examples may also be combined to provide other embodiments and/or examples.
In the following, different exemplifying embodiments will be described using, as an example of an access architecture to which the embodiments may be applied, a radio access architecture based on long term evolution advanced (LTE Advanced, LTE-A) or new radio (NR, 5G), without restricting the embodiments to such an architecture, however. It is obvious for a person skilled in the art that the embodiments may also be applied to other kinds of communications networks having suitable means by adjusting parameters and procedures appropriately. Some examples of other options for suitable systems are the universal mobile telecommunications system (UMTS) radio access network (UTRAN or E-UTRAN), longterm evolution (LTE, the same as E-UTRA), wireless local area network (WLAN or WiFi), worldwide interoperability for microwave access (WiMAX), Bluetooth®, personal communications services (PCS), ZigBee®, wideband code division multiple access (WCDMA), systems using ultra-wideband (UWB) technology, sensor networks, mobile ad-hoc networks (MANETs) and Internet Protocol multimedia subsystems (IMS) or any combination thereof.
The embodiments are not, however, restricted to the system given as an example but a person skilled in the art may apply the solution to other communication systems provided with necessary properties.
The example of
A communications system typically comprises more than one (e/g)NodeB in which case the (e/g)NodeBs may also be configured to communicate with one another over links, wired or wireless, designed for the purpose. These links may be used for signalling purposes. The (e/g)NodeB is a computing device configured to control the radio resources of communication system it is coupled to. The NodeB may also be referred to as a base station, an access point or any other type of interfacing device including a relay station capable of operating in a wireless environment. The (e/g)NodeB includes or is coupled to transceivers. From the transceivers of the (e/g)NodeB, a connection is provided to an antenna unit that establishes bi-directional radio links to user devices. The antenna unit may comprise a plurality of antennas or antenna elements. The (e/g)NodeB is further connected to core network 110 (CN or next generation core NGC). Depending on the system, the counterpart on the CN side can be a serving gateway (S-GW, routing and forwarding user data packets), packet data network gateway (P-GW), for providing connectivity of user devices (UEs) to external packet data networks, or mobile management entity (MME), etc.
The user device (also called UE, user equipment, user terminal, terminal device, etc.) illustrates one type of an apparatus to which resources on the air interface are allocated and assigned, and thus any feature described herein with a user device may be implemented with a corresponding apparatus, such as a relay node. An example of such a relay node is a layer 3 relay (self-backhauling relay) towards the base station.
The user device typically refers to a portable computing device that includes wireless mobile communication devices operating with or without a subscriber identification module (SIM), including, but not limited to, the following types of devices: a mobile station (mobile phone), smartphone, personal digital assistant (PDA), handset, device using a wireless modem (alarm or measurement device, etc.), laptop and/or touch screen computer, tablet, game console, notebook, and multimedia device. It should be appreciated that a user device may also be a nearly exclusive uplink only device, of which an example is a camera or video camera loading images or video clips to a network. A user device may also be a device having capability to operate in Internet of Things (IoT) network which is a scenario in which objects are provided with the ability to transfer data over a network without requiring human-to-human or human-to-computer interaction. The user device (or in some embodiments a layer 3 relay node) is configured to perform one or more of user equipment functionalities. The user device may also be called a subscriber unit, mobile station, remote terminal, access terminal, user terminal or user equipment (UE) just to mention but a few names or apparatuses.
Various techniques described herein may also be applied to a cyber-physical system (CPS) (a system of collaborating computational elements controlling physical entities). CPS may enable the implementation and exploitation of massive amounts of interconnected ICT devices (sensors, actuators, processors microcontrollers, etc.) embedded in physical objects at different locations. Mobile cyber physical systems, in which the physical system in question has inherent mobility, are a subcategory of cyber-physical systems. Examples of mobile physical systems include mobile robotics and electronics transported by humans or animals.
It should be understood that, in
Additionally, although the apparatuses have been depicted as single entities, different units, processors and/or memory units (not all shown in
5G enables using multiple input-multiple output (MIMO) antennas, many more base stations or nodes than the LTE (a so-called small cell concept), including macro sites operating in co-operation with smaller stations and employing a variety of radio technologies depending on service needs, use cases and/or spectrum available. 5G mobile communications supports a wide range of use cases and related applications including video streaming, augmented reality, different ways of data sharing and various forms of machine type applications, including vehicular safety, different sensors and real-time control. 5G is expected to have multiple radio interfaces, namely below 6 GHz, cmWave and mmWave, and also being integradable with existing legacy radio access technologies, such as the LTE. Integration with the LTE may be implemented, at least in the early phase, as a system, where macro coverage is provided by the LTE and 5G radio interface access comes from small cells by aggregation to the LTE. In other words, 5G is planned to support both inter-RAT operability (such as LTE-5G) and inter-RI operability (inter-radio interface operability, such as below 6 GHz-cmWave, below 6 GHz-cmWave-mmWave). One of the concepts considered to be used in 5G networks is network slicing in which multiple independent and dedicated virtual sub-networks (network instances) may be created within the same infrastructure to run services that have different requirements on latency, reliability, throughput and mobility.
The current architecture in LTE networks is fully distributed in the radio and fully centralized in the core network. The low latency applications and services in 5G require to bring the content close to the radio which leads to local break out and multi-access edge computing (MEC). 5G enables analytics and knowledge generation to occur at the source of the data. This approach requires leveraging resources that may not be continuously connected to a network such as laptops, smartphones, tablets and sensors. MEC provides a distributed computing environment for application and service hosting. It also has the ability to store and process content in close proximity to cellular subscribers for faster response time. Edge computing covers a wide range of technologies such as wireless sensor networks, mobile data acquisition, mobile signature analysis, cooperative distributed peer-to-peer ad hoc networking and processing also classifiable as local cloud/fog computing and grid/mesh computing, dew computing, mobile edge computing, cloudlet, distributed data storage and retrieval, autonomic self-healing networks, remote cloud services, augmented and virtual reality, data caching, Internet of Things (massive connectivity and/or latency critical), critical communications (autonomous vehicles, traffic safety, real-time analytics, time-critical control, healthcare applications).
The communication system is also able to communicate with other networks, such as a public switched telephone network or the Internet 112, or utilise services provided by them. The communication network may also be able to support the usage of cloud services, for example at least part of core network operations may be carried out as a cloud service (this is depicted in
Edge cloud may be brought into radio access network (RAN) by utilizing network function virtualization (NVF) and software defined networking (SDN). Using edge cloud may mean access node operations to be carried out, at least partly, in a server, host or node operationally coupled to a remote radio head or base station comprising radio parts. It is also possible that node operations will be distributed among a plurality of servers, nodes or hosts. Application of cloudRAN architecture enables RAN real time functions being carried out at the RAN side (in a distributed unit, DU 104) and non-real time functions being carried out in a centralized manner (in a centralized unit, CU 108).
It should also be understood that the distribution of labour between core network operations and base station operations may differ from that of the LTE or even be non-existent. Some other technology advancements probably to be used are Big Data and all-IP, which may change the way networks are being constructed and managed. 5G (or new radio, NR) networks are being designed to support multiple hierarchies, where MEC servers can be placed between the core and the base station or nodeB (gNB). It should be appreciated that MEC can be applied in 4G networks as well.
5G may also utilize satellite communication to enhance or complement the coverage of 5G service, for example by providing backhauling. Possible use cases are providing service continuity for machine-to-machine (M2M) or Internet of Things (IoT) devices or for passengers on board of vehicles, or ensuring service availability for critical communications, and future railway/maritime/aeronautical communications. Satellite communication may utilise geostationary earth orbit (GEO) satellite systems, but also low earth orbit (LEO) satellite systems, in particular mega-constellations (systems in which hundreds of (nano)satellites are deployed). Each satellite 106 in the mega-constellation may cover several satellite-enabled network entities that create on-ground cells. The on-ground cells may be created through an on-ground relay node 104 or by a gNB located on-ground or in a satellite.
It is obvious for a person skilled in the art that the depicted system is only an example of a part of a radio access system and in practice, the system may comprise a plurality of (e/g)NodeBs, the user device may have an access to a plurality of radio cells and the system may comprise also other apparatuses, such as physical layer relay nodes or other network elements, etc. At least one of the (e/g)NodeBs or may be a Home(e/g)nodeB. Additionally, in a geographical area of a radio communication system a plurality of different kinds of radio cells as well as a plurality of radio cells may be provided. Radio cells may be macro cells (or umbrella cells) which are large cells, usually having a diameter of up to tens of kilometers, or smaller cells such as micro-, femto- or picocells. The (e/g)NodeBs of
For fulfilling the need for improving the deployment and performance of communication systems, the concept of “plug-and-play” (e/g)NodeBs has been introduced. Typically, a network which is able to use “plug-and-play” (e/g)Node Bs, includes, in addition to Home (e/g)NodeBs (H(e/g)nodeBs), a home node B gateway, or HNB-GW (not shown in
6G networks are expected to adopt flexible decentralized and/or distributed computing systems and architecture and ubiquitous computing, with local spectrum licensing, spectrum sharing, infrastructure sharing, and intelligent automated management underpinned by mobile edge computing, artificial intelligence, short-packet communication and blockchain technologies. Key features of 6G will include intelligent connected management and control functions, programmability, integrated sensing and communication, reduction of energy footprint, trustworthy infrastructure, scalability and affordability. In addition to these, 6G is also targeting new use cases covering the integration of localization and sensing capabilities into system definition to unifying user experience across physical and digital worlds.
As described above, the access node operations may be carried out, at least partly, in a server, host or node operationally coupled to a remote radio head (equally called a radio head or radio unit). Said server, host or node may be called, for example, central or centralized unit, a central or centralized radio controller or a central or centralized baseband unit (BBU). The access node 104 of
The system 200 of
Referring to
The SFP module 202 (equally called the SFP transceiver) is a compact, hot-pluggable network interface module for carrying out signal conversion from an optical signal to an electrical signal (in reception) and from an electrical signal to an optical signal (in transmission).
The SFP module 202 may operate, at a given time, at particular channel having a particular channel number. Each channel may be associated with a particular optical wavelength (or equally a particular optical frequency). It should, therefore, be noted that the terms “channel” (or “channel number”), “optical wavelength” and “optical frequency” may be used, in many cases, in the context of the embodiments interchangeable as selecting or changing a value for one of the three quantities uniquely defines the values of the other two quantities. The mapping between channel numbers and optical wavelengths may follow an ITU (International Telecommunication Union) standard. This mapping may be assumed to be known to the host 201 as well as to any other host(s) of peer nodes.
The SFP module 202 may be, in particular, a tunable SFP module (TSFP) 202, that is, an SFP module whose (operating) channel/optical wavelength/optical frequency can be changed dynamically.
The SFP module 202 may be plugged into an SFP cage (not shown in
The SFP module 202 may comprise at least an optical transceiver 204 for carrying out said signal conversion from optical to electrical and vice versa and hardware logic and/or microcontroller 205 for controlling the optical transceiver 204. The microcontroller 205 may optionally also provide some diagnostic features. The optical transceiver 204 and the hardware logic and/or microcontroller 205 are connected to each other via at least one interface 214. The optical transceiver 204 comprises an optical transmitter 207 for performing electrical-to-optical (E/O) conversion in transmission and an optical receiver 208 for performing optical-to-electrical (O/E) conversion in reception. The optical transmitter 207 comprises at least an E/O converter (comprising a transmit laser), and the optical receiver 208 comprises at least an O/E converter (comprising a receiver photo diode). The optical transceiver 204 (i.e., each of the optical transmitter and receiver 207, 208) is connected to a cable or fiber connector 206 of the SFP module 202. The cable or fiber connector 206 enables connecting the SFP module 202 (or specifically the optical transceiver 204 thereof) to an optical cable or fiber of an optical transport network (OTN).
The host 201 may be equally called a computing device, a server or simply an apparatus. The host 201 may comprise one or more separate (computing) devices. The host 201 is configured to execute, in communication with the SFP module 202, a wavelength/channel tuning (or selection) algorithm according to embodiments, as will described in detail in connection with the following Figures.
The host 201 is configured to communicate with the SFP module 202 via the interfaces 211, 212, 213. Namely, the host 201 is connected to the optical transceiver 204 via a first interface 211 and to the hardware logic and/or microcontroller 205 via second and third interfaces 212, 213.
The first interface 211 may be specifically a (serial) high-speed (physical) interface such as a serializer/deserializer (SerDes) interface. The high-speed interface 211 may be used for reception of electrical signals from the optical receiver 208 and transmission of electrical signals to the optical transmitter 207 (for further transmission via the OTN after E/O conversion). The term “high-speed interface” may be defined, here and in the following, as an interface providing a symbol rate of multiple gigabauds.
The second interface 212 may be specifically a (serial) low-speed (physical) interface such as an inter-integrated circuit (I2C) interface. The low-speed interface 212 may be used for accessing internal memory banks of the SFP module 202. The low-speed interface 212 may be used for accessing digital diagnostic and monitoring features of the SFP module 202. The memory allocation and register settings may be standardized. Optionally, some of the registers of the SFP modules 202 may be configurable. The serial clock rate may be up to 100 kHz. The low-speed interface 212 may have a (maximum) symbol (or data) rate lower than the high-speed interface 211.
In some embodiments, the low-speed interface 212 may be a low-speed interface according to MSA (multiple source agreement) SFF-8419 standard.
The third interface 213 may be an interface for connecting to one or more (dedicated) hardware pins of the hardware logic 205. The one or more hardware pins provide access to specific SFP module functions by hardware. For example, one hardware pin may indicate the status of the SFP module 202 while another may be used to change the status, e.g., hardware pin for enabling/disabling laser of the optical transmitter 207 of the SFP module 202.
As mentioned above, the SFP module 202 may be specifically a tunable SFP module (or configurable SFP module). The term “tunable” refers here specifically to tunability of the optical frequency (or equally of the optical wavelength or channel). The optical frequency (or equally optical wavelength) of the transmitted and/or received signals may be configurable (by a user) using the host 201. The configuration of the optical frequency may be achieved, e.g., via a separate management interface (not shown in
As described in connection with
It should be noted that the interfaces 311 to 317 of
Referring to
Similarly, the signalling on the C-plane is also enabled via the one or more hardware pins over the third logical interface 313 and/or via the (serial) low-speed I2C interface over the fourth logical interface 314. As mentioned above, there may be no strict separation between M- and C-planes so that the same low-speed I2C interface and/or the same one or more HW pins are used for both M- & C-plane signaling. Any signal/register that is used for control (i.e., for control requests) may be mapped to the C-plane. Thus, the SFP module 302 may be controlled via the one or more hardware pins and/or the low-speed I2C interface (or bus). For example, a particular hardware pin may be used for keeping a transmit laser of an optical transmitter of the SFP module 302 in an off state in hardware while a particular register may be used for keeping said transmit laser off using I2C/in software.
The signalling on the U-plane is enabled via fifth, sixth and seventh logical interfaces 315 to 317 corresponding to the high-speed interface (being, e.g., a SerDes interface). Three options may exist here:
In
The Ethernet protocol 405 may be used at least for establishing a communication path between peer nodes, i.e., between far-end and near-end nodes.
The User Datagram Protocol (UDP)/Internet Protocol (IP) 404 may provide access to the host via IP addressing and a dedicated UDP port.
The tunable SFP algorithm 401 according to embodiments (to be discussed in detail) enables frequency (or wavelength) tuning functionality for the SFP module 402. This may comprise the frequency (wavelength/channel) detection and configuration.
The TSFP O&M function 403 may be used for configuring the protocol stack and/or the tunable SFP module 402.
The modulation protocol 406 has direct access to the physical layer 402. The TSFP messages are modulated for communication via high-speed and/or low-speed interfaces.
Based on
Initially, the first host may select, in block 501, a first channel for transmission via the first tunable SFP module over the OTN (i.e., over an optical fiber). The first channel is associated with (or uses) a first optical wavelength (and equally with a first optical frequency). The selection of the first channel in block 501 may be performed from a plurality of channels supported by the first tunable SFP module, where the plurality of channels may be associated, respectively, with a plurality of (different) optical wavelengths. The first channel has a first channel number (being, e.g., a positive or at least non-negative integer such as 1 or 4). The selection in block 501 may be carried out based on a pre-defined list or lookup table defining said plurality of channels stored in a memory. For example, the first host may select the initial or next channel/wavelength in said list or lookup table.
Moreover, the first host may configure or command, in block 501, the first tunable SFP module to use the first channel (and thus the first optical wavelength) for transmission. The configuring/commanding in block 501 may be carried out, e.g., using a management interface of the tunable SFP module.
The first host (forms and) transmits, in message 502, a first notification message via the first tunable SFP module over the OTN on the first channel to the second host by applying on-off keying to an optical transmitter (or a transmit laser) of the first tunable SFP module. Here, the first notification message comprises at least information on the first channel (and the associated first optical wavelength). The information on the first channel may comprise at least information enabling (unique) identification of the first channel (e.g., the first channel number, the first optical wavelength and/or the first optical frequency). The first notification message may further comprise a first message type identifier identifying the first notification message as a notification and/or cyclic redundancy check information. Additionally or alternatively, the first notification message may comprise one or more pilot bits for indicating a start of a frame.
The first notification message may comprise or correspond to a frame (possibly followed by a guard bit). The first notification message may have a pre-defined frame format. In some embodiments, the first notification message 502 may have a pre-defined frame format described in detail below in connection with
On-off keying is, in general, a simplistic form of amplitude-shift keying (ASK) modulation where digital data is represented as the presence or absence of a carrier wave. In its simplest form, the presence of a carrier for a pre-defined duration (known by the first and second hosts) represents a logical one while its absence for the same pre-defined duration represents a logical zero. Here, the on-off keying is implemented by switching on/off the optical transmitter (or specifically the transmit laser) of the first tunable SFP module.
The second host receives, in block 503, the first notification message via the second tunable SFP module over the OTN from the first host as an on-off keyed transmission (or on-off keyed bitstream).
The second host evaluates (i.e., decodes), in block 504, the first notification message for acquiring the information on the first channel. In reception, the rising edge of the transmitted bit stream may correspond to a switch from a logical zero to a logical one and consequently the falling edge may correspond to a switch from a logical one to a logical zero. The second host may store said information on the first channel to at least one memory of the second host.
The second host transmits, in message 505, a first notification response message via the second tunable SFP module over the OTN on a second channel to the first host by applying on-off keying to an optical transmitter of the second tunable SFP module. The second channel is associated with a second optical wavelength (and a second optical frequency). The first notification response message 505 is transmitted so as to inform the first host that the information on the first channel/wavelength was successfully communicated to the second host. The first notification response comprises at least the information on the first channel. The second channel/wavelength correspond to a transmit channel/wavelength of the second node. The first notification response message may further comprise a second message type identifier identifying the first notification response message as a notification response and/or cyclic redundancy check information. Additionally or alternatively, the first notification response message may comprise one or more pilot bits for indicating a start of a frame. The first notification response message may comprise or correspond to a frame (possibly followed by a guard bit). The first notification response message 505 may have the same pre-defined frame format as the first notification message 502.
In some embodiments, the second channel used for transmission of the first notification response message 505 may be determined based on the information on the first channel (e.g., via a pre-defined mapping between the two channels).
The first host receives, in block 506, the first notification response message via the first tunable SFP module over the OTN from the second host as an on-off keyed transmission on the second channel. The first host evaluates (i.e., decodes), in block 507, the first notification response message for acquiring the information on the first channel (i.e., information that the first channel and the associated first optical wavelength are usable for transmission to the second host). Also here, the rising edge of the transmitted bit stream may correspond to a switch from a logical zero to a logical one and consequently the falling edge may correspond to a switch from a logical one to a logical zero. The first host may store, in response to the evaluating in block 507, said information on the first channel communicated in the first notification response message to at least one memory of the first host.
The transmission of the notification message (message 502) and reception of the first notification response message (in block 506) in
The reception of the notification message (block 503) and transmission of the first notification response message (in message 505) in
The signalling shown in
Following the successful reception/evaluation of the first notification response message in blocks 506, 507, the first host may terminate the channel/wavelength selection procedure for the first channel and configure the first channel/wavelength (for enabling “normal” transmissions on the first channel). The termination may be stateful, that is, the first host may be storing, in at least one memory, all (relevant) channel/wavelength selection related information.
While above, in connection with
Similar to
Referring to
The second host transmits, in message 512, a second notification message via the second tunable SFP module over the OTN on the second channel to the first host by applying on-off keying to an optical transmitter of the second tunable SFP module. The second notification message comprises at least information on the second channel.
The first host receives, in block 513, the second notification message via the first tunable SFP module over the OTN from the second host as an on-off keyed transmission on the second channel. The first host evaluates, in block 514, the second notification message for acquiring the information on the second channel and transmits, in message 515, a second notification response message via the first tunable SFP module over the OTN on the first channel to the second host by applying on-off keying to the optical transmitter of the first tunable SFP module. Here, the second notification response message comprises at least the information on the second channel.
The second host receives, in block 516, the second notification response message via the second tunable SFP module over the OTN from the first host as an on-off keyed transmission on the first channel or on a second channel associated with a second optical wavelength. The second notification response message comprises at least the information on the second channel. Finally, the second host evaluates, in block 517, the second notification response message for acquiring the information on the second channel (indicating to the second host that the second channel is usable for transmission to the first host.
Following the successful reception/evaluation of the second notification response message in blocks 516, 517, the second host may terminate the channel/wavelength selection procedure for the second channel and configure the second channel/wavelength (for enabling “normal” transmissions on the second channel). The termination may be stateful, that is, the second host may be storing, in at least one memory, all (relevant) channel/wavelength selection related information.
The processes of
The processes of
When using bidirectional communication, one of the first and second peer nodes is configured to act as a primary node (i.e., a transmitting node) and the other as a secondary node (i.e., a receiving or listening node) at any given time. Thus, for bidirectional communication, transmitting operation may be in a halted or suspended state, at any given time, for at least one of the two peer nodes. The primary node is configured to transmit notification message(s) on a transmit channel(s) while the secondary node is configured not to transmit notification messages (or any other messages via the OTN) but only to listen and await reception of notification messages. Once the secondary node has received a valid notification message comprising the information on an associated transmit channel, the secondary node may leave the listener mode by configuring the acquired transmit channel or a channel paired with the acquired transmit channel to the tunable SFP module (i.e., it may start acting as a primary node). Then, this new primary node may transmit a notification response message (comprising the information on the acquired transmit channel) on the configured channel and optionally also start transmitting notification messages and awaiting the corresponding notification response messages. Correspondingly, the previous primary node may start listening for reception of the notification response message as well as any notification messages (i.e., it may start acting as a secondary node). This process may subsequently be repeated for the reverse direction (i.e., the procedure of
As implied in the previous paragraph, bidirectional communication may employ paired channels at the first and second peer nodes so that a first channel assigned for communication from a first peer node to a second peer node (i.e., from a first host to a second host) may determine a second channel assigned to the opposite direction. In other words, each first channel may be mapped to a particular (different) second channel (and vice versa). In other cases, the same channel may be employed for both transmission directions.
The channel/wavelength selection procedures as described above in connection with
Referring to
In response to reception and successful evaluation of the notification response message (and thus selection/configuration of the first channel for transmission), the first host initiates the acknowledgment procedure for the first channel by transmitting, in message 602, a first acknowledgment message via the first tunable SFP module over the OTN on the first channel to the second host by applying on-off keying to the optical transmitter of the first tunable SFP module. The transition into the acknowledgement procedure may be stateful, i.e., the first host may store any channel/wavelength selection related information. The first acknowledgment message comprises at least information on the first channel (i.e., the same information which was included in the notification and notification response messages previously). The first acknowledgment message 602 may further comprise a third message type identifier identifying the first acknowledgment message as an acknowledgment and/or cyclic redundancy check information. Additionally or alternatively, the first acknowledgment message 602 may comprise one or more pilot bits for indicating a start of a frame. The first acknowledgment message 602 may have the same frame format as the notification message (message 502) and the notification response message (message 505).
The second host receives, in block 603, the first acknowledgment message via the second tunable SFP module over the OTN from the first host as an on-off keyed transmission (or on-off keyed bitstream).
The second host evaluates (i.e., decodes), in block 604, the first acknowledgment message for acquiring information that the first channel has been successfully selected (and configured) by the first host.
The second host transmits, in message 605, a first acknowledgment response message via the second tunable SFP module over the OTN on the second channel associated with the second optical wavelength (or, in some embodiments, on the first channel) to the first host by applying on-off keying to the optical transmitter of the second tunable SFP module. The first acknowledgment response message 605 is transmitted so as to inform the first host that the acknowledgment for the first channel/wavelength was successfully communicated to the second host. The acknowledgment response comprises at least the information on the first channel. The first acknowledgment response message may further comprise a fourth message type identifier identifying the first acknowledgment response message as an acknowledgment response and/or cyclic redundancy check information. Additionally or alternatively, the first acknowledgment response message may comprise one or more pilot bits for indicating a start of a frame. The first acknowledgment response message 605 may have the same pre-defined frame format as the first acknowledgment message 602.
The first host receives, in block 606, the first acknowledgment response message via the first tunable SFP module over the OTN from the second host as an on-off keyed transmission on the second channel (or on the first channel). The first acknowledgment response message comprises at least the information on the first channel.
The first host evaluates (i.e., decodes), in block 607, the first acknowledgment response message for acquiring the information on the first channel (i.e., information that the acknowledgment procedure for the first channel and the associated first optical wavelength has been successfully completed).
The transmission of the first acknowledgment message (message 602) and reception of the first acknowledgment response message (in block 606) in
The reception of the first acknowledgment message (block 603) and transmission of the first acknowledgment response message (in message 605) in
Following the successful reception/evaluation of the first acknowledgment response message in blocks 606, 607, the first host may terminate the acknowledgment procedure for the first channel and configure the first channel (for enabling “normal” transmissions on the first channel). The termination may be stateful, that is, the first host may be storing, in at least one memory, all channel/wavelength selection related information.
The process described in connection with elements 602 to 607 of
The second host initiates the acknowledgment procedure for the second channel by transmitting, in message 608, a second acknowledgment message via the second tunable SFP module over the OTN on the second channel to the first host by applying on-off keying to the optical transmitter of the second tunable SFP module.
The first host receives, in block 609, the second acknowledgment message via the second tunable SFP module over the OTN from the second host as an on-off keyed transmission (or on-off keyed bitstream).
The first host evaluates (i.e., decodes), in block 610, the second acknowledgment message for acquiring information that the second channel has been successfully selected (and configured) by the second host.
The first host transmits, in message 611, a second acknowledgment response message via the second tunable SFP module over the OTN on the first channel associated with the first optical wavelength (or, in some embodiments, on the second channel) to the second host by applying on-off keying to the optical transmitter of the first tunable SFP module. The first acknowledgment response message 611 is transmitted so as to inform the second host that the acknowledgment for the second channel/wavelength was successfully communicated to the first host.
The second host receives, in block 612, the second acknowledgment response message via the first tunable SFP module over the OTN from the first host as an on-off keyed transmission on the first channel (or on the second channel).
The second host evaluates (i.e., decodes), in block 613, the second acknowledgment response message for acquiring the information on the second channel (i.e., information that the acknowledgment procedure for the second channel and the associated second optical wavelength has been successfully completed).
The process of
The signalling shown in
The transition into the acknowledgement procedure may be triggered only after a successful completion of channel/wavelength selection procedure (for one or both transmit directions), as described above.
The transition into the acknowledgement procedure may be stateful, i.e., the sending entity (i.e., the first/second host) is storing all wavelength/channel selection related information.
If the acknowledgment procedure fails for any reason, the channel/wavelength selection procedure may be (re)triggered. The acknowledgment procedure may fail, for example, if the first host fails to transmit the acknowledgment message or receive the acknowledgment response message or the second host fails to receive or respond to the acknowledgment message. In any of said failure cases, the host (or peer) detecting the failure may return to the channel/wavelength selection procedure.
After a return to the channel/wavelength selection procedure, the host (or peer) may resume at the last channel used before leaving the channel/wavelength selection procedure (i.e., the last channel using which the channel/wavelength selection procedure was carried out successfully). For this purpose, the peer shall maintain a stateful leave from the channel/wavelength selection procedure.
In some embodiments, a host (or a peer node) may reinitialize (i.e., start from the beginning) the channel/wavelength selection procedure once a pre-defined number or list of different channels/wavelengths has been covered.
In some embodiments, a host (or a peer node) may leave the acknowledgment procedure stateless, i.e., the peer may reuse latest/newest information when (re)entering the acknowledgment procedure. Therefore, there is no need to backup previous/older information.
In general, the pre-defined frame format 700 may have at least the following information elements:
More specifically and referring, in particular, to the example of
The frame 700 may have be a 32 bit frame. The least significant bit (LSB) may be the bit 0, and the most significant bit (MSB) may be the bit 31. The frames may be transferred in Big-Endian order.
As the sending/receiving of messages in binary format according to embodiments is asynchronous, i.e., there is no synchronization channel that can be used for indicating the start and end of a message, a separate pilot information element 701, 703 indicating the start of the frame is provided in the frame. The pilot information element 701, 703 may have a size of 5 bits. The pilot information element may be fragmented into a first pilot information element 701 (directly) preceding the message type identifier 702 and a second pilot information element 703 (directly) following the message type identifier 702. The pilot information element 701, 703 may be pre-defined and constant. The first pilot information element 701 may have a size of 3 bits while the second pilot information element 703 may have a size of 2 bits.
The message type identifier 702 may have a size of at least 3 bits. Unique message type identifiers may be defined at least for the notification message, the notification response message, the acknowledgment message and the acknowledgment response message.
The channel information element 704 may have a size of 16 bits. This element 704 may comprise, e.g., information on a channel number, an optical wavelength of the channel and/or an optical frequency of the channel. In an embodiment, the channel information element 704 comprises (or consists of) said information on the optical wavelength.
The CRC information element 705 may be, for example, a CRC8 information element. The CRC8 information element 705 may have a size of 8 bits. A first (transmitting) host may calculate the CRC8, append it to the message frame (as shown in
In other embodiments, the CRC information element 705 may be a CRC16 or CRC 32 information element.
It should be emphasized that the sizes of the information elements provided above are merely exemplary. Other sizes may be employed in other embodiments. The features described in connection with
As described above, a host (or a peer node) is configured to compile message frames and to sending these towards another host (another peer node) over the OTN. Notification messages may be, in most cases, transmittable without delay though, at some point in time, notification response messages also need to be transmitted. Thus, each host (or peer node) should configure and schedule transmission of frames.
The first (transmitting) host (or equally the first peer node) may start the channel/wavelength selection procedure at channel #1 801, unless otherwise configured. As described above, the first host may be stateful, i.e., it may perform bookkeeping so as to store all relevant information (e.g., which channel/wavelength is configured, which message type has been sent out and/or which message type has been received). This stateful approach enables returning to the channel/wavelength selection procedure following a failure of the acknowledgment procedure.
Each of the three frames shown in
Specifically, the frame 1814 corresponds to a notification message and comprises information a first channel (associated with a first wavelength and being usable for transmission from the first host to the second host over the OTN). The frame 1 814 is transmitted, first, on selected & configured channel #1 811. Then, before continuing with the next channel (i.e., the channel #2 812), the first (transmitting) host (compiles and) further transmits the frame 2 815 comprising information on a second channel (associated with a second wavelength and being usable for transmission from the second host to the first host over the OTN) on the same channel #1 811 as the previous frame 1814. In other words, the frame 1 814 (being a notification message frame) is clustered with the frame 2 815 (being a notification response message frame) to form the first cluster.
Following the transmission of the frames 1 & 2 814, 815 forming (with a guard bit 818) the first cluster, the first (transmitting) host selects and configures the channel #2 812 (being the next channel following the channel #1 811). Then, the first host transmits the frame 3 816 (being a notification message frame) and the frame 4 817 (being a notification response message frame) on the channel #2 812 in a similar manner as described above for the frames 1 & 2 814, 815.
Each of the four frames 814 to 817 shown in
The clustering principle illustrated in
The clustering principles discussed in connection with
As described in connection with above embodiments, the frame content may be transferred in a format of consecutive transferred bits, i.e., as a bitstream. The bitstream comprises transmitted logical ones and logical zeros. A logical one (i.e., a bit 1) may correspond to the case where an optical transmitter (or equally a laser or a laser diode) of a tunable SFP module is switched on (for a pre-defined amount of time corresponding to a bit duration) while a logical zero (i.e., a bit 0) may refer to the case where the optical transmitter of the tunable SFP module is switched off (for the pre-defined amount of time). On the receiving side, a rising edge of the received signal may correspond to a switch from a logical zero to a logical one and consequently a falling edge of the received signal may correspond to a switch from a logical one to a logical zero.
The bitrate and implicitly the bit duration may be assumed to be constant and known by both peer nodes (i.e., by both hosts). In some embodiments, the bitrate/-duration may be configurable. In such embodiments, both peer nodes need to know the new bitrate/-duration when it is changed.
For the transmit side, the transmitting of the bitstream is relative straightforward. The transmitting peer node (or host) may simply read the bits of a bitstream one-by-one and configure the optical transmitter to switch on/off accordingly.
For a constantly changing bit stream (e.g., 0xAA=10101010) in reception, the correct detection of the bitstream is also a relative straightforward task as each bit corresponds to a rising or falling edge. However, if at least two consecutive bits are received consecutively, the detection is somewhat more complicated due to the fact that received amplitude does not change when the received bit value does not change. In such a case, the receiving peer node (or host) must measure the time between the rising and the falling edge in the bitstream. The measured time must be divided by the bit duration. The outcome of the division is the number of received bits corresponding to a logical zero or one.
However, as the transmission of a logical zero corresponds to transmitting no signal (i.e., the optical transmitter is off), the correct interpretation of a pause in the transmitted bitstream is not straightforward. Namely, lack of signal reception may be interpreted to be caused by one of multiple different valid reasons.
Lack of signal reception may be due to an ongoing transmission of two or more logical zeros. In other words, the receiving peer node (or host) may be still measuring the time to a rising edge (indicating a logical one) following an earlier detection of a falling edge. It should be noted that the rising edge may not be received within the current cluster at the current frequency (N) but, instead, at the next cluster/frequency (N+1). In such a case, the receive side will not even detect the least significant bit of the cluster at the current frequency (N).
To overcome the problem mentioned in the previous paragraph, a so-called guard bit may be introduced to the transmitted clusters. The guard bit has value equal to a logical one XOR'ed with the least significant bit of the bitstream within a given cluster (i.e., 1⊕LSB0). Due to the guard bit, every cluster will be terminated either with a rising edge if the LSB is bit 0 or with a falling edge if the LSB is bit 1. Only after the guard bit has been processed, the transmit side is allowed to switch/change to a new channel (i.e., to a new optical wavelength or frequency). The use of guard bits 806, 807, 808, 818, 819 is shown in
Another reason for a lack of signal reception may be that the transmission of the bitstream has stopped due to a change of the frequency (or equally a change of channel or optical wavelength) at transmit side (i.e., at a transmitting peer node or host). In other words, the receive side (i.e., a receiving peer node or host) may be still measuring the time to a rising edge (indicating a logical one) following an earlier detection of a falling edge, but no rising edge is detected at the appropriate time due to said change of frequency at the transmitting end. In such a case, the receive side may continue measuring the time until a rising edge is detected at the next cluster (corresponding to the next channel/frequency/wavelength N+1), when the transmit side is configured again to a frequency which allows the transfer of the bitstream. The problem at the receiving side is that the receiving peer node or host does not have any knowledge of the unavailability of the transmit path. If the receiving peer node or host calculates the number of consecutively received logical zeros, the calculated number will be very high. Almost all of said logical zeros (all except one which is the LSB of the previous cluster) are, however, false logical zeros resulting from the unavailability of the transmit path.
To overcome the problem described in the previous paragraph, a so-called discard timer may be implemented in the receiving side (i.e., a host of the receiving side). The discard timer may count the time from a falling edge (i.e., a change from 1 to 0) to a pre-defined time limit. When the discard timer expires (i.e., the time matches or exceeds the pre-defined time limit), the receiving side (i.e., the host) discards the measured time. The pre-defined time limit for the discard timer may be n times the bit duration, where n is a positive integer larger than two. For example, n may have a value of 16. Here, the assumption is that, if at least 16 bits having the value 0 are received consecutively, a transmission has been missed (with a high likelihood). The discard timer may be a hardware timer.
The blocks, related functions, and information exchanges (messages) described above by means of
The apparatus 901 may comprise one or more communication control circuitry 920, such as at least one processor, and at least one memory 930, including one or more algorithms 931, such as a computer program code (software) wherein the at least one memory and the computer program code (software) are configured, with the at least one processor, to cause the apparatus to carry out any one of the exemplified functionalities of the apparatus or the (first/second) host described above. Said at least one memory 930 may also comprise at least one database 932.
Referring to
Referring to
Referring to
As used in this application, the term ‘circuitry’ may refer to one or more or all of the following: (a) hardware-only circuit implementations, such as implementations in only analog and/or digital circuitry, and (b) combinations of hardware circuits and software (and/or firmware), such as (as applicable): (i) a combination of analog and/or digital hardware circuit(s) with software/firmware and (ii) any portions of hardware processor(s) with software, including digital signal processor(s), software, and memory(ies) that work together to cause an apparatus, such as a terminal device or an access node, to perform various functions, and (c) hardware circuit(s) and processor(s), such as a microprocessor(s) or a portion of a microprocessor(s), that requires software (e.g. firmware) for operation, but the software may not be present when it is not needed for operation. This definition of ‘circuitry’ applies to all uses of this term in this application, including any claims. As a further example, as used in this application, the term ‘circuitry’ also covers an implementation of merely a hardware circuit or processor (or multiple processors) or a portion of a hardware circuit or processor and its (or their) accompanying software and/or firmware. The term ‘circuitry’ also covers, for example and if applicable to the particular claim element, a baseband integrated circuit for an access node or a terminal device or other computing or network device.
In an embodiment, at least some of the processes described in connection with
According to an embodiment, there is provided a first apparatus comprising means for:
According to an embodiment, there is provided a second apparatus comprising means for:
Embodiments as described may also be carried out in the form of a computer process defined by a computer program or portions thereof. Embodiments of the methods described in connection with
Even though the embodiments have been described above with reference to examples according to the accompanying drawings, it is clear that the embodiments are not restricted thereto but can be modified in several ways within the scope of the appended claims. Therefore, all words and expressions should be interpreted broadly and they are intended to illustrate, not to restrict, the embodiment. It will be obvious to a person skilled in the art that, as technology advances, the inventive concept can be implemented in various ways. Further, it is clear to a person skilled in the art that the described embodiments may, but are not required to, be combined with other embodiments in various ways.
| Number | Date | Country | Kind |
|---|---|---|---|
| 20225317 | Apr 2022 | FI | national |
