WO2017071759A1

WO2017071759A1 - Communication network control method and controller

Info

Publication number: WO2017071759A1
Application number: PCT/EP2015/075129
Authority: WO
Inventors: Fabio Cavaliere; Paola Iovanna; Stefano STRACCA; Stefano Ruffini
Original assignee: Telefonaktiebolaget Lm Ericsson (Publ)
Priority date: 2015-10-29
Filing date: 2015-10-29
Publication date: 2017-05-04

Abstract

A method (10) of controlling a communication network comprising a transport network and a radio network comprising a plurality of radio network nodes connected through the transport network. The method comprises: a. receiving (12) from the transport network available timing service information, ATSI, for a proposed path between a first one of the radio network nodes and a second one of the radio network nodes through the transport network, the proposed path being selected in relation to an event within the transport network; b. comparing (14) the ATSI with minimum timing service information, MTSI, of the proposed path; c. if the ATSI is worse than the MTSI, determining (16) whether an alternative one of the radio network nodes may perform a function performed by one of the first and second radio network nodes; and d. if so, selecting (18) a further proposed path between the alternative one of the radio network nodes and the other of the first and second radio network nodes through the transport network.

Description

COMMUNICATION NETWORK CONTROL METHOD AND CONTROLLER

Technical Field

The invention relates to a method of controlling a communication network comprising a transport network and a radio network and to a method of controlling a radio network comprising a plurality of radio network nodes connected through a transport network. The invention further relates to a communication network controller for a communication network comprising a transport network and a radio network, a radio network controller for a radio network comprising a plurality of radio network nodes connected through a transport network and a communication network comprising a transport network and a radio network.

Background

A Radio Base Station, RBS, can be functionally separated into a Digital Unit, DU, which generates and processes a digitized baseband radio frequency, RF, signal, and a Radio Unit, RU, which creates the analog RF signal from the baseband signal and delivers it to an antenna, and respectively digitizes RF signals received from the antenna. The DU and RU may be placed in two different locations, in what is referred to as a split RBS. The remote RU , RRU , is connected to the DU by what is known as a fronthaul connection, which may be a link or a network. Fronthaul links typically use a digital interface, for example the Common Public Radio Interface, CPRI , interface defined in CPRI Specification V6.0, in which amplitude and phase, I and Q, radio signals are sampled, digitized, encoded and sent across an optical fibre link together with data used for Operations, Administration and Management, OAM, and synchronization. CPRI is very sensitive to timing parameters such as latency, jitter and difference between upstream and downstream delay.

The new 5G generation of mobile networks could lead to review the radio protocols split between DU and RRU, with the main purpose to save bandwidth compared to CPRI . This does not necessarily lead to a relaxation of timing requirements, for at least two reasons: split options that do not relocate medium access control, MAC, and radio link control, RLC, protocols are as latency sensitive as CPRI ; and 5G end-to-end latency can be as low as 1 ms in the most time sensitive scenarios.

Mitigating interference between neighbouring cells in a mobile network requires some form of coordination between the cells. Fast coordination can be achieved among RRUs to be coordinated and connected through fronthaul links to a single baseband processing node. Otherwise, coordination between two macro evolved Node Bs, eNBs, or a macro eNB and its small cells can be implemented by exploiting the link used for backhaul, when slower coordination times are acceptable. Finally, direct connection between eNBs, usually referred as midhaul, guarantees intermediate coordination performance. DU and RRU are currently connected by point to point fibre links but there is a growing interest in deploying more complicated network architectures including point-to-multipoint architectures, typical of the fixed access infrastructure, to DWDM ring or meshed networks.

Summary

It is an object to provide an improved method of controlling a communication network comprising a transport network and a radio network. It is a further object to provide an improved method of controlling a radio network comprising a plurality of radio network nodes connected through a transport network. It is a further object to provide an improved communication network controller for a communication network comprising a transport network and a radio network. It is a further object to provide an improved radio network controller for a radio network comprising a plurality of radio network nodes connected through a transport network. It is a further object to provide an improved communication network comprising a transport network and a radio network.

One aspect of the invention provides a method of controlling a communication network comprising a transport network and a radio network. The radio network comprises a plurality of radio network nodes connected through the transport network. The method comprises steps a. to d. Step a. comprises receiving from the transport network available timing service information for a proposed path between a first one of the radio network nodes and a second one of the radio network nodes through the transport network. The proposed path is selected in relation to an event within the transport network. Step b. comprises comparing the available timing service information with minimum timing service information of the proposed path. Step c. comprises, if the available timing service information is worse than the minimum timing service information, determining whether an alternative one of the radio network nodes may perform a function performed by one of the first and second radio network nodes. Step d. comprises, if an alternative one of the radio network nodes may perform a function performed by one of the first and second radio network nodes requesting the transport network to select a further proposed path between the alternative one of the radio network nodes and the other of the first and second radio network nodes through the transport network.

The method may enable a connection having specific timing requirements to be established between two radio network nodes, across a transport network. The method may enable a handshake mechanism between the transport network and the radio network so that an event that occurs in the transport network either does not affect the timing performance of the connection between the two radio network nodes or the radio network can be notified of the event with sufficient advance notice to avoid a radio connection failure. The method may be compliant with the software defined networking , SDN, paradigm enabling technology details to be hidden from upper network layers.

In an embodiment, the event is one of a planned action and an unexpected failure. When the event is a planned action the method further comprises, if the available timing service information is at least equal to the minimum timing service information, generating a control signal configured to instruct the transport network to perform the planned action. Step c , when the available timing service information is worse than the minimum timing service information, further comprises generating a control signal configured to instruct the transport network not to perform the planned action. This may ensure that a planned action within the transport network can only proceed if it does not adversely affect timing service requirements of the radio network.

In an embodiment, the first radio network node is one of a plurality of digital units and the second radio network node is a remote radio unit. Step c. comprises determining whether an alternative one of the plurality of digital units may perform a function performed by the first radio network node. A different digital unit, DU, may therefore be used to serve a chosen remote radio unit, RRU, in order to enable a path to be configured across the transport network from a DU to the RRU that meets timing service requirements of the radio network. For example, an alternative DU may be chosen that is physically located closer to the RRU than the previously used DU, which may make it easier to meet the timing service requirements of the radio network.

In an embodiment, the first radio network node is a digital unit and the second radio network node is one of a plurality of remote radio units. Step c. comprises determining whether an alternative one of the plurality of remote radio units may perform a function performed by the second radio network node. A different RRU may therefore be used for the transmission of a radio signal in order to enable a path to be configured across the transport network from a chosen DU to an RRU that meets timing service requirements of the radio network. For example, an alternative RRU may be chosen that is physically located closer to the DU than the previously used RRU, which may make it easier to meet the timing service requirements of the radio network.

In an embodiment, each of the available timing service information and the minimum timing service information comprises at least one timing performance parameter of the respective proposed path. This may enable a connection to be established between two radio network nodes, across a transport network, having specific timing requirements in terms of one or more timing performance parameters of the path.

In an embodiment, each of the available timing service information and the minimum timing service information comprises a latency of the path and a jitter of the path. This may enable a connection to be established between two radio network nodes, across a transport network, having specific timing requirements in terms of latency and jitter. Jitter will be understood to mean any short term phase noise, including packet delay variation in a packet network and clock frequency accuracy in an optical network with 3R regenerators.

In an embodiment, each of the available timing service information and the minimum timing service information additionally comprises a measurement precision of the latency of the path and a measurement precision of the jitter of the path. In an embodiment, each of the available timing service information and the minimum timing service information additionally comprises a difference between an upstream delay and a downstream delay of the path. The method may enable a connection to be established between two radio network nodes, across a transport network, having specific timing requirements in terms of latency, jitter and upstream and downstream delay difference.

In an embodiment, the method additionally comprises step f. in which, if there is not an alternative one of the radio network nodes that may perform a function performed by one of the first and second radio network nodes, providing replacement minimum timing service information. More relaxed minimum timing service information may therefore be provided. This may enable a connection having less stringent timing requirements to be established between the two radio network nodes, across the transport network.

In an embodiment, step c. additionally comprises, if the available timing service information is worse than the minimum timing service information, determining whether an alternative path exists for which the available timing service information is at least equal to the minimum timing service information. Step c. comprises, if an alternative path does not exist, determining whether an alternative one of the radio network nodes may perform a function performed by one of the first and second radio network nodes.

In an embodiment, in step c. determining whether an alternative one of the radio network nodes may perform a function performed by one of the first and second radio network nodes comprises requesting identification of an alternative one of the radio network nodes to perform a function performed by one of the first and second radio network nodes. Step d. is performed if information identifying an alternative one of the radio network nodes is received.

In an embodiment, in step c. determining whether an alternative path exists comprises requesting identification of an alternative path and receiving an indication of an alternative path or an indication that an alternative path does not exist.

In an embodiment, the transport network is one of a circuit switched optical network, a packet network and a packet/optical network. The circuit switched optical network may be one of a synchronous digital hierarchy, SDH, network, a wavelength division multiplexing, WDM, network and an optical transport network, OTN, as defined in ITU-T G.709.

In an embodiment, the event is at least one of a planned wavelength rerouting, a planned rerouting of packets through Ethernet switches of the transport network and a planned rerouting of an optical channel data unit, ODU, client signal in an OTN frame.

In an embodiment, the event is a failure of a fibre link or a component within the optical network.

In an embodiment, the transport network is at least one of a fronthaul network, a backhaul network and a midhaul network. The term fronthaul will be understood as identifying a connection between two sections of a radio base station placed in two different locations. The term backhaul will be understood as identifying the connection between a core or backbone network and an access network. The term midhaul will be understood as identifying a direct connection between two base stations, for example two eNodeBs, of a radio network.

In an embodiment, the communication network has a software defined networking, SDN, architecture.

A further aspect of the invention provides a communication network controller for a communication network comprising a transport network and a radio network. The radio network comprises a plurality of radio network nodes connected through the transport network. The communication network controller is adapted to receive from the transport network available timing service information for a proposed path between a first one of the radio network nodes and a second one of the radio network nodes through the transport network. The proposed path is selected in relation to an event within the transport network. The communication network controller is adapted to compare the available timing service information with minimum timing service information of the proposed path. The communication network controller is adapted to, if the available timing service information is worse than the minimum timing service information, determine whether an alternative one of the radio network nodes may perform a function performed by one of the first and second radio network nodes. The communication network controller is adapted to, if an alternative one of the radio network nodes may perform a function performed by one of the first and second radio network nodes, transmit a request to the transport network to select a further proposed path between the alternative one of the radio network nodes and the other of the first and second radio network nodes through the transport network.

The communication network controller may enable a connection having specific timing requirements to be established between two radio network nodes, across a transport network. The communication network controller may enable a handshake mechanism between the transport network and the radio network so that an event that occurs in the transport network either does not affect the timing performance of the connection between the two radio network nodes or the radio network can be notified of the event with sufficient advance notice to avoid a radio connection failure. The communication network controller may be compliant with the software defined networking, SDN, paradigm enabling technology details to be hidden from upper network layers.

In an embodiment, the event is one of a planned action and an unexpected failure. The communication network controller is configured to, when the event is a planned action and if the available timing service information is at least equal to the minimum timing service information, generate a control signal configured to instruct the transport network to perform the planned action. The communication network controller is configured to, when the event is a planned action and if the available timing service information is worse than the minimum timing service information, generate a control signal configured to instruct the transport network not to perform the planned action. This may ensure that a planned action within the transport network can only proceed if it does not adversely affect timing service requirements of the radio network.

In an embodiment, the first radio network node is one of a plurality of digital units and the second radio network node is a remote radio unit. A different digital unit, DU, may therefore be identified to serve a chosen remote radio unit, RRU , in order to enable a path to be configured across the transport network from a DU to the RRU that meets timing service requirements of the radio network. For example, an alternative DU may be chosen that is physically located closer to the RRU than the previously used DU, which may make it easier to meet the timing service requirements of the radio network.

In an embodiment, the first radio network node is a digital unit and the second radio network node is one of a plurality of remote radio units. A different RRU may therefore be used for the transmission of a radio signal in order to enable a path to be configured across the transport network from a chosen DU to an RRU that meets timing service requirements of the radio network. For example, an alternative RRU may be chosen that is physically located closer to the DU than the previously used RRU, which may make it easier to meet the timing service requirements of the radio network.

In an embodiment, each of the available timing service information and the minimum timing service information comprises a latency of the path and a jitter of the path. This may enable a connection to be established between two radio network nodes, across a transport network, having specific timing requirements in terms of latency and jitter.

In an embodiment, each of the available timing service information and the minimum timing service information additionally comprises a measurement precision of the latency of the path and a measurement precision of the jitter of the path.

In an embodiment, each of the available timing service information and the minimum timing service information additionally comprises a difference between an upstream delay and a downstream delay of the path. This may enable a connection to be established between two radio network nodes, across a transport network, having specific timing requirements in terms of latency, jitter and upstream and downstream delay difference.

In an embodiment, to determine whether an alternative one of the radio network nodes may perform a function performed by one of the first and second radio network nodes, the communication network controller is adapted to transmit a request to the radio network to identify an alternative one of the radio network nodes to perform a function performed by one of the first and second radio network nodes. The communication network controller is adapted to transmit a request to the transport network to select the further proposed path if a response identifying an alternative one of the radio network nodes is received from the radio network.

In an embodiment, the communication network controller is adapted to receive replacement minimum timing service information from the radio network if no alternative radio network node is identified. More relaxed minimum timing service information may therefore be provided. This may enable a connection having less stringent timing requirements to be established between the two radio network nodes, across the transport network.

In an embodiment, the communication network controller is adapted to, if the available timing service information is worse than the minimum timing service information, transmit a request to the transport network to determine whether an alternative path exists for which the available timing service information is at least equal to the minimum timing service information and the communication network controller is adapted to receive an indication of an alternative path or an indication that an alternative path does not exist. The communication network controller is adapted to, if an alternative path does not exist, determine whether an alternative one of the radio network nodes may perform a function performed by one of the first and second radio network nodes.

In an embodiment, the event is at least one of a planned wavelength rerouting, a planned rerouting of packets through Ethernet switches of the transport network and a planned rerouting of an optical channel data unit, ODU , client signal in an OTN frame.

In an embodiment, the event is a failure of a fibre link or a component within the transport network

In an embodiment, the transport network is at least one of a fronthaul network, a backhaul network and a midhaul network.

In an embodiment, the communication network controller is an SDN control entity. In an embodiment, the communication network controller is an SDN orchestrator. The communication network controller could be implemented as one or more processors, hardware, processing hardware or circuitry.

References to processors, hardware, processing hardware or circuitry can encompass any kind of logic or analog circuitry, integrated to any degree, and not limited to general purpose processors, digital signal processors, ASICs, FPGAs, discrete components or logic and so on. References to a processor are intended to encompass implementations using multiple processors which may be integrated together, or co-located in the same node or distributed at different locations for example.

A further aspect of the invention provides a communication network comprising a transport network, a radio network and a communication network controller. The radio network comprises a plurality of radio network nodes. The radio network nodes are connected through the transport network. The communication network controller is configured for communication with the transport network and the radio network. The communication network controller is adapted to receive from the transport network available timing service information for a proposed path between a first one of the radio network nodes and a second one of the radio network nodes through the transport network. The proposed path is selected in relation to an event within the transport network. The communication network controller is adapted to compare the available timing service information with minimum timing service information of the proposed path. The communication network controller is adapted to, if the available timing service information is worse than the minimum timing service information, determine whether an alternative one of the radio network nodes may perform a function performed by one of the first and second radio network nodes. The communication network controller is adapted to, if an alternative one of the radio network nodes may perform a function performed by one of the first and second radio network nodes: select a further proposed path between the alternative one of the radio network nodes and the other of the first and second radio network nodes through the transport network; and generate a control signal configured to communicate the further proposed path to the transport network.

Embodiments corresponding to those described above in relation to the communication network controller are also applicable to the communication network.

In an embodiment, the transport network comprises a transport network controller configured to, in relation to an event within the transport network, select a proposed path between a first one of the radio network nodes and a second one of the radio network nodes through the transport network. The transport network controller is configured to obtain available timing service information for the proposed path. The transport network controller is configured to transmit information identifying the proposed path and the available timing service information for the proposed path to the communication network controller.

In an embodiment, the transport network controller is an SDN control entity.

The transport network controller could be implemented as one or more processors, hardware, processing hardware or circuitry.

In an embodiment, the radio network comprises a radio network controller adapted to receive a request to identify an alternative one of the radio network nodes to perform a function performed by a first radio network node. The radio network controller is adapted to determine whether a function performed by the first radio network node may be performed by an alternative one of the radio network nodes. The radio network controller is adapted to, if the function performed by the first radio network node may be performed by an alternative one of the radio network nodes: transmit information identifying said alternative one of the radio network nodes; and transmit a control signal comprising instructions to cause said alternative one of the radio network nodes to be configured to perform the function.

In an embodiment, the radio network controller is an SDN control entity. The radio network controller could be implemented as one or more processors, hardware, processing hardware or circuitry.

A further aspect of the invention provides a computer program, comprising instructions which, when executed on at least one processor, cause the at least one processor to carry out any of the above steps of the method of controlling a communication network comprising a transport network and a radio network.

A further aspect of the invention provides a carrier containing the above described computer program . The carrier is one of an electronic signal, optical signal, radio signal, or computer readable storage medium.

Brief Description of the drawings

Figure 1 shows the steps of a method according to an embodiment of the invention of controlling a communication network comprising a transport network and a radio network;

Figure 2 shows the steps of a method according to a further embodiment of the invention of controlling a communication network comprising a transport network and a radio network;

Figure 3 shows the steps of a method according to a further embodiment of the invention of controlling a communication network comprising a transport network and a radio network;

Figure 4 shows the steps of a method according to a further embodiment of the invention of controlling a communication network comprising a transport network and a radio network;

Figure 5 shows the steps of a method according to a further embodiment of the invention of controlling a communication network comprising a transport network and a radio network;

Figure 6 shows the steps of a method according to a further embodiment of the invention of controlling a radio network comprising a plurality of radio network nodes connected through a transport network;

Figure 7 shows the steps of a method according to a further embodiment of the invention of controlling a radio network comprising a plurality of radio network nodes connected through a transport network; Figure 8 shows the steps of a method according to a further embodiment of the invention of controlling a radio network comprising a plurality of radio network nodes connected through a transport network;

Figure 9 shows a table of parameters of the available timing service information and the minimum timing service information for a method according to a further embodiment of the invention of controlling a communication network comprising a transport network and a radio network;

Figure 10 is a schematic illustration of a communication network controller according to an embodiment of the invention;

Figure 1 1 is a schematic illustration of a communication network controller according to an embodiment of the invention;

Figure 12 is a schematic illustration of a communication network according to an embodiment of the invention;

Figure 13 is a schematic illustration of a communication network according to a further embodiment of the invention;

Figure 14 is a schematic illustration of a communication network according to a further embodiment of the invention;

Figure 15 is a schematic illustration of a communication network which may be controlled by a method according to a further embodiment of the invention of controlling communication network comprising a transport network and a radio network comprising a plurality of radio network nodes connected through a transport network; and

Figure 16 is a schematic illustration of a communication network which may be controlled by a method according to a further embodiment of the invention of controlling communication network comprising a transport network and a radio network comprising a plurality of radio network nodes connected through a transport network.

Detailed description

Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings.

The same reference numbers will used for corresponding features in different embodiments.

Referring to Figure 1 , one embodiment of the invention provides a method 10 of controlling a communication network. The communication network comprises a transport network and a radio network comprising a plurality of radio network nodes connected through the transport network.

The method comprises steps a. to d. Step a. comprises receiving 12 from the transport network available timing service information, ATSI , for a proposed path between a first one of the radio network nodes and a second one of the radio network nodes through the transport network. The proposed path is selected in relation to an event within the transport network. In step b. the ATSI is compared 14 with minimum timing service information, MTSI , of the proposed path. Step c. comprises, if the ATSI is worse than the MTSI , determining 16 whether an alternative one of the radio network nodes may perform a function performed by one of the first and second radio network nodes. In step d. , if an alternative one of the radio network nodes may perform a function performed by one of the first and second radio network nodes, the transport network is requested to select 18 a further proposed path between the alternative one of the radio network nodes and the other of the first and second radio network nodes through the transport network.

Referring to Figure 2, a further embodiment of the invention provides a method 30 of controlling a communication network comprising a transport network and a radio network comprising a plurality of radio network nodes connected through the transport network.

In this embodiment, the event in relation to which a proposed path is selected is either a planned action or an unexpected failure. When the event is a planned action the method further comprises, if the ATSI is at least equal to the MTSI , generating 34 a control signal configured to instruct the transport network to perform the planned action. When the event is a planned action and the ATSI is worse than the MTSI, step c. further comprises generating 36 a control signal configured to instruct the transport network not to perform the planned action. The control signal is generated prior to or in parallel with determining whether an alternative one of the radio network nodes may perform a function performed by one of the first and second radio network nodes.

Referring to Figure 3, a further embodiment of the invention provides a method 40 of controlling a communication network comprising a transport network and a radio network comprising a plurality of radio network nodes connected through the transport network.

In this embodiment, the first radio network node is one of a plurality of digital units, DUs, and the second radio network node is a remote radio unit, RRU.

Step a. comprises receiving 42 from the transport network an ATSI for a proposed path, through the transport network, between a first DU of the plurality of DUs and the RRU . Step c. comprises determining 44 whether an alternative one of the plurality of DUs may perform a function performed by the first DU. If so, step d . comprises requesting the transport network to select 46 a further proposed path between the alternative one of the plurality of DUs and the RRU, through the transport network.

The skilled person will understand a DU and an RRU as being parts of a radio base station, RBS, which may have a split architecture. The DU performs signal baseband processing and the RRU performs radio frequency conversion of the signal to be sent to or received from an antenna.

In a further embodiment, the first radio network node is one of a plurality of DUs and the second radio network node is a one of a plurality of RRUs. Referring to Figure 4, a further embodiment of the invention provides a method 50 of controlling a communication network comprising a transport network and a radio network comprising a plurality of radio network nodes connected through the transport network.

In this embodiment, the first radio network node is a DU and the second radio network node is one of a plurality of RRUs.

Step a. comprises receiving 52 from the transport network an ATSI for a proposed path, through the transport network, between the DU and a first one of the plurality of RRUs. Step c. comprises determining 54 whether an alternative one of the plurality of RRUs may perform a function performed by the first RRU. If so, step d. comprises requesting the transport network to select 56 a further proposed path between the DU and the alternative one of the plurality of RRUs, through the transport network.

In a further embodiment, the first radio network node is one of a plurality of DUs and the second radio network node is a one of a plurality of RRUs.

Referring to Figure 5, a further embodiment of the invention provides a method 60 of controlling a communication network comprising a transport network and a radio network comprising a plurality of radio network nodes connected through the transport network.

In this embodiment, the first radio network node is one of a plurality of DUs and the second radio network node is an RRU.

Step a. comprises receiving 62 from the transport network an ATSI for a proposed path, through the transport network, between a first DU of the plurality of DUs and the RRU.

Step c. comprises determining 64 whether an alternative one of the plurality of DUs may perform a function performed by the first DU. If so, step d. comprises requesting the transport network to select 66 a further proposed path between the alternative one of the plurality of DUs and the RRU, through the transport network.

In this embodiment, the event is a planned action and the method further comprises, if the ATSI is at least equal to the MTSI, generating 34 a control signal configured to instruct the transport network to perform the planned action. When the event is a planned action and the ATSI is worse than the MTSI , step c. further comprises generating 36 a control signal configured to instruct the transport network not to perform the planned action. The control signal is illustrated in Figure 6 as being generated prior to determining whether an alternative one of the DUs may perform a function performed by the first DU but it will be appreciated that the control signal may alternatively be generated in parallel with determining whether an alternative one of the DUs may perform a function performed by the first DU.

Referring to Figure 6, a further embodiment of the invention provides a method 20 of controlling a communication network comprising a transport network and a radio network comprising a plurality of radio network nodes connected through the transport network.

In this embodiment, the step of determining whether an alternative one of the radio network nodes may perform a function performed by one of the first and second radio network nodes, step c , comprises requesting 22 identification of an alternative one of the radio network nodes to perform a function performed by one of the first and second radio network nodes. Step d. is performed 24 if information identifying an alternative one of the radio network nodes is received.

Referring to Figure 7, a further embodiment of the invention provides a method 70 of controlling a communication network comprising a transport network and a radio access network, RAN , comprising a plurality of radio network nodes connected through the transport network and a RAN controller.

In this embodiment, the method 70 is implemented at an SDN orchestrator of the communication network.

Step a. , performed by the SDN orchestrator, comprises receiving 72 from the transport network ATSI for a proposed path between a first DU and an RRU through the transport network. The proposed path is selected in relation to a planned event within the transport network. In step b. , performed by the SDN orchestrator, the ATSI is compared 74 with MTSI, of the proposed path. Step c. comprises, if the ATSI is worse than the MTSI , determining whether an alternative one of the DUs may perform a function performed by the first DU . This is done by the SDN orchestrator transmitting 80 a request to the RAN controller for identification of an alternative DU to perform a function performed by the first DU. The RAN controller, following receipt of the request from the SDN orchestrator, determines 82 whether an alternative DU may perform a function performed by the first DU. If so, the RAN controller transmits 82 information to the SDN orchestrator identifying an alternative DU.

In step d ., performed by the SDN orchestrator, if information identifying an alternative is received, selected request is transmitted by the SDN controller to the transport network to select 84 a further proposed path between the alternative DU and the RRU.

The steps 82 performed by the RAN controller do not form part of this embodiment and are included only as an example of how information identifying an alternative DU may be provided to the SDN orchestrator.

Referring to Figure 8, a further embodiment of the invention provides a method 90 of controlling a communication network. The communication network comprises a transport network and a radio network comprising a plurality of radio network nodes connected through the transport network. The method 90 is similar to the method 10 described with reference to Figure 1 .

In this embodiment, step c. comprises, if the ATSI is worse than the MTSI, requesting the transport network to determine 92 whether an alternative path exists within the transport network for which the ATSI is at least equal to the MTSI. If an alternative path exists the alternative path is used.

Step c. comprises, if an alternative path does not exist, determining 94 whether an alternative one of the radio network nodes may perform a function performed by one of the first and second radio network nodes. Step c. in any of the above described embodiment may be similarly modified to include determining whether an alternative path exists, and only if an alternative path does not exist, determining whether an alternative one of the radio network nodes may perform a function performed by one of the first and second radio network nodes.

In a further embodiment, the ATSI and the MTSI of any of the above described embodiments each comprise at least one timing performance parameter of the respective proposed path. In the example shown in Figure 9, the ATSI and the MTSI each comprise estimated latency and estimated jitter for both downstream and upstream transmission directions across the proposed path, together with measurement precisions for each parameter.

In one example, ATSI and the MTSI also include a difference between an upstream delay and a downstream delay of the path, which may also be referred to as an uncompensated asymmetry in the upstream delay and the downstream delay of the path.

A further embodiment of the invention provides a communication network controller for a communication network. The communication network comprises a transport network and a radio network comprising a plurality of radio network nodes connected through the transport network.

The communication network controller is adapted to receive from the transport network ATSI for a proposed path between a first one of the radio network nodes and a second one of the radio network nodes through the transport network; the proposed path is selected in relation to an event within the transport network. The communication network controller is adapted to compare the ATSI with MTSI of the proposed path. The communication network controller is adapted to, if the ATSI is worse than the MTSI, determine whether an alternative one of the radio network nodes may perform a function performed by one of the first and second radio network nodes. The communication network controller is adapted to, if an alternative one of the radio network nodes may perform a function performed by one of the first and second radio network nodes, transmit a request to the transport network to select a further proposed path between the alternative one of the radio network nodes and the other of the first and second radio network nodes through the transport network.

Figure 109 illustrates one example of the communication network controller 100, in which the communication network controller 100 comprises a processor 102 and a memory 104. The communication network controller is adapted to receive ATSI for a proposed path between a first one of the radio network nodes and a second one of the radio network nodes through the transport network.

The memory 104 contains instructions executable by the processor, whereby the communication network controller 100 is operative to: receive from the transport network ATSI for a proposed path between a first one of the radio network nodes and a second one of the radio network nodes through the transport network, the proposed path being selected in relation to an event within the transport network; compare the ATSI with MTSI of the proposed path;

if the ATSI is worse than the MTSI , determine whether an alternative one of the radio network nodes may perform a function performed by one of the first and second radio network nodes; and

if an alternative one of the radio network nodes may perform a function performed by one of the first and second radio network nodes, transmit a request to the transport network to select a further proposed path between the alternative one of the radio network nodes and the other of the first and second radio network nodes through the transport network.

In one embodiment, the memory 104 contains instructions executable by the processor, whereby the communication network controller 100 is operative to, if the ATSI is worse than the MTSI , transmit a request to the transport network to select an alternative path between the first one of the radio network nodes and a second one of the radio network nodes for which the ATSI is at least equal to the MTSI. If a suitable alternative path exists, that path is used in place of the previously proposed path.

The communication network controller 100 is operative to, if there is no suitable alternative path, transmit a request to the radio network to determine whether an alternative one of the radio network nodes may perform a function performed by one of the first and second radio network nodes, as described above.

Figure 1 1 illustrates a further example of the communication network controller 120, in which the communication network controller 120 comprises a transport network communication unit 122, a comparison unit 124, and a radio network node selection unit 126.

The transport network communication unit 122 is for receiving from the transport network ATSI for a proposed path between a first one of the radio network nodes and a second one of the radio network nodes through the transport network; the proposed path is selected in relation to an event within the transport network.

The comparison unit 124 is for comparing the ATSI with MTSI of the proposed path. The radio network node selection unit 126 is for determining, if the ATSI is worse than the MTSI, whether an alternative one of the radio network nodes may perform a function performed by one of the first and second radio network nodes.

In a further example, transport network communication unit 122, the comparison unit 124, and the radio network node selection unit 126 may be implemented as a computer program running on the processor 102 of the communication network controller shown in Figure 10.

In one embodiment, the event is one of a planned action and an unexpected failure. The communication network controller 100, 120 is configured to, when the event is a planned action and if the ATSI is at least equal to the MTSI, generate a control signal configured to instruct the transport network to perform the planned action. The communication network controller 100, 120 is configured to, when the event is a planned action and if the ATSI is worse than the MTSI, generate a control signal configured to instruct the transport network not to perform the planned action. Referring to Figure 1 1 , the transport network communication unit 122 is configured to generate this control signal.

In an embodiment, the first radio network node is one of a plurality of DUs and the second radio network node is an RRU. Alternatively, the first radio network node is a DU and the second radio network node is one of a plurality of RRUs. In a further example, the first radio network node is one of a plurality of DUs and the second radio network node is one of a plurality of RRUs.

In an embodiment, in order to determine whether an alternative one of the radio network nodes may perform a function performed by one of the first and second radio network nodes, the communication network controller 100, 120 is configured to transmit a request to the radio network to identify an alternative one of the radio network nodes to perform a function performed by one of the first and second radio network nodes. The communication network controller is adapted transmit a request to the transport network to select a further proposed path if a response identifying an alternative one of the radio network nodes is received from the radio network. Referring to Figure 1 1 , the radio node selection unit is configured to transmit the request to the radio network and to receive the response from the radio network. The transport network communication unit is configured to transmit the request to the transport network to select a further proposed path.

As described above, the ATSI and the MTSI received by any of the above described communication network controllers each comprise at least one timing performance parameter of the respective proposed path. As shown in Figure 9, the ATSI and the MTSI each comprise estimated latency and estimated jitter for both downstream and upstream transmission directions across the proposed path, together with measurement precisions for each parameter.

In an embodiment, ATSI and the MTSI also include a difference between an upstream delay and a downstream delay of the path, which may also be referred to as an uncompensated asymmetry in the upstream delay and the downstream delay of the path.

Referring to Figure 12, a further embodiment of the invention provides a communication network 200 comprising a transport network 210, a radio network 220, and a communication network controller 100. The transport network comprises a transport network controller 212. The radio network 220 comprises a plurality of radio network, RN, nodes 222 connected through the transport network and a radio network, RN, controller 224.

The communication network controller 100, 120 is as described in any of the above embodiments, with the following modifications. The communication network controller 100, 120 is configured for communication with the transport network through the transport network 212 controller and is configured for communication with the radio network through the RN controller 224.

The transport network controller 212 is configured to, in relation to an event within the transport network, select a proposed path between a first one of the radio network nodes and a second one of the radio network nodes through the transport network. The transport network controller is configured to obtain ATSI for the proposed path and to transmit information 214 identifying the proposed path and the ATSI for the proposed path to the communication network controller 100, 120.

The communication network controller 100, 120 is configured to receive this information 214 from the transport network controller and to transmit a request 206 to the RN controller 224 to identify an alternative one of the RN nodes to perform a function performed by one of the first and second radio network nodes.

The RN controller 224 is adapted to receive the request from the communication network controller 100, 120 and to determine whether a function performed by the first RN node may be performed by an alternative one of the RN nodes. The RN controller is adapted to, if the function performed by the first RN node may be performed by an alternative one of the RN nodes: transmit information 226 identifying said alternative one of the RN nodes; and transmit a control signal 228 comprising instructions to cause said alternative one of the RN nodes to be configured to perform the function.

The communication network controller 100, 120 is adapted to, if it receives information from the RN controller identifying a said alternative one of the RN nodes, transmit a request to the transport network controller to select a further proposed path between the alternative one of the RN nodes and the other of the first and second RN nodes through the transport network.

The transport network controller 212 is configured to select a further proposed path between the alternative one of the RN nodes and the other of the first and second RN nodes through the transport network. The transport network controller 212 may then obtain ATSI for the proposed path and to transmit information 214 identifying the proposed path and the ATSI for the proposed path to the communication network controller 100, 120.

Referring to Figure 13, a further embodiment of the invention provides a communication network 230 which is similar to the communication network 200 of Figure 1 1 , with the following modifications.

In this embodiment, the first RN node is one of a plurality of DUs 232 (two are shown in the drawing but it will be appreciated that more DUs may be provided within the radio network 220). The second RN node is an RRU 234 (only one is shown in the drawing but it will be appreciated that a plurality of RRUs may be provided within the radio network 220). In this embodiment, the communication network controller 100, 120 is configured to transmit a request 206 to the RN controller 224 to identify an alternative one of the DUs 232 to serve the RRU 234.

Referring to Figure 14, a further embodiment of the invention provides a communication network 230 which is similar to the communication network 200 of Figure 1 1 , with the following modifications.

In this embodiment, the first RN node a DU 232 (only one is shown in the drawing but it will be appreciated that a plurality of DUs may be provided within the radio network 220). The second RN node is an RRU 234 (two are shown in the drawing but it will be appreciated that more RRUs may be provided within the radio network 220).

In this embodiment, the communication network controller 100, 120 is configured to transmit a request 206 to the RN controller 224 to identify an alternative one of the RRUs 234 to be served by the DU 232.

A further embodiment of the invention provides a method of controlling a communication network 250 comprising a transport network 252 and a radio network 220 comprising a plurality of radio network nodes 232, 234 connected through the transport network. The method of this embodiment may be implemented at a communication network controller 100, 120 to control the communication network illustrated in Figure 15.

The communication network 250 is similar to the communication network 200 shown in Figure 12, with the following modifications. The radio network 220 comprises a pool of DUs 232 and a cluster of RRUs (only one of each is shown for reasons of clarity). The transport network is an optical network 252 which may include fixed and reconfigurable optical add/drop multiplexers, OADMs, and amplifiers.

Each DU is connected to the optical network through a switch 254 configured to aggregate and disaggregate fronthaul links addressed to different DUs in the pool. The switch 254 can have several implementations; for example the switch may be an optical cross- connect, a CPRI switch or a switch meeting the requirements of the Optical Transport Network, OTN, standard as defined in ITU G.709, or a combination of these switches. Similarly, each RRU 234 is connected to the optical network through a similar switch 254 (Switch R) configured to aggregate and disaggregate fronthaul links addressed to different RRUs in the cluster of RRUs.

The method of this embodiment provides a centralized handshake mechanism between the radio network and the optical network, based on SDN, to manage issues that arise from any change in the level of service that the optical network can provide to the radio network. For each link of the optical network, available timing service information, ATSI , is defined by means of a list of parameters, individually specified for the downstream and upstream directions. The parameters include latency and jitter. The method may be used when, for example, a specific fronthaul connection cannot tolerate more than 100 με one-way latency, and an uncompensated delay asymmetry of 100ns (that would be related to the measurement precision).

The jitter definition can be different for different transport network types: for example, in packet networks it may be packet delay variation while in an optical network with 3R regenerators in between it may be the clock frequency accuracy.

In the handshake mechanism of this embodiment, the optical network controller sends to the communication network controller 100, 120 new ATSI values for any optical network port connected to the radio network that is affected by the event, and also informs the communication network controller whether the event is a planned event or an unexpected failure.

The communication network controller 100, 120 of this embodiment has a stored table containing the respective minimum timing service information, MTSI , for each possible connection between nodes of the radio network, i.e. between a DU and an RRU.

The communication network controller 100, 120 compares the new ATSI with the respective stored MTSI , and performs one of the following:

1 . If the new ATSI values are tolerable, i.e. at least equal to the MTSI values, the communication network controller takes no action;

2. If the new values are not tolerable, i.e. worse than the MTSI, and the event is a planned event, for example a wavelength rerouting, the communication network controller

100, 120 instructs the optical network, ON, controller not to perform the planned action and invites the ON controller to find a new path within the optical network that meets the MTSI. If a new path cannot be found, the communication network controller 100, 120 sends the new ATSI values to the radio network, RN , controller and requests the RN controller to determine whether an alternative one of the DUs or an alternative one of the RRUs can be used. If the RN controller is able to take some action, connecting all interested RRUs to another DU not affected by the planned event or connecting an alternative RRU not affected by the planned event to the DU, it will advise the communication network controller of the alternative DU or RRU. The communication network controller will transmit a request to the ON controller to select a further proposed path between the RRUs and the alternative DU or between the alternative RRU and the DU. The communication network controller 100, 120 will then enable the ON controller to implement the planned event. If neither an alternative DU nor an alternative RRU can be found, the RN controller communicates a new MTSI , having relaxed values compared to the initial MTSI values, to the communication network controller.

3. If the new ATSI values are not tolerable and the event is an unexpected failure, the communication network controller 100, 120 communicates to the RN controller the new ATSI values. The RN controller will then make any necessary consequential changes to the configuration of the radio network according to its policies. This may include one or more of selecting an alternative DU or RRU, as described above, downgrading mobile services which are not compatible with the new ATSL value, and relaxing the MTSI values.

The method provides an SDN compliant handshake mechanism between a radio network and a transport network so that any change of the timing performance that occurs in the transport network may be timely communicated to the communication network controller which may prevent radio connection failures.

A further embodiment of the invention provides a method of controlling a communication network 260 comprising a transport network 270 and a radio network 280 comprising a plurality of radio network nodes 232, 234 connected through the transport network. The method of this embodiment may be used to control the communication network illustrated in Figure 16.

The communication network 260 is similar to the communication network 250 shown in Figure 15, with the following modifications.

The transport network is an optical network 270 comprising a plurality of optical network nodes 274, a plurality of optical links 276 and an optical network, ON , controller 272.

The radio network is a radio access network, RAN, and comprises a pool of DUs 232, a cluster of RRUs 234 and a RAN controller 282.

The method of this embodiment is implemented at communication network controller in the form of an SND orchestrator 262, as follows.

Say the ON controller 272, wishes to perform a planned wavelength rerouting to route red, used to connect DU51 to both RRU21 and RRU22, from the optical path node#5 ->node#2 to the optical path node#5 ->node#3 ->node#2.

The ON controller calculates and sends new ATSL₅₂ parameter values to the SDN orchestrator 262 which compares the new ATSL₅₂ parameter values with stored MTSL₅₂ parameter values. The ON controller also notifies the SDN orchestrator that this is a planned event (labelled in Figure 14 as a 'Type 1 ' event).

If the new ATSL₅₂ parameter values are tolerable, i.e. at least equal to the stored MTSL₅₂ parameter values, the SDN orchestrator transmits a control signal to the ON controller to allow the optical network to go ahead with the planned event.

If the new ATSL₅₂ parameter values are worse than the stored MTSL₅₂ parameter values, the SDN orchestrator transmits a control signal to the ON controller to instruct the optical network not to go ahead with the planned event and transmits a request to the ON controller to find an alternative path within the optical network that meets the MTSL₅₂ parameter values. If the ON controller sends a reply that there is no alternative path that meets the MTSL₅₂ parameter values, the SDN orchestrator transmits a request to the RAN controller 282 to determine whether there is an alternative DU that could serve RRU21 and RRU22. The RAN controller determines, in this example, that DU 1 1 could replace DU51 to serve RRU21 and RRU22, and communicates information identifying the new DU to the SDN orchestrator. The SDN orchestrator maps this information into a new path in the optical network for the ON controller as "Use the path node#1 ->node#2 instead of node#5 ->node#2". The SDN orchestrator transmits the new path information to the ON controller.

The ON controller interprets the information "Use the path node#1 ->node#2 instead of node#5 ->node#2" as "Use violet instead of red". The ON controller then sends ATSL₁₂ parameter values to the SDN orchestrator, which compares the new ATSL₁₂ parameter values with stored MTSL₁₂ parameter values, as described above.

For events that are not under the control of the SDN orchestrator, i.e. unexpected failures including , for example, fast link restoration after a fibre break, the method is different in that the optical network acts autonomously from the SDN orchestrator and the radio controller; the SDN orchestrator does not provide any control signal to the ON controller instructing it to go ahead or not with implementing a new path to enable fast link restoration.

After such an unexpected event the SDN orchestrator compares the ATSL values for the new path with stored MTSL values. If the ATSL values are worse than the MTSL values, the SDN orchestrator asks the radio controller if it is possible to find alternative DUs to serve the same RRUs. The radio controller communicates the new DUs to the SDN orchestrator, which maps the information in a new optical path, and communicates the new path information to the optical network.

A further embodiment of the invention provides a computer program, comprising instructions which, when executed on at least one processor, cause the at least one processor to carry out any of the above steps of the method of controlling a communication network comprising a transport network and a radio network.

A further embodiment of the invention provides a carrier containing the above described computer program . The carrier is one of an electronic signal, optical signal, radio signal, or computer readable storage medium.

Claims

A method of controlling a communication network comprising a transport network and a radio network comprising a plurality of radio network nodes connected through the transport network, the method comprising steps:

a. receiving from the transport network available timing service information for a proposed path between a first one of the radio network nodes and a second one of the radio network nodes through the transport network, the proposed path being selected in relation to an event within the transport network;

b. comparing the available timing service information with minimum timing service information of the proposed path;

c. if the available timing service information is worse than the minimum timing service information, determining whether an alternative one of the radio network nodes may perform a function performed by one of the first and second radio network nodes; and

d. if an alternative one of the radio network nodes may perform a function performed by one of the first and second radio network nodes requesting the transport network to select a further proposed path between the alternative one of the radio network nodes and the other of the first and second radio network nodes through the transport network.

A method as claimed in claim 1 , wherein the event is one of a planned action and an unexpected failure and wherein when the event is a planned action the method further comprises, if the available timing service information is at least equal to the minimum timing service information, generating a control signal configured to instruct the transport network to perform the planned action and step c. further comprises generating a control signal configured to instruct the transport network not to perform the planned action.

A method as claimed in claim 1 or claim 2, wherein the first radio network node is one of a plurality of digital units and the second radio network node is a remote radio unit and wherein step c. comprises determining whether an alternative one of the plurality of digital units may perform a function performed by the first radio network node. A method as claimed in claim 1 or claim 2, wherein the first radio network node is a digital unit and the second radio network node is one of a plurality of remote radio units and wherein step c. comprises requesting determining whether an alternative one of the plurality of remote radio units may perform a function performed by the second radio network node.

A method as claimed in any preceding claim, wherein each of the available timing service information and the minimum timing service information comprises at least one timing performance parameter of the respective proposed path.

6. A method as claimed in claim 5, wherein each of the available timing service information and the minimum timing service information comprises a latency of the path and a jitter of the path.

7. A method as claimed in any preceding claim, wherein in step c. determining whether an alternative one of the radio network nodes may perform a function performed by one of the first and second radio network nodes comprises requesting identification of an alternative one of the radio network nodes to perform a function performed by one of the first and second radio network nodes and wherein step d. is performed if information identifying an alternative one of the radio network nodes is received.

8. A communication network controller for a communication network comprising a transport network and a radio network comprising a plurality of radio network nodes connected through the transport network, the communication network controller adapted to:

receive from the transport network available timing service information for a proposed path between a first one of the radio network nodes and a second one of the radio network nodes through the transport network, the proposed path being selected in relation to an event within the transport network;

compare the available timing service information with minimum timing service information of the proposed path;

if the available timing service information is worse than the minimum timing service information, determine whether an alternative one of the radio network nodes may perform a function performed by one of the first and second radio network nodes; and if an alternative one of the radio network nodes may perform a function performed by one of the first and second radio network nodes transmit a request to the transport network to select a further proposed path between the alternative one of the radio network nodes and the other of the first and second radio network nodes through the transport network.

9. A communication network controller as claimed in claim 8, wherein the event is one of a planned action and an unexpected failure and wherein the communication network controller is configured to, when the event is a planned action and if the available timing service information is at least equal to the minimum timing service information, generate a control signal configured to instruct the transport network to perform the planned action and if the available timing service information is worse than the minimum timing service information, generate a control signal configured to instruct the transport network not to perform the planned action.

10. A communication network controller as claimed in claim 8 or claim 9, wherein the first radio network node is one of a plurality of digital units and the second radio network node is a remote radio unit.

1 1. A communication network controller as claimed in claim 8 or claim 9, wherein the first radio network node is a digital unit and the second radio network node is one of a plurality of remote radio units.

12. A communication network controller as claimed in any preceding claim, wherein each of the available timing service information and the minimum timing service information comprises at least one timing performance parameter of the respective proposed path.

13. A communication network controller as claimed in claim 12, wherein each of the available timing service information and the minimum timing service information comprises a latency of the path and a jitter of the path.

14. A communication network controller as claimed in any of claims 8 to 13, wherein to determine whether an alternative one of the radio network nodes may perform a function performed by one of the first and second radio network nodes the communication network controller is adapted to transmit a request to the radio network to identify an alternative one of the radio network nodes to perform a function performed by one of the first and second radio network nodes and wherein the communication network controller is adapted to transmit a request to the transport network to select the further proposed path if a response identifying an alternative one of the radio network nodes is received from the radio network.

15. A communication network comprising:

a transport network;

a radio network comprising a plurality of radio network nodes connected through the transport network; and

a communication network controller as claimed in any of claims 8 to 14, the communication network controller configured for communication with the transport network and the radio network.

16. A computer program, comprising instructions which, when executed on at least one processor, cause the at least one processor to carry out the method according to any one of claims 1 to 7.

17. A carrier containing the computer program of the previous claim, wherein the carrier is one of an electronic signal, optical signal, radio signal, or computer readable storage medium.