Patent Description:
Modern cellular networks can support Centralised Radio Access Network (C-RAN) - also referred to as Cloud Radio Access Network and Disaggregated Radio Access Network - architectures in which a base station may be split into a Central Unit (CU) and one or more Distributed Units (DUs). Accordingly, the various protocol layers of the cellular protocol in use are also split between the CU and the DUs such that the DUs may implement the lowermost layer (e.g. the radio frequency layer) and optionally one or more higher layers, and all other higher layers may be implemented in the CU.

However, this functional split between the CU and the DUs may be to the detriment of efficiently and effectively coordinating communication between at least the CU and the DUs, and in particular may cause unnecessary latency.

It is therefore an aim of embodiments of the present invention to at least alleviate the aforementioned problems.

<CIT> discloses a relay node radio access network (RAN) configured to communicate using backhaul subframes over a Un radio interface with a donor base station node and to communicate using access subframes over a Uu radio interface with a wireless terminal. Downlink backhaul subframes and downlink access subframes are transmitted over an air interface using the same frequency band, but a beginning of a selected downlink access subframe precedes a beginning of a next-in- time downlink backhaul subframe by a downlink timing advance (TA). The relay node both receives downlink control information from the donor base station node and transmits downlink control information to the wireless terminal during the downlink backhaul subframe, e.g., during a time to which the downlink backhaul subframe has been allocated.

<CIT> discloses user equipment for a mobile communication network, the network having a radio access network including a plurality of cells and being configured to serve the user equipment within a cell. To receive a data packet from the radio access network, the user equipment is configured to receive a plurality of different versions of the data packet transmitted by the radio access network to the user equipment in parallel via different physical resources. To provide a data packet to the radio access network, the user equipment is configured to provide a plurality of different versions of the data packet and to transmit the plurality of different versions of the data packet to the radio access network in parallel via different physical resources.

According to a present invention, there is provided a method of controlling a telecommunications network as set forth in Claim <NUM>, a computer-readable storage medium as set forth in Claim <NUM>, a telecommunications network system as set forth in Claim <NUM> and further embodiments of the invention are set forth in dependent Claims <NUM>-<NUM>. The described embodiments are considered to be useful for understanding the invention and they do not restrict the scope of the invention as defined by the claims.

Preferably, the comparing is performed so as to identify a temporal misalignment. Preferably, the comparing is performed so as to identify a misalignment in the frames for causing a delay in communication between the first, second and third nodes. Preferably, identifying the first and/or second schedule includes identifying schedules associated with subframes of the first and/or second frame/s. Preferably, the comparing is performed so as to identify a misalignment in the subframes.

Optionally, applying the adjustment to the first schedule relative to the second schedule comprises: adjusting only the first schedule; adjusting only the second schedule; or adjusting the first and the second schedules.

Optionally, the telecommunications network is a wide area telecommunications network. Optionally, the telecommunications network is a cellular mobile telephone network. Optionally, the telecommunications network operates in accordance with a Wi-Fi, <NUM>, <NUM> and/or <NUM> protocol.

Optionally, the first node, the second node and/or the third node comprises at least two remote entities. Optionally, an uplink or downlink subframe is a type of subframe. Optionally, the method further comprises the steps of identifying a third schedule for a frame for facilitating communication between the first node, the second node or the third node and a further node, and wherein the comparing and adjustment is performed in dependence also on the third schedule.

Optionally, the adjustment is applied so as to align: reference signals; guard periods; synchronisation signals; broadcast signals; and/or control signals. Preferably, wherein the adjustment is a time shift. Optionally, the time shift is performed by applying a delay to a frame or by advancement of a frame. Optionally, the delay is applied by adding a subframe. Optionally, the advancement is applied by removing a subframe.

Preferably, the adjustment is a change in duration of an uplink and/or downlink subframe. Optionally, said change in duration is an increase or decrease. Optionally, the adjustment is an increase or decrease in the symbol period of a subframe. Preferably, the adjustment is a change in sequence of uplink and downlink subframes. Preferably, the first and/or the second schedule/s comprise/s timings of uplink and/or downlink subframes.

Preferably, the first and/or the second schedule/s comprise/s durations of uplink and/or downlink subframes. Preferably, the adjustment is applied so as to cause coincidence of: an uplink subframe associated with the first schedule and an uplink subframe associated with the second schedule; and/or a downlink subframe associated the first schedule and a downlink subframe associated with the second schedule. Optionally, the adjustment is applied so as to cause said coincidence throughout (and optionally only throughout) the duration of a communication being communicated between the first node, second node and/or the third node.

Preferably, the adjustment is applied so as to prevent coincidence, between the frames, of an uplink or a downlink subframe with a non-downlink and a non-uplink subframe, wherein a non-downlink and a non-uplink subframe include: reference signals; guard periods; synchronisation signals; broadcast signals; and control signals. Preferably, the method further comprises the step of determining a minimum latency period for communicating a communication to and/or from the first node, the second node and/or the third node.

Optionally, the minimum latency period comprises: travel time of a communication; processing time of the communication by the first and/or second node; communicating the, or another, communication, on to a further network location (e.g. the further node); and/or further processing of the, or the other, communication at the further network location. As used herein, the "minimum latency period" preferably connotes a period of time that is required to send and receive (or vice versa) a communication between the first node, the second node and/or the third node excluding delays due to a misalignment in frame structures. Accordingly, the term "minimum" may be used in a relative sense, and may not connote an absolute minimum, nor a static minimum.

Optionally, at least one minimum latency period is determined for a communication to and/or from the first node, the second node, the third node and/or the further network location. Optionally, the minimum latency period is predicted or derived from an identity of the first node, the second node and/or the third node.

Preferably, the communication is a: message; a service request; a data service; a non-data service; a control message; and/or a management message. Optionally, the communication is: only an uplink message; only a downlink message; an uplink and a downlink message; and/or a plurality of uplink and downlink messages.

Preferably, the communication originates from the first node, the second node, the third node or a core of the telecommunications network. Preferably, the adjustment is applied so as to separate: at least a portion of an uplink subframe of the first frame and at least a portion of an uplink subframe of the second frame by no more than the minimum latency period; and/or at least a portion of a downlink subframe of the first frame and at least a portion of a downlink subframe of the second frame by no more than the minimum latency period.

Optionally, said adjustment is performed so as to separate a point in time when a communication is available to be transmitted (e.g. from the first node, the second node or the third node) and a point in time when the communication is available to be received (e.g. by the first node, the second node or the third node).

Optionally, wherein the adjustment is applied so that a transition between an uplink and a downlink subframe occur at the same time for the first frame and for the second frame. Preferably, the method further comprises the step of calculating an adjustment value for applying the adjustment, and wherein the adjustment value is derived in dependence on the minimum latency period.

Optionally, said adjustment value is also derived in dependence on the duration of an uplink and/or downlink subframe for the first and/or second frame/s. Optionally, said adjustment value is also derived in dependence on a point in time when transition between an uplink and a downlink subframe occurs for the first and/or second frame/s.

Preferably, the adjustment is applied so that a point in time when a communication is received by a given node and a point in time when the communication is available to be transmitted by said given node both occur in the same subframe. In this way, the communication may be received by, and may be communicated from, a given node after no more than the minimum latency period. Preferably, first and the second nodes form part of a split Radio Access Network. Preferably, the first node, the second node or the third node is in the form of User Equipment, centralised unit and/or a distributed unit. Preferably, the first node is the UE, the second node is the distributed unit, and the third node is the centralised unit.

Preferably, the first node and the second node are connected via a wired telecommunications link. Optionally, the first node, the second node and/or the third node comprise, or consists of, a wired telecommunications link and/or a wireless telecommunications link. Optionally, the wired telecommunication link operates in accordance with: G. fast; Passive Optical Network; and/or DOCSIS.

Preferably, the second node and the third node are connected via a wireless telecommunications link. Optionally, the wireless telecommunication link operates in accordance with: radio; New Radio; microwave; Wi-Fi; <NUM>; <NUM>; <NUM>; Free-Space Optical (FSO) Communication.

Preferably, the first node is connected to a core of the telecommunications network. Optionally, the first node is directly connected to a core of the telecommunications network, and may be connected via a wired connection. Preferably, the first and second frames are time-division duplexed and/or frequency-division duplexed. Preferably, the first frame and the second frame are heterogeneous or homogenous as to frame channel type.

Preferably, the first frame and the second frame is a logical, transport or physical channel type frame. Optionally, the first frame or the second frame has a radio channel type. Preferably, the method is triggered by the first node, the second node, the third node and/or a core of the telecommunications network. Preferably, the method is triggered in response to: a communication; a request for a service; a request for a change in a standard of service; and/or a change in a processing load of the telecommunications network.

Optionally, the communication; the request for a service; the request for a change in a standard of service originates from the first node, the second node, the third node or a core of the telecommunications network. Optionally, the change in a processing load of the telecommunications network is detected by the first node, the second node, the third node or a core of the telecommunications network.

Optionally, the request for a service is for a low latency service, and for example a URLLC service. Optionally, the request for the low latency service originates from the first node, the second node, the third node or a core of the telecommunications network.

As used herein, a low latency service may connote a latency between the first node, the second node and the third node (and optionally back again) of no more than: <NUM>, more preferably <NUM>; still more preferably <NUM>; yet more preferably <NUM>; and more preferably still <NUM>, even more preferably <NUM>; still more preferably <NUM>; yet more preferably <NUM>; and all the more preferably <NUM>. Optionally, the request for a change in a standard of service is a request for a decrease in latency. Preferably, the method further comprises the step of reverting the applied adjustment so as to revert the identified misalignment.

According to another aspect of the invention, there is provided a computer-readable storage medium as set forth in Claim <NUM>.

According to another aspect of the invention, there is provided a telecommunications network system as set forth in Claim <NUM>.

As used herein, means plus function features may alternatively be expressed in terms of their corresponding structure, for example as a suitably-programmed processor. As used throughout, the word 'or' can be interpreted in the exclusive and/or inclusive sense, unless otherwise specified.

The invention extends to a method of controlling a telecommunications network and to a telecommunications network as described herein and/or substantially as illustrated with reference to the accompanying drawings. The present invention is now described, purely by way of example, with reference to the accompanying diagrammatic drawings, in which:.

<FIG> shows a cellular telecommunications network <NUM> incorporating a Centralised Radio Access Network (C-RAN) - or a split Radio Access Network (RAN) - architecture having a Central Unit (CU) <NUM>, and a plurality of Distributed Units (DUs) <NUM>. The CU <NUM> interconnects with each DU <NUM> and also to a cellular core network <NUM>, which includes or is associated with a Network Management System (NMS) <NUM>.

In turn, User Equipment (UE) <NUM>, for example in the form of a mobile cellular device, is configured to communicate with the DUs <NUM>.

<FIG> shows, in more detail, a portion of the telecommunications network <NUM>. The CU <NUM> comprises a first transceiver <NUM>, a processor <NUM>, memory <NUM>, and a second transceiver <NUM>, all connected via bus <NUM>. The first transceiver <NUM> is a wired communications interface such that the CU <NUM> may communicate with the core network <NUM>. The second transceiver <NUM> is a wired communications interface such that the CU <NUM> may communicate with the DUs <NUM>.

Each DU <NUM> comprises a first transceiver <NUM> for wired communication with the CU <NUM> (i.e. from the first transceiver <NUM>), a processor <NUM>, memory <NUM>, and a second transceiver <NUM> for wireless communication with a UE <NUM>, all connected via bus <NUM>.

The processors <NUM>, <NUM> of the CU <NUM> and the DUs <NUM> implement different functions of their operating protocols, such protocols including, for example, G. Fast and LTE for the CU <NUM> and the DU <NUM> respectively.

The various functions of the LTE protocol are split between the respective processors <NUM>, <NUM> of the CU <NUM> and the DU <NUM>, such that the DU <NUM> implements lower layer protocols, such as the Radio Link Control (RLC), Medium Access Control (MAC) and Physical (PHY) functions, whereas the CU <NUM> implements higher layer protocols, such as the Radio Resource Control (RRC) and the Packet Data Convergence Protocol (PDCP) functions.

In turn the CU processor <NUM> and the DU processor <NUM> further comprise a fronthaul scheduler and an access scheduler respectively (not shown) for controlling timings of frames for communications to and from each of the DU and the CU.

In one example the link between the CU and DU (i.e. between transceiver <NUM> and transceiver <NUM>) is a G. Fast connection, in which case Dynamic Resource Allocation (DRA) is utilised so as to effect scheduler coordination. In particular, DRA permits reconfiguration of the schedulers, and for example so as to change the number of symbol periods dedicated to an uplink and a downlink subframe.

The telecommunications network <NUM> is configured to facilitate connections at various standards of latency, and for example to provide an Ultra-Reliable Low-Latency Connection (URLLC).

<FIG> and <FIG> show frames <NUM> for facilitating data transmission over the network <NUM>. The frames <NUM> are structured so as to facilitate uplink and downlink communication using Time-Division Duplex (TDD). Accordingly, the frames <NUM> comprise subframes in the form of an uplink-type subframe <NUM> and a downlink-type subframe <NUM>.

In <FIG>, a pair of frames - a first frame <NUM>-<NUM> and a second frame <NUM>-<NUM> - are shown, in which each frame is associated with communication between distinct portions of the network <NUM>, and for example the first frame <NUM>-<NUM> is associated with communications between the CU <NUM> and the DU <NUM> (i.e. the link provided by transceiver <NUM> and transceiver <NUM>), whereas the second frame <NUM>-<NUM> is associated with communications between the DU <NUM> and the UE <NUM> (i.e. the link provided by transceiver <NUM> and a transceiver associated with the UE <NUM>). Accordingly, in the examples of <FIG>, each of the pair of frames is associated with a different type of protocol layer channel, and in particular the first frame <NUM>-<NUM> facilitates communication at a transport layer, whereas the second frame <NUM>-<NUM> facilitates communication at the radio layer.

Communication between the CU and the DU, and between the DU and the UE, therefore occurs in accordance with the frames <NUM> (which are controlled by the fronthaul and the access schedulers).

Due to time-division duplexing, for example, an uplink communication from the UE to the CU utilises an uplink subframe of the second frame <NUM>-<NUM>, followed by an uplink subframe of the first frame <NUM>-<NUM>. Uplink transmission over the first frame <NUM>-<NUM> can take place only after uplink transmission over the second frame <NUM>-<NUM> has arrived and has been processed by the DU.

Accordingly, misalignment in subframe types between the first and the second frames may cause delays in communications between the UE, DU and CU, which therefore introduces unnecessary latency to the telecommunications network <NUM>.

An example of such misalignment is shown in <FIG> in relation to a UE-originating communication. In more detail, in <FIG>, at times:.

The period t<NUM> to t<NUM> comprises, at least, an inherent - minimum - delay (Δtmin(<NUM>-<NUM>)) owing to propagation time of the communication from the UE to the DU and for processing time for the DU to process the communication.

In <FIG>, at t<NUM> the second frame <NUM>-<NUM> is at (the end of) an uplink subframe <NUM>; at this same instance the first frame <NUM>-<NUM> is at a downlink subframe <NUM>. Accordingly, the communication that is sent by the UE to the DU cannot immediately be received at t<NUM> by the DU to the CU, not until the first frame <NUM>-<NUM> enters an uplink subframe <NUM>. The period between times t<NUM> and t<NUM> (Δt<NUM>-<NUM>) also include an inherent - minimum - delay (Δtmin(<NUM>-<NUM>)) owing, at least, to propagation time of the communication from the DU to the CU and for processing time for the DU to send the communication to the CU.

The minimum possible time between receiving the communication at the DU from the UE (t<NUM>) and receiving the communication at the CU (t<NUM>) is therefore Δtmin(<NUM>-<NUM>), which may only occur if the first frame <NUM>-<NUM> is in an uplink subframe <NUM> cycle at t<NUM> + Δtmin(<NUM>-<NUM>).

However, in <FIG>, since the first frame <NUM>-<NUM> is in a downlink subframe <NUM> at t<NUM> + Δtmin(<NUM>-<NUM>), the communication cannot be received by the CU at this instance. Instead, the communication is only received by the CU at time t<NUM>, which is later than t<NUM> + Δtmin(<NUM>-<NUM>). An additional uplink delay of t<NUM> - (t<NUM> + Δtmin(<NUM>-<NUM>)) that forms part of Δt<NUM>-<NUM> in the example of <FIG> is therefore a delay caused due to having to wait for the first frame <NUM>-<NUM> to cycle to its next an uplink subframe <NUM>. Accordingly, In <FIG>, a delay in communication is caused by misalignment in subframe types between the first and the second frames at t<NUM> and at t<NUM> + Δtmin(<NUM>-<NUM>).

The period t<NUM> to t<NUM> (Δt<NUM>-<NUM>) also includes an inherent - minimum - delay (Δtmin(<NUM>-<NUM>)) owing, at least, to propagation time of the communication from the CU to the DU and to processing time for the CU to generate the response (which may include communication with, and processing by, other parts of the network <NUM>, such as the core network <NUM>, for example to process a URLCC request and generate a response). However, in <FIG>, Δtmin(<NUM>-<NUM>) is less than Δt<NUM>-<NUM>, and an additional downlink delay in having the CU send the response to the DU is caused by misalignment of the downlink subframe <NUM> at t<NUM> + Δtmin(<NUM>-<NUM>); this additional downlink delay is equal to t<NUM> - (t<NUM> + Δtmin(<NUM>-<NUM>)).

Furthermore, the response that is received at t<NUM> cannot be received by the UE until the second frame <NUM>-<NUM> is in a downlink subframe <NUM> cycle. The period between times t<NUM> and t<NUM> (Δt<NUM>-<NUM>) also includes an inherent - minimum - delay (Δtmin(<NUM>-<NUM>)) owing, at least, to propagation time of the communication from the DU to the UE and for processing time for the DU to send the communication to the UE.

In <FIG>, the response that is received by the DU at t<NUM> is only received by the UE at time t<NUM>, which is later than t<NUM> + Δtmin(<NUM>-<NUM>). An additional downlink delay of t<NUM> - (t<NUM> + Δtmin(<NUM>-<NUM>)) that forms part of Δt<NUM>-<NUM> in the example of <FIG> is caused due to having to wait for the second frame <NUM>-<NUM> to cycle to its next downlink subframe <NUM> so as to be able to receive the response. Accordingly, in <FIG>, a further delay in communication is caused by misalignment in subframe types between the first and the second frames at t<NUM> and at t<NUM> + Δtmin(<NUM>-<NUM>).

Roundtrip communication time between the UE to the CU and back again (all via the DU) is Δt<NUM>-<NUM>. In the example of <FIG>, Δt<NUM>-<NUM> includes a total delay due to subframe misalignment of [t<NUM> -(t<NUM> + Δtmin(<NUM>-<NUM>)) + t<NUM> - (t<NUM> + Δtmin(<NUM>-<NUM>)) + t<NUM> - (t<NUM> + Δtmin(<NUM>-<NUM>))]; this delay may be approximately <NUM> to <NUM> in the example of <FIG>, and more typically <NUM> to <NUM>.

The telecommunications network <NUM> is configured, by means of the fronthaul and access schedulers to adjust the first and/or second frames so as affect relative alignment of their subframes in an effort to reduce latency in the example of <FIG>. To do so, the fronthaul and/or the access scheduler/s is/are configured to identify the minimum delay associated with a given communication between the UE, DU and CU (e.g. Δtmin(<NUM>-<NUM>) and whether there is a misalignment in subframe type at the point of communication (i.e. t<NUM>, t<NUM>, t<NUM> and t<NUM>) and the minimum delay after such a point (e.g. t<NUM> + Δtmin(<NUM>-<NUM>)).

Upon identification of such misalignment, the fronthaul and/or access scheduler/s calculate a relative adjustment to apply so as to reduce the additional uplink and/or downlink delay/s; this adjustment is herein referred to as tA.

With reference to <FIG>, so as to eliminate the additional uplink delay constituent of Δt<NUM>-<NUM>, it is intended for an uplink subframe <NUM> of the first frame <NUM>-<NUM> to commence no later than t<NUM> + Δtmin(<NUM>-<NUM>), else (as in the example of <FIG>) Δt<NUM>-<NUM> > Δtmin(<NUM>-<NUM>).

Accordingly, with reference to <FIG>, so as to minimise any additional uplink delay constituent of Δt<NUM>-<NUM>, tA falls within the bounds of:.

When tA=t<NUM> - (t<NUM> + Δtmin(<NUM>-<NUM>)) this is the minimum adjustment that may be applied to minimise Δt<NUM>-<NUM>, which is hence referred to as tA, min. When tA = t<NUM> - (t<NUM> + Δtmin(<NUM>-<NUM>)) + Δtfirst frame, uplink this is the maximum adjustment that may be applied to minimise Δt<NUM>-<NUM>, which is hence referred to as tA, max.

So as to minimise the additional downlink delay forming part of Δt<NUM>-<NUM>or forming part of Δt<NUM>-<NUM>, tA is calculated in a corresponding manner to that for (Δt<NUM>-<NUM>), as is tA, max and tA, min. However, in order to minimise a plurality of (Δt<NUM>-<NUM>), (Δt<NUM>-<NUM>) and (Δt<NUM>-<NUM>), tA is optimised so as to minimise the appropriate additional delays. For example, in order to minimise Δt<NUM>-<NUM>, a value of tA, referred to as tA, <NUM>-<NUM>, is calculated that minimises (Δt<NUM>-<NUM>) + (Δt<NUM>-<NUM>) + (Δt<NUM>-<NUM>), so that: t<NUM> coincides with t<NUM> + Δtmin(<NUM>-<NUM>); t<NUM> coincides with t<NUM> + Δtmin(<NUM>-<NUM>); and t<NUM> coincides with t<NUM> + Δtmin(<NUM>-<NUM>). Accordingly, this yields a range of values for tA, <NUM>-<NUM> bound by a maximum value and a minimum value, referred to as tA, <NUM>-<NUM>, max and tA, <NUM>-<NUM>, min respectively.

It will also be appreciated that, in order to eliminate all additional delays, tA is calculated so as to avoid transmission or receipt coinciding with resources assigned to higher priority or non-dynamic services, and with non-uplink and non-downlink subframes (by the fronthaul and/or access scheduler/s), such as: reference signals, guard periods, synchronisation signals, broadcast signals and control signals.

In more detail, <FIG> shows, an adjusted first frame <NUM>-<NUM> that is equivalent to the first frame <NUM>-<NUM> of <FIG> with an adjustment in the form of a time shift of -tA, <NUM>-<NUM>, min, applied.

The form of the frames <NUM> are identical in <FIG> and <FIG>, and only a relative time shift has been applied to the first frame <NUM>-<NUM> in <FIG> so as to yield the adjusted first frame <NUM>-<NUM> of <FIG> and the adjusted first frame <NUM>-<NUM> of <FIG>. Likewise, times t<NUM> to t<NUM> carry the same significance in <FIG> and <FIG>, and the periods between t<NUM> and t<NUM>, t<NUM> and t<NUM>, t<NUM> and t<NUM>, and t<NUM> and t<NUM> also include the respective inherent - minimum - delays (i.e. Δtmin(<NUM>-<NUM>), Δtmin(<NUM>-<NUM>), Δtmin(<NUM>-<NUM>), and Δtmin(<NUM>-<NUM>)).

By applying the adjustment of -tA, <NUM>-<NUM>, min to the first frame <NUM>-<NUM>, the adjusted first frame <NUM>-<NUM> causes, in comparison to <FIG>, alignment between subframe types at the instances of transmission and receipt between the adjusted first frame <NUM>-<NUM> and the second frame <NUM>-<NUM>. Accordingly, the communications from the UE to the DU that is received at t<NUM> is only received at the CU (t<NUM>) at t<NUM> + Δtmin(<NUM>-<NUM>) since the uplink cycle <NUM> of the adjusted first frame <NUM>-<NUM> coincides with t<NUM> + Δtmin(<NUM>-<NUM>). Similarly, the response from the CU to the DU that is received at t<NUM> is received by the UE (t<NUM>) at t<NUM> + Δtmin(<NUM>-<NUM>) for corresponding reasons, and the value of tA, <NUM>-<NUM>, min is derived from the value of Δtmin(<NUM>).

In <FIG>, roundtrip communication time Δt<NUM>-<NUM> occurs without any of the additional downlink and uplink delays due to optimised subframe alignment.

Turning to <FIG>, as part of which <FIG> has been reproduced for reference, there is shown an adjusted first frame <NUM>-<NUM>, in which an adjustment in the form of a time shift of -tA, <NUM>-<NUM>, max has been applied to the first frame <NUM>-<NUM> so as to yield the adjusted first frame <NUM>-<NUM>. As with the example of <FIG>, this causes alignment between subframes at the instances of transmission and receipt between the adjusted first frame <NUM>-<NUM> and the second frame <NUM>-<NUM>.

In one example, tolerance is added to tA so as to account for variation in inherent minimum delays (i.e. Δtmin(<NUM>-<NUM>), Δtmin(<NUM>-<NUM>), Δtmin(<NUM>-<NUM>), and Δtmin(<NUM>-<NUM>)), for example due to network load.

In one example, there may be no suitable value of tA, <NUM>-<NUM>. Instead, a value of tA is calculated that reduces additional delay for a portion of the roundtrip communication, for example to reduce Δt<NUM>-<NUM> and/or Δt<NUM>-<NUM>, but not Δt<NUM>-<NUM>. In such cases an optimisation process is run so as to calculate the optimum reduction in additional delay.

<FIG> is a process <NUM> diagram of a method of controlling the telecommunications network <NUM> so as to reduce latency by improving subframe alignment between the first and the second frames. In a first step <NUM>, the telecommunications network <NUM> is instructed (e.g. having received a request from a UE) to provide a low latency service and an assessment is made by the network <NUM> as to whether the network is configured, and capable of, performing a reconfiguration that causes latency to be reduced for the network communication without having to adjust frame alignment, as described above. For example, such an alternative adjustment may include higher prioritisation of a network communication, reallocating resources on either schedulers and/or allocating additional processing resources.

If so, such an appropriate reconfiguration is performed <NUM>, after which the process <NUM> is available to end or to re-iterate (after a predetermined delay back to step <NUM>), not shown). If not, however, then the network <NUM> identifies values of tA, <NUM>-<NUM> <NUM>, as described above.

As described above, there may not be any possible or acceptable values of tA, <NUM>-<NUM>, and so a query is performed at a next step <NUM> as to whether such appropriate values have been (or may be) calculated. If not, then an additional delay value is accepted, and a value of tA is calculated so as to achieve no more than the accepted additional delay value <NUM> and to minimise the additional roundtrip delay to the extent possible. Steps <NUM> and <NUM> are available to reiterate until an acceptable value of tA is calculated.

If, however, an acceptable value of tA, <NUM>-<NUM> or tA is calculated, then a specific value of tA, <NUM>-<NUM> or tA is selected (for example, any value between tA, <NUM>-<NUM>, min and tA, <NUM>-<NUM>, max) and the fronthaul and/or access scheduler/s is/are instructed to apply an adjustment in accordance with the selected value <NUM>, thereby reduction or eliminating (in the case of tA, <NUM>-<NUM>) the additional delay components of t<NUM>-<NUM>.

Process <NUM> is available to reiterate (e. after a predetermined delay) or to be triggered in response to detecting an event. Such an event that causes triggering of process <NUM> includes:.

In one example, the RAN split of the network <NUM> is applied in accordance with that defined in <NUM>rd Generation Partnership Project, technical specifications <NUM> and <NUM> (in particular in relation to the F1 Interface), the contents of which are herein incorporated by reference. In another example, the RAN split is configured in accordance with O-RAN (formerly XRAN) technology, which facilitates a lower layer split. In yet another example, the RAN split is configured in accordance with Telecom Infra Project (TIP) vRAN technology, which also facilitates a lower layer split.

In one example, the first transceiver <NUM> and/or the second transceiver <NUM> are available to be wireless or wired transceivers. In one example, the second transceiver <NUM> and/or the first transceiver <NUM> and/or the DU are available to be part of the CU or DU respectively or are available to be part of a remote dedicated entity. The second transceiver <NUM> and/or the first transceiver <NUM> are also available to be wireless or wired transceivers.

In the examples described above, the radio components are described as operating in accordance with LTE split radio, whereas the fronthaul components are described as operating in accordance with G. However, the radio and fronthaul components are available to operate in accordance with any appropriate communication protocol. For example, the CU and/or DU are available to operate in accordance with: Wi-Fi; LTE; <NUM>; <NUM>; <NUM>; New Radio (NR); Passive Optical Networks (PON); DOCSIS; Free-Space Optical Communication; and/or a microwave link.

In another example, the telecommunications network is available to be configured using conventional - non-split RAN - radio architecture, and for example where a transport link is formed as part of the backhaul that then connects the radio to the rest of the network.

The examples described above rely on a UE-originating communication (in particular a service request) and UE-bound response. In an alternative, the process is available to be utilised for purely network-originating and/or network-bound communications (such as originating from or bound to the core network, CU and/or DUs), and/or for any form of communication, including a service request, a data service, a non-data service, a control message and/or a management message. The value of tA is available to be calculated in dependence on the origin and/or destination of the communication and/or of the nature of the communication.

In one alternative, the process of adjusting frames so as to improve the telecommunications network is applied for communications between any pair of nodes of the network, including between the core network and the CU; the CU and the DU; the DU and the UE; and/or for any other links between and/or beyond the aforementioned.

The frames <NUM> described above and shown in the Figures comprise a single cycle of uplink and downlink subframes, and a particular (and static) ratio of uplink to downlink subframe duration within a given frame and amongst the first and second frames. It will be appreciated that the foregoing principles may still be applied where uplink and downlink cycles comprise multiple uplink and/or downlink subframes, and/or with different (and time-dynamic) ratios of uplink to downlink subframe duration within a given frame and/or amongst the first and second frames.

In the examples of <FIG>, only the first frame has been adjusted so as to cause relative movement to the second frame. In alternatives, however, only the second frame is adjusted or the first and the second frames are both adjusted (according to a given proportion of tA).

In one example, the aforementioned process is also used, or is alternatively used, so as to align non-uplink and non-downlink subframes (by the fronthaul and/or access scheduler/s), such as: reference signals, guard periods, synchronisation signals, broadcast signals and control signals.

In yet another example, in addition to, or instead of, an adjustment in the form of a time shift, the duration of a particular subframe (i.e. uplink or downlink) is adjusted and/or the sequence of subframes is adjusted, for example using dynamic subframe ratios.

Due to the cyclicity of frames <NUM>, it will be appreciated that multiples of tA are also available to be applied based on the periodicity of the uplink and downlink cycles of the frame(s) to which tA is applied.

In one example, merely reducing, rather than minimising, Δt<NUM>-<NUM>, Δt<NUM>-<NUM> and/or Δt<NUM>-<NUM> is desirable. Accordingly, tA is calculated so as to effect a reduction, and indeed any reduction, in the additional delays.

In one example, the transceivers, processor and memory of the CU <NUM> and/or DU <NUM> are configured to cooperate to define a Software Defined Networking (SDN) operating environment, allowing the CU <NUM> and/or DU <NUM> to reconfigure on demand, thereby to provide any appropriate functional split of their operating protocol(s). Furthermore, the CU <NUM> and first DU <NUM> may implement further functions (in which case further functional splits would be possible).

Due to the re-configurability of the functional splits between the CU and the DU, the CU and/or the DU are available to provide the fronthaul scheduler and/or the access scheduler. In one example, the access scheduler is a radio access scheduler.

Each feature disclosed in the description, and (where appropriate) the claims and drawings may be provided independently or in any appropriate combination.

Claim 1:
A method (<NUM>) of controlling a telecommunications network (<NUM>), the telecommunications network having a first node, a second node and a third node, and the method comprising:
identifying a first schedule for a first frame (<NUM>-<NUM>) for facilitating communication between the first node and the second node;
identifying a second schedule for a second frame (<NUM>-<NUM>) for facilitating communication between the second node and the third node, wherein each of the first frame and the second frame comprises an uplink subframe (<NUM>) and a downlink (<NUM>) subframe;
comparing the first schedule and the second schedule so as to identify a misalignment in the first frame and the second frame (<NUM>); and
applying an adjustment to the first schedule relative to the second schedule so as to reduce the identified misalignment in the first frame and the second frame, thereby to reduce a delay in communication (<NUM>).