GB2594059A

GB2594059A - Beam alignment techniques for telecommunication systems

Info

Publication number: GB2594059A
Application number: GB2005393.0A
Authority: GB
Inventors: Svendsen Simon; Rosa Claudio; Vejlgaard Benny; Cudak Mark; Mnagalvedhe Nitin; Tan Jun; Vook Frederick; Harrebek Johannes
Original assignee: Nokia Technologies Oy
Current assignee: Nokia Technologies Oy
Priority date: 2020-04-14
Filing date: 2020-04-14
Publication date: 2021-10-20
Also published as: GB202005393D0

Abstract

A user device (UE) 14 receives a split parameter, defining a split between transmission and reception slots for signals sent from a base station 12 to the UE. The UE configures 33 a beam alignment algorithm based on a number of transmission slots, as defined by the split parameter. The UE receives a transmission signal 43 from the base station in each of the transmission slots of a first signal block. Each transmission signal is received by one of a plurality of beams of the user device in accordance with the configured beam alignment algorithm. The beam alignment algorithm is used 35 to determine an optimum beam at the user device for transmissions between the user device and the base station, based on the received transmission signals. First reference signals are transmitted 45 from the UE to the base station in each of the reception slots defined by the split parameter. The base station receives the reference signals and determines 46 a first optimum beam for transmissions between the UE and the base station.

Description

Beam Alignment Techniques for Telecommunication Systems

Field

This specification relates to beam alignment, for example beam alignment in mobile communication systems. By way of example, a node of a mobile communication system may include a number of beams for communication with other nodes of the mobile communication system. A beam alignment algorithm may select beams from a number of possible beam options.

Background

A base station of a communication system may comprise a number of beams that can be used for communications with user devices. Similarly, a user device may comprise a number of beams that can be used for communications with base stations. Although developments have been made for beam alignment in such systems, there remains a need for further

developments in this field.

Summary

In a first aspect, this specification describes an apparatus comprising means for performing: receiving, at a user device (or user equipment), a split parameter defining a split between transmission and reception slots for signals of each of a plurality of signal blocks sent from a mobile communication base station (e.g. a next generation node B) to the user device (or user equipment); configuring a beam alignment algorithm (e.g. a hierarchical beam alignment algorithm) based on a number of transmission slots as defined by the split parameter; receiving, at the user device, a transmission signal from the base station for each of the transmission slots within a first signal block, wherein each transmission signal is received by one of a plurality of beams of the user device in accordance with the configured beam alignment algorithm; using the beam alignment algorithm to determine an optimum beam at the user device for transmissions between the user device and the base station, based on the received transmission signals; and sending a first reference signal (e.g. static Beam Alignment Reference Signals) from the user device to the base station for each of the reception slots of the plurality of signal blocks, as defined by the split parameter.

The beam alignment algorithm may be configured to: determine which of a plurality of broad beams is an optimum broad beam for transmissions between the user device and the base station based on a first plurality of the received transmission signals; and determine which of a plurality of narrower beams within the optimum broad beam is an optimum narrower beam for transmissions between the user device and the based station base on a second plurality of received transmission signals.

Some example embodiments are further configured to perform: sending a plurality of second reference signals from the user device to the base station.

The split parameter may indicate the number of transmission slots and/or the number of reception slots within said signal blocks. Alternatively, or in addition, the split parameter may identify which slots of the signal blocks are transmission slots and/or which slots are reception slots.

io The said means may comprise: at least one processor; and at least one memory including computer program code, the at least one memory and the computer program configured, with the at least one processor, to cause the performance of the apparatus.

In a second aspect, this specification describes an apparatus comprising means for performing: setting a split parameter defining a split between transmission and reception slots for signals of each of a plurality of signal blocks sent between a mobile communication base station (e.g. a next generation node B) and one or more user devices (or lifEs); sending a transmission signal from the base station for each of the transmission slots within a first signal block, wherein the transmission signal indicates the split parameter; receiving a first reference signal (e.g. static Beam Alignment Reference Signals) from a first user device in each of the reception slots of the plurality of signal blocks, as defined by the split parameter; and determining a first optimum beam at the base station for transmissions between the base station and the first user device, based on the received transmission signals. Each transmission signal sent from the base station may be sent using a broad-band beam covering a fun sector covered by the mobile communication base station.

In some example embodiments, the means are further configured to perform: receiving a plurality of second reference signals from the user device at the base station; and determining a refined optimum beam at the base station for transmissions between the base station and 30 the first user device, based on the first optimum beam and the second reference signals.

The split parameter may indicate the number of transmission slots and/or the number of reception slots within said signal blocks. Alternatively, or in addition, the split parameter may identify which slots of the signal blocks are transmission slots and/or which slots are reception slots. -3 -

The said means may comprise: at least one processor; and at least one memory including computer program code, the at least one memory and the computer program configured, with the at least one processor, to cause the performance of the apparatus.

In a third aspect, this specification describes a message sequence comprising: transmitting a first signal block using a mobile communication base station, wherein the first signal block includes a split parameter defining a split between transmission and reception slots for signals of each of a plurality of signal blocks sent from the mobile communication base station (e.g. a next generation node B) to a user device (or a user equipment); receiving the io first signal block at the user device; configuring a beam alignment algorithm (e.g. a hierarchical beam alignment algorithm) based on a number of transmission slots as defined by the split parameter; sending a second signal block from the mobile communication base station to the user device, wherein the second signal block includes a transmission signal for each of the transmission slots; receiving the second signal block at the user device, wherein each transmission signal is received by one of a plurality of beams of the user device in accordance with the configured beam alignment algorithm; using the beam alignment algorithm to determine an optimum beam at the user device for transmissions between the user device and the base station, based on the received transmission signals; sending a first reference signal (e.g. static Beam Alignment Reference Signals) from the user device to the base station in each of the reception slots of the plurality of signal blocks, as defined by the split parameter; receiving the first reference signal at the base station; and determining an optimum beam at the base station for transmissions between the base station and the first user device, based on the received transmission signals.

In a fourth aspect, this specification describes a method comprising: receiving, at a user device, a split parameter defining a split between transmission and reception slots for signals of each of a plurality of signal blocks sent from a mobile communication base station to the user device; configuring a beam alignment algorithm (e.g. a hierarchical beam alignment algorithm) based on a number of transmission slots as defined by the split parameter; receiving, at the user device, a transmission signal from the base station for each of the transmission slots within a first signal block, wherein each transmission signal is received by one of a plurality of beams of the user device in accordance with the configured beam alignment algorithm; using the beam alignment algorithm to determine an optimum beam at the user device for transmissions between the user device and the base station, based on the received transmission signals; and sending a first reference signal (e.g. static Beam Alignment Reference Signals) from the user device to the base station for each of the reception slots of the plurality of signal blocks, as defined by the split parameter. -4 -

Some example embodiments further comprise: sending a plurality of second reference signals from the user device to the base station.

In a fifth aspect, this specification describes a method comprising: setting a split parameter defining a split between transmission and reception slots for signals of each of a plurality of signal blocks sent between a mobile communication base station and one or more user devices; sending a transmission signal from the base station for each of the transmission slots within a first signal block, wherein the transmission signal indicates the split parameter; receiving a first reference signal (e.g. static Beam Alignment Reference Signals) from a first user device in each of the reception slots of the plurality of signal blocks, as defined by the split parameter; and determining a first optimum beam at the base station for transmissions between the base station and the first user device, based on the received transmission signals.

Each transmission signal sent from the base station may be sent using a broad-band beam covering a full sector covered by the mobile communication base station. The method may further comprise: receiving a plurality of second reference signals from the user device at the base station; and determining a refined optimum beam at the base station for transmissions between the base station and the first user device, based on the first optimum beam and the second reference signals.

In a sixth aspect, this specification describes a method comprising: transmitting a first signal block using a mobile communication base station, wherein the first signal block includes a split parameter defining a split between transmission and reception slots for signals of each of a plurality of signal blocks sent from the mobile communication base station to a user device; receiving the first signal block at the user device; configuring a beam alignment algorithm (e.g. a hierarchical beam alignment algorithm) based on a number of transmission slots as defined by the split parameter; sending a second signal block from the mobile communication base station to the user device, wherein the second signal block includes a transmission signal for each of the transmission slots; receiving the second signal block at the user device, wherein each transmission signal is received by one of a plurality of beams of the user device in accordance with the configured beam alignment algorithm; using the beam alignment algorithm to determine an optimum beam at the user device for transmissions -5 -between the user device and the base station, based on the received transmission signals; sending a first reference signal (e.g. static Beam Alignment Reference Signals) from the user device to the base station in each of the reception slots of the plurality of signal blocks, as defined by the split parameter; receiving the first reference signal at the base station; and determining an optimum beam at the base station for transmissions between the base station and the first user device, based on the received transmission signals.

In a seventh aspect, this specification describes an apparatus configured to perform any method as described with reference to the fourth, fifth or sixth aspects.

In an eighth aspect, this specification describes computer-readable instructions which, when executed by computing apparatus, cause the computing apparatus to perform any method as described with reference to the fourth, fifth or sixth aspects.

In a ninth aspect, this specification describes a computer program comprising instructions for causing an apparatus to perform at least the following: receiving, at a user device, a split parameter defining a split between transmission and reception slots for signals of each of a plurality of signal blocks sent from a mobile communication base station to the user device; configuring a beam alignment algorithm (e.g. a hierarchical beam alignment algorithm) based on a number of transmission slots as defined by the split parameter; receiving, at the user device, a transmission signal from the base station for each of the transmission slots within a first signal block, wherein each transmission signal is received by one of a plurality of beams of the user device in accordance with the configured beam alignment algorithm; using the beam alignment algorithm to determine an optimum beam at the user device for transmissions between the user device and the base station, based on the received transmission signals; and sending a first reference signal (e.g. static Beam Alignment Reference Signals) from the user device to the base station for each of the reception slots of the plurality of signal blocks, as defined by the split parameter.

In a tenth aspect, this specification describes a computer program comprising instructions for causing an apparatus to perform at least the following: setting a split parameter defining a split between transmission and reception slots for signals of each of a plurality of signal blocks sent between a mobile communication base station and one or more user devices; sending a transmission signal from the base station for each of the transmission slots within a first signal block, wherein the transmission signal indicates the split parameter; receiving a first reference signal (e.g. static Beam Alignment Reference Signals) from a first user device in each of the reception slots of the plurality of signal blocks, as defined by the split parameter; and determining a first optimum beam at the base station for transmissions -6 -between the base station and the first user device, based on the received transmission signals. Each transmission signal sent from the base station may be sent using a broad-band beam covering a full sector covered by the mobile communication base station. The method may further comprise: receiving a plurality of second reference signals from the user device at the base station; and determining a refined optimum beam at the base station for transmissions between the base station and the first user device, based on the first optimum beam and the second reference signals.

In an eleventh aspect, this specification describes a computer program comprising Jo instructions for causing an apparatus to perform at least the following: transmitting a first signal block using a mobile communication base station, wherein the first signal block includes a split parameter defining a split between transmission and reception slots for signals of each of a plurality of signal blocks sent from the mobile communication base station to a user device; receiving the first signal block at the user device; configuring a beam alignment algorithm (e.g. a hierarchical beam alignment algorithm) based on a number of transmission slots as defined by the split parameter; sending a second signal block from the mobile communication base station to the user device, wherein the second signal block includes a transmission signal for each of the transmission slots; receiving the second signal block at the user device, wherein each transmission signal is received by one of a plurality of beams of the user device in accordance with the configured beam alignment algorithm; using the beam alignment algorithm to determine an optimum beam at the user device for transmissions between the user device and the base station, based on the received transmission signals; sending a first reference signal (e.g. static Beam Alignment Reference Signals) from the user device to the base station in each of the reception slots of the plurality of signal blocks, as defined by the split parameter; receiving the first reference signal at the base station; and determining an optimum beam at the base station for transmissions between the base station and the first user device, based on the received transmission signals.

In a twelfth aspect, this specification describes a computer-readable medium (such as a non-30 transitory computer-readable medium) comprising program instructions stored thereon for performing (at least) the method of the fourth, fifth or sixth aspects.

In a thirteenth aspect, this specification describes an apparatus comprising: at least one processor; and at least one memory including computer program code which, when executed 35 by the at least one processor, causes the apparatus to perform (at least) the method of the fourth, fifth or sixth aspects. -7 -

In a fourteenth aspect, this specification describes an apparatus comprising: means (such as first receiver) for receiving, at a user device, a split parameter defining a split between transmission and reception slots for signals of each of a plurality of signal blocks sent from a mobile communication base station (e.g. a next generation node B) to the user device (or user equipment); means (such as a beam alignment module) for configuring a beam alignment algorithm (e.g. a hierarchical beam alignment algorithm) based on a number of transmission slots as defined by the split parameter; means (such as the first receiver) for receiving, at the user device, a transmission signal from the base station for each of the transmission slots within a first signal block, wherein each transmission signal is received by one of a plurality ro of beams of the user device in accordance with the configured beam alignment algorithm; means (such as the beam alignment module) for using the beam alignment algorithm to determine an optimum beam at the user device for transmissions between the user device and the base station, based on the received transmission signals; and means (such as a transmitter) sending a first reference signal (e.g. static Beam Alignment Reference Signals) from the user device to the base station for each of the reception slots of the plurality of signal blocks, as defined by the split parameter.

In a fifteenth aspect, this specification describes an apparatus comprising: means (such as a control module) for setting a split parameter defining a split between transmission and reception slots for signals of each of a plurality of signal blocks sent between a mobile communication base station (e.g. a next generation node B) and one or more user devices; means (such as a transmitter) for sending a transmission signal from the base station for each of the transmission slots within a first signal block, wherein the transmission signal indicates the split parameter; means (such as a receiver) for receiving a first reference signal (e.g. static Beam Alignment Reference Signals) from a first user device in each of the reception slots of the plurality of signal blocks, as defined by the split parameter; and means (such as a beam alignment modue) for determining a first optimum beam at the base station for transmissions between the base station and the first user device, based on the received transmission signals.

In a sixteenth aspect, this specification describes an apparatus comprising: means for transmitting a first signal block using a mobile communication base station, wherein the first signal block includes a split parameter defining a split between transmission and reception slots for signals of each of a plurality of signal blocks sent from the mobile communication base station (e.g. a next generation node B) to a user device (or a user equipment); receiving the first signal block at the user device; means for configuring a beam alignment algorithm (e.g. a hierarchical beam alignment algorithm) based on a number of transmission slots as defined by the split parameter; means for sending a second signal block from the mobile -8 -communication base station to the user device, wherein the second signal block includes a transmission signal for each of the transmission slots; means for receiving the second signal block at the user device, wherein each transmission signal is received by one of a plurality of beams of the user device in accordance with the configured beam alignment algorithm; using the beam alignment algorithm to determine an optimum beam at the user device for transmissions between the user device and the base station, based on the received transmission signals; means for sending a first reference signal (e.g. static Beam Alignment Reference Signals) from the user device to the base station in each of the reception slots of the plurality of signal blocks, as defined by the split parameter; means for receiving the first io reference signal at the base station; and determining an optimum beam at the base station for transmissions between the base station and the first user device, based on the received transmission signals.

Brief description of the drawings

Example embodiments will now be described, by way of non-limiting examples, with reference to the following schematic drawings: FIG. 1 is a block diagram of a system in accordance with an example embodiment; FIG. 2 is a block diagram of a system in accordance with an example embodiment; FIG. 3 is a flow chart showing an algorithm in accordance with an example embodiment; FIG. 4 shows a message sequence in accordance with an example embodiment; FIG. 5 shows a message sequence in accordance with an example embodiment; FIG. 6 is a flow chart showing an algorithm in accordance with an example embodiment; FIG. 7 is a flow chart showing an algorithm in accordance with an example embodiment; 25 FIG. 8 shows a message sequence in accordance with an example embodiment; FIG. 9 is a plot showing messages exchanged in accordance with an example embodiment; FIG. 10 is a flow chart showing an algorithm in accordance with an example embodiment; FIG. ii is a block diagram of components of a system in accordance with an example embodiment; FIGS. 12A and 12B show tangible media, respectively a removable non-volatile memory unit and a company disc (CD) storing computer-readable code which when run by a computer perform operations according to example embodiment.

Detailed description

The scope of protection sought for various embodiments of the invention is set out by the independent claims. The embodiments and features, if any, described in the specification that do not fall under the scope of the independent claims are to be interpreted as examples useful for understanding various embodiments of the invention. -9 -

In the description and drawings, like reference numerals refer to like elements throughout.

FIG. 1 is a block diagram of a system, indicated generally by the reference numeral 10, in accordance with an example embodiment. The system 10 comprises a mobile base station 12, such as a next generation node B (gNB), a first user device 14 and a second user device 16.

Two-way communications are provided between each user device and the base station 12.

FIG. 2 is a block diagram of a system, indicated generally by the reference numeral 20, in io accordance with an example embodiment. The system 20 comprises a node 21 of a mobile communication system (such as the base station 12 or one of the user devices 14 and 16 described above). In use, the node 21 communicates with one or more other nodes of the communication system.

As shown in FIG. 2, the node 21 comprises a number of beams (such as the beam 22) that can be used for communications (e.g. between a base station and one or more user devices, between a user device and one or more base station or between one user device and another). As discussed in detail below, a beam selection algorithm may be provided to select one of the beams 22 for use in communication (e.g. the strongest beam according to some metric, such as received signal strength).

The 5G New Radio (NR) Release 15 provides a beam alignment procedure between user devices and gNBs (see 3GPP TR 38.802 section 6.1.6 and in TS 38.214 section 5.2). The beam alignment procedure includes three main phases: * Phase 1, in which transmission beam sweeping is used. In phase 1, the relevant user device (13E) measures the RSRP (or some other signal quality indicator) for multiple SSB beams transmitted by the communication node (gNB). The UE reports back the best SSB back to the gNB, at the next allocated time instance (RACH Group).

* Phase 2, in which the gNB performs refined DL CSI-RS beam sweeping. The user device measures RSRP (or some other signal quality indicator, such as CQI or RI) for all CST-RS or SSB beams received and reports the best beam ID back to gNB.

* Phase 3, in which the gNB transmits with best beam found in phase 2 and the 13E performs beam sweeping to identify the best narrow RX beam.

By the end of phase 3, alignment between gNB transmit beam and the UE receive beam is obtained for maximized directional gain and minimum interference to other users in serving and neighbouring cells.

-10 -The algorithm described above can be used, for example, in aligning the gNB transmit beam with the HE receive beam for frequency range FR2 below 52.6 GHz. However. 3C-PP is planning to include frequency ranges beyond 52.6 GHz in the near future (e.g. as high as 300 GHz), where the used antenna arrays will typically be larger with high antenna gain to compensate for the high propagation loss at these frequencies. Higher antenna gain will result in a narrower radiation beam width, which increases the granularity and the number of iterations needed in the beam alignment procedure. The current 5G NR 3GPP Re1.15 beam alignment procedure may be too slow to cope with this increase in granularity.

FIG. 3 is a flow chart showing an algorithm, indicated generally by the reference numeral 30, in accordance with an example embodiment. The algorithm 30 is implemented at the relevant user device (e.g. one of the user devise 14 and 16 described above).

The algorithm 30 starts at operation 32, where a split parameter (e.g. a rIX/Rx split parameter, as discussed in detail below) is received at the user device. The split parameter may define a split between transmission and reception slots for signals of each of a plurality of signal blocks sent from a mobile communication base station (such as the gNB) to the user device. For example, in the case of synchronisation signal blocks (SSBs) consisting of 64 SS bursts, the split parameter may define the split between transmit and receive bursts in the SS block. It should be noted that, in some embodiments, the operation 32 enables the split parameter to be retrieved (e.g. from some remote databases), rather than providing the split parameter within a transmitted message.

At operation 33, a beam alignment algorithm is configured at the user device, based on a number of transmission slots as defined by the split parameter received in operation 32.

At operation 34, a transmission signal (e.g. a plurality of synchronisation signal block (SSB) signals) is received at the user device, from the base station, for each of the transmission slots within a first signal block. Each transmission signal may be received by one of a plurality of beams of the user device in accordance with the configured beam alignment algorithm. Thus, the number of transmission slots is as defined by the split parameter received in operation 32.

At operation 35, a beam alignment algorithm is used to determine an optimum beam at the user device for transmissions between the user device and the base station, based on the received transmission signals. An antenna at the user device may be configured based on the determined optimum beam.

At operation 36, a first reference signal is sent from the user device to the base station for each of the reception slots of the plurality of signal blocks, as defined by the split parameter.

FIG. 4 shows a message sequence, indicated generally by the reference numeral 40, in accordance with an example embodiment. The message sequence 40 shows an example implementation of the algorithm 30 described above.

The message sequence 40 starts with a message 41 being sent from the base station 12 to the ro user device 14. The message 41 includes a split parameter (or identifies a location of the split parameter), such that the reception of the message 41 implements the operation 32 described above.

On receipt of the message 41, a beam alignment at the user is configured in the operation 33 /5 described above.

A message 43 is sent from the base station to the user device 14. The message 43 include a transmission signal and the reception of the message 43 at the user device 14 implements the operation 34 described above. As discussed in detail below, the messages 41 and 43 may be identical, such that both messages include the split parameter and the transmission signal discussed above.

On receipt of the message 43, the beam alignment algorithm (as configured in the operation 33) is used to determine an optimum beam (based on the Tx signals in the message 43) at the user device for transmissions between the user device and the base station, thereby implementing the operation 35 described above. The operation 35 may include an antenna at the user device being configured based on the determined optimum beam. (In some example embodiments, the operations 33 and 35 may be implemented at the same time.) A first reference signal 45 is sent from the user device to the base station for each of the reception slots of the plurality of signal blocks, as defined by the split parameter, thereby implementing the operation 36.

On receipt of the first reference signal 45, the base station 12 performs a beam alignment operation 46, as discussed further below.

FIG. 5 shows a message sequence, indicated generally by the reference numeral 50, in accordance with an example embodiment. The algorithm 5o is a hierarchical beam alignment -12 -algorithm, which may be used to implement the beam alignment operation 35 described above.

The message sequence 50 includes first messages 51, second messages 52 and third messages 53 sent from a base station (e.g. the base station 12) to a user device (e.g. the user device 14) and fourth message sent from the user device to the base station. The first, second and third messages 51 to 53 are collectively an example of the message 43 sent from the base station 12 to the user device 14. The fourth message 54 is an example of the first reference signal 45 sent from the user device 14 to the base station 12.

As shown in FIG. 5, the first message 51 includes 16 synchronisation signal block (SSB) signals, the second message 52 includes four SSB signals and the third message 53 includes four SSB signals. These signals are described by way of example only -alternative numbers of signals and alternative types of signals are possible. Indeed, as discussed further below, the total number of signals included in the first to third messages may be variable (e.g. dependent on a split parameter).

In response to the receipt of the first to third messages 51 to 53 at a user device, Rx sweeping is conducted at the respective user device. Similarly, in response to the receipt of the fourth message 54 at a base station, Rx sweeping is conducted at the respective base station.

In Rx beam sweeping, the relevant reference signals are transmitted with a static radiation beam from the first device (e.g. from a base station in the case of the messages 51 to 53 and from a user device in the case of the messages 54). The second device receives the reference signals using different receiver radiation beams (directions). The second device can determine the best radiation beam (direction) and can use that radiation beam immediately without any need for a feedback message to the transmitter.

By comparison, in Tx beam sweeping, reference signals are transmitted with different radiation beams (directions) from the first device and received with a static radiation beam at a second device. The second device sends a feedback message to the first device with information on which beam is the best seen from the second device.

An advantage of using Rx beam sweeping (rather than Tx beam sweeping) is the avoidance of 35 the feedback loop due to the need to transmit the feedback message.

As discussed above, the message sequence 50 includes a first message 51 including 16 SSB signals. Each SSB signal may be a simple repetition of the same signal that can be detected at -13 -the user device. The user device uses a different broad beam to receive each SSB signal and can therefore determine which of 16 broad beams has the best connection with the base station (e.g. based on RSRP, CQI, RI etc.).

Similarly, the second message 52 includes four SSB signals, which signals can be received using four different beams within the strongest beam identified above. Thus, the second message 52 can be used to identify the strongest narrower beam within the strongest broad beam, effectively determining the best of 16 x 4 (i.e. 64) narrower beams for communication.

/o Finally, the third message 53 includes four SSB signals, which signals can be received using four different beams within the strongest best identified above. Thus, the third message can be used to identify the strongest narrow beam within the strongest narrower beam referred to above, effectively determining the best of 64 x 4 (i.e. 256) narrow beams for communication.

/5 Thus, hierarchical Rx beam sweeping can be used at each user device that establishes a connection to the base station when the base station is transmitting SSB signals with a static radiation pattern, whereby the number of needed SSB signals can be reduced. For example, a gNB may only transmit 24 repetitions of SSB beams using a static radiation pattern and all UEs in communication with that gNB may perform a hierarchical RX beam sweep in for example a 164444 pattern as discussed above.

Following the receipt of the third message 53, the best communication channel (e.g. the best of 256 narrow beams) between the user device and the base station is identified and used to transmit the fourth message 54 from the user device to the base station. In the message sequence 50, the fourth message 54 consist of 40 static beam alignment reference signals (BARS). Each of those signals can be received at with a different receiver beam at the base station 40 such that the best beam out of 40 can be identified at the base station using a sequential Rx beam sweep. The Rx sweep pattern at the base station may be sequential and provide combined cover of the full sector, to ensure that the base station detects all user devices in the relevant cell. The base station can use these specific beams immediately for communications with the respective user devices, thereby increasing the combined antenna gain available (by using directional gain radiation patterns at both the user device and the base station).

Thus, at this stage, the best Rx beam out of 256 has been identified at the user device and the best Rx beam out of 40 has been identified at the base station.

-1.4 -FIG. 6 is a flow chart showing an algorithm, indicated generally by the reference numeral 60, in accordance with an example embodiment. The algorithm 60 may be used in an implementation of the message sequence 50 described above.

The algorithm 6o starts at operation 62 where a determination is made regarding which of a plurality of broad beams is an optimum broad beam for transmissions between a particular user device and the relevant base station based on a first plurality of received transmission signals. In the example message sequence 50, the first plurality of received transmission signals is provided by the first message 51.

Next, at operation 64, a determination is made regarding which of a plurality of narrower beams within the optimum broad beam described above is an optimum narrower beam for transmissions between the user device and the based station based on a second plurality of received transmission signals. In the example message sequence 50, the second plurality of received transmission signals is provided by the second message 52.

Finally, at operation 66, a determination is made regarding which of a plurality of narrow beams within the beam identified in the operation 64 is an optimum narrow beam for transmission between the user device and the based station base on a third plurality of received transmission signals. In the example message sequence 50, the third plurality of received transmission signals is provided by the third message 53.

The algorithm 6o (and the message sequence 50) includes three hierarchical levels in the hierarchical beam sweeping. This is not essential to all example embodiments. For example, one level could be provided (i.e. sequential beam sweeping), two levels could be provided, or more than three levels could be provided.

The SSB blocks of signals described above comprise 64 signals. In the example message sequence 5o, the SSB block consist of 24 signals sent from the base station to the user device and 40 signals sent from the user device to the base station. This is not essential to all embodiments; indeed, the split of how the SSB blocks are used may be varied, as discussed further below.

Each SSB signal may include a split parameter (e.g. ssb-TxRxSplit) to inform the user device of the split between transmit and receive slots in the SSB signals. This enables a dynamic approach to be used where each base station can be configured individually. In addition, a static approach could also be used where all base stations (e.g. gnBs) have the same split, whereby a new parameter is not needed.

-15 -If the sweeping split is set at 24 (as in the example above) then, in one example embodiment, the user devices will know that the base station will transmit SSBs at SSB index (embedded in the PBCH message) 1 to 24 at predetermined times and that the user device will have to transmit BARS/Msg#1 at the intervals reserved from SSB indices 25 to 64. In this phase#o, the base station and the user device will typically be frequency aligned but only partially time aligned (no timing advance), so the user device transmitted BARS may be required to have a sufficient length to cover the radius of the cell size. The BARS signal could be a preamble signal of sufficient duration or randomly picked by the UE orthogonal BARS signal from a /0 common pool.

In one example implementation, the total SSB burst length is 5 ms, such that the available time for transmitting a BARS/Msg#1 from the UE is theoretically 5 ms/64 78 [Is, which can be directly converted to a distance of 2.9988 m/s * 78-6 ms 23.4 km (which is sufficient /5 time to cover an FR2 cell).

FIG. 7 is a flow chart showing an algorithm, indicated generally by the reference numeral 70, in accordance with an example embodiment. The algorithm 70 may be implemented at a base station (such as a gNB) and may be used in an implementation of the message sequence 5o described above.

The algorithm 70 starts at operation 72 where a transmission signal is sent. The transmission signal may be a combination of the first to third messages 51 to 53. As noted above, the transmission signal includes a split parameter defining a split between transmission and reception slots for signals of each of a plurality of signal blocks sent between a mobile communication base station and one or more user devices. Indeed, the operation 72 of the algorithm 70 may including setting said split parameter.

At operation 73, a second transmission signal is sent. The transmission signals 72 and 73 may be identical (and both may include the first to third messages 51 to 53 and the split parameter). Indeed, transmission signals may be sent periodically within the first signal block. It should be noted that the messages 41 and 43 of the message sequence 40 described above may be the transmission signals sent in the operations 72 and 73.

The second transmission signal sent in the operation 73 may therefore correspond to the message 43 of the message sequence 40 and to the first to third message 51 to 53 of the message sequence 5o. The first transmission signal sent in the operation 72 may correspond -16 -to the message 41 of the message sequence 40 and may therefore be sent before the messages shown in the message sequence 50.

Each of the transmission signals sent in the operations 72 and 73 may comprise a broad-band 5 beam covering a full sector covered by the mobile communication base station.

At operation 74, a first reference signal is received from a first user device in a reception slot of a signal block (as defined by the split parameter). Indeed, a reference signal may be received in each of the reception slots of a plurality of signal blocks. The first reference signal ro received in the operation 74 may correspond to the message 45 of the message sequence 40 and the fourth message 54 of the message sequence so.

At operation 75, Rx beam sweeping is carried out at the base station, such that, at operation 76, a first optimum beam is determined at the base station for transmissions between the base station and the first user device, based on the received transmission signals. An antenna at the base station can then be configured based on the determined optimum beam.

It should be noted that the beam sweeping arrangements implemented in the operations 60 and 70 do not require feedback (either from the user device to the base station or from the base station to the user device). Thus, both algorithm use Rx beam sweeping (and not Tx beam sweeping), as discussed above.

FIG. 8 shows a message sequence, indicated generally by the reference numeral 80, in accordance with an example embodiment. The message sequence 80 comprises four phases 25 (Phase#o, Phase#1, Phase#2 and Phase#3).

Example signalling is shown in the message sequence 80 for a 24/40 split between a gNB 81 and a UE 82. This split can, of course, be chosen differently if for example the gNB 81 has a much larger antenna array than the UE 82. The total number of 64 is used as a non-limiting example, since this may be the maximum number of possible/allowed beam alignment reference signal in the 5ms SSB block. Future mmWave and TeraWave systems will most likely use high SCSs and that could allow for more than 64 beam alignment reference signals in the SSB block, which this invention easily scales to.

The message sequence 8o starts at step 1, where the gNB 81 transmits 24 SSB signals using the same broad-banded radiation beam covering the full sector of the gNB. The signals transmitted includes the split parameter (ssb-TxRxSplit) defining the split between -17 -transmission and receiption slots for signals of each of a plurality of signal blocks sent from the gNB to the UE.

At step 2, the UE 81 receives the signal transmitted in step 1 and reads the split parameterr 5 (ssb-TxRxSplit) from the SIB1 (or MIB). The UE can use one beam or multiple beams in this phase depending on the estimated signal conditions.

A beam alignment algorithm (e.g. the hierarchical beam alignment algorithm described above) may be configured at this stage, based on a number of transmission slots as defined by io the split parameter.

Next, step 1 is repeated such that the gNB 81 transmits 24 SSB signals (including the split parameter) using the same broad-banded radiation beam covering the full sector of the gNB. Thus, a second signal block is sent from the gNB (or mobile communication base station) to the UE (or user device). As noted above, multiple instances of the step 1 may be repeated periodically. The second signal block may be received at the UE, wherein each transmission signal is received by one of a plurality of beams of the UE in accordance with the configured beam alignment algorithm; At step 3, the UE 82 performs a beam alignment (e.g a hierarchical beam alignment) based on the ssb-TxRxSplit value using predefined beams that combined will cover the full sector of that array and receives one SSB signal RSRP value per beam per. beam sweep, which is stored temporary at the UE. The UE then determine the best beam of the theoretical 256 beams (UE Rx beams). The beam alignment algorithm may be configured as part of the step 3.

At step 4, the LIE configures that array with the best beam. The array may be configured based on the optimum beam for transmissions between the user device and the base station as determined by the beam alignment algorithm in step 3.

At step 5, the UE 82 transmits 40 BARS signals using the beam configured in steps 3 and 4. The gNB 81 sweeps through 40 predefined beams that combined will cover the full sector and receives one BARS signal RSRP value per beam, which is stored temporary at the gNB. The 40 BARS signals implement the first reference signal described above, which signal is sent in each of the reception slots defined by the split parameter. The first reference signal is received at the gNB.

-18 -At step 6, the gNB 81 determines the best beam out of 40 for all the performed sweeps. Thus, an optimum beam is determined at the gNB for transmissions between the gNB and the UE, based on the received transmission signals.

At step 7, the antenna array at the gNB is configured based on the beam identified in step 6.

At step 8, the gNB 81 transmit Msg2 in the directions of the UEs (including the UE 82). At step 9, the UE 82 transmits Msg3 to the gNB 81. At step 10, the gNB 91 transmits Msg4 to the UE.

At step ii, the UE 82 transmits four SRS signals (or some other signal, such as BARS) configured by the gNB e.g. using the beam configured in step 3. The gNB 81 sweeps through four predefined beams that combined will cover the radiation beam-width of the beam configured in step 6 and receives one SRS signal RSRP value per beam (or some other signal), which is stored temporary at the gNB.

At step 12, the gNB 81 determines the best beam of all the performed sweeps in step 11.

Thus, steps ii and 12 involve sending a plurality of second reference signals (e.g. static SRS signals or BARS signals) from the UE to the gNB; receiving a plurality of second reference signals sent from the UE to the gNB; and determining a refined optimum beam at the gNB for transmissions between the gNB and the first UE.

At step 13, the gNB 81 configures (or reconfigures) the array to that best beam (e.g. the best beam out of 16() at this stage, as discussed above).

At step 14, the UE transmits four signals (e.g. SRS signals) using the beam configured in step 3. The gNB sweeps through four predefined beams that combined will cover the radiation beam-width of the beam found in step# 12 and receives one SRS signal RSRP value per beam, 30 which is stored temporary at the gNB.

At step 15, the gNB determines the best beam of all the performed sweeps in step 14.

At step 16, the gNB configures the array to the beam determined in step 15 (e.g. the best Beam out of 640, as discussed above).

At step 17, the beam alignment procedure is complete, and the data messages are now sent and received with maximum available antenna gain.

-19 -As noted above, the message sequence 80 comprises four phases (Phase #0, Phase#1, Phase#2 and Phase#3). Phase#0 consists of steps ito 7, phase#1 consists of steps 8 to 10, phase#2 consists of steps 11 to 13 and phase #3 consists of steps 14 to 16.

Phase#1, phase#2 and phase#3 are used for beam refinement and are illustrated in this example with SRS signals in phase#2 and phase#3. However, these two phases could also be implemented using CSI-RS transmitted from the gNB as specified in Phase#2 of the current 5G NR 3GPP Re1.15 beam alignment procedure or the UE could use the BARS signals defined for phase#o. Many other variants are also possible.

FIG. 9 is a plot, indicated generally by the reference numeral 90, showing messages exchanged in accordance with an example embodiment. Specifically, the plot 90 shows messages sent and received by a base station (such as the gNB 81) and message sent and received by a user device (such as the UE 82) in example applications of the message sequence 80 described above.

The gNB shown in the plot 90 transmits SSB signals (implementing the two instances of step described above), configures the gNB antenna (implementing steps 5 to 7 of phase#0), sends Msg2 and Msg4 signals (implementing steps 8 and 10 of phase#1), and reconfigures 20 the gNB array in phases #2 and #3 (implementing steps 11 to 13 and steps 14 to 16 respectively). The process can then be repeated.

Similarly, the UE shown in the plot 90 receives the SSB signals, including the split parameter (implementing steps ito 3 described above), send BARS signals (implementing step 5) to complete phasno, send Msg3 signals (implementing step 9), and sends static SRS signals in phase #2 and #3 (implementing steps n and 14 respectively).

The estimated time needed for the message sequence 90 in this example is less than 14 ms (assuming that all signals are received and decoded the first time) as shown in FIG. 9, when using 8 SRSs in phase#2 and phase#3. 1.9 ms for 24 SSB (19/64*5ms) and 1.6 ms for 40 BARS/Msg#2 (391[5 duration per signal 4* 40/64/2*5ms).

FIG. 10 is a flow chart showing an algorithm, indicated generally by the reference numeral 100, in accordance with an example embodiment. The algorithmic:AD (which may be 35 implemented at a base station) can be used to implement phase#2 and phase#3 of the message sequence 90 described above.

-20 -The algorithm 100 starts at operation 102, which operation may follow from the operation 76 of the algorithm 70. In the operation 102, a plurality of second reference signals are received (e.g received at the gNB 81 from the HE 82). The second reference signals may be the signals sent in step 11 of the message sequence 80.

At operation 104, an optimum beam is identified, which beam may be a narrow beam from within the broad beam identified in the operation 76 described above. Thus, the operation 104 may implement the step 12 of the algorithm 80.

At operation 106, a plurality of third reference signals are received (e.g received at the gNB 81 from the UE 82). The third reference signals may be the signals sent in step 14 of the message sequence 80. At operation 108, an optimum beam is identified, which beam may be a narrow beam from within the beam identified in the operation 104. Thus, the operation 108 may implement the step 15 of the algorithm 80.

Example implementation details of some of the principles described above are provided below.

The traditional msgi (PRACH) may be used for the UE transmitted BARS signal as shown in 20 Table 1 below for the short sequence PRACH preamble specified for FR2.

< 38.211Table 6.13.1-2: Preamble formats for where mtie se.te AI 436, ^ c *-, ;C...; r. .1.-CO 136 j -, ..; .. *:.; g * , 2>fr.Hz k' Table 1: Short sequence PRACH preamble specified for FR2 The longest of these is format B4 with the following duration calculated for a SCS of 120 kHz: or * Cyclic Prefix 3.8 ps * 12 preamble R. 12 8.33 iLis 100 is * Guard band R.. 3.2 us Giving a total time of approximately 107 us, which is larger than the maximum theoretical 78 us in order to keep the 64 beam sweeps with an SSB burst period of 5 ms. The second longest -21 -PRACH formats only uses six preambles, so the rest of the specified PRACH preambles could be used as the BARS signal for this concept.

The UE will have to transmit its Msg#1 multiple times, 40 times in this example, since the gNB uses 40 Rx sweeps, so the Rx sweeping beam alignment procedure described herein uses 24 SSBs and 40 Msg#1, where the current NR 3GGP Re1.15 Tx sweeping Beam Alignment procedure uses 64 SSBs and 1 Msg#1. Consequently, the number of Tx transmissions are approximately the same, but the gNB only needs to configure one RACE groups and not 64 as currently needed for 64 SSB beams. This will reduce the overhead of needed RACH group io scheduling.

The user device (UE) may locally generate a wideband BARS with duration of e.g. approx.

its corresponding to a cell radius of 3000 m: To that end, the UE may use a common pool of resources: 7.5 * an orthogonal cover code (OCC) matrix 0 of size B; The OCC matrix is common to all the users, i.e. all users know B and the generation algorithm. For example, the UEs can implement a Walsh-Hadamard matrix.

* a set S of constant-amplitude zero autocorrelation sequences. The set is common to all the users, i.e. all users have the mechanism of generating the same set built in, e.g. they can implement Zadoff-Chu sequences of length L and roots r E R = fr1, rA}, where L and R are known across all users.

To generate the BARS, the UE may pick at random a code ouE from matrix 0 and a sequence suE from sets and generates the sequence BARS = oUE.* Sus. If the BARS signals received from different UE's at the gNB are orthogonal, then the gNB will be able to distinguish between different UE's when performing its RN beam sweep. The gNB then sends Msg2 in those directions and continue the initial access procedure.

In case of orthogonal BARS signals, the gNB may only send out a Msg2 in the direction of the 30 beam with the strongest RSRP level.

As discussed above, the base station (gNB) may signal to the user device (UE) the used Rx/Tx split of the assigned resources in the SSB burst. The UE should receive this novel information together with the other relevant SSB parameters, where some are part of the SIM message (ssb-PeriodicityServingCell), as shown below for a stand-alone 5G NR mmWave system (TS 38.314 section 6.3.2).

-22 -Adding a container, called ssb-TxRxSplit, after the ssb-PeriodicityServingCell container may be implemented as follows: ccvingsallsonfiacoam=srs:a dcavnliakconflecommon 401inkconfig6ommon supplementaryupl ink 0-rimine8dvanceoffset ssb-maitionsinsurst SEQUENCE --Need R --Need R inose6roup i3HthiS.c=fj_f2i'fin,US OPTIONAL. OPTIONAL, --Need s eraapmreseace UplinkConfigCommonSTB OPTIONAL, ENUMERATED nO, n25160, 839916 1 SEQUENCE { BIT STRING (SIZE (8)). BIT STRING (SIZE (8)) OPTIONAL --cond Abave606zonly 4sb-aariodicltysarsongce/1 ENUMERATED (msS, msI0, ms20, ms40, ms80, MS1501, sse-sscozaSmlit I.NTEr:LR (1_64).

tdd-1.8..-0L-eanfigurationcommon 1-00-0L-6L-zonfigoammon OPTIONAL. --cond TOO ss-msek-slockmamer INTEGER (-60..50), The format of the ssb-TxRxSplit container could be fully flexible, as shown above, as an 8-bit integer allowing the Tx-Rx Split to be assigned at any of the allocated 64 SSB bursts. A less flexible format using e.g. only 2 or 3-bits is also a possible solution where one out of four (or eight) pre-selected values can be as follows: ii-TxkxSpi t format s 1. SSb-TxRx5Dlitl as a INTEGER 4) 4 full flex) 2 ssb-18asSplit.; as EP:51,1E66780(16,12,16,64) + less aasplit: as ENSSIESaIs0(8,15.11,31.40,4&,66, *ITS zi bits 4 ssf)-18assplit; as ENtwasaTE0(I5,20.24,28,12,36,40 a:itt: 3 bits A ssb-TxRxSplit value of 24, may indicate that the first 24 bursts are used by the gNB for transmission and the last 40 bursts are used by the UE's for transmissions.

A ssb-TxRxSplit value of 64, may indicate that only the gNB is transmitting and inform the UE's to revert back to legacy (3GPP Re.15) beam alignment procedure, with full Tx sweeping at the gNB.

sarvingsellconfiasomammsm la downliakconflscomman upliakeonfigcemmon supplementaryuplin8 n-Tiedng4dvanceoffset sse-PositionsIaserst SEQUENCE { --Need R --Need R inonearcup,;(,iinHaNn'it:Cc,.,nlonSIE OPTIONAL, OPTIONAL, --Need s grasemresaNce eplinkemnfigcommonsis OPTIONAL.

ENUMERATED nO, a25160, n34916 1 SEQUENCE { BIT STRING (SIZE (8)).

BIT STRING (SIZE (8)) OPflONAL send Above6s6z0nly asb-aeriodicltyservingcell ENUMERATED CMSS, am14, ms20, mse0, rasa°, ms160/, tdd-1.4,-m-caeficuratiancommos 700-us-e4.-configcommon OPTIONAL, --cond TOO ss-azek-slockamwer INTEGER (-60..50), " -23 -Lower and higher values of ssb-TxRxSplit may be less efficient (except value 64) and having a high granularity of the central values (format 4 above) will added more flexibility for the gNB with the same number of used bits.

Other values and/or formats including a different number of values are of course also possible. In addition, other placements of the ssb-TxRxSplit container in the signalling flow from the gNB to the UE will also be valid (for example in the MIB for more robustness).

The same implementation of the ssb-TxRxSplit container may be valid for a Non-Standro Alone 5G NR mmWave system and shown below for the ITE Anchor message (TS 38.311, section 6.3.2): SErViUcJCeIlCGnFiQCOrYEOn::= SEQUENCE f SSb-POSitiOnSInBurSt CHOICE short:Siena:, BIT STRING (SIZE (4)), meduilBitnrap BIT STRING (SIZE (8)), longSimmap BIT STRING (SIZE (64)) SSb-petHodicity,Se'rvis,9Ce11 ENUMERATED <sicS, mS10, MS20, ms40, r.p80, mS160, spare2, sparel 1 64; is A number of variants and combinations to the features described above are possible. For example: * The number of reference signals in phase#1 could be different.

* Any split between reference signals transmitted by the base station (gNB) and the user device (UE) could be used depending on for example the size difference between the antenna arrays used at the base station and at the user device * The first reference signals could be transmitted from the user device (UE).

* Any combination of how many reference signals are transmitted could be used. The examples described herein use 24 from the base station followed by 40 from the user device, but it could as well have been 12 from the base station, then 20 from the user device, then 12 again from the base station and finally 20 again from the user device. Many other variants are also possible.

* Msgt to Msg4 could in theory be transmitted in between the beam alignment reference signals.

* Each Rx beam sweep can be averaged over more than one reference signal if needed due to low SNR/SINR.

* Phases #2 to #4 could be interchanged in any order.

* Phases #2 to #4 could include any number of reference signals * Phases #2 and #4 could be based on Tx sweeping with a feedback signal.

-24 -For completeness, FIG. 11 is a schematic diagram of components of one or more of the example embodiments described previously, which hereafter are referred to generically as a processing system 300. The processing system 300 may, for example, be the apparatus referred to in the claims below.

The processing system 300 may have a processor 302, a memory 304 closely coupled to the processor and comprised of a RAM 314 and a ROM 312, and, optionally, a user input 310 and a display 318. The processing system 300 may comprise one or more network/apparatus interfaces 308 for connection to a network/apparatus, e.g. a modem which may be wired or wireless. The network/apparatus interface 308 may also operate as a connection to other apparatus such as device/apparatus which is not network side apparatus. Thus, direct connection between devices/apparatus without network participation is possible.

The processor 302 is connected to each of the other components in order to control operation thereof.

The memory 304 may comprise a non-volatile memory, such as a hard disk drive (HDD) or a solid state drive (SSD). The ROM 312 of the memory 304 stores, amongst other things, an operating system 315 and may store software applications 316. The RAM 314 of the memory 304 is used by the processor 302 for the temporary storage of data. The operating system 315 may contain code which, when executed by the processor implements aspects of the algorithms or message sequences 30, 40, 50, 6o, 70, 80 and roo described above. Note that in the case of small device/apparatus the memory can be most suitable for small size usage or i.e. not always a hard disk drive (HDD) or a solid state drive (SSD) is used.

The processor 302 may take any suitable form. For instance, it may be a microcontroller, a plurality of microcontrollers, a processor, or a plurality of processors.

The processing system 300 may be a standalone computer, a server, a console, or a network thereof. The processing system 300 and needed structural parts may be all inside device/apparatus such as loT device/apparatus i.e. embedded to very small size.

In some example embodiments, the processing system 300 may also be associated with external software applications. These may be applications stored on a remote server device/apparatus and may run partly or exclusively on the remote server device/apparatus. These applications may be termed cloud-hosted applications. The processing system 300 -25 -may be in communication with the remote server device/apparatus in order to utilize the software application stored there.

FIGS. 12A and 12B show tangible media, respectively a removable memory unit 365 and a compact disc (CD) 368, storing computer-readable code which when run by a computer may perform methods according to example embodiments described above. The removable memory unit 365 may be a memory stick, e.g. a USB memory stick, having internal memory 366 storing the computer-readable code. The internal memory 366 may be accessed by a computer system via a connector 367. The CD 368 may be a CD-ROM or a DVD or similar. io Other forms of tangible storage media may be used. Tangible media can be any device/apparatus capable of storing data/information which data/information can be exchanged between devices/apparatus/network.

Embodiments of the present invention may be implemented in software, hardware, application logic or a combination of software, hardware and application logic. The software, application logic and/or hardware may reside on memory, or any computer media. In an example embodiment, the application logic, software or an instruction set is maintained on any one of various conventional computer-readable media. In the context of this document, a "memory" or "computer-readable medium" may be any non-transitory media or means that can contain, store, communicate, propagate or transport the instructions for use by or in connection with an instruction execution system, apparatus, or device, such as a computer.

Reference to, where relevant, "computer-readable medium", "computer program product", "tangibly embodied computer program" etc., or a "processor" or "processing circuitry" etc. should be understood to encompass not only computers having differing architectures such as single/multi-processor architectures and sequencers/parallel architectures, but also specialised circuits such as field programmable gate arrays FPGA, application specify circuits ASIC, signal processing devices/apparatus and other devices/apparatus. References to computer program, instructions, code etc. should be understood to express software for a programmable processor firmware such as the programmable content of a hardware device/apparatus as instructions for a processor or configured or configuration settings for a fixed function device/apparatus, gate array, programmable logic device/apparatus, etc. If desired, the different functions discussed herein may be performed in a different order 35 and/or concurrently with each other. Furthermore, if desired, one or more of the above-described functions may be optional or may be combined. Similarly, it will also be appreciated that the flow diagrams and messages sequences of Figures 3 to 8 and 10 are -26 -examples only and that various operations depicted therein may be omitted, reordered and/or combined.

It will be appreciated that the above described example embodiments are purely illustrative and are not limiting on the scope of the invention. Other variations and modifications will be apparent to persons skilled in the art upon reading the present specification.

Moreover, the disclosure of the present application should be understood to include any novel features or any novel combination of features either explicitly or implicitly disclosed ro herein or any generalization thereof and during the prosecution of the present application or of any application derived therefrom, new claims may be formulated to cover any such features and/or combination of such features.

Although various aspects of the invention are set out in the independent claims, other aspects 15 of the invention comprise other combinations of features from the described example embodiments and/or the dependent claims with the features of the independent claims, and not solely the combinations explicitly set out in the claims.

It is also noted herein that while the above describes various examples, these descriptions should not be viewed in a limiting sense. Rather, there are several variations and modifications which may be made without departing from the scope of the present invention as defined in the appended claims.

Claims

-27 -Claims 1. An apparatus comprising means for performing: receiving, at a user device, a split parameter defining a split between transmission and reception slots for signals of each of a plurality of signal blocks sent from a mobile communication base station to the user device; configuring a beam alignment algorithm based on a number of transmission slots as defined by the split parameter; receiving, at the user device, a transmission signal from the base station for each of io the transmission slots within a first signal block, wherein each transmission signal is received by one of a plurality of beams of the user device in accordance with the configured beam alignment algorithm; using the beam alignment algorithm to determine an optimum beam at the user device for transmissions between the user device and the base station, based on the received transmission signals; and sending a first reference signal from the user device to the base station for each of the reception slots of the plurality of signal blocks, as defined by the split parameter.
2. An apparatus as claimed in claim 1, wherein the beam alignment algorithm is configured to: determine which of a plurality of broad beams is an optimum broad beam for transmissions between the user device and the base station based on a first plurality of the received transmission signals; and determine which of a plurality of narrower beams within the optimum broad beam is 25 an optimum narrower beam for transmissions between the user device and the based station base on a second plurality of received transmission signals.
3. An apparatus as claimed in claim 1 or claim 2, wherein the means are further configured to perform: sending a plurality of second reference signals from the user device to the base station.
4. An apparatus as claimed in any one of claims ito 3, wherein the beam alignment algorithm is a hierarchical beam alignment algorithm.
5. An apparatus comprising means for performing: setting a split parameter defining a split between transmission and reception slots for signals of each of a plurality of signal blocks sent between a mobile communication base station and one or more user devices; -28 -sending a transmission signal from the base station for each of the transmission slots within a first signal block, wherein the transmission signal indicates the split parameter; receiving a first reference signal from a first user device in each of the reception slots of the plurality of signal blocks, as defined by the split parameter; and determining a first optimum beam at the base station for transmissions between the base station and the first user device, based on the received transmission signals.
6. An apparatus as claimed in claim 5, wherein each transmission signal sent from the base station is sent using a broad-band beam covering a full sector covered by the mobile /0 communication base station.
7. An apparatus as claimed in claim 5 or claim 6, wherein the means are further configured to perform: receiving a plurality of second reference signals from the user device at the base station; and determining a refined optimum beam at the base station for transmissions between the base station and the first user device, based on the first optimum beam and the second reference signals.
8. An apparatus as claimed in any one of the preceding claims, wherein the first reference signal comprises static Beam Alignment Reference Signals.
9. An apparatus as claimed in any one of the preceding claims, wherein the means comprise: at least one processor; and at least one memory including computer program code, the at least one memory and the computer program configured, with the at least one processor, to cause the performance of the apparatus.
10. A message sequence comprising: transmitting a first signal block using a mobile communication base station, wherein the first signal block includes a split parameter defining a split between transmission and reception slots for signals of each of a plurality of signal blocks sent from the mobile communication base station to a user device; receiving the first signal block at the user device; configuring a beam alignment algorithm based on a number of transmission slots as defined by the split parameter; -29 -sending a second signal block from the mobile communication base station to the user device, wherein the second signal block includes a transmission signal for each of the transmission slots; receiving the second signal block at the user device, wherein each transmission signal is received by one of a plurality of beams of the user device in accordance with the configured beam alignment algorithm; using the beam alignment algorithm to determine an optimum beam at the user device for transmissions between the user device and the base station, based on the received transmission signals; ro sending a first reference signal from the user device to the base station in each of the reception slots of the plurality of signal blocks, as defined by the split parameter; receiving the first reference signal at the base station; and determining an optimum beam at the base station for transmissions between the base station and the first user device, based on the received transmission signals.n.
An apparatus as claimed in any one of claims ito 9 or a message sequence as claimed in claim 10, wherein the mobile communication base station is a next generation node B.
12. An apparatus or a message sequence as claimed in any one of the preceding claims, wherein the split parameter indicates the number of transmission slots and/or the number of reception slots within said signal blocks.
13. An apparatus or a message sequence as claimed in any one of the preceding claims, wherein the split parameter identifies which slots of the signal blocks are transmission slots and/or which slots are reception slots.
14. A method comprising: receiving, at a user device, a split parameter defining a split between transmission and reception slots for signals of each of a plurality of signal blocks sent from a mobile communication base station to the user device; configuring a beam alignment algorithm based on a number of transmission slots as defined by the split parameter; receiving, at the user device, a transmission signal from the base station for each of the transmission slots within a first signal block, wherein each transmission signal is received 35 by one of a plurality of beams of the user device in accordance with the configured beam alignment algorithm; -30 -using the beam alignment algorithm to determine an optimum beam at the user device for transmissions between the user device and the base station, based on the received transmission signals; and sending a first reference signal from the user device to the base station for each of the reception slots of the plurality of signal blocks, as defined by the split parameter.
15. A method as claimed in claim 14, wherein the method further comprises: determining which of a plurality of broad beams is an optimum broad beam for transmissions between the user device and the base station based on a first plurality of the ro received transmission signals; and determining which of a plurality of narrower beams within the optimum broad beam is an optimum narrower beam for transmissions between the user device and the based station base on a second plurality of received transmission signals.
16. A method as claimed in claim 14 or claim 15, further comprising sending a plurality of second reference signals from the user device to the base station.
17. A method as claimed in any one of claims 14 to 16, wherein the beam alignment algorithm is a hierarchical beam alignment algorithm. 20
18. A method comprising: setting a split parameter defining a split between transmission and reception slots for signals of each of a plurality of signal blocks sent between a mobile communication base station and one or more user devices; sending a transmission signal from the base station for each of the transmission slots within a first signal block, wherein the transmission signal includes the split parameter; receiving a first reference signal from a first user device in each of the reception slots of the plurality of signal blocks, as defined by the split parameter; and determining a first optimum beam at the base station for transmissions between the base station and the first user device, based on the received transmission signals.
19. A method as claimed in claim 18, wherein each transmission signal sent from the base station is sent using a broad-band beam covering a full sector covered by the mobile communication base station.
20. A method as claimed in claim 18 or claim 19, wherein the method further comprises: receiving a plurality of second reference signals from the user device to the base station; and -31 -determining a refined optimum beam at the base station for transmissions between the base station and the first user device, based on the first optimum beam and the second reference signals.
21. A method comprising: transmitting a first signal block using a mobile communication base station, wherein the first signal block includes a split parameter defining a split between transmission and reception slots for signals of each of a plurality of signal blocks sent from the mobile communication base station to a user device; ro receiving the first signal block at the user device; configuring a beam alignment algorithm based on a number of transmission slots as defined by the split parameter; sending a second signal block from the mobile communication base station to the user device, wherein the second signal block includes a transmission signal for each of the transmission slots; receiving the second signal block at the user device, wherein each transmission signal is received by one of a plurality of beams of the user device in accordance with the configured beam alignment algorithm; using the beam alignment algorithm to determine an optimum beam at the user device for transmissions between the user device and the base station, based on the received transmission signals; sending a first reference signal from the user device to the base station in each of the reception slots of the plurality of signal blocks, as defined by the split parameter; receiving the first reference signal at the base station; and determining an optimum beam at the base station for transmissions between the base station and the first user device, based on the received transmission signals.
22. A method as claimed in any one of claims 14 to 21, wherein the split parameter indicates the number of transmission slots and/or the number of reception slots within said 3o signal blocks.
23. A method as claimed in any one of claims 14 to 22, wherein the split parameter identifies which slots of the signal blocks are transmission slots and/or which slots are reception slots.
24. A computer program comprising instructions for causing an apparatus to perform at least the following: -32 -receiving, at a user device, a split parameter defining a split between transmission and reception slots for signals of each of a plurality of signal blocks sent from a mobile communication base station to the user device; configuring a beam alignment algorithm based on a number of transmission slots as defined by the split parameter; receiving, at the user device, a transmission signal from the base station for each of the transmission slots within a first signal block, wherein each transmission signal is received by one of a plurality of beams of the user device in accordance with the configured beam alignment algorithm; ro using the beam alignment algorithm to determine an optimum beam at the user device for transmissions between the user device and the base station, based on the received transmission signals; and sending a first reference signal from the user device to the base station for each of the reception slots of the plurality of signal blocks, as defined by the split parameter.
25. A computer program comprising instructions for causing an apparatus to perform at least the following: setting a split parameter defining a split between transmission and reception slots for signals of each of a plurality of signal blocks sent between a mobile communication base station and one or more user devices; sending a transmission signal from the base station for each of the transmission slots within a first signal block, wherein the transmission signal includes the split parameter; receiving a first reference signal from a first user device in each of the reception slots of the plurality of signal blocks, as defined by the split parameter; and determining a first optimum beam at the base station for transmissions between the base station and the first user device, based on the received transmission signals.