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US-20260129637-A1 - FLEXIBLE LAYER GROUPING FOR FRONTHAUL CONTROL PLANE MESSAGING

US20260129637A1US 20260129637 A1US20260129637 A1US 20260129637A1US-20260129637-A1

Abstract

A method, system and apparatus are disclosed. A method in a network node is described. The network node includes a distributed unit (DU), where the DU is configured to communicate with a radio unit (RU) via a fronthaul interface (FI). The FI is in a signal path between the DU and the RU. The method includes selecting a plurality of identifiers to create one or more subgroups within an identifier group. The identifier group is represented by a group identifier, and each identifier represents a processing entity in the RU. The method also includes creating the one or more subgroups within the identifier group and determining one or more section extensions usable by one or more control plane (C-plane) messages sent with the group identifier to specify one subgroup of the one or more subgroups. The one subgroup is associated to a C-plane section.

Inventors

  • Lev VDOVIN
  • Chenguang Lu
  • Stefan HEIMGÅRD
  • Lars Hennert
  • Aditya Sriram RAJASEKARAN
  • Björn Pohlman

Assignees

  • TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)

Dates

Publication Date
20260507
Application Date
20240813

Claims (20)

  1. 1 .- 25 . (canceled)
  2. 26 . A method in a network node, the network node comprising a distributed unit, DU, the DU being configured to communicate with a radio unit, RU, via a fronthaul interface, FI, the FI being in a signal path between the DU and the RU, the method comprising: selecting a plurality of identifiers to create one or more subgroups within an identifier group, the identifier group being represented by a group identifier, each identifier representing a processing entity in the RU; creating the one or more subgroups within the identifier group; and determining one or more section extensions usable by one or more control plane, C-plane, messages sent with the group identifier to specify one subgroup of the one or more subgroups, the one subgroup being associated to a C-plane section; and transmitting the one or more C-plane messages to the RU.
  3. 27 . The method of claim 26 , wherein one or more of: the plurality of identifiers is a plurality of a plurality of extended antenna carrier identifiers, eAxC IDs; the identifier group is an eAxC ID group; and the group identifier is a group eAxC ID.
  4. 28 . The method of claim 27 , wherein one or more of: the group identifier is an eAxC ID representing a corresponding processing entity in the RU; the RU is an endpoint; the eAxC ID is a representative eAxC ID for the identifier group; and each processing entity in the RU that is the endpoint identified by a corresponding eAxC ID is one processing entity for processing one user data layer.
  5. 29 . The method of claim 26 , wherein: the identifier group being represented by the group identifier is defined in a management plane, M-plane, configuration; and the M-plane configuration is configured by the DU.
  6. 30 . The method of claim 26 , wherein the method further includes: performing one or more actions based on the one or more section extensions.
  7. 31 . The method of claim 30 , wherein the one or more actions include one or more of: transmitting a C-plane message to the RU; performing scheduling for user data layers; and composing control plane messages including section types and section extensions to convey scheduling information.
  8. 32 . The method of claim 26 , wherein the method further includes one or more of: mapping a wireless device identifier of a plurality of wireless device identifiers to a port list index, the plurality of wireless device identifiers corresponding only to wireless devices that are in use; mapping the port list index to a list entry of a configured post list, the list entry being mapped to a port list identifier; and including mapping information associated with the wireless device identifier, the port list index, the list entry, and the port list identifier in the one or more section extensions.
  9. 33 . The method of claim 26 , wherein the one or more subgroups are specified by a set of indexes relative to positions in a first list of the eAxC IDs.
  10. 34 . The method of claim 26 , wherein the one or more section extensions includes one or both of: a first section extension with a subgroup specified by a mask; and a second section extension with the subgroup specified by a second list.
  11. 35 . The method of claim 34 , wherein one or more of: the first section extension includes a bitmask, a position of each bit of the bitmask representing a list index; the second section extension includes a third list of indices, each index of the third list of indices representing a port list index; and the one or more section extensions are usable with section types associated with an open radio access network, O-RAN, fronthaul specification.
  12. 36 . The method of claim 26 , wherein the method further includes one or more of: transferring common DMRS configuration parameters for one or more layers in at least one subgroup of the one or more subgroups from the DU to the RU; reporting measurement data for the one or more layers in the at least one subgroup; and transmitting information of beamforming weights usable by the at least one subgroup of the processing entity to perform beamforming for a user data layer.
  13. 37 . A network node, the network node comprising a distributed unit, DU, the DU being configured to communicate with a radio unit, RU, via a fronthaul interface, FI, the FI being in a signal path between the DU and the RU, the network node being configured to: select a plurality of identifiers to create one or more subgroups within an identifier group, the identifier group being represented by a group identifier, each identifier representing a processing entity in the RU; create the one or more subgroups within the identifier group; and determine one or more section extensions usable by one or more control plane, C-plane, messages sent with the group identifier to specify one subgroup of the one or more subgroups, the one subgroup being associated to a C-plane section; and transmit the one or more C-plane messages to the RU.
  14. 38 . A method in a network node, the network node comprising a radio unit, RU, the RU being configured to communicate with a distributed unit, DU, via a fronthaul interface, FI, the FI being in a signal path between the DU and the RU, the method comprising: receiving one or more control plane, C-plane, messages from the DU, the one or more C-plane messages including one or more section extensions and a group identifier to specify one subgroup of one or more subgroups, the one subgroup being associated to a C-plane section, the one or more subgroups being created within an identifier group, the identifier group being represented by the group identifier, each identifier of the plurality of identifiers representing a processing entity in the RU, the plurality of identifiers being selected to create the one or more subgroups within an identifier group; and determining a first configuration for a processing entity associated with the RU based on the one or more C-plane messages; and performing one or more actions based on the first configuration.
  15. 39 . The method of claim 38 , wherein one or more of: the plurality of identifiers is a plurality of a plurality of extended antenna carrier identifiers, eAxC IDs; the identifier group is an eAxC ID group; and the group identifier is a group eAxC ID.
  16. 40 . The method of claim 39 , wherein one or more of: the group identifier is an eAxC ID representing a corresponding processing entity in the RU; the RU is an endpoint; the eAxC ID is a representative eAxC ID for the identifier group; and each processing entity in the RU that is the endpoint identified by a corresponding eAxC ID is one processing entity for processing one user data layer.
  17. 41 . The method of claim 38 , wherein: the identifier group being represented by the group identifier is defined in a second configuration, the second configuration being a management plane, M-plane, configuration; and the second configuration is configured by the DU.
  18. 42 . The method of claim 38 , wherein the one or more subgroups are specified by a set of indexes relative to positions in a first list of the eAxC IDs.
  19. 43 . The method of claim 38 , wherein the one or more section extensions includes one or both of: a first section extension with a subgroup specified by a mask; and a second section extension with the subgroup specified by a second list.
  20. 44 . The method of claim 43 , wherein one or more of: the first section extension includes a bitmask, a position of each bit of the bitmask representing a list index; the second section extension includes a third list of indices, each index of the third list of indices representing a port list index; and the one or more section extensions are usable with section types associated with an open radio access network, O-RAN, fronthaul specification.

Description

TECHNICAL FIELD The present disclosure relates to wireless communications, and in particular, to performing layer grouping for fronthaul control plane (C-plane) messaging in wireless communication networks. BACKGROUND The Third Generation Partnership Project (3GPP) has developed and is developing standards for Fourth Generation (4G) (also referred to as Long Term Evolution (LTE)) and Fifth Generation (5G) (also referred to as New Radio (NR)) wireless communication systems. Such systems provide, among other features, broadband communication between network nodes, such as base stations, and mobile wireless devices (WD), as well as communication between network nodes and between WDs. The 3GPP is also developing standards for Sixth Generation (6G) wireless communication networks. Further, the Open Radio Access Network (ORAN) alliance is a world-wide community that has developed and is developing international standards, guides and recommendations associated with wireless communication systems such as 5G, LTE, etc. Massive multiple input multiple output (MIMO) techniques have been first adopted to practice in LTE. In 5G, it becomes one key technology component, which may be deployed on a much larger scale than in LTE. MIMO features a large number of antennas used on the network node side (e.g., base-station side), where the number of antennas is typically much larger than the number of user-layers. For example, 64 antennas serving 8 or 16 user-layers may be used in frequency range 1 (FR1), which comprises sub-6 GHz frequency bands. Further, 256/512 antennas serving 2 or 4 layers may be used in FR2, which comprises frequency bands from 24.25 GHz to 71 GHz. The term user layer may be used in the present disclosure and may refer to an independent downlink or uplink data stream intended for one user. One user or WD (e.g., UE) may have one or multiple user layers. User layer is also referred to as layer, e.g., in 3GPP terminology. Massive MIMO is also referred to as massive beamforming, which is able to form narrow beams focusing on different directions to counteract against the increased path loss at higher frequency bands. It also benefits multi-user MIMO which allows for transmissions from/to multiple users simultaneously over separate spatial channels resolved by the massive MIMO technologies, while keeping high capacity for each user. Therefore, it can significantly increase the spectrum efficiency and cell capacity. At the network node side (e.g., base-station side), the interface between the distributed unit (DU) and the radio unit (RU) is the fronthaul interface, as shown in FIG. 1. The benefits of massive MIMO at the air-interface also introduce new challenges at the network node side (e.g., base-station side). The legacy Common Public Radio Interface (CPRI) type fronthaul transports time-domain in-phase and quadrature (IQ) samples per antenna branch. As the number of antennas scales up in massive MIMO systems, the required fronthaul capacity also increases proportionally, which significantly drives up the fronthaul costs. To address this challenge, the fronthaul interface evolves from CPRI to evolve CPRI (eCPRI), a packet-based fronthaul interface. In eCPRI, other functional split options between a DU and a RU are supported, referred to as different lower-layer split (LLS) options. In the eCPRI standard specification, the terms eCPRI Radio Equipment Control (eREC) and eCPRI Radio Equipment (eRE) are used instead of DU and RU. The basic idea is to move the frequency-domain beamforming function from DU to RU so that frequency samples or data of user-layers are transported over the fronthaul interface. The frequency-domain beamforming is sometimes also referred to as precoding in the downlink (DL) direction and equalizing or pre-equalizing in uplink (UL) direction. By doing this, the required fronthaul capacity and thereby the fronthaul costs may be reduced, as the number of user layers is typically much fewer than the number of antennas in massive MIMO. In Open Radio Access Network (O-RAN), DU is referred to as O-DU while RU is referred to as O-RU. FIG. 1 shows an example fronthaul interface between RU and DU. FIG. 2 shows the UL Weight-based Dynamic Beamforming (WDBF) implementation supported by the current O-RAN work group 4 (WG4) specification. By having the beamforming function in the O-RAN RU (O-RU), the number of streams going through the fronthaul interface becomes smaller than the number of antenna branches. However, the beamforming weights are calculated in the O-RAN DU (O-DU) based on the Sounding Reference Signal (SRS) signal sent back from the O-RU. Since the SRS channel estimates correspond to an earlier channel, the required number of streams is still much larger than the number of layers to avoid performance loss, compared to that using CPRI-based fronthaul. There is a tradeoff between the number of streams used and the performance. FIG. 3 shows the control-plane (C-plane) and user-plane (U-pla