Abstract: There is provided mechanisms for determining a precoder for APs in a cell-free communication system. A method is performed by a controller of the APs. The method comprises obtaining channel estimates of a radio propagation channel between the APs and user equipment served in the cell-free communication system. The method comprises determining a precoder for the APs. The precoder has a ZF precoding factor and a power allocation factor. The ZF precoding factor is determined from the channel estimates. The power allocation factor is determined by maximizing total transmission power for all user symbols to be transmitted to the user equipment, one user symbol per each user equipment. Transmission power of each of the APs is not larger than a power constraint. Transmission power for each of the user equipment is lower bounded by a scaled heuristic value. The method comprises initiating transmission of precoded user symbols from the APs towards the user equipment.

Abstract: A network node in a communications network can perform adaptive hybrid precoding. The network node can be communicatively coupled to an access point via a fronthaul. The network node can determine an amount of available bandwidth on the fronthaul. The network node can further determine whether to have the access point perform precoding of signals communicated between the access point and a communication device based on the amount of available bandwidth on the fronthaul. Responsive to determining whether to have the access point perform the precoding, the network node can transmit an indication to the access point indicating whether to perform the precoding.

Abstract: A method performed by a network function is provided. The method is for handling a set of paths between a baseband node and a radio unit in a mesh fronthaul network of a communications network. The network function establishes a set of paths between ports in a port pair. The port pair comprises a port in the baseband node and port in the radio unit. The paths in the set of paths comprise different paths connected between the port in the baseband node and multiple endpoints associated with the port of the radio unit. Each path is associated with an individual path Identifier (ID). For each path out of the set of paths, the network function instructs (404) the baseband node or the radio unit, to perform a one-way delay measurement for the path associated with the individual path ID. The network function receives (405) results from the baseband node. The results relate to the one-way delay measurement performed for each path out of the set of paths.

Abstract: A method performed by a system having a plurality of base station systems, each base station system comprising a baseband unit, BBU and a radio unit, RU interconnected via a fronthaul connection that is shared between the base station systems. Fronthaul capacity information on transmission capacity of the shared fronthaul connection and information on required capacity for transmission and/or reception of wireless signals by the RU of the respective base station system are obtained. Time unit transmission restrictions for the respective base station system is determined based on the fronthaul capacity information and on the information on required capacity, which time unit transmission restrictions results in fronthaul usage below the transmission capacity of the part of the fronthaul connection. Information on the determined time unit transmission restrictions is sent to the BBU of the respective base station system.

Abstract: Disclosed is a method for mitigating intercell interference experienced in a distributed base station system comprising a Digital Unit (DU), a Hub, and a plurality of Radio Heads (RH) connected to the Hub via a fronthaul connection. The plurality of RHs comprises a first set logically arranged in a first cell and a second set logically arranged in a second cell. The method comprises obtaining, for individual of the first set of RHs, interference information on estimated interference experienced in an area served by the individual of the first set of RHs from signals sent by the plurality of RHs excluding the first set of RHs, determining, based on the obtained interference information, that a first RH of the first set of RHs suffers from intercell interference, and initiating change of the logical arrangement of the first RH from the first cell to the second cell.

Abstract: A transmitting node in a fronthaul communications network that includes a receiving node, can determine that a loss has occurred in the fronthaul communications network between the transmitting node and the receiving node. Responsive to determining that the loss has occurred, the transmitting node can determine to duplicate control plane, CP, messages being transmitted toward the receiving node based on a redundancy factor. The transmitting node can further schedule transmission of a CP message and a duplicate of the CP message toward the receiving node.

Abstract: A method performed by a system having a plurality of base stations, each base station system comprising a baseband unit (BBU) and a radio unit (RU) interconnected via a fronthaul connection that is shared between the base station systems. Fronthaul capacity information on transmission capacity of the shared fronthaul connection and information on required capacity for transmission and/or reception of wireless signals by the RU of the respective base station system are obtained. Time unit transmission restrictions for the respective base station system is determined based on the fronthaul capacity information and on the information on required capacity, which time unit transmission restrictions results in fronthaul usage below the transmission capacity of the part of the fronthaul connection. Information on the determined time unit transmission restrictions is sent to the BBU of the respective base station system.

Abstract: A method performed by a first fronthaul network unit (RU1, RU2, . . . , RUm) for synchronizing with a second fronthaul network unit (GM; DU1, DU2, . . . , DUn) across a fronthaul network (100) carrying TDD radio transmissions through obtaining control information indicating UL and DL time periods of TDD radio transmissions and local timing information in a first fronthaul network unit and determining: a first set of synchronization messages transferred between the units within determined fronthaul DL and UL intervals during which there are no TDD transmissions, and a second set of synchronization messages transferred outside of the determined intervals, and synchronizing, based on the synchronization messages, depending on which set the synchronization message belongs to.

Abstract: Embodiments described herein relate to methods and apparatus for transmitting radio data over a fronthaul network. The method comprises receiving radio data for transmission over the fronthaul network; and translating the radio data between a time domain multiplexing protocol and packet based protocol before transmitting the data over the fronthaul network; wherein the step of translating comprises: receiving control information indicative of a level of congestion over a part of the radio network using the packet based protocol; and modifying the radio data during the step of translating to control the level of congestion.

Abstract: A method performed by a network entity is provided. The method comprises obtaining information indicating uplink, UL, and downlink, DL, time periods in the packet-based fronthaul network occupied by Time-Division Duplex, TDD, radio transmissions transmitted and/or received by the one or more second fronthaul network units over its radio interface. The method further comprises scheduling packet-based synchronization messages between at least the one or more first fronthaul network units and the one or more second fronthaul network units over the packet-based fronthaul network based on the obtained information. A network entity is also provided, as well as, computer programs and carriers.

Abstract: It is provided a method for determining packet loss in a fronthaul link between a baseband node and a radio node of a radio access network. The method being performed in a packet loss determiner. The method comprises: detecting at least one empty input data slot of a plurality of input data slots of a communication chain operation in a first time period, wherein the communication chain operation is one in a sequence of communication chain operations in a device on a receiving end of the fronthaul link; determining that data was intended to be provided to the at least one empty input data slot; and determining that a packet loss has occurred in the fronthaul link, based on the detecting the at least one empty input data slot and the determining that data was intended to be provided.

Abstract: Techniques are described for mitigating the negative effects of temporary loss of connectivity or temporary loss of service between a RU and a BU. In embodiments of the present disclosure, the radio unit is configured to transmit reference signals during a temporary loss of connectivity with the baseband unit to allow the UEs served by the radio unit to maintain synchronization with the radio unit and avoid or minimize radio link failures. Applying these techniques, the UEs served by the radio unit can maintain connection with the radio unit during the temporary outage and avoid the need to engage in Radio Resource Control (RRC) signaling to re-establish a connection with the radio unit and/or handover to neighboring radio units.

Abstract: A method performed by a CPU of a cascade cell-free massive MIMO network where APs are connected in a cascaded fronthaul chain to the CPU using a shared fronthaul bus. An AP at the end of the cascaded fronthaul chain is assigned as a last AP. Responsive to determining that fronthaul UL data is received by the CPU from the last AP, it is determined that the last AP is healthy. Responsive to fronthaul UL data not being received for a period of time, data addressed to the last AP is transmitted through DL broadcast structure of the shared fronthaul bus; Responsive to the ACK signal being received, it is determined that the last AP is healthy and responsive to the ACK signal not being received, it is determined that a fronthaul segment until the last AP is not healthy.

Abstract: A network node in a communications network can perform adaptive hybrid precoding. The network node can be communicatively coupled to an access point via a fronthaul. The network node can determine an amount of available bandwidth on the fronthaul. The network node can further determine whether to have the access point perform precoding of signals communicated between the access point and a communication device based on the amount of available bandwidth on the fronthaul. Responsive to determining whether to have the access point perform the precoding, the network node can transmit an indication to the access point indicating whether to perform the precoding.

Abstract: Embodiments described herein relate to methods and apparatus for managing packet dropping in the fronthaul network. A method in a packet processing system includes receiving a plurality of data packets for transmission over the fronthaul network, wherein the plurality of data packets include radio data; obtaining first information for the plurality of data packets, wherein the first information is related to transmission of the radio data over a radio access interface in the radio network; and responsive to a requirement to decrease a load in the fronthaul network, selecting at least one of the plurality of packets to drop by applying at least one prioritization rule to the plurality of data packets based on the obtained first information.

Abstract: There is provided mechanisms for determining a precoder for APs in a cell-free communication system. A method is performed by a controller of the APs. The method comprises obtaining channel estimates of a radio propagation channel between the APs and user equipment served in the cell-free communication system. The method comprises determining a precoder for the APs. The precoder has a ZF precoding factor and a power allocation factor. The ZF precoding factor is determined from the channel estimates. The power allocation factor is determined by maximizing total transmission power for all user symbols to be transmitted to the user equipment, one user symbol per each user equipment. Transmission power of each of the APs is not larger than a power constraint. Transmission power for each of the user equipment is lower bounded by a scaled heuristic value. The method comprises initiating transmission of precoded user symbols from the APs towards the user equipment.

Abstract: A method performed by a first fronthaul network unit (RU1, RU2,..., RUm) for synchronizing with a second fronthaul network unit (GM; DU1, DU2,..., DUn) across a fronthaul network (100) carrying TDD radio transmissions through obtaining control information indicating UL and DL time periods of TDD radio transmissions and local timing information in a first fronthaul network unit and determining: a first set of synchronization messages transferred between the units within determined fronthaul DL and UL intervals during which there are no TDD transmissions, and a second set of synchronization messages transferred outside of the determined intervals, and synchronizing, based on the synchronization messages, depending on which set the synchronization message belongs to.

Abstract: A method performed by a system having a plurality of base station systems, each base station system comprising a baseband unit, BBU and a radio unit, RU interconnected via a fronthaul connection that is shared between the base station systems. Fronthaul capacity information on transmission capacity of the shared fronthaul connection and information on required capacity for transmission and/or reception of wireless signals by the RU of the respective base station system are obtained. Time unit transmission restrictions for the respective base station system is determined based on the fronthaul capacity information and on the information on required capacity, which time unit transmission restrictions results in fronthaul usage below the transmission capacity of the part of the fronthaul connection. Information on the determined time unit transmission restrictions is sent to the BBU of the respective base station system.

Abstract: It is presented a method for determining packet loss in a fronthaul link of a radio access network. The method being performed in a packet loss determiner and comprising the steps of: obtaining a set of user equipments, UEs, that are all scheduled to communicate over a radio interface in a scheduling interval; creating a subset of UEs, comprising a number of UEs, from the set of UEs, that are the UEs in the set being most vulnerable to fronthaul packet loss; determining, for each UE in the subset of UEs, whether the communication in the scheduling interval was unsuccessful; and determining a packet loss in the fronthaul link depending on to what extent each one of the UEs in the subset of UEs is determined to have had unsuccessful use of the radio interface.

Abstract: A method performed by a network entity is provided. The method comprises obtaining information indicating uplink, UL, and downlink, DL, time periods in the packet-based fronthaul network occupied by Time-Division Duplex, TDD, radio transmissions transmitted and/or received by the one or more second fronthaul network units over its radio interface. The method further comprises scheduling packet-based synchronization messages between at least the one or more first fronthaul network units and the one or more second fronthaul network units over the packet-based fronthaul network based on the obtained information. A network entity is also provided, as well as, computer programs and carriers.