Network nodes and methods for optimizing network load in hybrid wireless communication network

Abstract

Network node and method therein for optimizing network load in a hybrid wireless communication network (100) comprising one or more static base stations (sBS1, sBS2,.. sBSi) and one or more mobile base stations (mBS1, mBS2, mBS3, mBS4). The one or more sBSs are serving one or more user equipment (UE1, UE2, UE3) with multicarrier operation capability. The network node obtains serving cell status information (SCSI) for at least one static base station (sBSi) and configures at least one mobile base station (mBS1) for serving the one or more UEs (UE1, UE2, UE3) based on the obtained SCSI to offload the at least one sBS (sBSi)

Description

[0001] NETWORK NODES AND METHODS FOR OPTIMIZING NETWORK LOAD IN HYBRID WIRELESS COMMUNICATION NETWORK

[0002] TECHNICAL FIELD

[0003] Embodiments herein relate to network nodes and methods in a wireless communication network. In particular, they relate to network nodes and methods for optimizing network load in a hybrid wireless communication network comprising one or more static base stations (sBS), one or more mobile base stations (mBS) and one or more user equipment (UE) with multicarrier operation capability.

[0004] BACKGROUND

[0005] Wireless communication networks, such as Global System for Mobile Communications (GSM) networks, Long Term Evolution (LTE) networks, Fifth Generation (5G) New Radio (NR) and 6G networks, usually cover a geographical area which is divided into cell areas. Each cell area is served by a base station (BS), which may also be referred as a network node, gNB, eNB, an access node etc. A wireless communication network may include a number of cells that can support communications for a number of wireless communication devices or user equipment (UEs).

[0006] A UE may be configured with one or more serving cells. Examples of serving cells are special cell (SpCell), secondary cell (SCell) etc. Examples of SpCell are primary cell (PCell), primary secondary cell (PSCell) etc. The carrier frequencies also called component carriers (CC) of SpCell, SCell, PCell and PSCell are called special CC (SpCC) or simply SpC, secondary CC (SCC), primary CC (PCC) and primary secondary CC (PSCC) or simply PSC respectively.

[0007] A UE may have multicarrier (MC) operation capability. In the MC operation, the UE can operate on multiple carriers for communication e.g. for receiving and / or transmitting signals between the UE and one or more base stations. Examples of MC operations are carrier aggregation (CA), dual connectivity (DC), multi-connectivity (MuC) etc. The carrier frequency is also called frequency layer, serving carrier, frequency channel etc.

[0008] A UE may need to perform a cell change, e.g. cell reselection, handover etc. during communication. The existing solution of the cell change is fundamentally UE centric as it relies on the UE measured signal level e.g. signal strength such as Reference Signal Received Power (RSRP), signal quality such as Reference Signal Received Quality (RSRQ). This traditional cell change mechanism works also well for offloading the base stations in static network deployment, e.g. in a terrestrial network (TN), when the base stations are static and fixed.

[0009] The TN is traditionally deployed using fixed or static base stations (sBSs), which do not move. Therefore, a fixed BS is statically deployed in certain location within the coverage area. The cell planning for the static deployment is based on the two- dimensional deployment. Typically, the cell planning is based on traditional hexagonal cells with directional antennas to secure radio coverage and radio performance. However, recently there are several types of mobile stations such as drone, High Altitude Platform Stations (HAPS), Non-terrestrial Networks (NTN) nodes etc. Their proliferation will lead to hybrid deployment comprising of traditional static or fixed base stations and dynamically or semi-statically deployed network nodes referred herein as mobile base stations (mBSs). mBSs can move from one location to another. Therefore, the introduction of the mBSs enables dynamic deployment of the base stations based on the need. These mobile base stations can be part of terrestrial networks e.g. cell or BS on wheels, or can be part of non-terrestrial networks e.g. aerial base stations, platforms e.g. HAPS as International Mobile Telecommunications (IMT) BS (HIBS), drone base stations, integrated access and backhaul (lABs) on airplanes etc. From time to time, such mobile base stations in the air can be semi statically deployed by positioning them in certain locations for certain time period. The mobile base stations can also be in the air all the time, hovering over a certain location or change positions constantly.

[0010] The combination of statically deployed base stations and base stations that is dynamically deployed opens new ways to perform base station deployments and dynamically adjust radio performance. Therefore, new and complimentary methods of performing cell change will be required in the hybrid deployment. The static base stations are typically customized for the static deployment scenario and region, where they are deployed. Therefore, new mechanisms are needed to manage the static and mobile stations operating in such hybrid environment.

[0011] SUMMARY

[0012] Therefore, it is an object of embodiments herein to provide network nodes and methods for managing and optimizing network performance and load in a hybrid wireless communication network comprising one or more sBSs and one or more mBSs. According to one aspect of embodiments herein, the object is achieved by a first network node and method therein for optimizing network load in a hybrid wireless communication network comprising one or more sBSs and one or more mBSs. The one or more sBSs are serving one or more UEs with multicarrier operation capability. The first network node obtains serving cell status information (SCSI) for at least one sBS and configures at least one mBS for serving the one or more UEs based on the obtained SCSI to offload the at least one sBS.

[0013] According to some embodiments herein, the first network node configures at least one mBS for serving the one or more UE by transmitting a message to at least one mBS for moving or sending the at least one mBS to a region where the at least one sBS is located. The at least one mBS may be configured to be geographically co-located with the at least one sBS or not geographically co-located with the at least one sBS.

[0014] According to one aspect of embodiments herein, the object is achieved by a second network node and method therein for obtaining and transmitting serving cell status information (SCSI) in a hybrid wireless communication network comprising one or more sBSs and one or more mobile base stations mBSs. The one or more sBSs are serving one or more UEs with multicarrier operation capability. The second network node obtains SCSI for at least one sBS and transmitting the obtained SCSI to a first network node or a third network node.

[0015] According to some embodiments herein, the SCSI may comprise one or more of the following information on:

[0016] 1) a maximum operational time difference (MOTD) of a UE served or managed by the at least one sBS;

[0017] 2) a number of different types of the serving cells of a UE served or managed by the at least one sBS;

[0018] 3) whether the at least one sBS supports co-location operation with another base station located at the same geographical site or location;

[0019] 4) activation or deactivation status of the serving cells of a UE served or managed by the at least one sBS;

[0020] 5) dormant and / or non-dormant bandwidth part, BWP, status of the serving cells of a UE served or managed by the at least one sBS;

[0021] 6) resource status of the at least one sBS. In other words, according to the embodiments herein, the first network node is a network optimizing node which uses the serving cell status information of a static or fixed base station located in an area to determine the need to configure and send a mobile base station to the area to offload the static base station. The offloading may be realized by triggering a cell change e.g. handover for some UEs towards the mobile base station. The location or placement of the mobile base station may be determined based on whether the serving cells of one or more UEs have to be co-located or can be non-co-located which in turn is based on the SCSI on e.g. MOTD supported by one or more UEs.

[0022] The solutions according to embodiments herein have following advantages but not limited to:

[0023] Enhancing overall network performance by enabling a UE to operate using the maximum number of supported serving cells e.g. using CA or DC.

[0024] Throughput of a UE is not limited due to lack of resources in a base station since one or more serving cells e.g. SCells, may be operated by a mobile base station.

[0025] Dynamically enabling synchronous or asynchronous deployment depending on the UE capabilities, network load etc.

[0026] Therefore, embodiments herein provide methods and network nodes for managing and optimizing network performance in a hybrid wireless communication network comprising one or more sBSs and one or more mBSs.

[0027] BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Examples of embodiments herein are described in more detail with reference to attached drawings in which:

[0029] Figure 1 is a schematic block diagram depicting a hybrid wireless communication network in which embodiments herein for managing and optimizing network performance and network load may be implemented;

[0030] Figure 2 is a schematic block diagram illustrating UEs served by their static base stations using single or multicarrier operations in certain coverage area;

[0031] Figure 3 is a flow chart illustrating a method performed in a first network node according to embodiments herein;

[0032] Figure 4 is a schematic block diagram illustrating an example of obtaining serving cell status information (SCSI) associated with a static BS; Figure 5 is a schematic block diagram illustrating another example of obtaining serving cell status information (SCSI) associated with a static BS;

[0033] Figure 6 is a schematic block diagram depicting an example of configuring a mBS which is co-located with a sBS;

[0034] Figure 7 is a schematic block diagram illustrating another example of configuring a mBS which is non-co-located with a sBS;

[0035] Figure 8 is a flow chart illustrating a method performed in a second network node according to embodiments herein;

[0036] Figure 9 is a schematic block diagram illustrating a first network node according to embodiments herein; and

[0037] Figure 10 is a schematic block diagram illustrating a second network node according to embodiments herein.

[0038] DETAILED DESCRIPTION

[0039] Figure 1 illustrates a hybrid wireless communication network 100, in which methods for managing and optimizing network performance and network load may be implemented. The hybrid wireless communication network 100 comprises one or more sBSs, e g. sBS1, sBS2, sBS3, ... sBSi, ... sBSk, one or more mBSs e g. mBS1, mBS2, mBS3, mBS4, one or more network nodes, e.g. a first network node 110, a second network node 120, a third network node 130, and a fourth network node 140. Each sBS covers an area or a cell, e.g. a serving cell 101 covered by the sBS1 , a serving cell 102 covered by the sBS2. A number of UEs e.g. UE1, UE2, UE3 operate in the hybrid wireless communication network 100. The one or more UEs UE1, UE2, UE3 are served in an area 150 covered by the one or more sBSs sBS1 , sBS2, sBS3, ... sBSi, ... sBSk. The first network node 110 is a network optimizing node according to embodiments herein which may directly or indirectly communicate with the one or more sBSs deployed in the coverage area 150. The first network node 110 can also communicate, configure and manage one or more mBSs e.g. mBS1, mBS2. The first network node 110 may optimize the number of serving cells of a sBS for one or more UEs by configuring a mBS, e.g. mBS1 , based on a serving cell status of the sBS to serve one or more UEs. The fourth network node 140 is also a network optimizing node according to embodiments herein which may directly or indirectly communicate with one or more sBSs deployed in another coverage area and can communicate, configure and manage one or more mBSs e.g. mBS3, mBS4. The second network node 120 may be any one of the sBSs, e.g. sBSi or a centralized network node e.g. a coordinating network node which controls and manages a set of sBSs, e.g. sBS1 , sBS2, sBS3, ... sBSi, ... sBSk installed in certain area or zone, e.g. the area 150. The third network node 130 may be any one of a centralized network node, coordinating network node, core network node, self-organizing network node etc. controlling and managing a set of sBSs.

[0040] In this disclosure the term node is used, which can be a user equipment (UE) or a network node.

[0041] In some embodiments the non-limiting term “user equipment” (UE) is used and it refers to any type of wireless device communicating with a network node and / or with another UE in a cellular or mobile communication system. The UE can also be an aerial vehicle, which can be any type of flying object equipped with a UE. Examples of UE are target device, device to device (D2D) UE, machine type UE or UE capable of machine to machine (M2M) communication, PDA, tablet computer, mobile terminals, smart phone, laptop embedded equipped (LEE), laptop mounted equipment (LME), Universal Serial Bus (USB) dongles, ProSe UE, vehicle to vehicle (V2V) UE, Vehicle-to-everything (V2X) UE, machine-type communications (MTC) UE, enhanced machine-type communications (eMTC) UE, further-enhanced machine-type communication (FeMTC) UE, UE Cat O, UE Cat M1 or M2, narrowband Internet of Things (NB-loT) UE, UE Cat NBI or NB2, passive loT device, ambient loT device, aerial UE (AUE), e.g. UE operating above certain height, AUE is also called as drone UE or aerial vehicle etc.

[0042] The term ‘network node’ refers to any type of node which communicates with a UE and / or with another network node e.g. with a BS. Examples of network nodes are NodeB, base station (BS), multi-standard radio (MSR) node such as MSR BS, eNodeB, gNodeB, MeNB, SeNB, location measurement unit (LMU), integrated access backhaul (IAB) node, network controller, radio network controller (RNC), base station controller (BSC), relay, donor node controlling relay, base transceiver station (BTS), Central Unit e.g. in a gNB, Distributed Unit e.g. in a gNB, Baseband Unit, Centralized Baseband, C-RAN, access point (AP), transmission points, transmission nodes, transmission reception point (TRP), remote radio unit (RRU) and remote radio head( RRH) nodes in distributed antenna system (DAS), core network node e.g. Mobile Switching Center (MSC), Mobility Management Entity (MME) etc., Operation and Maintenance (O&M), Operations Support Systems (OSS), Self-Organizing Networks (SON), positioning node e.g. Evolved Serving Mobile Location Center (E-SMLC) etc.

[0043] The term “static base station (sBS)” used in some embodiments refers to a base station whose geographical location does not change over time. The sBS may also be called as stationary BS, fixed BS or immovable BS. The term “mobile base station (mBS)” used in some embodiments refers to a base station whose geographical location may change over time or at least have the capability to change its geographical location. For example, the mBS has necessary circuitry and aerodynamic capability which enables it to physically fly or move in the air or in 3- dimensional space in any direction. The mBS can however also remain stationary for certain time-period. The mBS can be an independent node or it can be located or housed in another node or device e.g. on a satellite etc. The movement of the mBS may be controlled by another node or autonomously e.g. based on pre-configured information such as an event of a planned race. The mBS may also be called non-stationary BS, drone BS, non-terrestrial network (NTN) node, movable BS or high-altitude platform station (HAPS).

[0044] In some embodiments the term co-located base station is used and it refers to any base station which is co-located with another base station at the same geographical site or location. The base station which is not co-located with any other base station is called as non-co-located base station or isolated base station. The non-co-located base station may still be deployed in a geographical area containing other base stations.

[0045] The one or more UEs e.g. UE1 , UE2, UE3 have multicarrier operation capability, e.g. carrier aggregation. In carrier aggregation, the UE has one primary serving cell (PCell) and one or more secondary serving cells (SCells). The PCell is considered more important and for example some control signaling is handled via the PCell.

[0046] Multi-connectivity (MuC) comprises of two or more cell groups (CG). Doubleconnectivity (DC), which is special case of MuC, comprises of 2 CGs: a master cell group (MCG) which contains at least a PCell and a secondary cell group (SCG). Each of MCG and SCG may further contain one or more SCells. The PCell manages e.g., configures, changes, release etc., all SCells in MCG and PSCell in SCG. PSCell manages all SCells in SCG. The cells in MCG and SCG may belong to the same RAT e.g., all cells are NR in both MCG and SCG like in NR-DC, or they may belong to different Radio access Technologies (RATs), e.g. LTE cells in MCG and NR cells in SCG like in EN-DC or NR cells in MCG and LTE cells in SCG like in NE-DC.

[0047] Certain types of serving cells can also be activated or deactivated by a network node to enable UE battery power saving. For example, SCell and PSCell can be activated or deactivated. But PCell is always activated. The cells may be configured or deconfigured using Radio Resource Control (RRC) signaling. The entire cell group e.g., SCG, can also be activated or deactivated. The serving cells like PSCell and SCells or the CG e.g., SCG, can be activated or deactivated by a network node using different mechanism e.g., by sending Medium Access Control (MAC) control element, by RRC message e.g., direct activation / deactivation etc. During the time when a serving cell is deactivated, the UE is expected to receive or transmit data in that serving cell.

[0048] Certain types of serving cells e.g., SCells can also be put in dormant state by a network node to enable UE battery power saving. In NR the dormant state is called as dormant bandwidth part (BWP). During the dormant BWP on a serving cell the UE does not monitor the downlink (DL) channel e.g., physical downlink control channel (PDCCH), physical downlink shared channel (PDSCH) etc. and does not transmit in the corresponding uplink channel. However, the UE is required to perform and report channel state information (CSI) measurements e.g., channel quality indication (CQI) measurements on configured CQI resources such as CSI-RS, synchronization signal block (SSB) etc. to the network node. The switching between non-dormant BWP and dormant BWP on certain serving cell of the UE can be performed by the network node by sending a command or message in e.g., Downlink Control Information (DCI), MAC control element (MAC-CE) etc.

[0049] Figure 2 shows an example scenario of one or more UEs served by one or more sBSs using single or multicarrier operations in certain coverage area. The scenario comprises of at least one coverage area or zone 200 in which one or more UEs e.g. UE1 , UE2, UE3, UE4, UE5, UE6 are served by one or more static base stations e.g. sBS1, sBS2, sBS3, sBS4. The one or more UEs e.g. UE1, UE2, UE3, UE4, UE5, UE6 are capable of multicarrier (MC) operation e.g. CA and / or DC. The one or more UEs e.g. UE1, UE2, UE3, UE4, UE5, UE6 are also configured or expected to be configured using MC operation by their respective serving static base stations. Therefore, a UE may be served by 2 or more serving cells e.g. PCell and one or more SCells, PCell, PSCell and one or more SCells etc. The one or more static base stations have limited capacity or resources and therefore can serve certain maximum number of UEs. Due to the limited capacity or resources, the static base stations can operate only limited number of serving cells in total and / or limited number of serving cells per UE. Figure 2 shows that UE1 , UE5 and UE6 are configured in single carrier operation i.e. only with PCell by their respective static base stations namely sBS1 , sBS3 and sBS4 respectively. However, UE2, UE3 and UE4 are configured in multi-carrier operation. Moreover, UE2 is served in CA by sBS1 and sBS2, which are non-located base stations and can be regarded as non-co-located CA operation. UE4 is served in DC by sBS3 and sBS4, which are also non-located base stations and can also be regarded as non-co-located DC operation. But UE3 is served in CA using PCell and SCell by the same BS i.e. sBS2, which can be regarded as co-located CA operation.

[0050] In the following, a method performd in a network node e.g. the first network node 110, for managing and optimizing network performance and load in the hybrid wireless communication network 100 will be descibed with refence to Figure 3. The first network node 110 may be a separate node in the hybrid wireless communication network 110 or a function unit in a core network node or a coordinating network node 130, or a selforganizing network node. The method comprises the following actions which may be performed in any suitable order.

[0051] Action 310

[0052] The first network node 110 obtains serving cell status information (SCSI) for at least one sBS, e.g. sBSi.

[0053] According to some embodiments herein, the first network node 110 may receive the SCSI from the at least one sBS. That is the first network node 110 receives the SCSI associated with a sBS e.g. sBSi, directly from that sBS e.g. sBSi. This may also be called as distributed system. In this case the sBS determines its SCSI and transmits a message containing at least part of the SCSI to the first network node 110. Each sBS directly and independently transmits its SCSI to the first network node 110. This mechanism is illustrated in Figure 4 in which a sBS sends its SCSI to the first network node 110 e.g. by transmitting a message on the interface between the sBS and the first network node 110. The sBS may transmit the SCSI to the first network node 110 using one or more of the following mechanisms:

[0054] In one example, the sBS periodically transmits the SCSI to the first network node 110 e.g. once every P1 time units, e.g. once every P11 seconds, once every P12 minutes etc., once every P2 time resource e.g. once every P21 frames, once every P22 singlefrequency network (SFN) cycles, once every P23 hyper SFN (H-SFN) cycles etc. In one example, the SCSI is periodically transmitted for unlimited time. In another example, the periodic transmission of the SCSI may be limited for certain time period, which can be pre-defined or configured by another node e.g. by the first network node 110, or autonomously determined by the sBS.

[0055] In one example, sBS proactively starts or initiates periodic transmission of the SCSI to the first network node 110 e.g. without receiving any request from the first network node 110. In another example, sBS starts or initiates periodic transmission the SCSI to the first network node 110 upon receiving a request from the first network node 110.

[0056] In another example, sBS transmits the SCSI to the first network node 110 when one or more conditions or criteria are met. Examples of such conditions are: a) When any content of the SCSI changes; b) When number of UEs served by the sBS is changed by a certain threshold e.g. increased or decreased by a certain threshold; c) When number of serving cells of the UEs served by the sBS is changed by a certain threshold e.g. increased or decreased by a certain threshold. d) Upon receiving a request from a third network node 130 e.g. a selforganizing network (SON) node to transmit the SCSI.

[0057] According to some embodiments herein, the first network node 110 may receive the SCSI associated with a sBS e.g. sBSi, from a third network node 130, e.g. a centralized node which has the SCSI of that sBS e.g. sBSi.

[0058] This may also be called as centralized system. An example of the centralized node is a coordinating network node (CNN), which obtains the SCSI of one or more sBSs installed in a certain area or zone. The area may be a service area or coverage or geographical area e.g. the area 150 shown in Figure 1. For example, each sBS in the area 150 determines its SCSI and transmits its SCSI or related information to the third network node 130. The third network node 130 then transmits the SCSI of one or multiple sBS to the first network node 110. This mechanism is illustrated in Figure 5. The third network node130 may transmit the obtained one or more SCSIs of their respective sBSs to the first network node 110 using one or more of the same signaling mechanisms e.g. periodically or when one or more conditions are met as described above for the distributed system.

[0059] According to some embodiments herein, the contents of SCSI may comprise one or more of the following information on:

[0060] 1) a maximum operational time difference, MOTD, of a UE served or managed by the at least one sBS;

[0061] 2) a number of different types of the serving cells of a UE served or managed by the at least one sBS;

[0062] 3) whether the at least one sBS supports co-location operation with another base station located at the same geographical site or location;

[0063] 4) activation or deactivation status of the serving cells of a UE served or managed by the at least one sBS; 5) dormant and / or non-dormant bandwidth part, BWP, status of the serving cells of a UE served or managed by the at least one sBS;

[0064] 6) resource status of the at least one sBS.

[0065] The above contents of SCSI will be discussed in detailed in the following.

[0066] According to some embodiments herein, the contents of the SCSI associated with each sBS may comprise at least a first set of information which directly or indirectly indicates at least a maximum operational time difference (MOTD) for multicarrier (MC) operation of at least one UE served by the sBS.

[0067] MOTD is defined as the maximum time difference, which can be handled by a UE, between signals received at the UE or between signals transmitted by the UE. Specific examples of MOTD are Maximum Receive Timing Difference (MRTD), Maximum Transmission Timing Difference (MTTD) etc. MRTD is the maximum received time difference of signals received at the UE from two different serving cells. The MRTD is also defined as the maximum relative receive timing difference between the closest time resource e.g. slot, subframe, timing boundaries of: a signal from one serving cell and a signal from another serving cell.

[0068] MTTD is the maximum transmission time difference between signals transmitted by the UE in two different serving cells belonging to two different transmit timing management groups (TMG). Examples of TMG are timing advance groups (TAG) such as primary timing advance group (pTAG), secondary timing advance group (sTAG), primary secondary timing advance group (psTAG) etc. In each TMG the UE maintains one common transmission timing for transmitting uplink signals from all serving cells belonging to that i.e. the same TMG. For example, the UE applies one timing advance command for all the serving cells belonging to the same TMG. The MTTD is also defined as the maximum relative transmission timing difference between time resource e.g. slot, subframe, timing boundaries of a signal transmitted in one serving cell and a signal transmitted in another serving cell. The MOTD depends on numerology e.g. subcarrier spacing (SCS), Cyclic Prefix (CP) length, slot length etc. of signals, frequency range (FR), UE radio frequency architecture, type of multicarrier e.g. intra-band CA, inter-band CA etc. For example, the UE may support MRTD = 3 is for intra-band CA with SCS=15 kHz and MRTD = 33 is for inter-band CA with SCS=15 kHz.

[0069] In other words, MOTD is the maximum time difference between a timing of a first signal operated between the UE and a first serving cell and a timing of a second signal operated between the UE and a second serving cell. The generic term “a signal operated” or “operating a signal” or “operation of a signal” used herein comprises the reception of the signal at the UE in a cell and / or transmission of the signal by the UE in a cell. The signal may be a reference signal (RS) e.g. cell specific RS (CRS), SSB, CSI-RS etc.

[0070] The MOTD depends on the type of MC operation supported by the UE and / or UE capability, which in turns depends on the UE architecture. Examples of the type of MC operation are intra-band contiguous CA, intra-band non-contiguous CA, inter-band CA etc. For example, certain UEs may support larger MOTD compared to the MOTD supported by others UEs. However, the UE supporting larger MOTD e.g. above a certain threshold such as more than 3 .s, requires independent or separate radio chains for operating at least two serving cells increasing cost and complexity. Thanks to independent chains in the UE, the large MOTD e.g. 33 .s, supported by the UE enables the network node to configure the serving cells from non-co-located nodes or BSs e.g. PCell from one BS and SCell from another BS. On the other hand if the UE supports smaller MOTD e.g. 3 .s, then the network node has to configure the serving cells from the same node or BS or co-located nodes or BSs e.g. PCell and SCell from the same BS.

[0071] Therefore, according to some embodiments herein, the SCSI on MOTD may comprise at least one of: a) a maximum relative receive timing difference, MRTD, between the closest time resource e.g. slot, timing boundaries of a first signal from one serving cell e.g. PCell and a second signal from another serving cell e.g. SCell; b) a maximum relative transmission timing difference, MTTD, between time resource e.g. slot, timing boundaries of a signal from one Transmission and Reception Point (TRP) belonging to a cell and of a signal from another TRP belonging to the same cell.

[0072] According to some embodiments herein, MOTD may be indirectly or directly indicated. Examples of SCSI which indirectly or directly indicate the MOTD are described below.

[0073] Table 1 shows an example of the SCSI in terms of the physical location of the serving cells of different groups or sets of UEs served by a sBS. This is an example of indirect indication of the MODT supported by the UEs served by the sBS. For example, a UE whose serving cells e.g. PCell, SCell, PSCell etc., can be served only by the same sBS or co-located sBSs indicates that the UE supports smaller MOTD e.g. MOTD below or equal to a certain threshold e.g. 0.26 us, 3 us etc. On the other hand, a UE whose serving cells e.g. PCell, SCell, PSCell etc., can be served by different non co-located sBSs indicates that the UE supports larger MOTD e.g. MOTD above a certain threshold e.g. larger than 3 us or up to 33 us etc. Table 1. An example of grouping UEs based on the location of their serving cells

[0074] In one example, the SCSI may indicate a number of UEs e.g. N11 , whose serving cells are served by the same sBS or by co-located BSs in the same physical site or location.

[0075] In another example, the SCSI may indicate a number of UEs e.g. N12, whose serving cells are served by the sBSs which are non-co-located BSs e.g. PCell is served by sBS1 and SCell is served by sBS2 where sBS1 and sBS2 are geographical separated with respect to each other. The groups may further be divided in terms of number of non- co-located sBSs serving / managing the UEs’ serving cells.

[0076] Table 2 shows another example of the SCSI in terms of the synchronization level of the multicarrier operation of different groups or sets of UEs served by a sBS. This is also an example of indirect indication of the MODT supported by the UEs served by the sBS. For example, a UE supporting only synchronous multicarrier operation implicitly indicates that the UE supports smaller MOTD e.g. MOTD below or equal to a certain threshold e.g. 0.26 pts, 3 |is etc. This in turn also indicates that the serving cells of such UE should be served by the same sBS or co-located sBSs. On the other hand, a UE supporting asynchronous multicarrier operation implicitly indicates that the UE supports larger MOTD e.g. MOTD above a certain threshold e.g. larger than 3 is or up to 33 is etc. This in turn also indicates that the serving cells of such UE can be served by different non-co-located sBSs.

[0077] Table 2. An example of grouping UEs based on their supported synchronization level

[0078] In one example, the SCSI may indicate a number of UEs e.g. N21 , which support synchronous multicarrier operation. In another example, the SCSI may indicate a number of UEs e.g. N22, which support asynchronous multicarrier operation.

[0079] In another example, the SCSI may indicate a number of UEs e.g. N23 which support both synchronous and asynchronous multicarrier operation e.g. the same UE may support synchronous multicarrier operation for certain type of multicarrier e.g. intra-band CA / DC and asynchronous multicarrier operation for another type of multicarrier e.g. interband CA / DC.

[0080] The above information may further indicate the type of multicarrier operation supported by the UEs within each group e.g. intra-band CA / DC or inter-band CA / DC etc.

[0081] Table 3 shows another example of the SCSI which directly indicates MOTD supported by different groups or sets of UEs served by a sBS. The groups can be determined based on two or more sets of MOTD values. Table 3 is a general example which shows n groups of UEs where each group supports the same MOTD value. Table 4 shows another example, which shows that the SCSI comprises of two groups or sets of UEs: a first group ID#0 supporting MOTD up to a certain threshold H1 and a second group I D#1 supporting MOTD above the threshold H1. Table 5 shows a specific example of the 3 groups of the UEs supporting 3 different values of MOTD e.g. a first group ID#0 supporting MOTD up to 3 .s, a second group I D#1 supporting MOTD up to 33 is and a first group I D#2 supporting MOTD up to 500 .s.

[0082] Table 3. An example of n groups of UEs based on their supported MOTD

[0083] Table 4. An example of two groups of UEs based on their supported MOTD

[0084] Table 5. A specific example of 3 groups of UEs based on their supported MOTD in terms of MRTD Therefore, according to some embodiments herein, the SCSI on MOTD of one or more UEs may comprise any one or more of the following information: a) a number of UEs whose serving cells are served by the same sBS or by colocated sBSs in the same physical site or location; b) a number of UEs whose serving cells are served by two or more sBSs which are non-co-located BSs; c) a number of UEs which support synchronous multicarrier operation; d) a number of UEs which support asynchronous multicarrier operation; e) a number of UEs which support both synchronous and asynchronous multicarrier operation; f) the type of multicarrier operation supported by the UEs within each group of multicarrier operation; g) a number of groups of UEs where each group supports the same MOTD value; h) a first group of UEs supporting the MOTD up to a first threshold, a second group of UEs supporting the MOTD above the first threshold; i) a first group of UEs supporting the MOTD up to a first threshold, a second group of UEs supporting the MOTD up to a second threshold, and a third group of UEs supporting the MOTD up to a third threshold.

[0085] According to some embodients herein, the SCSI may further comprise a number of different types of the serving cells of the UE(s) served or managed by the sBS. This information may include a total number of serving cells, a total number of SpCells, a total number of SCells etc. The information may further indicate the RRC states e.g. RRC idle, RRC inactive state, RRC connected state, of different serving cells managed by the sBS.

[0086] Table 6 shows an example of the SCSI in terms of number of different types of serving cells operated or managed by a sBS. Without multicarrier operation a UE is configured with only one serving cell e.g. with PCell. But in multicarrier operation the same UE may be configured with one or more SpCells e.g. PCell, PSCell etc., and one or more SCells. For example, the group ID # 0 indicates that the total number of serving cells, which include SpCells and SCells, currently served or managed by the sBS is N61. Similarly, the group ID # 4 indicates that the total number of SCells currently served or managed by the sBS is N64. Similarly, the group ID # 5 indicates that the total number of PCell and SCells currently served or managed by the sBS is N65 and the group ID # 6 indicates that the total number of PSCell and SCells currently served or managed by the sBS is N66.

[0087] Table 6. An example of number of serving cells operated by a sBS

[0088] Table 7 shows another example of the SCSI which indicates the grouping of UEs based on their respective RRC state and whose serving cells are served or managed by a sBS. This information is indicated in terms of a number of UEs currently operating in the same RRC state e.g. a number of UEs in RRC idle state is N71 etc. In RRC idle / inactive the UE is served by only one serving cell i.e. by PCell. In RRC connected state the UE can be served by one or more serving cells e.g. in MC operation. The serving cells of the UEs in RRC idle / inactive require less processing compared to the serving cells of the UEs in RRC connected state.

[0089] Table 7. An example of UEs in different RRC states served by a sBS Table 8 shows another example of the SCSI which indicates the grouping of serving cells whose UEs are in the same RRC state. This information is indicated in terms of number of serving cells whose UEs are currently operating in the same RRC state e.g. the number of serving cell whose UEs are in RRC idle state is N81 etc.

[0090] Table 8. An example of UEs in different RRC states served by a sBS

[0091] Therefore, according to some embodiments herein, the SCSI on the number of different types of the serving cells of a UE served or managed by the at least one sBS may comprise any one or more of the following information: a) a number of all type of serving cells of a UE served or managed by the at least one sBS; b) a total number of special cells of a UE served or managed by the at least one sBS; c) a total number of primary cells of a UE served or managed by the at least one sBS; d) a total number of primary secondary cells of a UE served or managed by the at least one sBS; e) a total number of secondary cells of a UE served or managed by the at least one sBS; f) a number of UEs currently operating in Radio Resource Control, RRC, idle state; g) a number of UEs currently operating in RRC inactive state; h) a number of UEs currently operating in RRC connected state; i) a number of serving cells whose UEs are in RRC idle state; j) a number of serving cells whose UEs are in RRC inactive state; k) a number of serving cells whose UEs are in RRC connected state.

[0092] According to some embodients herein, the SCSI may further comprise information about support of co-located base station operation. The information may indicate whether the sBS can operate with another co-located base station. The information may indicate the frequency range and / or frequency bands in which the sBS can operate with another co-located base station.

[0093] In one example, this aspect of the SCSI may comprise a simple indication indicating whether the sBS e.g. sBSi, can operate when geographically co-located with another base station e.g. BS2. That is whether sBSi and BS2 can operate in the same or colocated site. In another example, the SCSI may further comprise one or more frequency ranges within which the sBS supports co-location operation with another BS. Examples of frequency ranges are between 800-850 MHz, 1850-1910 MHz, 1920-1980 MHz etc. In another example, the SCSI may further comprise one or more frequency bands e.g. pre- defined frequency band identifiers, within which the sBS supports co-location operation with another BS.

[0094] The co-located BSs are typically installed in the same building. The minimum coupling loss (MCL) between the two co-located BSs of the same BS class can be in the order of 30 dB. On the other hand, the MCL between the two co-located BSs for wide area, medium range and local area BS classes can be 70 dB, 53 dB and 45 dB respectively. Therefore, the sBS supporting co-location operation with another BS is required to fulfil several co-location transmitter and receiver radio requirements to avoid or minimize interference to the other co-located BSs. The sBS needs additional hardware support e.g. radio frequency (RF) filters, to fulfil these requirements. Therefore, every sBS may or may not support co-location operation. The sBS not capable of co-located operation can however co-exists with another non-located BS in the same geographical area e.g. if the distance or path loss between the two BSs is above a threshold.

[0095] Examples of co-location transmitter requirements are unwanted radio emissions e.g. BS spurious emissions limit, which are regulatory and may depend also on the region. For example, the sBS supporting co-location operation with another BS in certain frequency range e.g. 1850 - 1910 MHz, shall limit the spurious emission within this frequency to -96 dBm measured over 100 kHz. On the other hand, as an example the sBS which does not support co-location operation with another BS in this frequency range e.g. 1850 - 1910 MHz, shall limit the spurious emission within this frequency to -61 dBm measured over 100 kHz. This example clearly demonstrates that the spurious emission limits for the colocation BS operation are clearly much more stringent i.e. smaller allowed emission power than those for the non-co-location BS operation.

[0096] Examples of co-location receiver requirements are BS receiver blocking requirements. For example, the sBS supporting co-location operation with another BS is required to block an interfering signal of up to +16 dBs within certain frequency range. On the other hand, as an example the sBS which does not support co-location operation with another BS, is required to block an interfering signal in the order of -15 dBm to -35 dBm in certain frequency range and depending on the frequency range. This example also clearly demonstrates that the BS receiver blocking requirements for the co-location BS operation are clearly much more stringent i.e. handle larger blocker, than those for the non-co- location BS operation.

[0097] Therefore, according to some embodiments herein, the SCSI on whether the at least one sBS supports co-location operation with another base station located at the same geographical site or location may comprise one or more of the following information: a) an indication indicting whether the at least one sBS can operate when geographically co-located with another base station; b) one or more frequency ranges within which the at least one sBS supports co-location operation with another BS; c) one or more frequency bands within which the at least one sBS supports colocation operation with another BS.

[0098] According to some embodients herein, the SCSI may further comprise infromation on activation or deactivation status of the serving cells of one or more UE(s) served or managed by a sBS. This information may include a total number of serving cells which are activated, a total number of serving cells which are deactivated etc.

[0099] Table 9 shows an example of the SCSI in terms of the activation and deactivation status of different types of serving cells operated or managed by a sBS. For example, the information indicates e.g. the total number of serving cells which are currently activated is N91 , the total number of serving cells which are currently deactivated is N92, the total number of SCells which are currently activated is N93, the total number of SCells which are currently deactivated is N94 etc.

[0100] Table 9. An example of activation / deactivation status of serving cells operated by a sBS

[0101] Some of the serving cells such as SCell and PSCell can be deactivated by the network node by sending a message or command e.g. MAC-CE, RRC etc. to the UE. The purpose is to save the UE battery power e.g. when there is no or small data in the buffer. The deactivated serving cell can be activated by the network node by sending another command or message e.g. MAC-CE, RRC etc. to the UE e.g. upon arrival of the data in the buffer. Some of the serving cells such as PCell cannot be deactivated i.e. always remain activated. The UE cannot be scheduled with data on the deactivated serving cell. The UE however only performs measurements e.g. RSRP, RSRQ etc. on the deactivated serving cells with lower measurement rate compared to the measurements performed on the activated serving cells. Therefore, the deactivated serving cells require less processing and overheads in the base station compared to the activated serving cells.

[0102] According to some embodients herein, the SCSI may further comprise infromation on dormant and / or non-dormant BWP status of the serving cells of the UE(s) served or managed by a sBS. This information may include a total number of serving cells whose active bandwidth part is in dormant state, a total number of serving cells whose active bandwidth part is in non-dormant state etc.

[0103] Table 10 shows an example of the SCSI in terms of the dormant and non-dormant status of the BWP of different types of serving cells operated or managed by the sBS. For example, the information indicates e.g. the total number of serving cells with non-dormant BWP is N 101 , the total number of serving cells with dormant BWP is N102, the total number of SCells with non-dormant BWP is N 103 etc.

[0104] Table 10. An example of dormant / non-dormant BWP status of serving cells operated by a sBS

[0105] To enable the UE power saving and avoid interference, the UE can be configured by the higher layer with a set of bandwidth parts (BWPs) for signal receptions e.g. PDCCH, PDSCH etc., by the UE, e.g. DL BWP set e.g. up to 4 DL BWPs, and a set of BWPs for signal transmissions e.g. PUCCH, PUSCH by the UE, e.g. UL BWP set e.g. up to 4 UL BWPs, in a serving cell e.g. SpCell, PCell, PSCell, SCell etc. Each BWP can be associated with multiple parameters. Examples of such parameters are bandwidth (BW) e.g. number of time-frequency resources, resource blocks such as 25 PRBs etc., location of BWP in frequency e.g. starting RB index of BWP or center frequency etc., subcarrier spacing (SCS), cyclic prefix (CP) length, any other baseband parameter e.g. MIMO layer, receivers, transmitters, Hybrid automatic repeat request (HARQ) related parameters etc. At least one of the configured BWP can be activate BWP. The UE is scheduled with data within the BW of the activate BWP. The active BWP can also be configured in dormant state or in non-dormant state e.g. via a message or command send by the UE, upon expiry of a timer etc. In the dormant state, the UE cannot be scheduled with data by the network node; but the UE can be configured to estimate and report channel state information (CSI) e.g. CQI to the network node e.g. to the serving base station. In the nondormant state, the UE can be scheduled with data and configured to estimate and report CSI to the network node. The dormant state of the BWP enables the UE to save its battery power e.g. by not monitoring the DL control channel such as PDCCH.

[0106] Therefore, according to some embodiments herein, the SCSI on dormant and / or non-dormant BWP status of the serving cells of a UE served or managed by the at least one sBS may comprise one or more of the following information: a) a total number of serving cells with non-dormant BWP; b) a total number of serving cells with dormant BWP; c) a total number of primary secondary cells and a total number of secondary cells with non-dormant BWP; d) a total number of primary secondary cells and a total number of secondary cells with dormant BWP.

[0107] According to some embodiemnst herein, the SCSI may further comprise infromation on resource status of a sBS. For example, the resource status of a sBS may comprise radio resource status, transport network load etc. The SCSI in terms of the resource status of the sBS can be expressed in terms of overall available or currently used resources of the sBS. Broadly the sBS resource status may be expressed in terms of one or more of the following: a) radio resource status (RRS), b) transport network resource status (TN RS), c) hardware resource status (HRS), which may further comprise processor resource status and / or memory resource status.

[0108] In one example, the SCSI on RRS may comprises one or more of the following information: a) a number of resource blocks (RBs) in a sBS current used or allocated to one or more UEs served by the sBS; b) a number of RBs in a sBS current unused or not allocated to one or more UEs served by the sBS; c) a percentage of RBs with regard to the total available RBs in a sBS current used or allocated to one or more UEs served by the sBS; d) a percentage of RBs with regard to the total available RBs in a sBS current unused or not allocated to one or more UEs served by the sBS.

[0109] In one example, the SCSI on TNRS may comprise one or more of the following information: a) a number of transport network layer resources (TNLR) in a sBS current used or unavailable, b) a number of TNLR in a sBS current unused or available, c) a percentage of TNLR with regard to the total available RNLR in a sBS current used or unavailable, d) percentage of TNLR with regard to the total available RNLR in a sBS current unused or available.

[0110] In one example, the the SCSI on HRS may comprise one or more of the following information: a) a percentage of processor resources with regard to the total available processor resources in a sBS current used or unavailable, b) a percentage of processor resources with regard to the total available processor resources in a sBS current unused or available, c) a percentage of memory resources with regard to the total available memory resources in a sBS current used or unavailable, d) a percentage of memory resources with regard to the total available memory resources in a sBS current unused or available

[0111] Action 320

[0112] The first network node 110 configures at least one mBS for serving the one or more UEs based on the obtained SCSI to offload the at least one sBS.

[0113] In this Action 320, the first network node 110 uses the obtained SCSI associated with certain sBSi for determining whether to configure one or more mBSs to support that sBSi e.g. to offload the sBSi. The first network node 110 further uses the obtained SCSI for determining whether the mBS, if configured, should be co-located with the sBSi or not co-located with the sBSi in the same site. If the first network node 110 determines that at least one mBS is needed to offload the sBSi, then the first network node 110 configures or requests at least one mBS, co-located or non-co-located with sBSi, to move in the region where the sBSi is located. The configuration may be realized by the first network node 110 transmitting a message to the mBS. The message may further include the geographical coordinates of the region, the time period during which the mBS needs to operate in the indicated region, configuration parameters e.g. transmit power level etc.

[0114] Therefore, according to some embodiments herein, the first network node 110 configures at least one mBS for serving the one or more UE by transmitting a message to at least one mBS for moving or sending the at least one mBS to a region where the at least one sBS is located. The message may comprise one or more of the following information: a) geographical coordinates of a region where the at least one sBS is located; b) a time period during which the at least one mBS needs to operate in an indicated region; c) configuration parameters.

[0115] The first network node 110 may configure the at least one mBS to be geographically co-located with the at least one sBS or configure the at least one mBS to be in a region where the at least one sBS is located but not geographically co-located with the at least one sBS.

[0116] Figure 6 shows an example illustrating the first network node 110 configures one mBS in an area where the sBSi is located. The mBS is configured as geographically colocated with the requested sBSi.

[0117] Figure 7 shows another example illustrating the first network node 110 configures one mBS in an area where the sBSi is located. In this case, the configured mBS is not geographically co-located with the requested sBSi.

[0118] The mechanism of selecting and determining one or more mBS to offload the sBSi based on the obtained SCSI is described below with examples.

[0119] In one example, if the number of serving cells currently being operated by the sBS is above a certain threshold then the first network node 110 may decide to configure at least one mBS to support the sBSi.

[0120] In another example, if the number of UEs supporting smaller value of MOTD e.g. 3 pts, is above a certain threshold then the first network node 110 may decide to configure at least one mBS which can co-locate with the sBSi. The first network node 110 may further determine based on the obtained SCSI whether the sBSi supports co-location operation i.e. can operate when co-located with another BS e.g. mBS in this case. The first network node 110 may further determine whether mBS supports co-located operation with another BS e.g. with sBSi, in a certain frequency range. The first network node 110 configures the mBS co-located with the sBSi only if both mBS and sBSi are capable of colocation operation in at least the same frequency range. In another example, if the number of UEs supporting larger value of MOTD e.g. 33 pts, is above a certain threshold then the first network node 110 may decide to configure at least one mBS which can be non-co-locate with the sBSi. In another example, if the sBSi does not support co-location operation then the first network node 110 may configure mBS which is not co-located with the sBSi.

[0121] In another example, the first network node 110 may configure one or more mBSs to offload the sBSi using any of the above principles provided that the number of activated serving cells is above a certain threshold. Otherwise, the first network node 110 may not configure any mBS or it may configure fewer number of mBS e.g. 1 mBS for offloading the sBSi. The reason is that the sBS processing and complexity are higher when a serving cell is activated compared to the case when the serving cell is deactivated.

[0122] In another example, the first network node 110 may configure one or more mBSs to offload the sBSi using any of the above principles provided that the resource status indicates that at least one type of resource in the sBSi is below a certain threshold e.g. a number of available RBs is below a certain threshold. Otherwise, the first network node 110 may not configure any mBS or it may configure fewer number of mBS e.g. 1 mBS for offloading the sBSi.

[0123] In another example, the first network node 110 may configure one or more mBSs to offload the sBSi using any of the above principles provided that the number of serving cells with non-dormant BWP is above a certain threshold. Otherwise, the first network node 110 may not configure any mBS or it may configure fewer number of mBS e.g. 1 mBS, for offloading the sBSi. The sBS schedules data to the UE only when the BWP is non-dormant. Therefore, the processing and complexity of the sBS are higher for handling a serving cell with non-dormant BWP compared to the serving cell with dormant BWP.

[0124] Therefore, according to some embodiments herein, the first network node 110 performs the configuring of at least one mBS for serving the one or more UE if one or more of the following criteria is fulfilled: a) if the number of serving cells currently being operated by the at least one sBS is above a certain threshold; b) if the number of UEs supporting a certain value of MOTD is above a threshold; c) if the number of activated serving cells being operated by the at least one sBS is above a certain threshold; d) if the resource status indicates that at least one type of resource in the at least one sBS is below a certain threshold; e) if the number of serving cells with non-dormant band width part, BWP, being operated by the at least one sBS is above a certain threshold.

[0125] According to some embodiments herein, the first network node 110 may also inform the sBSi or CNN e.g. the third network node 130 by sending a message, whether the first network node 110 is configuring or has configured one or more mBS to support and offload the sBSi. The first network node 110 may further inform the sBSi or CNN, whether the mBS will be co-located or non-co-located with the sBSi. The information may further comprise indication of the time period during which the configured mBS can operate and offload the sBSi, one or more configuration parameters e.g. transmit power, mBS class etc. Therefore, the method my further comprise the following actions.

[0126] Action 330

[0127] The first network node 110 may send a message to the second network node 120, e.g. the at least one sBSs or a third network node 130, to indicate one or more of the following: a) whether the first network node 110 is configuring or has configured one or more mBS to support and offload the at least one sBS; b) whether the one or more mBS will be co-located or non-co-located with the at least one sBSs; c) a time period during which the configured one or more mBS operates and offloads the at least one sBS; d) one or more configuration parameters.

[0128] Sometimes the required mBSs for offloading one or more sBSs may not be available, then the first network node 110 may request and configure another mBS to offload the one or more sBSs. Therefore, according to some embodiments herein, the method may further comprise the following action.

[0129] Action 340

[0130] The first network node 110 may send a message to a fourth network node 140 for requesting one or more mBSs managed by the fourth network node 140 for serving the one or more UEs when a certain type of mBS is not available among the mBSs managed by the first network node 110.

[0131] The information about the availability of the mBSs can be stored in the first network node 110. The stored information may comprise for example, the identifiers of the available mBSs, their supported class e.g. wide area, medium range, local area etc. and indication whether they support co-location operation in one or more frequency ranges and / or in one or more frequency bands. If the mBS or certain type of the mBS, e.g. which supports the co-location with other BS, is not currently available, then the first network node 110 may request another network node, e.g. the fourth network node 140 which is also a network optimizing node, by sending a message to the other network node to provide the requested one or more mBS e.g. mBS 3, for a certain time period for operation in the indicated geographical region.

[0132] According to embodiments herein, a method performed in a second network node 120 for obtaining and transmitting serving cell status information (SCSI) in the hybrid wireless communication network 100 will be described with reference to Figure 8. The method comprises the following actions which may be performed in any suitable order.

[0133] Action 810

[0134] The second network node 120 obtains SCSI for at least one sBS. The contents of SCSI are the same as described in Action 310. The SCSI may comprise at least information about the maximum operational time difference (MOTD) for multicarrier operation of the UE served by the sBS. The second network node 120 may be a sBS or a centralized network node (CNN) which communicates with one or more sBSs installed in an area. When the second network node 120 is a sBS, as in the case of distributed system described above in Action 310, the sBS determines its SCSI and transmits a message containing at least part of the SCSI to the first network node 110. Each sBS directly and independently transmits its SCSI to the first network node 110 using one or more of the mechanisms described above in Action 310. When the second network node 120 is a centralized network node (CNN), as in the case of centralized system described above in Action 310, each sBS determines its SCSI and transmits its SCSI or related information to the second network node 120. That is the second network node 120 obtains the SCSI of one or more sBSs from the one or more sBSs.

[0135] Action 820

[0136] The second network node 120 transmits the obtained SCSI to the first network node 110 or to a third network node 130 for optimizing network peformance. As discussed above, the second network node 120 may be any one of sBSs which determines its SCSI and transmits a message containing at least part of the SCSI to the first network node 110 in the distributed system or to the third network node 130 in the centralized system.

[0137] Action 830

[0138] This action is operational. The second network node 120 may receive configuration information about at least one mBS from the first network node 110. That is the second network node 120 may receive a message from the first network node 110 indicating one or more of the following information: a) whether the first network node 110 is configuring or has configured one or more mBS to support and offload the at least one sBS; b) whether the one or more mBS will be co-located or non-co-located with the at least one sBSs; c) a time period during which the configured one or more mBS can operate and offload the at least one sBS; d) one or more configuration parameters.

[0139] Accoring to some embodiments herein, if the second network node 120 is a CNN contolling and managing the one or more sBS, the method may further comprise the following action.

[0140] Action 840

[0141] The second network node 120 may send the message received from the first network node 110 to one or more sBS located in the region controlled or managed by a CNN. That is if the second network node 120 is the CNN, it may further forward the information received from the first network node 110 or transmit a part of the received information to one or more sBSs located in the area controlled or managed by the CNN, i.e. the second network node 120.

[0142] According to some embodiments herein, the second network node 120 may further use the information received from the first network node 110 to perform cell change of one or more UEs served by the sBS. The objective is to offload the sBS by distributing the UE load e.g. serving cells across the sBSs and mBSs in the area. Therefore the method may further comprises the following action.

[0143] Action 850

[0144] The second network node 120 may perform a cell change for at least one UE to the mBS. The cell change will involve one or more mBS configured by the first network node 110 in the area. Examples of cell change are cell reselection, handover, RRC release with redirection, serving cell change e.g. SCell change, PSCelll change etc.

[0145] For example, the The second network node 120, e.g. sBSi, may request the UE to perform cell change to the newly configured mBS.

[0146] In another example, the second network node 120, e.g. sBSi, may deconfigure one or more SCells of one or more UEs served by the sBSi. The sBSi may try to retain the SpCells, which are more critical for MC operations than SCells since the former also carry control signalling, system information etc. The sBSi may further configure one or more UEs with one or more SCells which are managed or served by the mBS. The sBSi may alternatively request the newly configured mBS to configure the UE with one or more SCells.

[0147] Therefore, according to some embodiments herein, performing a cell change for at least one UE to the one or more mBS may comprise performing one or more of the following: a) a cell reselection; b) a handover; c) a RRC release with redirection; d) a serving cell change; e) a cell change to a configured mBS; f) de-configuring one or more secondary cells of one or more UEs served by the at least one sBS; g) configuring one or more UEs with one or more secondary cells which are managed or served by the one or more mBS; h) requesting a configured mBS to configure at least one UE with one or more secondary cells; i) de-configuring one or more cell groups of one or more UEs served by the at least one sBS; j) configuring one or more UEs with one or more cell groups which are managed or served by the one or more mBS; k) requesting a configured mBS to configure at least one UE with one or more cell groups.

[0148] In the above examples, the cell change for the offloading purpose may still be based on the radio measurements e.g. RSRP, RSRQ etc., which are performed by the UE. This is to ensure that the UE signal quality with repect to the new serving BS i.e. mBS is within acceptable range. For example, the cell change from the sBS to the mBS is performed provided that the received signal level (RSL) of the UE with repect to the mBS is above a certain threshold. Examples of RSL are received signal strength (RSS), received signal quality (RSQ) etc. Examples of the RSS are RSRP, path loss etc. Examples of the RSQ are RSRQ, SINR, SNR etc. Therefore, the method may further comprise the following action.

[0149] Action 860

[0150] The second network node 120 may obtain information on received signal level of the at least one UE with respect to the one or more mBS and perform a cell change for at least one UE from at least one sBS to the one or more mBS if the received signal level is above a certain threshold.

[0151] To perform the method in the first network node 110 for optimizing network load in a hybrid wireless communication network 100 according to embodiment herein, the first network node 110 comprises modules as shown in Figure 9. The first network node 110 comprises a receiving module 910, a transmitting module 920, a determining module 930, a processing module 940, a memory 950 etc. The first network node 110 may a separate node in the hybrid wireless communication network 100 or a function unit in any one of a core network node, a coordinating network node, a self-organizing network node, a centralized network node etc. The first network node 110 is configured to perform any one of the method actions 310-340 described above.

[0152] The first network node 110 is configured to, e.g. by means of the receiving module 910 being configured to, obtain serving cell status information (SCSI) for at least one sBS.

[0153] The first network node 110 is further configured to, by means of the transmitting module 920 being configured to, configure at least one mBS for serving the one or more UEs based on the obtained SCSI to offload the at least one sBS.

[0154] The method according to embodiments herein may be implemented through one or more processors, such as the processor 960 in the first network node 110 together with computer program code for performing the functions and actions of the embodiments herein. The program code mentioned above may also be provided as a computer program product, for instance in the form of a data carrier 980 carrying computer program code 970, as shown in Figure 9, for performing the embodiments herein when being loaded into the first network node 110. One such carrier may be in the form of a CD ROM disc. It is however feasible with other data carriers such as a memory stick. The computer program code may furthermore be provided as pure program code on a server or a cloud and downloaded to the first network node 110.

[0155] The memory 950 in the first network node 110 may comprise one or more memory units and may be arranged to be used to store received information, report, measurements, data, configurations and applications to perform the method herein when being executed in the first network node 110.

[0156] To perform the method in the second network node 120 for obtaining and transmitting serving cell status information (SCSI) in a hybrid wireless communication network 100, the second network node 120 comprises modules as shown in Figure 10. The second network node comprises a receiving module 1010, a transmitting module 1020, a determining module 1030, a processing module 1040, a memory 1050 etc. The second network node 120 may be any one of a sBS, a core network node, a coordinating network node, a self-organizing network node, a centralized network node etc. The second network node is configured to perform any one of the method actions 810-860 described above.

[0157] The second network node 120 is configured to, e.g. by means of the determining module 1030 being configured to, obtain SCSI for at least one sBS;

[0158] The second network node 120 is configured to, e.g. by means of the transmitting module 1020 being configured to, transmit the obtained SCSI to a first network node 110 or a third network node 130.

[0159] The method for determining and transmitting serving cell status information (SCSI) in a hybrid wireless communication network 100 according to embodiments herein may be implemented through one or more processors, such as the processor 1060 in the second network node 120 together with computer program code for performing the functions and actions of the embodiments herein. The program code mentioned above may also be provided as a computer program product, for instance in the form of a data carrier 1080 carrying computer program code 1070, as shown in Figure 10, for performing the embodiments herein when being loaded into the second network node 120. One such carrier may be in the form of a CD ROM disc. It is however feasible with other data carriers such as a memory stick. The computer program code may furthermore be provided as pure program code on a server or a cloud and downloaded to the second network node 120.

[0160] The memory 1050 in the second network node 120 may comprise one or more memory units and may be arranged to be used to store received information, report, measurements, data, configurations and applications to perform the method herein when being executed in the second network node 120.

[0161] To summarize, embodiments herein provide a network optimizing node, i.e. the first network node 110 and method therein for managing and optimizing network performance and load based on serving cell status information of one or more static or fixed base stations in a hybrid wireless communication network. Embodiments herein further provide a second network node 120 and method therein for obtaining and transmitting the serving cell status information associated with one or more static or fixed base stations. The first network node 110 uses the serving cell status information of one or more static or fixed base station located in an area to determine the need to configure and send one or mobile base stations to the area to offload the one or more static base stations. The offloading may be realized by triggering a cell change e.g. handover for some UEs towards the mobile base station. The location or placement of the mobile base station may be determined based on whether the serving cells of one or more UEs have to be non-co-located or can be co-located, which in turn is based on the serving cell status information on e.g. the maximum operational time difference supported by one or more UEs.

[0162] The solutions according to embodiments herein have following advantages but not limited to:

[0163] Enhancing overall network performance by enabling a UE to operate using the maximum number of supported serving cells e.g. using CA or DC.

[0164] Throughput of a UE is not limited due to lack of resources in a base station since one or more serving cells e.g. SCells, may be operated by a mobile base station.

[0165] Dynamically enabling synchronous or asynchronous deployment depending on the UE capabilities, network load etc.

[0166] When using the word "comprise" or “comprising” it shall be interpreted as nonlimiting, i.e. meaning "consist at least of".

[0167] The embodiments herein are not limited to the above described preferred embodiments. Various alternatives, modifications and equivalents may be used. Therefore, the above embodiments should not be taken as limiting the scope of the invention, which is defined by the appended claims.

Claims

Claims1. A method performed in a first network node (110) for optimizing network load in a hybrid wireless communication network (100) comprising one or more static base stations, sBSs (sBS1, sBS2,..sBSi), and one or more mobile base stations, mBSs (mBS1, mBS2, mBS3, mBS4), wherein the one or more sBSs are serving one or more user equipment, UEs (UE1 , UE2, UE3), with multicarrier operation capability, the method comprising: obtaining (310) serving cell status information, SCSI, for at least one sBS (sBSi); and configuring (320) at least one mBS (mBS1) for serving the one or more UEs (UE1 , UE2, UE3) based on the obtained SCSI to offload the at least one sBS (sBSi).

2. The method according to claim 1 , wherein obtaining (320) SCSI for at least one sBS comprises: receiving the SCSI from the at least one sBS; or receiving the SCSI from a third network node (130).

3. The method according to any one of claims 1-2, wherein configuring (320) at least one mBS for serving the one or more UE comprises: transmitting a message to at least one mBS for moving the at least one mBS to a region where the at least one sBS is located.

4. The method according to claim 3, wherein the message comprises one or more of the following information: a) geographical coordinates of a region where the at least one sBS is located; b) a time period during which the at least one mBS needs to operate in an indicated region; c) configuration parameters.

5. The method according to any one of claims 1-4, wherein the SCSI comprises one or more of the following information on:1) a maximum operational time difference, MOTD, of a UE served or managed by the at least one sBS;2) a number of different types of the serving cells of a UE served or managed by the at least one sBS;3) whether the at least one sBS supports co-location operation with another base station located at the same geographical site or location;4) activation or deactivation status of the serving cells of a UE served or managed by the at least one sBS;5) dormant and / or non-dormant bandwidth part, BWP, status of the serving cells of a UE served or managed by the at least one sBS;6) resource status of the at least one sBS.

6. The method according to claim 5, wherein configuring (320) at least one mBS for serving the one or more UEs comprises: configuring (320) the at least one mBS as geographically co-located with the at least one sBS; or configuring (320) the at least one mBS in a region where the at least one sBS is located but not geographically co-located with the at least one sBS.

7. The method according to any one of claims 5-6, wherein configuring (320) at least one mBS for serving the one or more UE is performed if one or more of the following criteria is fulfilled: a) if the number of serving cells currently being operated by the at least one sBS is above a certain threshold; b) if the number of UEs supporting a certain value of MOTD is above a threshold; c) if the number of activated serving cells being operated by the at least one sBS is above a certain threshold; d) if the resource status indicates that at least one type of resource in the at least one sBS is below a certain threshold; e) if the number of serving cells with non-dormant band width part, BWP, being operated by the at least one sBS is above a certain threshold.

8. The method according to any one of claims 5-7, wherein the SCSI on MOTD comprises at least one of:a) a maximum relative receive timing difference, MRTD, between the closest time resource timing boundaries of a first signal from one serving cell and a second signal from another serving cell; b) a maximum relative transmission timing difference, MTTD, between time resource timing boundaries of a signal from one Transmission and Reception Point, TRP, belonging to a cell and of a signal from another TRP belonging to the same cell.

9. The method according to any one of claims 5-8, wherein the SCSI on MOTD of one or more UEs comprises any one or more of the following information: a) a number of UEs whose serving cells are served by the same sBS or by co-located sBSs in the same physical site or location; b) a number of UEs whose serving cells are served by two or more sBSs which are non-co-located BSs; c) a number of UEs which support synchronous multicarrier operation; d) a number of UEs which support asynchronous multicarrier operation; e) a number of UEs which support both synchronous and asynchronous multicarrier operation; f) the type of multicarrier operation supported by the UEs within each group of multicarrier operation; g) a number of groups of UEs where each group supports the same MOTD value; h) a first group of UEs supporting the MOTD up to a first threshold, a second group of UEs supporting the MOTD above the first threshold; i) a first group of UEs supporting the MOTD up to a first threshold, a second group of UEs supporting the MOTD up to a second threshold, and a third group of UEs supporting theMOTD up to a third threshold;10. The method according to any one of claims 5-9, wherein the SCSI on the number of different types of the serving cells of a UE served or managed by the at least one sBS comprises any one or more of the following information:a) a number of all type of serving cells of a UE served or managed by the at least one sBS; b) a total number of special cells of a UE served or managed by the at least one sBS; c) a total number of primary cells of a UE served or managed by the at least one sBS; d) a total number of primary secondary cells of a UE served or managed by the at least one sBS; e) a total number of secondary cells of a UE served or managed by the at least one sBS; f) a number of UEs currently operating in Radio Resource Control, RRC, idle state; g) a number of UEs currently operating in RRC inactive state; h) a number of UEs currently operating in RRC connected state; i) a number of serving cells whose UEs are in RRC idle state; j) a number of serving cells whose UEs are in RRC inactive state; k) a number of serving cells whose UEs are in RRC connected state.

11. The method according to any one of claims 5-10, wherein the SCSI on whether the at least one sBS supports co-location operation with another base station located at the same geographical site or location comprises one or more of the following information: a) an indication indicting whether the at least one sBS can operate when geographically co-located with another base station; b) one or more frequency ranges within which the at least one sBS supports co-location operation with another BS; c) one or more frequency bands within which the at least one sBS supports co-location operation with another BS.

12. The method according to any one of claims 5-11 , wherein the SCSI on activation or deactivation status of the serving cells of a UE served or managed by the at least one sBS comprises one or more of the following information: a) a total number of serving cells which are currently activated; b) a total number of serving cells which are currently deactivated; c) a total number of secondary cells which are currently activated.

13. The method according to any one of claims 5-12, wherein the SCSI on dormant and / or non-dormant BWP status of the serving cells of a UE served or managed by the at least one sBS comprises one or more of the following information: a) a total number of serving cells with non-dormant BWP; b) a total number of serving cells with dormant BWP; c) a total number of primary secondary cells and a total number of secondary cells with non-dormant BWP; d) a total number of primary secondary cells and a total number of secondary cells with dormant BWP.

14. The method according to any one of claims 5-13, wherein the SCSI on resource status of the at least one sBS comprises one or more of the following information: a) radio resource status, RRS; b) transport network resource status, TN RS; c) hardware resource status HRS.

15. The method according to claim 14, wherein the SCSI on the RRS comprises one or more of the following information: a) a number of resource blocks, RBs, in a sBS current used or allocated to a UE served by the sBS; b) a number of RBs in a sBS current unused or not allocated to a UE served by the sBS; c) a percentage of RBs with regard to the total available RBs in a sBS current used or allocated to one or more UEs served by the sBS; d) a percentage of RBs with regard to the total available RBs in a sBS current unused or not allocated to one or more UEs served by the sBS.

16. The method according to claim 14, wherein the SCSI on the TNRS comprises one or more of the following information: a) a number of transport network layer resources, TNLR, in a sBS current used or unavailable; b) a number of TNLR in a sBS current unused or available; c) a percentage of TNLR with regard to the total available RNLR in a sBS current used or unavailable;d) a percentage of TNLR with regard to the total available RNLR in a sBS current unused or available.

17. The method according to claim 14, wherein the SCSI on the HRS comprises one or more of the following information: a) a percentage of processor resources with regard to the total available processor resources in a sBS current used or unavailable; b) a percentage of processor resources with regard to the total available processor resources in a sBS current unused or available; c) a percentage of memory resources with regard to the total available memory resources in a sBS current used or unavailable; d) a percentage of memory resources with regard to the total available memory resources in a sBS current unused or available.

18. The method according to any one of claims 1-17, further comprising: sending (330) a message to the at least one sBS or a third network node (130) to indicate one or more of the following: a) whether the first network node (110) is configuring or has configured one or more mBS to support and offload the at least one sBS; b) whether the one or more mBS will be co-located or non-co-located with the at least one sBSs; c) a time period during which the configured one or more mBS operates and offloads the at least one sBS; d) one or more configuration parameters.

19. The method according to any one of claims 1-18, further comprising: sending (340) a message to a fourth network node (140) for requesting one or more mBSs managed by the fourth network node (140) for serving the one or more UEs when a certain type of mBS is not available among the mBSs managed by the first network node (110).

20. A method performed in a second network node (120) for obtaining and transmitting serving cell status information, SCSI, in a hybrid wireless communication network (100) comprising one or more static base stations, sBS (sBS1 , sBS2,..sBSi), and one or more mobile base stations, mBS (mBS1 , mBS2, mBS3, mBS4), whereinthe one or more sBS are serving one or more user equipment, UE (UE1 , UE2, UE3), with multicarrier operation capability, the method comprising: obtaining (810) SCSI for at least one sBS; transmitting (820) the obtained SCSI to a first network node (110) or a third network node (130).

21. The method according to claim 20, wherein the SCSI comprises one or more of the following information on:1) a maximum operational time difference, MOTD, of a UE served or managed by the at least one sBS;2) a number of different types of the serving cells of a UE served or managed by the at least one sBS;3) whether the at least one sBS supports co-location operation with another base station located at the same geographical site or location;4) activation or deactivation status of the serving cells of a UE served or managed by the at least one sBS;5) dormant and / or non-dormant bandwidth part, BWP, status of the serving cells of a UE served or managed by the at least one sBS;6) resource status of the at least one sBS.

22. The method according to any one of claims 20-21, further comprising: receiving (830) a message from the first network node (110) indicating one or more of the following information: a) whether the first network node (110) is configuring or has configured one or more mBS to support and offload the at least one sBS; b) whether the one or more mBS will be co-located or non-co- located with the at least one sBSs; c) a time period during which the configured one or more mBS can operate and offload the at least one sBS; d) one or more configuration parameters.

23. The method according to claim 22, further comprising:sending (840) the message received from the first network node (110) to one or more sBS located in the region controlled or managed by the second network node (120).

24. The method according to any one of claims 20-23, further comprising: performing (850) a cell change for at least one UE to the one or more mBS.

25. The method according to claim 24, wherein performing (850) a cell change for at least one UE to the one or more mBS comprises performing one or more of the following: a) a cell reselection; b) a handover; c) a RRC release with redirection; d) a serving cell change; e) a cell change to a configured mBS; f) de-configuring one or more secondary cells of one or more UEs served by the at least one sBS; g) configuring one or more UEs with one or more secondary cells which are managed or served by the one or more mBS; h) requesting a configured mBS to configure at least one UE with one or more secondary cells; i) de-configuring one or more cell groups of one or more UEs served by the at least one sBS; j) configuring one or more UEs with one or more cell groups which are managed or served by the one or more mBS; k) requesting a configured mBS to configure at least one UE with one or more cell groups.

26. The method according to any one of claims 24-25, further comprising: obtaining (860) information on received signal level of the at least one UE with respect to the one or more mBS; performing (850) a cell change for at least one UE from at least one sBS to the one or more mBS if the received signal level is above a certain threshold.

27. A first network node (110) configured to perform the method according to any one of claims 1-19.

28. The first network node (110) according to claim 27, wherein the first network node (110) is a separate node in a hybrid wireless communication network (100) or a function unit in any one of a core network node, a coordinating network node, a self-organizing network node, a centralized network node.

29. A second network node (120) configured to perform the method according to any one of claims 20-26.

30. The second network node (120) according to claim 29, wherein the second network node (120) is any one of a static base station, a core network node, a coordinating network node, a self-organizing network node, a centralized network node.

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