WO2016122384A1

WO2016122384A1 - Network node and method in a wireless telecommunications network

Info

Publication number: WO2016122384A1
Application number: PCT/SE2016/050052
Authority: WO
Inventors: Oscar Ohlsson; Andreas HÖGLUND; Emre YAVUZ
Original assignee: Telefonaktiebolaget Lm Ericsson (Publ)
Priority date: 2015-01-30
Filing date: 2016-01-28
Publication date: 2016-08-04

Abstract

A method, performed by a network node (110), for managing transmission of System Information Blocks, SIBs. The network node (110) is adapted to send notifications of a change in system information to UEs (121) during a first modification period. The network node (110) is further adapted to transmit changed system information to the UEs (121) during a second modification period following the first modification period. The network node (110) identifies (301a) that a parameter to be modified is present in a SIB, which SIB is intended for a coverage enhanced UE (122). The network node further sends (302a) a notification about the identified SIB to the coverage enhanced UE (122) during an extended first modification period, wherein the extended first modification period is extended in comparison to the first modification period.

Description

NETWORK NODE AND METHOD IN A WIRELESS TELECOMMUNICATIONS

NETWORK

TECHNICAL FIELD

Embodiments herein relate to a wireless telecommunication networks, such as cellular radio networks. In particular, a method and a network node for improving performance of coverage enhanced User Equipment (UEs) in a wireless telecommunications network are disclosed.

BACKGROUND

Communication devices such as User Equipment (UEs) are enabled to communicate wirelessly in a cellular communications network or wireless communication system, sometimes also referred to as a cellular radio system or cellular networks. The communication may be performed e.g. between two UEs, between a UE and a regular telephone and/or between a UE and a server via a Radio Access Network (RAN) and possibly one or more core networks, comprised within the cellular communications network.

UEs may further be referred to as wireless terminals, wireless devices (WD), mobile terminals and/or mobile stations, mobile telephones, cellular telephones, laptops, tablet computers or surf plates with wireless capability, Machine Type Communications (MTC) devices just to mention some further examples. The UEs in the present context may be, for example, portable, pocket-storable, hand-held, computer-comprised, or vehicle- mounted mobile devices, enabled to communicate voice and/or data, via the RAN, with another entity, such as another wireless terminal or a server.

The cellular communications network covers a geographical area which is divided into cell areas, wherein each cell area being served by a network node. A cell is the geographical area where radio coverage is provided by the network node.

The network node may further control several transmission points, e.g. having Radio Units (RRUs). A cell can thus comprise one or more network nodes each controlling one or more transmission/reception points. A transmission point, also referred to as a transmission/reception point, is an entity that transmits and/or receives radio signals. The entity has a position in space, e.g. an antenna. A network node is an entity that controls one or more transmission points. The network node may e.g. be a base station such as a Radio Base Station (RBS), Evolved Node B (eNB or eNodeB), NodeB, B node, or BTS (Base Transceiver Station), depending on the technology and terminology used. The base stations may be of different classes such as e.g. macro eNodeB, home eNodeB or pico base station, based on transmission power and thereby also cell size.

Further, each network node may support one or several communication technologies. The network nodes communicate over the air interface operating on radio frequencies with the UEs within range of the network node. In the context of this disclosure, the expression Downlink (DL) is used for a transmission path from the base station to the mobile station. The expression Uplink (UL) is used for a transmission path in the opposite direction, i.e. from the UE to the base station.

In 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE), base stations, which may be referred to as eNodeBs or even eNBs, may be directly connected to one or more core networks. In LTE, the cellular communication network is also referred to as Evolved Universal Terrestrial Radio Access Network (E-UTRAN).

An E-UTRAN cell is defined by certain signals which are broadcasted from the eNB. These signals contain information about the cell which can be used by UEs in order to connect to the network through the cell. The signals comprise reference and synchronization signals which the UE uses to find frame timing and physical cell identification as well as system information which comprises parameters relevant for the whole cell.

An existing means to reduce the battery power consumption in UEs is to use Discontinuous Reception (DRX), a feature in which the UE's receiver is switched off except during configured periods at configured intervals.

The basic mechanism in DRX is a configurable DRX cycle, which may also be referred to as a DRX pattern, in the UE. With a DRX cycle configured, the UE only monitors the control signaling during an onDuration of the DRX cycle. The onDuration may be one or more subframes, which may be referred to as an active subframe or active subframes. In the remaining subframes of the DRX cycle, the UE may switch off its receiver, which may also be referred to as the UE sleeping or as an offDuration of the DRX cycle. This allows for a significant reduction in power consumption, i.e. the longer the DRX cycle and the shorter the onDuration, the lower the power consumption will be. In some situations, if the UE has been scheduled and active with receiving or transmitting data in one subframe, it is likely that it will be scheduled again in the near future. Waiting until the next active subframe according to the DRX cycle may lead to additional delays in transmission. Hence, to reduce delays, the UE may remain in the active state for a certain configurable time after being scheduled, this may also be referred to as the active time or the drx-lnactivityTimer, as defined in 3GPP TS 36.321 Ch3.1 . The duration of the active time is set by an inactivity timer, which is the duration in downlink subframes that the UE waits before it switches off and re-enters offDuration from the last successful decoding of a Physical Downlink Control Channel (PDCCH). The UE may restart the inactivity timer after a single successful decoding of a PDCCH for a transmission. The time it takes for the UE to re-enter offDuration after the last transmission may also be referred to as the inactivity time.

It would therefore be beneficial to extend the DRX cycle lengths to further reduce the battery power consumption, especially for the benefit of MTC devices where there is no possibility for interactive charging or changing of the battery on a regular basis. Although longer DRX cycle lengths naturally cause larger delays in the downlink, this is typically not a problem for delay insensitive traffic such as that generated by MTC devices.

It is however important for a UE operating with DRX to maintain up-to-date system information because otherwise it cannot interact with the network in an interoperable manner. In particular, if the UE does not have recent system information, it must acquire the latest version of the system information prior to access, which means that it cannot access the system, such as e.g. transmitting random access requests, etc., before it has obtained the latest version of the system information. On the other hand, frequent acquisition of system information has an adverse impact on the battery life time. In E- UTRA networks, the information required to enable reliable communications with the network is referred to as System Information (SI) and is transmitted to the UE in a number of different System Information Blocks (SIBs) and a Master Information Block (MIB). One such element of System Information in E-UTRAN is the System Frame Number (SFN), which the UE uses to keep synchronization with the network and which acts as a timing reference.

The SFN is defined in a Master Information Block (MIB) in a "systemFrameNumber" field which defines the 8 most significant bits of the system frame number (SFN). 3GPP TS 36.21 1 "E-UTRA; Physical Channels and Modulation" v1 1 .1 .0 (2012-12) [section 21 , 6.6.1 ] indicates that the 2 least significant bits of the SFN are acquired implicitly in the physical broadcast channel (P-BCH) decoding, i.e. timing of 40ms P-BCH transmission time interval (TTI) indicates the 2 least significant bits (within 40ms P-BCH TTI, the first radio frame: 00, the second radio frame: 01 , the third radio frame: 10, the last radio frame: 1 1 ). One value applies for all serving cells. Hence, the associated functionality is common, which may also be referred to as not being performed independently for each cell.

A typical scenario is to have sensors sending measurements infrequently, where each of the transmissions would consist of only small amounts of data. This type of communication is called machine to machine (M2M) communication in the literature, or machine-type communication (MTC), in 3GPP. UEs in cellular systems, such as e.g. 3GPP Wideband Code Division Multiple Access fWCDMA), LTE, are most commonly battery driven and the power consumption of these devices is therefore an important factor. In the context of MTC, many of the devices are expected to be battery operated as well. Sensors and other devices may reside in remote locations and the number of deployed devices could be so large that it would be practically infeasible to replace or frequently recharge the batteries in these kinds of devices. Thus, it is an important goal to aim for reduction in the power consumption when considering improvements for current cellular systems.

In order for system information to be decodable by all devices in a cell, including devices at the cell edge and devices with poor radio conditions, the network may rely on a technique known as soft combining. In this technique a SIB is first encoded, which may be done using a rate 1/3 turbo encoder, and then transmitted multiple times. The receiver combines the received transmission with the previous transmissions and attempts to decode the message. After a sufficient number of repetitions the accumulated signal energy will be high enough that the decoding will succeed.

System information is normally only updated at specific radio frames in which SFN mod N = 0, where N is known as the modification period. The UE may improve decoding by combining SIB transmissions sent within the same modification period. The shortest modification period may be 640ms, while the longest modification period may be 40.69s. In practice, however, the longest modification period may be limited by the SFN periodicity which is usually only 10.24s. Prior to an SI update, UEs present in the cell are notified by means of a special paging message, a so called change notification. During a first modification period, the change notification is sent to the UE. This first modification period may also be referred to as a notification period. In the next modification period, i.e. a second modification period, the network node transmits the updated system information to the UE. This second modification period may also be referred to as an update period.

An option considered in Rel-13 is to introduce a new information block, such as a SIB, for coverage enhanced UEs. This SIB may be small in size and may contain only the most essential information from the other SIBs (SIB1 -17) required for accessing the cell. Moreover, the SIB may be repeated frequently, potentially hundreds of times, within a modification period to reach UEs in enhance coverage, which may also be referred to as coverage enhanced UEs. This new information block may be referred to as an enhanced SIB. However, even though the new information block, such as the enhanced SIB, is repeated frequently, the coverage enhanced UEs may not be able to decode the message.

SUMMARY

It is therefore an object of embodiments herein to enhance the performance in a wireless communications network comprising coverage enhanced UEs.

According to a first aspect of embodiments herein, the object is achieved by a method, performed by a network node, for managing transmission of System Information Blocks (SIBs). The network node is adapted to send a notification of a change in system information to a UE during a first modification period. The network node is further adapted to transmit changed system information to the UEs during a second modification period following the first modification period. The network node identifies that a parameter to be modified is present in a SIB, which SIB is intended for a coverage enhanced UE. The network node further sends a notification about the identified SIB to the coverage enhanced UE during an extended first modification period. The extended first modification period is extended in comparison to the first modification period.

According to a second aspect of embodiments herein, the object is achieved by a network node for performing a method for managing transmission of System Information Blocks (SIBs). The network node is adapted to send a notification of a change in system information to a UE during a first modification period. The network node is further adapted to transmit changed system information during a second modification period following the first modification period. The network node is configured to identify that a parameter to be modified is present in a System Information Block, SIB, which SIB is intended for a coverage enhanced UE. The network node is further configured to send a notification about the identified SIB to the coverage enhanced UE during an extended first modification period. The extended first modification period is extended in comparison to the first modification period. By applying an extended modification period for the coverage enhanced UEs, the coverage enhanced UEs are allowed to accumulate sufficient energy to be able to decode a message, such as the notification, since a higher number of retransmissions may be performed during the extended modification period. Since every re-transmission contains the same information, such as data and parity bits, the receiver may combine the received bits with the same bits from previous transmissions. Every re-transmission may be considered as adding extra energy to the received transmission until the received message is strong enough to be decoded. At the same time the shorter, i.e. the non- extended, first modification period, which may also be referred to as a legacy modification period, allows system information in a legacy information block, such as the SIBs, to be updated at a faster rate. Thereby, the performance of coverage enhanced UEs may be improved, without worsening the performance of normal coverage UEs, which may also be referred to as legacy UEs.

BRIEF DESCRIPTION OF THE DRAWINGS

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

Figure 1 is a schematic block diagram illustrating embodiments of a wireless communications network,

Figure 2 is a scheduling diagram illustrating the notification procedure according to embodiments herein,

Figure 3 is a flowchart depicting embodiments of a method in a network node,

Figure 4 is a schematic block diagram illustrating embodiments of a network node, Figure 5 is a schematic block diagram illustrating a second embodiment of a wireless communications network, and

Figure 6 is a scheduling diagram illustrating the notification procedure according to some further embodiments herein.

DETAILED DESCRIPTION

Terminology

The following common terminology is used in the embodiments and are elaborated below.

Radio network node: In some embodiments the non-limiting term radio network node is more commonly used and it refers to any type of network node serving UE and/or connected to other network node or network element or any radio node from where UE receives signal. Examples of radio network nodes are Node B, base station (BS), multi- standard radio (MSR) radio node such as MSR BS, eNode B, network controller, radio network controller (RNC), base station controller, relay, donor node controlling relay, base transceiver station (BTS), access point (AP), transmission points, transmission nodes, RRU, RRH, nodes in distributed antenna system (DAS) etc.

Network node: In some embodiments a more general term "network node" is used and it can correspond to any type of radio network node or any network node, which communicates with at least a radio network node. Examples of network node are any radio network node stated above, core network node (e.g. MSC, MME etc), O&M, OSS, SON, positioning node (e.g. E-SMLC), MDT etc.

User equipment: In some embodiments the non-limiting term user equipment (UE) is used and it refers to any type of wireless device communicating with a radio network node in a cellular or mobile communication system. Examples of UE are target device, device to device UE, machine type UE or UE capable of machine to machine communication, PDA, iPAD, Tablet, mobile terminals, smart phone, laptop embedded equipped (LEE), laptop mounted equipment (LME), USB dongles etc.

Note that although terminology from 3GPP LTE has been used in this disclosure to exemplify the embodiments herein, this should not be seen as limiting the scope of the embodiments herein to only the aforementioned system. Other wireless systems, including WCDMA/UMTS, WiMax, Ultra Mobile Broadband (UMB) and the Global System for Mobile communication (GSM), may also benefit from exploiting the ideas covered within this disclosure. The solution is described in terms of a LTE network with Evolved Packet Core (EPC). The embodiments disclosed herein may be applicable to other cellular and wireless systems as well, such as WCDMA/UMTS.

Also note that terminology such as eNodeB and UE should be considering non- limiting and does in particular not imply a certain hierarchical relation between the two; in general "eNodeB" could be considered as device 1 and "UE" device 2, and these two devices communicate with each other over some radio channel. Herein, the focus is on wireless transmissions in the downlink, but the embodiments herein are equally applicable in the uplink.

In Rel-13 of the 3GPP specification for LTE battery life, cost/complexity, and coverage optimizations for machine type communications (MTC) is introduced. MTC devices may sometimes be placed or situated in challenging locations, for which locations the radio network, such as an LTE network, may not be dimensioned for full coverage. For example, electronic devices with communication functionality, such as smart meters, are often placed or situated in building basements and may sometimes even be contained in metal enclosures, which may limit the coverage of the electronic devices. MTC devices in such locations may be referred to as coverage enhanced UEs. Similarly challenging 5 locations may be found in smart agriculture, where devices may be located in rural and isolated areas where the coverage is extremely poor.

One particular type of information that requires reliable transmission is System Information (SI). The SI is information that may be repeatedly broadcast by the network and which a UE has to acquire in order to access a cell and which, in general, is required

10 for the UE to operate properly within the cell and the network. In order to support the UE in connecting to a cell, which may also be referred to as accessing the cell, System Information Blocks (SIBs) are transmitted in a control channel, i.e. a logical channel in the down link. The control channel may e.g. be a Broadcast Control Channel (BCCH) logical channel in the downlink, which may be mapped to a PDSCH, i.e. a physical channel. In

15 LTE a number of different SIBs are defined, which are characterized by the type of information they are carrying. For example, cell access related parameters, such as information about the operator of the cell, restrictions on which users may be allowed to access the cell and the allocation of subframes to uplink/downlink are carried by SIB1 and radio resource configuration is carried by SIB2. SIB1 further carries information about

20 scheduling of other SIBs.

In this section, the embodiments herein will be illustrated in more detail by a number of exemplary embodiments. It should be noted that these embodiments are not mutually exclusive. Components from one embodiment may be tacitly assumed to be present in another embodiment and it will be obvious to a person skilled in the art how those

25 components may be used in the other exemplary embodiments.

Figure 1 depicts an example of a wireless communications network 100 according to a first scenario in which embodiments herein may be implemented. The wireless communications network 100 may be an LTE, E-Utran, WCDMA, GSM network, any 3GPP cellular network, Wimax, or any other cellular network or system.

30 The wireless communications network 100 comprises a network node 110 as depicted in Figure 1 . The first network node 1 10 may be a transmission point such as a radio base station, for example an eNB, an eNodeB, or an Home Node B, an Home eNode B or any other network node capable to serve a wireless terminal such as a user equipment or a MTC device in a wireless communications network. The first network node

35 1 10 serves a plurality of cells 130. The wireless communications network 100 comprises a set of UEs 120, which set may comprise one or more UEs, such as coverage enhanced UEs 121 and legacy UEs 122. The UE 120 is within radio range of the first network node 1 10, which means that the UE 120 can hear signals from the first network node 1 10.

The UE 120 may e.g. be a wireless terminal, a wireless device, a mobile wireless terminal or a wireless terminal, a mobile phone, a computer such as e.g. a laptop, a Personal Digital Assistant (PDA) or a tablet computer, with wireless capability, or any other radio network units capable to communicate over a radio link in a wireless communications network. Please note the term wireless terminal used in this document also covers other wireless devices such as MTC or Machine to machine (M2M) devices.

Figure 2 illustrates a notification procedure according to embodiments herein, when the system information parameter to be updated is present in both the enhanced SIB, which may also be referred to as a SIB intended for coverage enhanced UEs 121 , and in one of the legacy SIBs, which may also be referred to as a SIB intended for legacy UEs 122. The system parameters present in the different SIBs are defined in 3GPP 36.331 rel.12.4.1 . Coverage enhanced UEs 121 may be notified using the new modification period, which is extended in comparison to the legacy modification cycle, while UEs 122 in normal coverage are notified using the legacy modification cycle. The extended modification period is extended in comparison to the legacy modification period. Since the old system information has to be discarded by all UEs at the same time, since there would otherwise be two versions of the system information active simultaneously, notification starts earlier for coverage enhanced UEs 121 than for UEs 122 in normal coverage but ends at the same time. This requires that the end of the new modification period coincides with the end of the legacy modification period, which may be accomplished by e.g. setting the new modification period to be a multiple of the legacy modification period.

In the following the basic steps performed by the UE 120 and the eNB 1 10 are described. Some modifications of the steps are possible without departing from the scope of the embodiments as defined by the appended set of claims. It is assumed that the modification period has been configured in the UEs 120 and that different modification periods are used for some UEs 122 operating in normal mode, which may also be referred to as legacy UEs 122, and some other UEs 121 in enhanced coverage mode, which may also be referred to as coverage enhanced UEs 121 . The modification period may be included in the system information or configured in some other way by the network. It may also be possible to use a pre-configured or default value that is stored in the UE 120 or read from e.g. a SIM card.

Example of embodiments of a method in the network node 1 10 for managing transmission of System Information Blocks, SIBs, will now be described with reference to a flowchart depicted in Figure 3. The network node 1 10 operates one or more cells and is configured to transmit to both the coverage enhanced UEs 121 and the normal coverage UEs 122. The coverage enhanced UEs 121 may refer to UEs that are placed or situated in challenging locations, for which locations the radio network, such as an LTE network, was not dimensioned for full coverage. The method may comprise the following actions, which actions may be taken in any suitable order. Dashed lines of a box in Figure 3 indicate that this action is not mandatory.

Action 301 : Prior to system information update, the network node 1 10 identifies, which may also be referred to as checks, a SIB in which a parameter to be modified is present. In a first step 301 a, the network node 1 10 identifies that the parameter to be modified is present in a SIB intended for the coverage enhanced UEs 121 . In a further step 301 b, the network node 1 10 may further indentify that the parameter to be modified is present in a legacy SIB intended for the normal coverage UEs 122. The network node 1 10 may further perform both steps 301 a and 301 b to identify that the parameter to be modified is present in a SIB intended for both the coverage enhanced and the normal coverage UEs 121 , 122.

Action 302: The network node 1 10 then sends a message, such as a change notification, to UEs for which the SIB is intended.

In a first step 302a, when the network node 1 10 has identified that the parameter to be modified is present in only the SIB intended for the coverage enhanced UEs 121 , the network node sends a change notification, which may also be referred to as notifies or notifying, only to the coverage enhanced UEs 121 .

In a second step 302b, when the network node 1 10 has identified that the parameter to be modified is present in a legacy SIB intended for the normal coverage UEs 122, the network node sends a change notification only to the normal coverage UEs 122. If the parameter to be updated is present in only one of the SIB types, the network node 1 10 may notify, i.e. sends the change notification to, the UEs 120 in the corresponding UE group at the start of the next modification cycle. The network node 1 10 may use the new extended modification period, which may also be referred to as the extended first modification period, when the parameter applies to coverage enhanced UEs 121 and the legacy modification period when the parameter applies to the al coverage UEs 122. When the parameter to be modified is present in both of the SIB types, the network node 1 10 sends a change notification to both UE groups. The coverage enhanced UEs 121 may be notified using the new extended modification period while the normal coverage UEs 122 are notified using the legacy modification cycle. The notification may be sent during the first modification period. Since the old system information has to be discarded by all UEs 120 at the same time, since there would otherwise be two versions of the system information active simultaneously, notification starts earlier for the coverage enhanced UEs 121 than for the normal coverage UEs 122, but ends at the same time. This requires that the end of the new modification period coincides with the end of the legacy modification period, which may be accomplished by e.g. setting the new modification period to be a multiple of the legacy modification period. Figure 2 illustrates this step.

This action 302 may be performed by a sending module within a network node, such as the network node 1 10.

By using an extended modification period/cycle for the enhanced coverage UEs

121 , a higher number of SIB repetitions may to be sent to the coverage enhanced UEs 121 at a reasonable system resource cost without impacting the behavior of the legacy normal coverage UEs 122. Furthermore, system information change notifications may be sent only to those UEs 120 that are affected by the change and that use the updated parameter. Thereby, signaling over the air interface may be reduced and unnecessary processing at the UE 120 may be avoided. The extended modification cycle period further allows for a longer DRX cycle which reduces power consumption of the UE 120.

If the network node 1 10 would like to update system information, which information is not common to both types of UEs 120, yet once more for legacy normal coverage UEs 121 after a recent modification, this may be done by the end of the second legacy modification cycle. The network node 1 10 does not have to wait until the end of the new modification cycle for the coverage enhanced UEs 121 , which most likely also is longer, before it sends the updated system information to the normal coverage UEs 122.

The UE 120 starts acquiring the new system information in the modification period immediately following the modification period in which the change notification was received. Note that it will typically take longer time for the coverage enhanced UEs 121 to decode the system information, than for the normal coverage UEs 122. From the viewpoint of the UE 121 , 122 the update procedure appears identical to the legacy update procedure. Since the UE 121 , 122 only sees its own modification period, the UE 121 , 122 may not even be aware that there are two different modification periods. It is the network side, such as e.g. the network node 1 10, that is aware of both modification periods. Thereby backwards compatibility may be assured.

To perform the method actions for managing transmission of CRS described above in relation to Figure 3, the network node 1 10 may comprise the following arrangement depicted in Figure 4. As mentioned above the network node 1 10 operates one or more cells and is configured to serve coverage enhanced and normal coverage UEs. Dashed lines of a box in Figure 4 indicate that this box is not mandatory.

The network node 1 10 comprises a radio circuitry 401 to communicate with UEs 120 and a processing unit 402. The network node may further comprise a communication circuitry 403 to communicate with other network nodes, which may e.g. be an X2 interface.

The network node 1 10 may be configured to, e.g. by means of an identifying module 404 being configured to, identify if a system information parameter to be modified is present in a SIB intended for coverage enhanced UEs 120, in a legacy SIB intended for normal coverage UEs 120, or in a SIB intended for both coverage enhanced and normal coverage UEs. The network node 1 10 may further be configured to, e.g. by means of a sending module 405 being configured to, send a change notification only to the coverage enhanced UEs 121 , when the parameter to be modified is present in only the SIB intended for the coverage enhanced UEs 121 . The network node 1 10 may further be configured to, e.g. by means of the sending module 405 being configured to, send a change notification only to the normal coverage UEs 122, when the parameter to be modified is present in only a legacy SIB intended for the normal coverage UEs 122. The network node 1 10 may further be configured to, e.g. by means of the sending module 405 being configured to, send a change notification to both UE groups, when the parameter to be modified is present in both of the SIB types.

In further embodiments herein the network node 1 10 may further be configured to, e.g. by means of the sending module 405 being configured to, send the change notification to the coverage enhanced UEs 121 using an extended modification period while being configured to send change notifications to the normal coverage UEs 122 using a legacy modification period. The sending module 405 may be comprised in the radio circuitry 401 .

The embodiments herein for managing transmission of SIBs may be implemented through one or more processors, such as the processing unit 402 in the network node 1 10 depicted in Figure 4, 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 carrying computer program code for performing the embodiments herein when being loaded into the network node 1 10 and/or the core network node. 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 and downloaded to the network node 1 10 and/or the core network node.

The network node 1 10 may further comprise a memory 406 comprising one or more memory units. The memory 406 is arranged to be used to store obtained information, measurements, data, configurations, schedulings, and applications to perform the methods herein when being executed in the network node 1 10.

Those skilled in the art will also appreciate that the identifying module 404 described above may refer to a combination of analog and digital circuits, and/or one or more processors configured with software and/or firmware, e.g. stored in the memory 406 that when executed by the one or more processors such as the processing unit 402 as described above. One or more of these processors, as well as the other digital hardware, may be included in a single Application-Specific Integrated Circuitry (ASIC), or several processors and various digital hardware may be distributed among several separate components, whether individually packaged or assembled into a system-on-a-chip (SoC).

Figure 5 illustrates another wireless network 100 comprising a more detailed view of network node 1 10 and a UE 120, in accordance with a particular embodiment. For simplicity, figure 5 only depicts network 100, network nodes 1 10 and 1 10a, and UE 120. The network node 1 10 may comprise a processor 402, a memory 406, an interface 201 , and an antenna 201 a. Similarly, the UE 120 may comprise a processor 212, a memory 213, an interface 21 1 and an antenna 21 1 a. These components may work together in order to provide the network node and/or the wireless device functionality, such as providing wireless connections in a wireless network and allowing for a change in estimated DL Component Carrier (CC). In different embodiments, the wireless network may comprise any number of wired or wireless networks, network nodes, base stations, controllers, wireless devices, relay stations, and/or any other components that may facilitate or participate in the communication of data and/or signals whether via wired or wireless connections.

The network 220 may comprise one or more IP networks, public switched telephone networks (PSTNs), packet data networks, optical networks, wide area networks (WANs), local area networks (LANs), wireless local area networks (WLANs), wired networks, wireless networks, metropolitan area networks, and other networks to enable communication between devices.

The network node 1 10 may comprise a processor 402, a memory 406, an interface 5 201 , and an antenna 201 a. These components are depicted as single boxes located within a single larger box. In practice however, a network node may comprise multiple different physical components that make up a single illustrated component, e.g. interface 201 may comprise terminals for coupling wires for a wired connection and a radio transceiver for a wireless connection. Similarly, the network node 1 10 may be composed0 of multiple physically separate components, such as e.g. a NodeB component and a RNC component, a BTS component and a BSC component, etc., which may each have their own respective processor, memory, and interface components. In certain scenarios in which the network node 1 10 comprises multiple separate components, such as e.g. BTS and BSC components, one or more of the separate components may be shared among5 several network nodes. In some embodiments for example, a single RNC may control multiple NodeB's. In such a scenario, each unique NodeB and BSC pair may be a separate network node. In some embodiments, network node 1 10 may be configured to support multiple radio access technologies (RATs). In such embodiments, some components may be duplicated, such as e.g. separate memory 406 for the different RATs,0 and some components may be reused, such as e.g. the same antenna 201 may be shared by the RATs.

The processor 402 may be a combination of one or more of a microprocessor, controller, microcontroller, central processing unit, digital signal processor, application specific integrated circuit, field programmable gate array, or any other suitable computing5 device, resource, or combination of hardware, software and/or encoded logic operable to provide, either alone or in conjunction with other network node 1 10 components, such as memory 406, network node 1 10 functionality. For example, processor 402 may execute instructions stored in memory 406. Such functionality may include providing various wireless features discussed herein to a wireless devices, such as UE 120, including any0 of the features or benefits disclosed herein.

The memory 406 may comprise any form of volatile or non-volatile computer readable memory including, without limitation, persistent storage, solid state memory, remotely mounted memory, magnetic media, optical media, random access memory (RAM), read-only memory (ROM), removable media, or any other suitable local or remote5 memory component. The memory 406 may store any suitable instructions, data or information, including software and encoded logic, utilized by network node 1 10. Memory 406 may be used to store any calculations made by processor 402 and/or any data received via interface 201 .

The network node 1 10 also comprises interface 201 which may be used in the wired or wireless communication of signaling and/or data between network node 1 10, network 220, and/or UE 120. For example, interface 201 may perform any formatting, coding, or translating that may be needed to allow network node 1 10 to send and receive data from network 220 over a wired connection. Interface 201 may also include a radio transmitter and/or receiver that may be coupled to or a part of antenna 201 a. The radio transmitter and/or receiver in combination with the antenna 201 a may correspond to the radio circuit 401 disclosed in figure 4. The interface 201 may further comprise the communication circuit 403 to communicate with other network nodes. The radio may receive digital data that is to be sent out to other network nodes or UEs via a wireless connection 230. The radio may convert the digital data into a radio signal having the appropriate channel and bandwidth parameters. The radio signal may then be transmitted via antenna 201 a to the appropriate recipient, such as e.g. the UE 120.

The antenna 201 a may be any type of antenna capable of transmitting and receiving data and/or signals wirelessly. In some embodiments, antenna 201 a may comprise one or more omni-directional, sector or panel antennas operable to transmit/receive radio signals between, for example, 2 GHz and 66 GHz. An omnidirectional antenna may be used to transmit/receive radio signals in any direction, a sector antenna may be used to transmit/receive radio signals from devices within a particular area, and a panel antenna may be a line of sight antenna used to transmit/receive radio signals in a relatively straight line.

The UE 120 may be any type of wireless endpoint, mobile station, mobile phone, wireless local loop phone, smartphone, user equipment, desktop computer, PDA, cell phone, tablet, laptop, VoIP phone or handset, which is able to wirelessly send and receive data and/or signals to and from a network node, such as network node 1 10 and/or other UEs. UE 120 comprises processor 212, memory 213, interface 21 1 , and antenna 21 1 a. Like network node 1 10, the components of UE 120 are depicted as single boxes located within a single larger box, however in practice a wireless device may comprise multiple different physical components that make up a single illustrated component. As an example, the memory 213 may comprise multiple discrete microchips, each microchip representing a portion of the total memory capacity. The processor 212 may be a combination of one or more of a microprocessor, controller, microcontroller, central processing unit, digital signal processor, application specific integrated circuit, field programmable gate array, or any other suitable computing device, resource, or combination of hardware, software and/or encoded logic operable to provide, either alone or in combination with other UE 120 components, such as memory 213, UE 120 functionality. Such functionality may include providing various wireless features discussed herein, including any of the features or benefits disclosed herein.

The memory 213 may be any form of volatile or non-volatile memory including, without limitation, persistent storage, solid state memory, remotely mounted memory, magnetic media, optical media, random access memory (RAM), read-only memory (ROM), removable media, or any other suitable local or remote memory component. Memory 213 may store any suitable data, instructions, or information, including software and encoded logic, utilized by UE 120. Memory 213 may be used to store any calculations made by processor 212 and/or any data received via interface 21 1 .

The interface 21 1 may be used in the wireless communication of signalling and/or data between UE 120 and network node 1 10, 1 10a. For example, interface 21 1 may perform any formatting, coding, or translating that may be needed to allow UE 120 to send and receive data from any of the network nodes 1 10, 1 10a over a wireless connection 230, 240. Interface 21 1 may also include a radio transmitter and/or receiver that may be coupled to or a part of antenna 21 1 a. The radio may receive digital data that is to be sent out to network node 201 via a wireless connection. The radio may convert the digital data into a radio signal having the appropriate channel and bandwidth parameters. The radio signal may then be transmitted via antenna 21 1 a to network node 1 10.

The antenna 21 1 a may be any type of antenna capable of transmitting and receiving data and/or signals wirelessly. In some embodiments, antenna 21 1 a may comprise one or more omni-directional, sector or panel antennas operable to transmit/receive radio signals between 2 GHz and 66 GHz. For simplicity, antenna 21 1 a may be considered a part of interface 21 1 to the extent that a wireless signal is being used.

In some embodiments, the components described above may be used to implement one or more functional modules used in system information update for coverage enhanced UEs. The functional modules may comprise software, computer programs, subroutines, libraries, source code, or any other form of executable instructions that are run by, for example, a processor. In general terms, each functional module may be implemented in hardware and/or in software. Preferably, one or more or all functional modules may be implemented by processors 212 and/or 402, possibly in cooperation with memory 213 and/or 406. The processors) 212 and/or 402 and the memory(/ies) 213 and/or 406 may thus be arranged to allow the normal coverage processors) 212 and/or 402 to fetch instructions from the memory(/ies) 213 and/or 406 and execute the fetched 5 instructions to allow a respective functional module to perform any features or functions disclosed herein. The modules may further be configured to perform other functions or steps not explicitly described herein but which would be within the knowledge of a person skilled in the art.

10 Figure 6 is another flowchart depicting the method performed in the communications network 100 according to some of the embodiments herein.

Action 601 : The UE 120 may receive a modification period configuration, which may e.g. be a legacy modification period if the UE 120 is a legacy UE or an extended coverage modification period, which may also be referred to as a coverage enhanced 15 modification period, if the UE 120 is a coverage enhanced UE. The modification period configuration may be received from a network node 1 10.

Action 602: The network node 1 10 may then determine a parameter update relevant for a UE 120.

Action 603: The network node 1 10 may further check if the parameter update 20 impacts, which may also be referred to as being intended for, either legacy UEs 122, extended coverage UEs 121 or both legacy and extended coverage UEs.

Action 604: When the parameter update only impacts legacy UEs 122 , the network node 1 10 notifies the legacy UEs 122 about the parameter update in the next legacy modification period.

25 Action 605: When the parameter update only impacts extended coverage UEs 121 , the network node 1 10 notifies the extended coverage UEs 121 about the parameter update in the next extended coverage modification period.

Action 606: When the parameter update impacts both legacy UEs 122 and extended coverage UEs 121 , the network node 1 10 notifies the extended coverage UEs

30 121 about the parameter update in the next extended coverage modification period.

Action 607: The network node further notifies the legacy UEs 122 about the parameter update in the next legacy modification period. The network node 1 10 selects the legacy modification period such that the legacy modification period ends at the same time as the extended coverage modification period. Action 608: When the parameter update has been notified to the UEs 120, 121 , 122, 210 the network node 1 10 discards the old parameter settings and starts using the new parameter settings for transmissions.

Action 609: The UEs 120, 121 , 122, 210 that have been updated also start to receive data transmissions using the updated parameter information.

According to embodiments herein, the object is achieved by a method, performed by a network node, for managing transmission of information blocks, such as System Information Blocks, SIBs.

By applying an extended modification period for the coverage enhanced UEs, the coverage enhanced UEs are allowed to accumulate sufficient energy to be able to decode a message, such as e.g. a paging message, which may be a change notification. Since every re-transmission contains the same information (data and parity bits), the receiver may combine the received bits with the same bits from previous transmissions. One could think of every re-transmission as adding extra energy to the received transmission until the received message is strong enough to be decoded. At the same time the shorter legacy modification period allows system information in the legacy information block, such as the SIBs, to be updated at a faster rate.

In an example herein, when a system information parameter is to be updated, the network node identifies whether the parameter to be modified is present in any one or more out of an information block, such as e.g. a SIB, intended for coverage enhanced UEs and an information block intended for legacy UEs. When the parameter to be modified is present in only the information block intended for coverage enhanced UEs, the network node sends the message, such as e.g. a paging message, which may be a change notification, only to the coverage enhanced UEs. When the parameter to be modified is present in both an information block intended for coverage enhanced UEs and in an information block intended for legacy UEs, the network node sends the message to both UE groups. The network node sends the message to the coverage enhanced UEs using an extended modification period, i.e. the extended first modification period, while change notifications to legacy UEs are sent using a legacy modification period, i.e. the first (non-extended) modification period.

According to a second aspect of embodiments herein, the object is achieved by a network node configured to manage transmission of information blocks, such as System Information Blocks, SIBs. The network node is configured to identify whether a system information parameter to be modified is present in an information block intended for coverage enhanced UEs, in a legacy information block intended for legacy UEs, or both. The network node may further be configured to send a message, such as e.g. a paging message, which may be a change notification, only to the coverage enhanced UEs, when the parameter to be modified is present in only the information block intended for coverage enhanced UEs. The network node may further be configured to send a message, such as e.g. a paging message, which may be a change notification, to both UE groups, when the parameter to be modified is present in both an information block intended for coverage enhanced UEs and in an information block intended for legacy UEs. The network node may further be configured to send the message to the coverage enhanced UEs using an extended modification period while being configured to send paging messages, such as change notifications, to legacy UEs using a legacy modification period.

In some scenarios, the network node may begin sending the message to the coverage enhanced UEs before beginning to send the message to the legacy UEs such that the modification period for both groups ends at approximately the same time.

When using the word "comprise" or "comprising" it shall be interpreted as non- limiting, i.e. meaning "consist at least of". When using the word "set" herein, it shall be interpreted as meaning "one or more".

The embodiments herein are not limited to the above described embodiments. Various alternatives, modifications and equivalents may be used. Therefore, the above embodiments should not be taken as limiting the scope of the embodiments as defined by the appended set of claims. The embodiments herein also applies to the multi-point carrier aggregation systems.

Certain aspects of the inventive concept have mainly been described above with reference to a few embodiments. However, as is readily appreciated by a person skilled in the art, embodiments other than the ones disclosed above are equally possible and within the scope of the inventive concept. Similarly, while a number of different combinations have been discussed, all possible combinations have not been disclosed. One skilled in the art would appreciate that other combinations exist and are within the scope of the inventive concept. Moreover, as is understood by the skilled person, the herein disclosed embodiments are as such applicable also to other standards and communication systems and any feature from a particular figure disclosed in connection with other features may be applicable to any other figure and or combined with different features.

Claims

1 . A method, performed by a network node (1 10), for managing transmission of System Information Blocks, SIBs, wherein the network node (1 10) is adapted to send notifications of a change in system information to UEs (121 ) during a first modification period, and to transmit changed system information to the UEs (121 ) during a second modification period following the first modification period, wherein the method comprises:

- identifying (301 a) that a parameter to be modified is present in a SIB, which SIB is intended for a coverage enhanced UE (122), and

- sending (302a) a notification about the identified SIB to the coverage

enhanced UE (122) during an extended first modification period, wherein the extended first modification period is extended in comparison to the first modification period.

2. The method according to claim 1 , wherein the method further comprises:

- identifying (301 b) that a parameter to be modified is present in a SIB, which SIB is intended for a normal coverage UE (121 ), and

- sending (302b) a notification about the identified SIB to the normal coverage UE (121 ) during the first modification period.

3. The method according to claim 1 or 2, wherein the extended first modification period is longer than the first modification period.

4. The method according to any of the claims 1 to 3, wherein the first and the extended first modification period end simultaneously.

5. The method according to any of the claims 1 to 4, wherein a length of the extended first modification period is a multiple of a length of the first modification period.

6. The method according to any of the previous claims, wherein the notification is a

paging message.

7. A network node (101 ) configured for managing transmission of System Information Blocks, SIBs, wherein the network node (1 10) is adapted to send notifications of a change in system information to UEs (121 ) during a first modification period, and to transmit changed system information during a second modification period following

5 the first modification period, wherein the network node (1 10) is configured to:

- identify that a parameter to be modified is present in a System Information Block, SIB, which SIB is intended for a coverage enhanced UE (122), and

- send a notification about the identified SIB to the coverage enhanced UE (122) during an extended first modification period, wherein the extended first

10 modification period is extended in comparison to the first modification period.

8. The network node (1 10) according to claim 7, wherein the network node (1 10) is

further configured to:

- identify that the parameter to be modified is further present in a SIB, which SIB 15 is intended for a normal coverage UE (121 ), and

- send a notification the identified SIB to the normal coverage UE (121 ) during the first modification period.

9. The network node (1 10) according to claim 7 or 8, wherein the extended first

20 modification period is longer than the first modification period.

10. The network node (1 10) according to any of the claims 7 to 9, wherein the first and the extended first modification period end simultaneously.

25 1 1 . The network node (1 10) according to any of the claims 7 to 10, wherein a length of the extended first modification period is a multiple of a length of the first modification period.

12. The network node (1 10) according to any of the claims 7 to 1 1 , wherein the

30 notification is paging message.