WO2015086053A1

WO2015086053A1 - Apparatus and method for communication

Info

Publication number: WO2015086053A1
Application number: PCT/EP2013/076171
Authority: WO
Inventors: Beatriz SORET; Klaus Ingemann Pedersen
Original assignee: Nokia Solutions And Networks Oy
Priority date: 2013-12-11
Filing date: 2013-12-11
Publication date: 2015-06-18

Abstract

The invention relates to apparatuses and methods in a communication system. The solution comprises receiving (302) a first indicator related to how the quality of service experienced by user equipment of a given set of cells relates to the quality of service requirement of the user equipment; receiving (304) a second indicator related to how the quality of service experienced by user equipment of a macro cell overlaying the given set of cells relates to the quality of service requirement of the user equipment of the macro cell; comparing (306) the first indicator and the second indicator; and controlling (308) the usage of transmission resources utilised by the macro cell on the basis of the comparison.

Description

DESCRIPTION

TITLE

APPARATUS AND METHOD FOR COMMUNICATION FIELD

The exemplary and non-limiting embodiments of the invention relate generally to wireless communication networks. Embodiments of the invention relate especially to an apparatus and a method in communication networks.

BACKGROUND

The following description of background art may include insights, discoveries, understandings or disclosures, or associations together with disclosures not known to the relevant art prior to the present invention but provided by the invention. Some of such contributions of the invention may be specifically pointed out below, whereas other such contributions of the invention will be apparent from their context.

Wireless communication systems are constantly under development.

Developing systems provide a cost-effective support of high data rates and efficient resource utilization. One communication system under development is the 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) Release 8. An improved version of the Long Term Evolution radio access system is called LTE-Advanced (LTE-A). The LTE is designed to support various services, such as high-speed data, multimedia unicast and multimedia broadcast services.

Typically, in a geographical area of a radio communication system there is provided a plurality of different kinds of radio cells as well as a plurality of radio cells. A radio system may be implemented as a multilayer network including several kinds of cells, such as macro-, micro- and picocells. Radio cells may be macro cells (or umbrella cells) which are large cells, usually having a diameter of up to tens of kilometres, or smaller cells such as micro, femto or pico cells. The smaller cells may be located within the coverage area of a larger macro cell. Typically, small cells are used to increase the capacity of the system in areas where the traffic density is high. The co-operation of different kind of cells must be planned carefully so that the capacity and quality of service of the system may be maximised.

SUMMARY

The following presents a simplified summary of the invention in order to provide a basic understanding of some aspects of the invention. This summary is not an extensive overview of the invention. It is not intended to identify key/critical elements of the invention or to delineate the scope of the invention. Its sole purpose is to present some concepts of the invention in a simplified form as a prelude to a more detailed description that is presented later.

According to an aspect of the present invention, there is provided an apparatus comprising: at least one processor; and at least one memory including computer program code, the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus at least to perform: receive a first indicator related to how the quality of service experienced by user equipment of a given set of cells relates to the quality of service requirement of the user equipment; receive a second indicator related to how the quality of service experienced by user equipment of a macro cell overlaying the given set of cells relates to the quality of service requirement of the user equipment of the macro cell; compare the first indicator and the second indicator; and control the usage of transmission resources utilised by the macro cell on the basis of the comparison.

According to an aspect of the present invention, there is provided an apparatus, comprising: at least one processor; and at least one memory including computer program code, the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus at least to perform: determine a first indicator related to how the quality of service experienced by user equipment of a cell served by the apparatus relates to the quality of service requirement of the user equipment; control the transmission of the first indicator to a base station serving a macro cell overlaying the cell served by the apparatus.

According to another aspect of the present invention, there is provided a method in a communication system, comprising: receiving a first indicator related to how the quality of service experienced by user equipment of a given set of cells relates to the quality of service requirement of the user equipment; receiving a second indicator related to how the quality of service experienced by user equipment of a macro cell overlaying the given set of cells relates to the quality of service requirement of the user equipment of the macro cell; comparing the first indicator and the second indicator; and controlling the usage of transmission resources utilised by the macro cell on the basis of the comparison.

According to yet another aspect of the present invention, there is provided a method in a communication system, comprising: determining a first indicator related to how the quality of service experienced by user equipment of a cell served by the apparatus relates to the quality of service requirement of the user equipment; controlling the transmission of the first indicator to a base station serving a macro cell overlaying the cell served by the apparatus.

LIST OF DRAWINGS

In the following the invention will be described in greater detail by means of preferred embodiments with reference to the attached [accompanying] drawings, in which Figure 1A shows a simplified block diagram illustrating an exemplary system architecture;

Figure 1 B illustrates an example of an apparatus according to embodiments of the invention;

Figure 2 illustrates an example of enhanced inter-cell interference coordination;

Figures 3 and 4 are flowcharts illustrating embodiments of the invention; and Figure 5 is a signalling chart illustrating an embodiment of the invention.

DESCRIPTION OF SOME EMBODIMENTS

Exemplary embodiments of the present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all embodiments of the invention are shown. Indeed, the invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. Although the specification may refer to "an", "one", or "some" embodiment(s) in several locations, this does not necessarily mean that each such reference is to the same embodiment(s), or that the feature only applies to a single embodiment. Single features of different embodiments may also be combined to provide other embodiments.

Embodiments are applicable to any base station, server, corresponding component, and/or to any communication system or any combination of different communication systems that support required functionality.

The protocols used, the specifications of communication systems, servers and user terminals, especially in wireless communication, develop rapidly. Such development may require extra changes to an embodiment. Therefore, all words and expressions should be interpreted broadly and they are intended to illustrate, not to restrict, embodiments.

Many different radio protocols to be used in communications systems exist. Some examples of different communication systems are the universal mobile telecommunications system (UMTS) radio access network (UTRAN or E-UTRAN), long term evolution (LTE, known also as E-UTRA), long term evolution advanced (LTE-A), Wireless Local Area Network (WLAN) based on IEEE 802.1 1 stardard, worldwide interoperability for microwave access (WiMAX), Bluetooth®, personal communications services (PCS) and systems using ultra-wideband (UWB) technology. IEEE refers to the Institute of Electrical and Electronics Engineers. LTE and LTE-A are developed by the Third Generation Partnership Project 3GPP.

With reference to Figure 1A, let us examine an example of a radio system to which embodiments of the invention can be applied. In this example, the radio system is based on LTE network elements. However, the invention described in these examples is not limited to the LTE radio systems but can also be implemented in other radio systems.

A general architecture of a communication system is illustrated in Figure 1A. Figure 1A is a simplified system architecture only showing some elements and functional entities, all being logical units whose implementation may differ from what is shown. The connections shown in Figure 1A are logical connections; the actual physical connections may be different. It is apparent to a person skilled in the art that the systems also comprise other functions and structures. It should be appreciated that the functions, structures, elements, and protocols used in or for group communication are irrelevant to the actual invention. Therefore, they need not be discussed in more detail here.

The exemplary radio system of Figure 1A comprises a service core of an operator including the following elements: an MME (Mobility Management Entity) 108 and an SAE GW (SAE Gateway) 104.

Base stations that may also be called eNodeBs (Enhanced node Bs) 100, 102 of the radio system may host the functions for Radio Resource Management: Radio Bearer Control, Radio Admission Control, Connection Mobility Control, Dynamic Resource Allocation (scheduling). The MME 108 is responsible for distributing paging messages to the eNodeBs 100, 102. The eNodeBs are connected to the SAE GW with an S1_U interface and to MME with an S1_MME interface. The eNodeBs may communicate with each other using an X2 interface.

Figure 1A shows user equipment 1 10 connected to the eNodeB 100 and user equipment 1 14 connected to the eNodeB 102. The user equipment refers to a portable computing device. Such computing devices include wireless mobile communication devices operating with or without a subscriber identification module (SIM), including, but not limited to, the following types of devices: mobile phone, smartphone, personal digital assistant (PDA), handset, laptop computer.

Figure 1A only illustrates a simplified example. In practice, the network may include more base stations and more cells may be formed by the base stations. The networks of two or more operators may overlap, the sizes and form of the cells may vary from what is depicted in Figure 1A, etc.

It should be appreciated that the communication system may also comprise other core network elements besides SAE GW 104 and MME 108. Direct communication between different eNodeBs over an air interface is also possible by implementing a relay node concept, wherein a relay node may be considered as a special eNodeB having wireless backhauls or, for instance, X2 and S1 interfaces relayed over the air interface by another eNodeB. The communication system is also able to communicate with other networks, such as a public switched telephone network.

The embodiments are not, however, restricted to the network given above as an example, but a person skilled in the art may apply the solution to other communication networks provided with the necessary properties. For example, the connections between different network elements may be realized with Internet Protocol (IP) connections.

Figure 1 B illustrates examples of an apparatus according to an embodiment of the invention. Figure 1 B shows a base station or eNodeB 118. The structure of eNodeBs 100 and 102 is similar to the illustrated node. The eNodeB 118 comprises a controller 120 operationally connected to a memory 122 and a transceiver 124. The controller 120 controls the operation of the base station. The memory 122 is configured to store software and data. The transceiver 124 is configured to set up and maintain a wireless connection to user equipment within the service area of the base station. The transceiver 124 is operationally connected to an antenna arrangement 126. The antenna arrangement may comprise a set of antennas. The number of antennas may be two to four, for example. The number of antennas is not limited to any particular number.

The base station may be operationally connected to other network elements of the communication system. The network element may be an MME (Mobility Management Entity), an SAE GW (SAE Gateway), a radio network controller (RNC), another base station, a gateway, or a server, for example. The base station may be connected to more than one network element. The base station 100 may comprise an interface 128 configured to set up and maintain connections with the network elements. The connections with other network elements may be realized with wireless or wired connections.

As mentioned, a radio communication system may utilise a plurality of different kinds of radio cells. Due to the increase in the amount of traffic in communication systems, the communication systems must be able to offer high capacity and quality of service. A multi-layer radio access network (RAN) is a promising technology. A typical multi-layer network comprises a set of macro-cells, also called "umbrella" cells served by eNodeBs, and one or more smaller cells under this "umbrella". The lower-layer cells may be called micro, femto or pico cells. Each lower-layer cell is served by an eNodeB. The network may simultaneously be not only a multi-layer system, but also a multi-vendor system.

In Figure 1A, the eNodeBs may be serving either an overlaying umbrella or macro cell or a lower-layer pico cell. Let us assume for the sake of simplicity that the eNodeB 100 is an upper-layer node serving a macro cell and the eNodeB 102 is a lower- layer node serving a pico cell.

As known, the user equipment and nodes of a multi-layer network may experience interference originating from a transmitter operating on different layer if same transmission resources are utilised on both layers. Thus, some co-operation and planning is required in the use of resources in a multi-layer network.

The use of time-domain (TDM) enhanced inter-cell interference coordination (elCIC) has been proposed between macro-eNBs and small cell nodes. Figure 2 illustrates this method. Figure 2 show sub-frames 200 used by an eNodeB 100 serving an overlaying cell and sub-frames 202 used by an eNodeB 102 serving a small cell within the overlaying cell. The sub-frames with normal transmission are hatched and almost blank sub-frames (ABS) are without hatches.

In elCIC, a macro-eNodeB 100 starts to mute (i.e. using so-called almost blank sub-frames) some of its sub-frames. During the muted sub-frames, the small cell eNodeB 102 is able to schedule users that would otherwise experience too high interference from the macro layer. However, muting sub-frames at the macro-eNodeB will of course also mean lower macro-cell capacity. Thus, the muting pattern at the macro cells needs to be carefully optimized in order to achieve real gain from elCIC in a multilayer system.

In Figure 2, the eNodeB serving the overlaying cell has muted sub-frames

204. The eNodeB 102 serving the small cell may schedule the user equipment which suffers most from interference originating from the overlaying cell to those sub-frames 204.

In homogeneous networks, the MAC scheduler is a key element for the provisioning of Quality of Service (QoS). By taking the QoS requirements of the users into account when deciding the allocation of the radio resources, the different needs of the users can be accommodated. However, the number of users connected to an eNB may typically be very low in networks comprising overlaying cells and using QoS-aware single- cell schedulers will not have a significant impact in the provisioning of QoS.

In networks comprising overlaying cells, multicell decisions on the resource partitioning can improve the performance of the network while accomplishing the QoS requirements. A network element configured to decide if an eNodeB serving a macro cell shall mute (ABS), or use normal transmission may take QoS requirements into account in the decision. If normal transmission is used in a macro cell, it means that macro-users can be scheduled. Otherwise, no macro-users are schedulable. The small-cell-users are scheduled in each of their cells, but such decisions naturally depend on whether the users are subject to macro-interference, or not.

Figure 3 is a flow chart illustrating an embodiment. In this example, let us assume that a given QoS constraint for each user has to be fulfilled. The QoS constraint can range from plain best effort (i.e. no strict requirement) without guaranteed bit rate (non-GBR), guaranteed bit rate (GBR) users, delay and jitter requirements, etc. Each eNodeB is assumed to monitor the experienced QoS of the users in the cell versus their QoS requirement: macro users in the macro eNodeB and small cell users in the small cell eNodeBs.

In an embodiment, the steps of Figure 3 are performed by a network element configured to control the use of transmission resources utilised by a macro cell overlaying a set of pico sells.

The flowchart of Figure 3 may illustrate the operation executed in the eNodeB 100 serving a cell overlaying a set on pico cells served by eNodeBs 102. The steps may be performed in a controller or processor of the eNodeB, for example. The process begins in 300.

In step 302, the controller or processor of the network element is configured to receive a first indicator related to how the quality of service experienced by user equipment of a given set of cells relates to the quality of service requirement of the user equipment. In an embodiment, the set of cells may be pico cells.

In step 304, the controller or processor of the network element is configured to receive a second indicator related to how the quality of service experienced by user equipment of a macro cell overlaying the given set of cells relates to the quality of service requirement of the user equipment of the macro cell. If the network element is the eNodeB serving the macro cell, it may control the determination of the second indicator.

In step 306, the controller or processor of the network element is configured to compare the first indicator and the second indicator.

In step 308, the controller or processor of the network element is configured to control the usage of transmission resources utilised by the eNodeB serving the macro cell on the basis of the comparison.

In an embodiment, the controller or processor of the network element is configured to increase the number of muted sub frames in the macro cell downlink transmission if the first indicator and the second indicator indicate that the experienced quality of service relation to the quality of service requirement is worse in the given set of cells compared to the macro cell.

The process ends in 310.

The flowchart of Figure 4 illustrates the operation executed in the eNodeB 102 serving a pico cell which is overlayerd by the macro cell served by the eNodeB 100. The steps may be performed in a controller or processor of the eNodeB, for example. The process begins in 400.

In step 402, the controller or processor of the eNodeB is configured to determine a first indicator related to how the quality of service experienced by user equipment of a cell served by the apparatus relates to the quality of service requirement of the user equipment.

In step 404, the controller or processor of the eNodeB is configured to control the transmission of the first indicator to a base station serving a macro cell overlaying the cell served by the apparatus.

The process ends in 406.

A basic division of services in LTE based systems is between Guaranteed Bit

Rate (GBR) and non-GBR. If the QoS requirement of interest is the GBR, there are several ways for defining the indicators, which may be called Key Performance Indicators KPI. In an embodiment, the first and/or the second indicator may be determined on the basis of the sum of the user equipment data rates which are below required guaranteed bit rate of the user equipment:

^ (GBR - R_u) , where _u is user bit rate, where the subscript u refers to user u, and that the summation is over all users.

In an embodiment, the first and/or the second indicator may be determined on the basis of the number of user equipment having data rates which are below required guaranteed bit rate of the user equipment.

In an embodiment, the first and/or the second indicator may be determined on the basis of the difference between the guarantee bit rate and the data rate of the user equipment among the user equipment having a data rate below the guaranteed bit rate of the user equipment.

Similarly, other QoS requirements may be selected for the KPI definition (delay, jitter, error probability, for example...).

In an embodiment, the above procedures of Figures 3 and 4 may be performed before each ABS adaptation interval.

If the eNodeBs serving macro and small cells are connected through X2 interface, the information of the KPIs of the small cell eNodeBs has to be known by the macro eNodeB in order to decide on the ABS. One possibility for the signalling exchange is to extend the Resource Status Update sent by the small cell eNodeBs to the macro cell eNodeB with the information of the ABS status to include also the KPIs of interest. The interaction is illustrated in Figure 5. The Figure illustrates signalling between the eNodeB 100 serving a macro cell and the eNodeB 102 serving a pico cell.

The eNodeB 100 serving a macro cell requests 500 ABS status from the eNodeB 102 serving a pico cell. The eNodeB 102 replies 502 with ABS status and KPI. Based on the ABS status and the KPI in the macro and pico cells the eNodeB 100 may configure a new ABS pattern and transmit 504 information on the pattern to the eNodeB 102.

As a non-limiting example, the inter-eNB X2 signalling of KPIs of the small cells could be a simple scalar enumerated [0,1 , 2, ...,100]. Low values of KPIs of the small cells could indicate that users in the small cell layer are not fulfilling their QoS requirements, while high values of KPIs could indicate that users in the small cell layer are having acceptable performance, or even much better experienced QoS as compared to their minimum QoS requirements. As an example, a value of 50 for the KPI of a small cell could be defined to express that QoS requirements are just fulfilled, and thus KPI>50 will indicate "better than promised experienced QoS", while KPI<50 indicates "lower than promised experienced QoS". With slow ABS adaptation, the muting ratio is adapted in a slow basis of several seconds. The X2 signalling in Figure 5 can be used by the macro layer every time it is desired to adapt the ABS to new network or load conditions, or in a regular basis.

If the ABS adaptation is to be done in a fast basis (e.g. every transmission time interval TTI or every 10-TTIs), then one option is to have the small cell in the form of Remote Radio Heads RRH and connected to the macro eNodeB with a high bandwidth, low latency link. In this case, the radio resource management functionality of the macro and the small cells can be centralized at the macro layer, so that the information of the KPIs in the different cells is available in the macro eNB. Shortly before the beginning of a TTI, the macro can decide whether to use the coming subframe as normal or protected subframe.

The steps and related functions described in the above and attached figures are in no absolute chronological order, and some of the steps may be performed simultaneously or in an order differing from the given one. Other functions can also be executed between the steps or within the steps. Some of the steps can also be left out or replaced with a corresponding step.

The apparatuses or controllers able to perform the above-described steps may be implemented as an electronic digital computer, or a circuitry which may comprise a working memory (RAM), a central processing unit (CPU), and a system clock. The CPU may comprise a set of registers, an arithmetic logic unit, and a controller. The controller or the circuitry is controlled by a sequence of program instructions transferred to the CPU from the RAM. The controller may contain a number of microinstructions for basic operations. The implementation of microinstructions may vary depending on the CPU design. The program instructions may be coded by a programming language, which may be a high-level programming language, such as C, Java, etc., or a low-level programming language, such as a machine language, or an assembler. The electronic digital computer may also have an operating system, which may provide system services to a computer program written with the program instructions.

As used in this application, the term 'circuitry' refers to all of the following: (a) hardware-only circuit implementations, such as implementations in only analog and/or digital circuitry, and (b) combinations of circuits and software (and/or firmware), such as (as applicable): (i) a combination of processor(s) or (ii) portions of processor(s)/software including digital signal processor(s), software, and memory(ies) that work together to cause an apparatus to perform various functions, and (c) circuits, such as a microprocessor(s) or a portion of a microprocessor(s), that require software or firmware for operation, even if the software or firmware is not physically present.

This definition of 'circuitry' applies to all uses of this term in this application. As a further example, as used in this application, the term circuitry' would also cover an implementation of merely a processor (or multiple processors) or a portion of a processor and its (or their) accompanying software and/or firmware. The term 'circuitry' would also cover, for example and if applicable to the particular element, a baseband integrated circuit or applications processor integrated circuit for a mobile phone or a similar integrated circuit in a server, a cellular network device, or another network device.

An embodiment provides a computer program embodied on a distribution medium, comprising program instructions which, when loaded into an electronic apparatus, are configured to control the apparatus to execute the embodiments described above.

The computer program may be in source code form, object code form, or in some intermediate form, and it may be stored in some sort of carrier, which may be any entity or device capable of carrying the program. Such carriers include a record medium, computer memory, read-only memory, and a software distribution package, for example. Depending on the processing power needed, the computer program may be executed in a single electronic digital computer or it may be distributed amongst a number of computers.

The apparatus may also be implemented as one or more integrated circuits, such as application-specific integrated circuits ASIC. Other hardware embodiments are also feasible, such as a circuit built of separate logic components. A hybrid of these different implementations is also feasible. When selecting the method of implementation, a person skilled in the art will consider the requirements set for the size and power consumption of the apparatus, the necessary processing capacity, production costs, and production volumes, for example.

It will be obvious to a person skilled in the art that, as technology advances, the inventive concept can be implemented in various ways. The invention and its embodiments are not limited to the examples described above but may vary within the scope of the claim.

Claims

1. An apparatus, comprising:

at least one processor; and

at least one memory including computer program code,

the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus at least to perform:

receive a first indicator related to how the quality of service experienced by user equipment of a given set of cells relates to the quality of service requirement of the user equipment;

receive a second indicator related to how the quality of service experienced by user equipment of a macro cell overlaying the given set of cells relates to the quality of service requirement of the user equipment of the macro cell;

compare the first indicator and the second indicator; and

control the usage of transmission resources utilised by the macro cell on the basis of the comparison.

2. The apparatus of claim 1 , the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus further to perform:

increase the number of muted sub frames in the macro cell downlink transmission if the first indicator and the second indicator indicate that the experienced quality of service relation to the quality of service requirement is worse in the given set of cells compared to the macro cell.

3. The apparatus of claim 1 or 2, the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus further to perform:

determine the first and/or the second indicator on the basis of the sum of the user equipment data rates which are below required guaranteed bit rate of the user equipment.

4. The apparatus of claim 1 or 2, the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus further to perform:

determine the first and/or the second indicator on the basis of the number of user equipment having data rates which are below required guaranteed bit rate of the user equipment.

5. The apparatus of claim 1 or 2, the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus further to perform:

determine the first and/or the second indicator on the basis of the difference between the guarantee bit rate and the data rate of the user equipment among the user equipment having a data rate below the guaranteed bit rate of the user equipment.

6. The apparatus of any preceding claim, the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus further to perform: receive the first indicator from a base station serving a cell in a Resource Status Update message.

7. The apparatus of any preceding claim, wherein the first and/or second indicator may have integer values ranging from 0 to 100.

8. The apparatus of any preceding claim, the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus further to perform: control the usage of transmission resources at predetermined time intervals.

9. The apparatus of any preceding claim, the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus further to perform: control the usage of transmission resources once per at most ten Transmission Time Intervals.

10. An apparatus, comprising:

at least one processor; and

at least one memory including computer program code,

determine a first indicator related to how the quality of service experienced by user equipment of a cell served by the apparatus relates to the quality of service requirement of the user equipment;

control the transmission of the first indicator to a base station serving a macro cell overlaying the cell served by the apparatus.

11. The apparatus of claim 10, the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus further to perform: determine the first second indicator on the basis of the sum of the user equipment data rates which are below required guaranteed bit rate of the user equipment.

12. The apparatus of claim 10, the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus further to perform:

determine the first indicator on the basis of the number of user equipment having data rates which are below required guaranteed bit rate of the user equipment.

13. The apparatus of claim 10, the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus further to perform:

determine the first indicator on the basis of the difference between the guarantee bit rate and the data rate of the user equipment among the user equipment having a data rate below the guaranteed bit rate of the user equipment.

14. The apparatus of any preceding claim, the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus further to perform:

transmit the first indicator in a Resource Status Update message.

15. The apparatus of any preceding claim, wherein the first indicator may have integer values ranging from 0 to 100.

16. The apparatus of any preceding claim, the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus further to perform: control the transmission of the first indicator at predetermined time intervals.

17. A method in a communication system, comprising:

receiving a first indicator related to how the quality of service experienced by user equipment of a given set of cells relates to the quality of service requirement of the user equipment;

receiving a second indicator related to how the quality of service experienced by user equipment of a macro cell overlaying the given set of cells relates to the quality of service requirement of the user equipment of the macro cell;

comparing the first indicator and the second indicator; and

controlling the usage of transmission resources utilised by the macro cell on the basis of the comparison.

18. The method of claim 17, further comprising:

increasing the number of muted sub frames in the macro cell downlink transmission if the first indicator and the second indicator indicate that the experienced quality of service relation to the quality of service requirement is worse in the given set of cells compared to the macro cell.

19. The method of claim 17, further comprising:

receiving the first indicator from a base station serving a cell in a Resource Status Update message.

20. The method of any preceding claim 17 to 19, wherein the first and/or second indicator may have integer values ranging from 0 to 100.

21. The method of any preceding claim 17 to 20, further comprising: controlling the usage of transmission resources at predetermined time intervals.

22. The method of any preceding claim 17 to 21 , further comprising: controlling the usage of transmission resources once per at most ten

Transmission Time Intervals.

23. A method in a communication system, comprising:

determining a first indicator related to how the quality of service experienced by user equipment of a cell served by the apparatus relates to the quality of service requirement of the user equipment;

controlling the transmission of the first indicator to a base station serving a macro cell overlaying the cell served by the apparatus.

24. A computer program product embodied on a distribution medium readable by a computer and comprising program instructions which, when loaded into an apparatus, execute the method according to any of claims 17 to 23.