WO2013008190A2

WO2013008190A2 - Wireless Communications

Info

Publication number: WO2013008190A2
Application number: PCT/IB2012/053543
Authority: WO
Inventors: Tero Henttonen; Timo Roman; Christopher Callender; Anders Ostergaard NIELSON; Kaj Jansen
Original assignee: Renesas Mobile Corporation
Priority date: 2011-07-12
Filing date: 2012-07-11
Publication date: 2013-01-17
Also published as: WO2013008190A3

Abstract

Apparatus and methods relating to wireless communications in, for example, Long Term Evolution (LTE) networks are described. A measurement pattern for at least one automatic gain control tracking loop in a user equipment device is determined, when resource restrictions have been applied to the user equipment device, the resource restrictions comprising at least one measurement restriction pattern. Then automatic gain control measurements are performed by the user equipment device according to the measurement patterns of the at least one automatic gain control tracking loop. (Fig. 2)

Description

Wireless Communications

Field of the Invention

The invention is in the field of wireless communications and relates to automatic gain control. More particularly, though not exclusively, the invention relates to automatic gain control measurements.

Background of the Invention

Long Term Evolution (LTE) is a 4G wireless broadband technology developed by the Third Generation Partnership Project (3 GPP). LTE provides significantly increased peak data rates, reduced latency, scalable bandwidth capacity, and backwards compatibility with existing GSM and UMTS technologies. The upper layers of LTE are based upon TCP/IP. LTE supports mixed data, voice, video and messaging traffic. LTE uses Orthogonal Frequency Division Multiplexing (OFDM) and/or Multiple Input Multiple Output (MIMO) antenna technology.

LTE radio access technology (E-UTRAN) may use enhanced inter- cell interference coordination (elCIC) functionality. The use of elCIC techniques is motivated by the emergence of denser and less coordinated network deployments with smaller cells. Having additional pico or femto co-channel layer within a typical (for example, homogeneous) macro network topology can provide significant system capacity benefit. The idea is that network nodes coordinate resources between them in such a way that it enhances overall system capacity. The benefits come from the fact that user equipment (UE) may for example access a pico layer enhanced NodeB (eNB) with a better link budget compared to a macro layer eNB, which leads to increased downlink throughput and better uplink coverage - meaning also less uplink transmit power which means less uplink interference caused to other cells.

Two basic types of exemplary use case have been envisioned: Macro/pico deployment and a macro/femto deployment. In a macro/pico deployment, macro nodes may mute a subset of subframes to enable terminals connected to pico nodes to exchange data with reduced interference from the macro node. In a macro/femto deployment, closed-access femto nodes may mute some subframes to allow macro terminals in the vicinity of the femtos to stay connected to their serving macro cell. The muted subframes are called Almost Blank Subframes (ABS). In the muted subframes, there may still be residual interference due to transmission of Common Reference Symbols (CRS) and other physical channels containing essential information (for example, system information, paging).

Time Division Multiplexing (TDM) elCIC is typically utilized when it is assumed that the UE may experience heavy co-channel interference from neighbor cells. In such a case, the co-channel interference patterns become time -varying by nature, partly because of TDM partitioning causing some resources to be occasionally muted. The ABS patterns utilized in TDM elCIC that are used by the network at a given point of time are unknown to the UE. However, subsets of the patterns, intended for restricting Radio Resource Management (RRM), Radio Link Monitoring (RLM) or Channel State Information (CSI) measurements may be configured for the UE to enable elCIC techniques. When such resource restrictions are configured, a UE device may be signaled one subset of subframes to be used for serving cell RRM/RLM measurement purposes, one subset of subframes for neighbor cell RRM measurement purposes and two subsets of subframes for CSI (Channel Quality Indicator (CQI); Precoding Matrix Index (PMI); Rank Indicator (RI)) measurement purposes. Such subsets of subframes are also called patterns.

An Automatic Gain Control (AGC) operation in a UE device is typically a slowly adapting loop which follows the received signal amplitude and power over several contiguous subframes in time. Its purpose is to adjust the received signal level such that the signal can be decoded properly and efficiently.

When ABS patterns are used, normal AGC operation may be degraded because the received signal power fluctuates faster and with larger dynamic range than expected. In TDM elCIC operation, a UE receiver front-end may experience high signal amplitude in one subframe and markedly lower signal amplitude in another subframe, which means that the variation of received power from one subframe to another depends on the ABS pattern used by network nodes (neighbor cells) and also on the overall load of the network itself. Hence, the received power variations may fluctuate heavily, leading to inefficient AGC operation.

Based on the above, there is a need for a solution that would solve or at least mitigate the above problems or drawbacks.

Summary of the Invention According to a first aspect of the invention, there is provided a method comprising determining a measurement pattern for at least one automatic gain control tracking loop according to resource restrictions that are applied to a user equipment, the resource restrictions comprising at least one measurement restriction pattern; and performing automatic gain control measurements according to the measurement patterns of the at least one automatic gain control tracking loop.

According to a second aspect of the invention, there is provided an apparatus comprising: means for determining a measurement pattern for at least one automatic gain control tracking loop according to resource restrictions that are applied to a user equipment, the resource restrictions comprising at least one measurement restriction pattern; and means for performing automatic gain control measurements according to the measurement patterns of the at least one automatic gain control tracking loop.

According to a third aspect of the invention, there is provided a computer-readable medium carrying a computer program comprising computer program code, which, when executed by a processor, performs according to the aforementioned method.

According to a fourth aspect of the invention, there is provided a method comprising determining a measurement pattern for at least one automatic gain control tracking loop according to resource restrictions that are applied to a user equipment, the resource restrictions comprising at least one measurement restriction pattern; and causing the measurement pattern for at least one automatic gain control tracking loop to be transmitted to the user equipment.

According to a fifth aspect of the invention, there is provided an apparatus comprising means for determining a measurement pattern for at least one automatic gain control tracking loop according to resource restrictions that are applied to a user equipment, the resource restrictions comprising at least one measurement restriction pattern; and means for causing the measurement pattern for at least one automatic gain control tracking loop to be transmitted to the user equipment.

According to some embodiments, broadly-speaking, an arbitrary number of automatic gain control tracking loops is/are, effectively, associated with (e.g. controlled to perform according to) at least one measurement restriction pattern.

According to some embodiments, the resource restrictions relate to enhanced inter-cell interference coordination functionality in a Long Term Evolution radio access network.

In some embodiments, the above apparatus is a receiver in a user equipment device. In other embodiments, the apparatus is a user equipment device itself.

Advantages relating to at least some embodiments of the invention include the possibility to apply AGC measurements more accurately in a radio access network. The advantages of at least some embodiments of the invention also include allowing for efficient AGC operation in the presence of elCIC restrictions, or in the presence of multiple configurations of measurement restrictions.

The accompanying drawings, illustrate by way of example only embodiments of the invention and together with the description help to explain the principles of the invention. In the drawings: Figure 1 is a flow diagram illustrating a method according to one embodiment of the invention;

Figure 2 is a diagram of a subframe arrangement and illustrates general principles of automatic gain control measurements according to one embodiment of the invention;

Figure 3 is a diagrammatic representation ofa configuration between a macro cell and a pico cell according to one embodiment of the invention;

Figure 4 illustrates a block diagram of an apparatus according to one embodiment of the present invention;

Figure 5 is a block diagram of a receiver according to one embodiment of the invention; and

Figure 6 is a simplified block diagram of an apparatus for determining a measurement pattern for at least one automatic gain control tracking loop.

Detailed Description of the Drawings

Reference will now be made in detail to exemplary embodiments of the present invention, which are illustrated in the accompanying drawings.

Figure 1 is a flow diagram illustrating a method according to one embodiment of the invention. An apparatus, for example UE, determines in step 100 a measurement pattern for at least one AGC tracking loop according to resource restrictions that are applied to the UE. The resource restrictions comprise at least one measurement restriction pattern. A measurement restriction pattern refers, for example, to a subset of subframes. In step 201 the apparatus performs automatic gain control measurements according to the measurement pattern(s) of the at least one automatic gain control tracking loop. The above steps provide the possibility to apply AGC measurements more accurately in a radio access network.

In one embodiment of Figure 1, determining a measurement pattern for at least one automatic gain control tracking loop comprises determining the measurement pattern for the at least one automatic gain control tracking loop based on the at least one measurement restriction pattern.

In another embodiment of Figure 1 , determining a measurement pattern for at least one automatic gain control tracking loop comprises receiving the measurement pattern for the at least one automatic gain control tracking loop from a base station. This means that the UE does not itself make the determination of the measurement pattern based on the measurement restriction patterns.

In the embodiment of Figure 1 , LTE radio access technology uses elCIC functionality. The radio access network includes at least one macro cell of a base station, i.e. eNodeB. One or more smaller cell (pico or femto cells) may be present in the coverage area of the macro cell. Having an additional pico or femto co-channel layer within a typical (for example, homogeneous) macro network topology proves to provide significant system capacity benefit. The network nodes coordinate resources between them in such a way that overall system capacity is enhanced. UEUE may, for example, access pico layer eNodeBs with a better link budget compared to macro layer eNodeB, which leads to increased downlink throughput and better uplink coverage - meaning also less uplink transmit power, which means less uplink interference caused to other cells. The embodiment allows efficient AGC operation in the presence of elCIC restrictions, or in the presence of multiple configurations of measurement restrictions.

For example, in a macro/pico deployment, macro nodes mute a subset of subframes during which terminals connected to pico nodes can exchange data without almost any interference from the macro node. In a macro/femto deployment, closed-access femto nodes mute some subframes (i.e. ABS) to allow macro terminals in their vicinity to stay connected to their serving cell. In the muted subframes, there may still be residual interference due to CRS transmission and other physical channels (system information, paging).

In one embodiment of Figure 1, the measurement restriction patterns tell the UE when various measurements can be executed, for example, measurement relating to serving cell RLM/ RRM), neighbour cell RRM, CSI etc. The AGC tracking loops make use of these measurement restriction patterns and muted subframes when performing AGC measurements.

Figure 2 illustrates general principles of AGC measurements according to one embodiment of the invention. Figure 2 discloses a set of subframes used in LTE radio access technology which uses elCIC functionality. The length of each subframe is, for example, 1ms. A UE AGC performs radio frequency gain measurements in a subframe n and applies the measurements at the start of subframe n+1. In another embodiment, the measurements can be averaged over several subframes n, n-1, n-2, ... . Figure 2 illustrates the general principle of performing AGC tracking per subframe subset. Rectangles filled with lines belong to a first subset of subframes and empty rectangles belong to a second subset of subframes. The starting point of each arrow represents the time of measurement and the end point of each arrow represents when the measurements are applied. In one embodiment, the measurements can be averaged over several subframes within the same subframe subset.

Figure 3 illustrates a system according to an embodiment of the invention. The system comprises a simple macro-pico scenario in a (LTE radio access network where elCIC is applied. The simplified configuration comprises one macro cell 300 when a macro base station 302 is operating. A pico cell 304 is a smaller cell arranged, for example, to a certain location where traffic is denser than normal within the macro cell 300. A pico base station 306 operates the pico cell 304. Reference number 308 refers to an enlarged area of the pico cell 304 called a Cell Range Expansion (CRE) 308. UE 310 is shown as having reached the CRE 308 area. The pico cell 304 has an X2 connection to the macro cell 300.

It is assumed that UE 310 of the macro cell 300 is moving towards the pico cell 304 and the macro cell 300 wishes to handover the UE 310 to the pico cell 304 as fast as possible. In this way, the macro cell 300 offloads traffic to the pico cell 304. To offload the UE 310 to the pico cell 304, the macro cell 300 starts utilizing ABS subframes and configures a RRM pattern for neighbour cell measurements for the UE. This means that the UE 310 starts trying to measure neighbor cell(s) according to the pattern, and can find the pico cell 304 earlier than it would otherwise have done due to the lower interference level during protected subframes. The term "protected subframes", as used herein, refers, for example, to subframes where the macro cell utilizes ABS subframes. After the UE 310 reports the pico cell 304, the macro cell 300 can handover the UE to the pico cell 304.

In one embodiment an AGC loop is operating with measurement restriction patterns.

Table 1

Table 1 represents an exemplary macro-pico case, which includes measurement patterns for neighbour cell RRM and serving cell RLM/RRM in a Frequency Division Duplex (FDD) configuration. While within (i.e. connected to) the pico cell, the UE would be given the serving cell RLM/RRM pattern. This is because the UE would need to stay connected to the pico cell, and while it is still "closer" (in radio terms) to the macro cell, it would need protection against the macro cell interference. However, since there could be more than one pico cell, the UE may also need the neigbour cell RRM pattern to measure those pico cells during the protected subframes (i.e. macro ABS). This means that the UE would then have both patterns (the serving cell RLM/RRM pattern and neigbour cell RRM pattern) active at the same time. The patterns may be identical with each other (as disclosed in Table 1), but need not be identical with each other.

Furthermore, as disclosed in Table 1 , there is an AGC pattern for an AGC tracking loop. The AGC pattern causes the AGC to measure radio frequency gain during the muted subframes. The AGC tracking loop operates according to RLM/RRM pattern configured at the UE for elCIC.

In another embodiment, two AGC loops are operating with measurement restriction patterns in a UE.

Table 2

The situation illustrated in Table 2 is similar to that of Table 1. The difference is that now there are two AGC tracking loops in Table 2. The pattern relating to the first AGC tracking loop is identical with the restriction pattern for serving cell RLM/RRM measurements. The pattern relating to the second AGC tracking loop is complementary to (i.e. is the inverse of) the restriction pattern for serving cell RLM/RRM measurements or identical with the restriction pattern for neighbor cell RRM measurements. Table 2 discloses only an exemplary situation where the pattern relating to the second AGC tracking loop is complementary to the restriction pattern for serving cell RLM/RRM measurements. Furthermore, the 1st and 2nd AGC tracking loop patterns may be in use simultaneously in user equipment. In another embodiment, the user equipment may not use all the configured AGC tracking loop patterns simultaneously.

The idea for having an AGC tracking loop over the complementary part of the RLM/RRM patterns is that the UE may happen to be scheduled over these subframes and thus the AGC needs to be controlled there as well.

In another embodiment of Figure 3, three AGC loops are operating with measurement restriction patterns in a UE.

CSI (CQI,PMI,RI) feedback based on interference measurement in restricted subsets of subframes is enabled through configured subsets of subframes indicated by a CSI measurement subframe configuration. Subframe subsets are signalled by Radio Resource Control (RRC) (for example, with bitmaps of size matching the size of ABS pattern), 0 or 2 subframe subsets can be configured per UE. The UE only reports CSI for each configured subframe subset. If no subframe subsets are configured, interference measurement in restricted subsets of subframes is not enabled. The two CSI subframe subsets may or may not be the complement (i.e. the inverse) of each other. It is assumed that two subframe subsets are configured for CSI measurement restrictions and denote the two CSI restrictive patterns by CSI l and CSI 2.

Restriction pattern, in blocks of 8 subframes

Macro-Pico

1 = Measurements allowed

case

0 = Measurements disallowed

Neighbour

10000000 10000000 10000000 10000000 10000000 cell RRM Pattern

Serving cell

RLM/R M 10000000 10000000 10000000 10000000 10000000 Pattern

CSI l pattern 10000000 10000000 10000000 10000000 10000000

CSI 2 pattern 00000001 00000001 00000001 00000001 00000001

Pattern for

1st AGC 10000000 10000000 10000000 10000000 10000000 tracking loop

Pattern for

2^nd AGC 00000001 00000001 00000001 00000001 00000001 tracking loop

Pattern for 3^rd

AGC tracking 01111110 01111110 01111110 01111110 01111110 loop

Table 3

The situation disclosed in Table 3 is similar to that of Table 2. The difference is that now there are three AGC tracking loops. The pattern relating to the first AGC tracking loop is identical with the restriction pattern for first CSI measurements. The pattern relating to the second AGC tracking loop is identical with the restriction pattern for second CSI measurements. The pattern relating to the third AGC tracking loop is complementary to (i.e. is the inverse of) a logical OR combination of both CSI patterns. Furthermore, the 1st, 2nd and 3rd AGC tracking loop patterns may be in use simultaneously. In another embodiment, the user equipment may not use all the configured AGC tracking loop patterns simultaneously. In this example, the patterns for neighbor cell RRM and serving cell RLM/RRM happen to coincide with the first CSI pattern. The idea for having an AGC tracking loop over the complementary part of the first CSI pattern and the second CSI pattern is that UE may happen to be scheduled over these subframes and thus the AGC needs to be controlled there as well.

In another embodiment of Figure 3, adaptive TDM resource partitioning is used.

Table 4 Table 4 illustrates an example where macro and pico cells exchange traffic and ABS pattern information over the X2 interface on a relatively fast timescale (for example, 1 to 100 ms). Offloading between macro and pico nodes becomes dynamic and depends on traffic conditions. Therefore the true ABS pattern in use at the macro cell changes relatively often, which would require frequent R C reconfigurations of the UE if these were kept up-to-date of the true ABS pattern. One solution to avoid increased network load due to frequent RRC signaling is to configure CSl restrictions in such a way that the true ABS pattern always guarantees stable interference conditions over two subsets of subframes. This is possible if two portions of the true ABS pattern remain invariant over time, while the rest may change dynamically. As illustrated in Table 4, there are two CSl patterns, CSI l and CSI 2, not being the complement of each other, and the network may perform adaptive TDM partitioning by dynamically changing the true ABS pattern in the subset of subframes that do not belong to either CSI l or CSI 2. In the exemplary patterns in Table 4, CSI l coincides with subframes with guaranteed (low) ABS interference and CSI 2 coincides with subframes with (high) full load non-ABS interference. Subframes marked with X can be either ABS or non-ABS at the macro depending on the true ABS pattern at a given time, and adaptive TDM partitioning is thus performed over the subset of subframes marked with X.

The 1st, 2nd and 3rd AGC tracking loop patterns may be in use simultaneously in the UE. In another embodiment, the UE may not use all the configured AGC tracking loop patterns simultaneously.

The AGC tracking loop patterns in Table 4 are identical with the AGC tracking loop patterns in Table 3.

In another embodiment of Figure 3, semi-static TDM resource partitioning is used.

Restriction pattern, in blocks of 8 subframes

Macro-Pico

1 = Measurements allowed

case

0 = Measurements disallowed True ABS

pattern at

10000000 10000000 10000000 1 10000000 10000000 macro (0=non

ABS, 1=ABS)

CSI l pattern

10000000 10000000 looooooo i looooooo 10000000 for pico UE

CSI 2 pattern

01111111 01111111 01111111 \ 01111111 01111111 for pico UE

Pattern for 1st

AGC tracking 10000000 10000000 10000000 i 10000000 10000000 loop

Pattern for 2^nd

AGC tracking 01111111 01111111 01111111 j 01111111 01111111 loop

Table 5

In this example, adaptive TDM partitioning is not used, and the true ABS pattern changes on a relatively low timescale. Reconfiguring UE upon such a change is not an issue from a network signaling perspective as this would occur rarely. In this case at the pico UE, CSI l is simply configured to coincide with ABS (i.e. low) interference subframes at the macro cell while CSI 2 contains most (or even all) of the remaining subframes. As illustrated in Table 5, CSI l and CSI 2 are the complement of each other, and the first and second AGC tracking loops directly coincide with CSI l and CSI 2 respectively due to this. Furthermore, the 1st and 2nd AGC tracking loop patterns may be in use simultaneously in the UE. In another embodiment, the UE may not use all the configured AGC tracking loop patterns simultaneously.

Tables 1 to 5 show examples of patterns for AGC tracking loops. The determination process of the patterns for AGC tracking loops makes use, for example, of one or more known measurement restriction patterns (for example, Neighbour cell RRM, Serving cell RLM/RRM, CSI l and CSI 2). Depending on the situation, the AGC tracking loop pattern may be identical with at least one of these restriction patterns or be a complement (i.e. inverse) of the at least one of these restriction patterns. The AGC tracking loop pattern determination and configuration may be performed by a UE. Alternatively, a network entity (for example, an eNodeB, a network management node or any other network entity) other than the UE determines and configures the AGC tracking loop patterns and transmits them to the UE.

Furthermore, it can be seen from Tables 1 to 5 that an AGC tracking loop pattern may relate to one or more measurement restriction patterns. In other words, an AGC tracking loop pattern may relate, for example, to at least one of neighbour cell RRM pattern, serving cell RLM/R M pattern, CSI l pattern and CSI 2 pattern. For example, in Table 2, the first AGC tracking loop is identical with the restriction pattern for serving cell RLM/RRM measurements. In another embodiment, additionally or alternatively, an AGC tracking loop pattern may relate to more than one measurement restriction pattern, for example with two measurement restriction patterns. Table 3 discloses an example where the pattern relating to the third AGC tracking loop is a complement of a logical OR combination of both CSI patterns. In other words, the third AGC tracking loop pattern is determined based on two different measurement restriction patterns (i.e. CSI l and CSI 2).

Figure 4 discloses a simplified block diagram of an exemplary apparatus that is suitable for use in practicing the exemplary embodiments of at least part of this invention. In Figure 4, the apparatus 400 may include a processor 402 (or a plurality of processors), a memory 404 coupled to the processor 402, and a suitable transceiver 406 (having a transmitter (TX) and a receiver (RX)) coupled to the processor 402 and to an antenna unit 408.

The processor 402 or some other form of generic central processing unit (CPU) or special-purpose processor such as digital signal processor (DSP), may operate to control the various components of the apparatus 400 in accordance with embedded software or firmware stored in memory 404 or stored in memory contained within the processor 402 itself. In addition to the embedded software or firmware, the processor 402 may execute other applications or application modules stored in the memory 404 or made available via wireless network communications. The application software may comprise a compiled set of machine-readable instructions that configures the processor 402 to provide the desired functionality, or the application software may be high-level software instructions to be processed by an interpreter or compiler to indirectly configure the processor 402.

The transceiver 406 is for bidirectional wireless communications with another wireless device, for example, an eNodeB. The transceiver 406 may provide for example, frequency shifting, converting received RF signals to baseband and converting baseband transmit signals to RF. In some descriptions a radio transceiver or RF transceiver may be understood to include other signal processing functionality such as modulation/demodulation, coding/decoding, and other signal processing functions. In some embodiments, the transceiver 406, portions of the antenna unit 408, and an analog baseband processing unit may be combined in one or more processing units and/or application specific integrated circuits (ASICs).

The antenna unit 408 may be provided to convert between wireless signals and electrical signals, enabling the apparatus 400 to send and receive information from a cellular network or some other available wireless communications network or from a peer wireless device. The antenna unit 508 may include antenna tuning and/or impedance matching components, RF power amplifiers, and/or low noise amplifiers.

In one embodiment, the apparatus 400 is for example, UE of a LTE network or of any other applicable wireless network.

Figure 5 is a block diagram of a receiver according to one embodiment of the invention. The receiver comprises an input from an antenna 504. The antenna 504 is connected to an amplifier (LNA) 506. The output of the LNA 506 goes to a mixer 508. The mixer 508 is also connected to a local oscillator 520. The output of the mixer 508 goes to an analog channel filter 510. The output of the analog channel filter 510 is amplified by a low-noise amplifier 512. The output from the low-noise amplifier is input to an analog-to-digital converter (ADC) 522. The output from the ADC 522 is input to a digital channel filter 516. The output from the digital channel filter 516 is input to a digital gain stage 518. Finally, the output from the digital gain stage 518 is connected to a baseband processing unit 500. The baseband processing unit 500 comprises also an AGC unit 502, which is connected to the amplifiers 506 and 512 and to the digital gain stage 518.

Figure 6 discloses a simplified block diagram of an apparatus 600 for determining a measurement pattern for at least one AGC tracking loop. The apparatus 600 comprises a processor 602 (or a plurality of processors), and a memory 604 (or memories) coupled to the processor 602. The processor 602 is configured to determine a measurement pattern for at least one AGC tracking loop when resource restrictions have been configured for a UE. The resource restrictions comprise at least one measurement restriction pattern. Each AGC tracking loop is associated with at least one measurement restriction pattern. The processor 602 is further configured to cause the measurement pattern for at least one automatic gain control tracking loop to be transmitted to the UE. The determination is made for example, based on the at least one measurement restriction pattern configured for the UE. The restriction pattern refers for example, to a neighbor cell RRM pattern, a serving cell RLM or RRM pattern, or a CSI pattern. Examples of measurement patterns for the AGC tracking loops are presented in Tables 1-5 above.

The apparatus 600, for example, may be a radio access network node or a network management node or any other network entity.

In one embodiment, the term "radio frequency gain" used in the invention covers the combined gain from an antenna to the digital output of the radio frequency stage.

Furthermore, although the invention has been described by using a FDD configuration as an example, the invention may be applied also in a Time Division Duplex (TDD) configuration.

Although the invention has been described by using the LTE radio access technology as an example, a skilled person understand that the invention is applicable in any wireless communication network where automatic gain control functionality disclosed is needed.

For example, the invention may be implemented with an AGC of user equipment as a software implementation. In another embodiment, the invention is implemented with a combination of software and hardware or with hardware only.

Embodiments of the present invention may be implemented in software, hardware, application logic or a combination of software, hardware and application logic. In an example embodiment, the application logic, software or an instruction set is maintained on any one of various conventional computer- readable media. In the context of this document, a "computer-readable medium" may be any media or means that can contain, store, communicate, propagate or transport the instructions for use by or in connection with an instruction execution system, apparatus, or device, such as a computer. A computer-readable medium may comprise a computer-readable storage medium that may be any media or means that can contain or store the instructions for use by or in connection with an instruction execution system, apparatus, or device, such as a computer.

The exemplary embodiments can store information relating to various processes described herein. This information can be stored in one or more memories, such as a hard disk, optical disk, magneto-optical disk, RAM, and the like. The processes described with respect to the exemplary embodiments can include appropriate data structures for storing data collected and/or generated by the processes of the devices and subsystems of the exemplary embodiments in one or more databases.

As stated above, the components of the exemplary embodiments can include computer readable medium or memories for holding data structures, tables, records, and/or other data described herein. A computer readable medium can include any suitable medium that participates in providing instructions to a processor for execution. Such a medium can take many forms, including but not limited to, non-volatile media, volatile media, transmission media, and the like. Non-volatile media can include, for example, optical or magnetic disks, magneto- optical disks, and the like. Volatile media can include dynamic memories, and the like. Transmission media can include coaxial cables, copper wire, fiber optics, and the like. Transmission media also can take the form of acoustic, optical, electromagnetic waves, and the like, such as those generated during radio frequency (RF) communications, infrared (IR) data communications, and the like. Common forms of computer-readable media can include, for example, a floppy disk, a flexible disk, hard disk, magnetic tape, any other suitable magnetic medium, a CD-ROM, CDRW, DVD, any other suitable optical medium, punch cards, paper tape, optical mark sheets, any other suitable physical medium with patterns of holes or other optically recognizable indicia, a RAM, a PROM, an EPROM, a FLASH-EPROM, any other suitable memory chip or cartridge, a carrier wave or any other suitable medium from which a computer can read.

Although various aspects of the invention are set out in the independent claims, other aspects of the invention comprise other combinations of features from the described embodiments and/or the dependent claims with the features of the independent claims, and not solely the combinations explicitly set out in the claims. The embodiments of the invention described hereinbefore in association with the figures presented may be used in any combination with each other. Several of the embodiments may be combined together to form a further embodiment of the invention.

It is also noted herein that while the above describes example embodiments of the invention, these descriptions should not be viewed in a limiting sense. Rather, there are several variations and modifications which may be made without departing from the scope of the present invention as defined in the appended claims.

Claims

1. A method of performing automatic gain control measurements, comprising:

determining a measurement pattern for at least one automatic gain control tracking loop according to resource restrictions that are applied to a user equipment, the resource restrictions comprising at least one measurement restriction pattern; and

performing automatic gain control measurements according to the measurement patterns of the at least one automatic gain control tracking loop.

2. The method according to claim 1, wherein determining a measurement pattern for at least one automatic gain control tracking loop comprises:

determining the measurement pattern for the at least one automatic gain control tracking loop based on the at least one measurement restriction pattern.

3. The method according to claim 1 or claim 2, wherein determining a measurement pattern for at least one automatic gain control tracking loop comprises:

receiving the measurement pattern for the at least one automatic gain control tracking loop from a base station.

4. The method according to any of claims 1 to 3, wherein a measurement pattern of an automatic gain control tracking loop is identical with at least one of a measurement restriction pattern relating to serving cell radio link monitoring/radio resource management measurements and a measurement restriction pattern relating to neighbor cell radio resource management measurements.

5. The method according to any of claims 1 to 3, wherein:

a measurement pattern of a first automatic gain control tracking loop is identical with a measurement restriction pattern relating to serving cell radio link monitoring/radio resource management measurements; and

a measurement pattern of a second automatic gain control tracking loop is complementary to the measurement restriction pattern relating to serving cell radio link monitoring/radio resource management measurements or identical with a measurement restriction pattern relating to neighbor cell radio resource management measurements.

6. The method according to any of claims 1 to 3, wherein:

a measurement pattern of a first automatic gain control tracking loop is identical with a measurement restriction pattern relating to first channel state information measurements; and

a measurement pattern of a second automatic gain control tracking loop is identical with a measurement restriction pattern relating to second channel state information measurements.

7. The method according to claim 6, wherein a measurement pattern of a third automatic gain control tracking loop is a complement of a logical OR combination of the measurement restriction pattern relating to first channel state information measurements and the measurement restriction pattern relating to second channel state information measurements..

8. The method according to any of claims 1 to 7, wherein the resource restrictions relate to enhanced inter-cell interference coordination functionality in a Long Term Evolution radio access network.

9. An apparatus for performing automatic gain control measurements, the apparatus comprising:

means for determining a measurement pattern for at least one automatic gain control tracking loop according to resource restrictions that are applied to a user equipment, the resource restrictions comprising at least one measurement restriction pattern; and

means arranged to perform automatic gain control measurements according to the measurement patterns of the at least one automatic gain control tracking loop.

10. The apparatus according to claim 9, wherein in the determining the at least one processor is configured to cause the apparatus to determine the measurement pattern for the at least one automatic gain control tracking loop based on the at least one measurement restriction pattern.

11. The apparatus according to claim 9 or claim 10, wherein in the determining the at least one processor is configured to cause the apparatus receive the measurement pattern for the at least one automatic gain control tracking loop from a base station.

12. The apparatus according to any of claims 9 to 11, wherein a measurement pattern of an automatic gain control tracking loop is identical with at least one of a measurement restriction pattern relating to serving cell radio link monitoring/radio resource management measurements and a measurement restriction pattern relating to neighbor cell radio resource management measurements .

13. The apparatus according to any of claims 9 to 11, wherein: a measurement pattern of a first automatic gain control tracking loop is identical with a measurement restriction pattern relating to serving cell radio link monitoring/radio resource management measurements; and

14. The apparatus according to any of claims 9 to 11, wherein: a measurement pattern of a first automatic gain control tracking loop is identical with a measurement restriction pattern relating to first channel state information measurements; and

15. The apparatus according to claim 13, wherein a measurement pattern of a third automatic gain control tracking loop is a complement of a logical OR combination of the measurement restriction pattern relating to first channel state information measurements and the measurement restriction pattern relating to second channel state information measurements.

16. The apparatus according to any of claims 9 to 15, wherein the apparatus comprises user equipment.

17. The apparatus according to any of claims 9 to 16, wherein the resource restrictions relate to enhanced inter-cell interference coordination functionality in a Long Term Evolution radio access network

18. A computer-readable medium carrying a computer program comprising computer program code, which, when executed by a processor, performs a process according to the method of any one of claims 1 to 8.

19. A method comprising determining a measurement pattern for at least one automatic gain control tracking loop according to resource restrictions that are applied to a user equipment, the resource restrictions comprising at least one measurement restriction pattern; and causing the measurement pattern for at least one automatic gain control tracking loop to be transmitted to the user equipment.

20. An apparatus comprising means for determining a measurement pattern for at least one automatic gain control tracking loop according to resource restrictions that are applied to a user equipment, the resource restrictions comprising at least one measurement restriction pattern; and means for causing the measurement pattern for at least one automatic gain control tracking loop to be transmitted to the user equipment.