WO2015082554A1

WO2015082554A1 - Method and apparatus

Info

Publication number: WO2015082554A1
Application number: PCT/EP2014/076440
Authority: WO
Inventors: Mihai Enescu; Timo Erkki Lunttila; Karri Markus Ranta-Aho
Original assignee: Nokia Solutions And Networks Oy
Priority date: 2013-12-03
Filing date: 2014-12-03
Publication date: 2015-06-11
Also published as: GB201321321D0; GB2520944A

Abstract

A method comprises receiving in a user equipment from at least one cell, at least one group of network assistance information, the or each group comprising a subset of network assistance information and using said at least one group of assistance information to reduce interference from at least one interfering cell.

Description

DESCRIPTION

TITLE METHOD AND APPARATUS

Some embodiments relate to a method and apparatus and in particular but not exclusively to methods and apparatus which use network assisted interference cancellation and/or suppression.

A communication system can be seen as a facility that enables communication sessions between two or more nodes such as fixed or mobile communication devices, access points such as base stations, servers, machine type servers, routers, and so on. A communication system and compatible communicating devices typically operate in accordance with a given standard or specification which sets out what the various entities associated with the system are permitted to do and how that should be achieved. For example, the standards, specifications and related protocols can define the manner how communication devices shall communicate with the access points, how various aspects of the communications shall be implemented and how the devices and functionalities thereof shall be configured.

A user can access the communication system by means of an appropriate communication device. A communication device of a user is often referred to as user equipment (UE) or terminal.

Signals can be carried on wired or wireless carriers. Examples of wireless systems include public land mobile networks (PLMN), satellite based communication systems and different wireless local networks, for example wireless local area networks (WLAN). Wireless systems can be divided into coverage areas referred to as cells, such systems being often referred to as cellular systems. A cell can be provided by a base station, there being various different types of base stations. Different types of cells can provide different features. For example, cells can have different shapes, sizes, functionalities and other characteristics.

A communication device is provided with an appropriate signal receiving and transmitting arrangement for enabling communications with other parties. In wireless systems a communication device provides a transceiver station that can communicate with another communication device such as e.g. a base station and/or another user equipment. A communication device such as a user equipment (UE) may access a carrier provided by a base station, and transmit and/or receive on the carrier.

An example of cellular communication systems is an architecture that is being standardized by the 3rd Generation Partnership Project (3GPP). One development in this field is referred to as t e long-term evolution (LTE) of the Universal Mobile Telecommunications System (UMTS) radio-access technology. In LTE base stations providing the cells are commonly referred to as enhanced NodeBs (eNB). An eNB can provide coverage for an entire cell or similar radio service area.

Network assisted interference cancellation and suppression (NAICS) has been proposed for the third generation partnership project (3GPP). Techniques developed under NAICS target interference suppression and interference cancellation (ISIC) at a user equipment (UE).

According to an aspect, there is provided a method comprising: receiving in a user equipment from at least one cell, at least one group of network assistance information, the or each group comprising a subset of network assistance information; and using said at least one group of assistance information to reduce interference from at least one interfering cell.

The method may comprise providing information indicating which one or more of a plurality of groups of network assistance information are supported by said user equipment.

The method may comprise providing said information to a serving cell with which said user equipment is associated.

The method may comprise receiving decoding information for decoding said received group of network assistance.

The method may comprise receiving said at least one group of network assistance information via at least one downlink control channel.

The method may comprise receiving said at least one group of network assistance information from at least one of a serving cell and said at least one interfering cell.

The method may be performed by an apparatus. The apparatus may be provided in a user equipment.

According to another aspect, there is provided a method comprising: causing transmission to a user equipment, of at least one group of network assistance information, the or each group comprising a subset of network assistance information for use by the user equipment to reduce interference from at least one interfering cell.

The method may comprise receiving a request from a serving cell requesting the transmitting of said at least one group of network assistance information.

The method may comprise receiving user equipment information indicating which one or more groups of network assistance information are supported by said user equipment,

The method may comprise receiving said user equipment information from a serving cell of said user equipment.

The method may comprise determining which one or more groups of network assistance information are to be transmitted to said user equipment in dependence on one or more of said user equipment information and characteristics of said at least one interfering cell.

The causing may comprise causing said at least one group of network assistance information to be signalled to said user equipment.

The method may comprise providing decoding information for decoding at least one group of network assistance information

The method may comprise providing said decoding information to a serving cell of said user equipment.

The method may be performed by an apparatus. The apparatus may be provided in a base station.

According to an aspect, there is provided a method comprising: receiving user equipment information indicating which one or more groups of network assistance information are supported by said user equipment, the or each group comprising a subset of network assistance information for use by the user equipment to reduce interference from at least one interfering cell.

The method may comprise causing said user equipment information or information dependent on said user equipment information to be provided to said at least one interfering cell.

The method may comprise receiving decoding information for decoding at least one group of network assistance information.

The method may comprise causing the transmitting of decoding information for decoding at least one group of network assistance information, to said user equipment.

The method may be performed by an apparatus. The apparatus may be provided in a base station or a controller.

One or more of the following features may be used with any one or more of the above aspects.

At least one group of network assistance may be dependent on a category or capability of said user equipment.

The at least one group of network assistance may be dependent on a type of receiver used by said user equipment.

At least one group of network assistance may be dependent on characteristics of at least one interfering cell

The characteristics of said at least one interfering cell may comprise one or more of: transmission characteristics; transmission mode; transmission scheme; information about the relative transmission power of the data compared to reference signals; precoding matrix indicator; rank; and resource allocation. A plurality of groups of network assistance information may be usable by said user equipment.

The decoding information may comprise a temporary identifier associated with at least one group of network assistance information.

A different temporary identifier may be associated with each group of network assistance information.

A temporary identifier may be associated with a plurality of groups of network assistance information.

The decoding information may comprise identity information associated with an interfering cell.

According to another aspect, there is provided an apparatus in a user equipment comprising at least one processor and at least one memory including computer code for one or more programs, the at least one memory and the computer code configured, with the at least one processor, to cause the apparatus at least to: receive from at least one cell, at least one group of network assistance information, the or each group comprising a subset of network assistance information; and use said at least one group of assistance information to reduce interference from at least one interfering cell.

The at least one memory and the computer code may be configured, with the at least one processor, to cause the apparatus to provide information indicating which one or more of a plurality of groups of network assistance information are supported by said user equipment.

The at least one memory and the computer code may be configured, with the at least one processor, to cause the apparatus to provide said information to a serving cell with which said user equipment is associated.

The at least one memory and the computer code may be configured, with the at least one processor, to cause the apparatus to receive decoding information for decoding said received group of network assistance.

The at least one memory and the computer code may be configured, with the at least one processor, to cause the apparatus to receive said at least one group of network assistance information via at least one downlink control channel.

The at least one memory and the computer code may be configured, with the at least one processor, to cause the apparatus to receive said at least one group of network assistance information from at least one of a serving cell and said at least one interfering cell.

The apparatus may be provided in a user equipment.

According to another aspect, there is provided an apparatus comprising at least one processor and at least one memory including computer code for one or more programs, the at least one memory and the computer code configured, with the at least one processor, to cause the apparatus at least to: cause transmission to a user equipment, of at least one group of network assistance information, the or each group comprising a subset of network assistance information for use by the user equipment to reduce interference from at least one interfering cell.

The at least one memory and the computer code may be configured, with the at least one processor, to cause the apparatus to receive a request from a serving cell requesting the transmitting of said at least one group of network assistance information.

The at least one memory and the computer code may be configured, with the at least one processor, to cause the apparatus to receive user equipment information indicating which one or more groups of network assistance information are supported by said user equipment,

The at least one memory and the computer code may be configured, with the at least one processor, to cause the apparatus to receive said user equipment information from a serving cell of said user equipment.

The at least one memory and the computer code may be configured, with the at least one processor, to cause the apparatus to determine which one or more groups of network assistance information are to be transmitted to said user equipment in dependence on one or more of said user equipment information and characteristics of said at least one interfering cell.

The at least one memory and the computer code may be configured, with the at least one processor, to cause the apparatus to cause said at least one group of network assistance information to be signalled to said user equipment.

The at least one memory and the computer code may be configured, with the at least one processor, to cause the apparatus to provide decoding information for decoding at least one group of network assistance information

The at least one memory and the computer code may be configured, with the at least one processor, to cause the apparatus to provide said decoding information to a serving cell of said user equipment.

The apparatus may be provided in a base station.

According to another aspect, there is provided an apparatus comprising at least one processor and at least one memory including computer code for one or more programs, the at least one memory and the computer code configured, with the at least one processor, to cause the apparatus at least to: receive user equipment information indicating which one or more groups of network assistance information are supported by said user equipment, the or each group comprising a subset of network assistance information for use by the user equipment to reduce interference from at least one interfering cell. The at least one memory and the computer code may be configured, with the at least one processor, to cause the apparatus to cause said user equipment information or information dependent on said user equipment information to be provided to said at least one interfering cell.

The at least one memory and the computer code may be configured, with the at least one processor, to cause the apparatus to receive decoding information for decoding at least one group of network assistance information.

The at least one memory and the computer code may be configured, with the at least one processor, to cause the apparatus to cause the transmitting of decoding information for decoding at least one group of network assistance information, to said user equipment.

The apparatus may be provided in a base station or a controller.

The characteristics of said at least one interfering cell may comprise one or more of: transmission characteristics; transmission mode; transmission scheme; information about the relative transmission power of the data compared to reference signals; precoding matrix indicator; rank; and resource allocation.

A plurality of groups of network assistance information may be usable by said user equipment.

According to another aspect, there is provided an apparatus in a user equipment comprising: means for receiving from at least one cell, at least one group of network assistance information, the or each group comprising a subset of network assistance information; and means for using said at least one group of assistance information to reduce interference from at least one interfering cell.

The apparatus may comprise means for providing information indicating which one or more of a plurality of groups of network assistance information are supported by said user equipment.

The providing means may be for providing said information to a serving cell with which said user equipment is associated.

The receiving means may be for receiving decoding information for decoding said received group of network assistance.

The receiving means may be for receiving said at least one group of network assistance information via at least one downlink control channel.

The receiving means may be for receiving said at least one group of network assistance information from at least one of a serving cell and said at least one interfering cell.

A user equipment may comprise the apparatus.

According to another aspect, there is provided an apparatus comprising: means for causing transmission to a user equipment, of at least one group of network assistance information, the or each group comprising a subset of network assistance information for use by the user equipment to reduce interference from at least one interfering cell.

The apparatus may comprise means for receiving a request from a serving cell requesting the transmitting of said at least one group of network assistance information.

The receiving means may be for receiving user equipment information indicating which one or more groups of network assistance information are supported by said user equipment,

The receiving means may be for receiving said user equipment information from a serving cell of said user equipment.

The apparatus may comprise means for determining which one or more groups of network assistance information are to be transmitted to said user equipment in dependence on one or more of said user equipment information and characteristics of said at least one interfering cell.

The means for causing the transmitting may be for causing said at least one group of network assistance information to be signalled to said user equipment.

The apparatus may comprise providing decoding information for decoding at least one group of network assistance information

The providing means may provide said decoding information to a serving cell of said user equipment.

A base station may comprise the apparatus. According to an aspect, there is provided an apparatus comprising: means for receiving user equipment information indicating which one or more groups of network assistance information are supported by said user equipment, the or each group comprising a subset of network assistance information for use by the user equipment to reduce interference from at least one interfering cell.

The apparatus may comprise means for causing said user equipment information or information dependent on said user equipment information to be provided to said at least one interfering cell.

The apparatus may comprise means for receiving decoding information for decoding at least one group of network assistance information.

The apparatus may comprise means for causing the transmitting of decoding information for decoding at least one group of network assistance information, to said user equipment.

A base station or a controller may comprise the apparatus.

The decoding information may comprise identity information associated with an interfering cell. A computer program comprising program code means adapted to perform t e method(s) may also be provided. The computer program may be stored and/or otherwise embodied by means of a carrier medium.

In the above, many different embodiments have been described. It should be appreciated that further embodiments may be provided by the combination of any two or more of the embodiments described above.

Various other aspects and further embodiments are also described in the following detailed description and in the attached claims.

Some embodiments will now be described, by way of example only, with respect to the following Figures in which:

Figure 1 schematically shows part of an LTE network;

Figure 2 schematically shows part of an UMTS network;

Figure 3 shows a schematic diagram of a mobile communication device according to some embodiments;

Figure 4 shows a schematic diagram of a control apparatus according to some embodiments;

Figure 5 schematically shows the signalling of aggressor information over the interface between base stations and to a victim user equipment UE;

Figure 6 schematically shows the signalling of aggressor information; Figure 7 schematically shows a NAICS signalling procedure in LTE;

Figure 8 schematically shows NAICS signal procedure in UMTS; and

Figure 9 shows schematically one embodiment in which groups are provided in dependence on user equipment capability and transmission characteristics.

In the following certain exemplifying embodiments are explained with reference to a wireless or mobile communication system serving mobile communication devices. Before explaining in detail the exemplifying embodiments, certain general principles of a wireless communication system and nodes thereof and mobile communication devices are briefly explained with reference to Figures 1 to 4 to assist in understanding the context of the described examples.

A non-limiting example of the recent developments in communication system architectures is the long-term evolution (LTE) of the universal mobile telecommunications system (UMTS) that is being standardized by the 3rd Generation Partnership Project (3GPP). The LTE employs a mobile architecture known as the evolved universal terrestrial radio access network (E-UTRAN). Base stations of such systems are known as evolved or enhanced Node Bs (eNBs) and may provide E-UTRAN features such as user plane radio link control/medium access control/physical layer protocol (RLC/MAC/PHY) and control plane radio resource control (RRC) protocol terminations towards t e communication devices.

Figure 1 shows an example of an LTE network architecture. Three eNBs 2, 4 and 6 are shown. The eNBs may be coupled to one or more other eNBs via an X2 connection. The eNBs provide the E-UTRAN. The RRC layer controlling the UE radio resources resides in the eNB, and each eNB has a direct connection to the core network over the S1 interface. The eNBs are configured to communicate with one or more MME/S-GW (mobility management entity/serving gateway) entities 10 of the core network via the S1 interface.

HSPA (high speed packet access) is a protocol that has been proposed to provide higher performance in UMTS. Reference is made to Figure 2 which shows an example of an UMTS network architecture which may support HSPA. The RRC layer controlling the UE radio resources resides in a RNC (radio network controller) 12. The RNC 12 controls each Node B 4 connected to it via a respective lub interface. In this example two RNCs are shown. In some embodiments, there may be many more RNCs. Each RNC is shown as being coupled to three Node Bs 4. This is by way of example only and RNCs may be coupled to more or less than three Node Bs. The Node Bs 4 connect to the core network through a respective RNC, which is coupled to the core network 14 directly via an lu interface. One RNC may be coupled to one or more other RNCs via an lur interface. The UTRAN (universal terrestrial radio access network) is made up by the RNCs and the Node Bs. Each RNC and the associated Node Bs comprise a RNS (radio network subsystem).

A possible mobile communication device for transmitting to and receiving from a plurality of base stations (e.g. Node B or eNB) will now be described in more detail with reference to Figure 3 showing a schematic, partially sectioned view of a mobile communication device 200. Such a device is often referred to as user equipment (UE) or terminal. An appropriate mobile communication device may be provided by any device capable of sending radio signals to and/or receiving radio signals from multiple cells. Non- limiting examples include a mobile station (MS) such as a mobile phone or what is known as a 'smart phone', a portable computer provided with a wireless interface card, and USB stick or 'dongle' with radio, or other wireless interface facility, personal data assistant (PDA) provided with wireless communication capabilities, or any combinations of these or the like. A mobile communication device may provide, for example, communication of data for carrying communications such as voice, electronic mail (email), text message, multimedia and so on.

The mobile device may receive and transmit signals over an air interface 207 with multiple base stations via an appropriate transceiver apparatus. In Figure 3 transceiver apparatus is designated schematically by block 206. The transceiver apparatus 206 may be provided for example by means of a radio part and associated antenna arrangement. The radio part is arranged to communicate simultaneously with different stations. The radio part may also be arranged to communicate via different radio technologies. For example, the radio part can provide a plurality of different radios. The antenna arrangement may be arranged internally or externally to the mobile device.

A mobile communication device is also provided with at least one data processing entity 201 , at least one memory 202 and other possible components 203 for use in software and hardware aided execution of tasks it is designed to perform, including control of access to and communications with access systems and other communication devices. The data processing, storage and other relevant control apparatus can be provided on an appropriate circuit board and/or in chipsets. This feature is denoted by reference 204.

The user may control the operation of the mobile device by means of a suitable user interface such as key pad 205, voice commands, touch sensitive screen or pad, combinations thereof or the like. A display 208, a speaker and a microphone can also be provided. Furthermore, a mobile communication device may comprise appropriate connectors (either wired or wireless) to other devices and/or for connecting external accessories, for example hands-free equipment, thereto.

Figure 4 shows an example of a control apparatus 300. This control apparatus may be provided in one or more of the RNC, Node B and eNB. The control apparatus comprises at least one memory 301 , at least one data processing unit 302, 303 and an input/output interface 304. The control apparatus is implemented at least partially in circuitry. For example the memory may be provided by memory circuitry. The data processing unit may be provided by processing circuitry. Via the interface the control apparatus can be coupled to a receiver and/or transmitter of the RNC, Node b and eNB. The control apparatus can be configured to execute an appropriate software code to provide the control functions. These control functions will be described in more detail hereinafter.

Some embodiments relate to NAICS. This may be part of LTE and/or HSPA. In HSPA, reference is made to NAIC (network assistance interference cancellation) whilst LTE refers to NAICS. This document will refer to NAICS and this is intended to cover both NAICS and NAIC.

Some embodiments may relate to the way in which advanced receivers can be operated in LTE and/or HSPA systems.

A NAICS receiver may enhance the interference cancellation (IC)/interference suppression (IS) capability of the UEs by providing more support from the network side. For example using network coordination, favorable interference conditions can be created for the UE so that IC/IS may be achieved, compensating for the losses coming from the network coordination constraints. Some scheduling flexibility may be lost. Another mechanism for facilitating UE IC/IS is by network signaling where information regarding the structure of an aggressor interferer is signaled to the victim UE for the purpose of IC/IS. Some parameters characterizing the interference may be obtained by blind estimation at the UE. However this may require increased UE complexity.

In the following, the "victim cell" may be the serving cell of the UE of interest.

Moreover, the UE of interest may also be referred to as the "victim UE." The "interference cell" can be the cell transmitting signal(s) which interferes with the UE of interest. The term "interference UE" can refer to a UE being served by an interference cell and whose downlink data traffic may be interfering with the victim user equipment.

In general, interference may be created by the data traffic of the UEs as well as common signals and channels transmitted in a cell. Hence there may be multiple interference forms: inter-stream interference due to the non-orthogonality of spatial MIMO (multiple input multiple output) streams dedicated to the same UE (the so called SU-MIMO (single user MIMO) interference), inter-user interference which can arise between users served in the same cell, for example sharing the same resources (the so called MU-MIMO (multi user MIMO) interference). Interference may occur between UEs located in different cells - inter-cell interference. UEs located at the cell edge may suffer in particular from inter- cell interference. Canceling this form of interference may improve the cell capacity and/or coverage. On the other hand, sending the information characterizing the aggressor interference structure to the victim becomes non-trivial as the aggressor may be located in one cell while the victim is located in a neighbor cell. This situation may happen in both homogeneous and heterogeneous network deployments.

Backhaul information may be also available. In some embodiments the eNBs serving the aggressor and victim UEs are connected e.g. through an X2 interface.

When considering network assistance, aggressor interference information can be transmitted to the victim UE, for the purpose of IC/IS, by several means.

Reference is made to Figure 5 which shows three eNBs 2, 4 and 6 along with their associated cells 20, 22 and 24 respectively. The three cells, in this example, partially overlap and an interfering UE 9 and a victim UE 8 are both provided in a region of overlap. However the interfering UE 9 is associated with interfering or aggressor eNB 4 whilst the victim UE 8 is associated with the serving cell 2. The aggressor (i.e. interfering) eNB 4 can send the interference characteristics of the aggressor UE(s) over the X2 interface to the serving eNB 2 of the victim UE 8 and the serving eNB can further signal to the victim UE the interference characteristics. This is illustrated in Figure 5 where the aggressor UE characteristics are part of PDCCH_i (physical downlink control channel) message. This may expose the interference parameterization of the aggressor UEs to delays inherent in X2 signaling, which may affect the IC/IS efficiency. For example information such as CSI (channel state information) feedback (in the form of PMI/RI (precoding matrix indicator/rank indicator) is typically short term information and may be sensitive to backhaul delay.

Reference is made to Figure 6 which show the same arrangement of eNBs and UEs as in Figure 5. In this example, the aggressor/interfering eNB 4 can send the interference characteristics of the aggressor UE 9 directly to the victim UE 8. This avoids sending the interference characteristics information via the X2 interface to the serving eNB 2, hence avoiding the delays of X2 interface. However, the victim UE has to have the capability to decode such interference information. This is illustrated in Figure 6, where the aggressor UE interference characteristics are part of PDCCHM message that is sent directly from interfering eNB 4 to the victim UE 8.

Creating a direct communication link between the victim UE 8 and the aggressor eNB 4 would consume resources from the aggressor eNB. It may be desirable for the aggressor eNB 4 to be aware of the IC/IS capability of the UEs in the victim eNB so that such resource consumption is beneficial. The interference information carried over the (E)PDCCHM may need to be such that excessive UE complexity can be avoided (due to (E)PDCCHM detection) and/or such that the PDCCH (physical downlink control channel) overhead is not excessive.

In another proposal, the victim UE needs to cancel the aggressor PDSCH (physical downlink shared channel), which in practice is accompanied by an aggressor PDCCH. Thus the signaling information characterizing the aggressor PDSCH may be already available. However the victim UE needs to get access to such information. The CRC (cyclic redundancy check) of the aggressor PDCCH is scrambled by the aggressor UE specific C_RNTI (cell_radio network temporary identifier), hence getting access to aggressor PDCCH would mean knowing the aggressor UE ID. Such signaling of the aggressor UE ID would need to be dynamic, in order to match the dynamic nature of the PDSCH interference. This approach may require the aggressor eNB signaling dynamically the UE ID of the interferers to the victim UE so that the victim UE can perform decoding of the aggressor's PDCCH and further cancel the aggressor PDSCH. A NAICS DCI (downlink control information) may be signaled from the aggressor cell and contain aggressor C_RNTIs. The victim UE would need to: 1 . Decode the NAICS DCI coming from the aggressor cell and get access to the C_RNTIs and 2. Further decode the PDCCHs indicated by the corresponding C_RNTIs. The victim UE may need to be complex to do this processing.

Some suggested addressing signaling options for NAICS will now be described. Signaling interference parameters from aggressor eNB - In this example interfering cells signal network assistance information and schedule the interfering UEs in the same subframe, thereby avoiding advanced scheduling and dynamic coordination between the interfering and victim cells. The victim cell may reserve blanked resources so that the interfering cell could signal network assistance information info in these reserved resources. This may facilitate the victim UE decoding the interfering cell NAI.

It has been suggested to provide new NAICS specific signaling, for example a new DCI. For example, network assistance from an aggressor cell is provided. Signaling of the RB (resource block) allocations of a subframe may be provided and for each RB or a group of RBs (depending on allocation type) the physical layer transmission parameters are provided.

A NAICS RNTI has been suggested.

Blind decoding of the interfering cell PDCCH may be used as a method to acquire interfering cell PDSCH transmission information. Some parameters may be estimated blind and others may be semi-statically signaled such as reduced set of data to CRS ERPE (cell specific reference signal energy per resource element) ratios in order to facilitate reduced complexity blind estimation.

The scenarios discussed above may require a relatively high load of interfering information to be signaled. Traffic from one cell may create interference which needs to be canceled in a different cell. In some embodiments, not all the scheduling information conveyed via PDCCH characterizing this interference need be signaled to the victim UEs. As will be discussed in more detail, some embodiments provide a plurality of groups. Each group may comprise a subset of the required information. These groups may be predefined so that there are N groups. This may grouping may facilitate more efficient signaling. This is referred to as NAICS assistance information grouping (N-AIG).

The table below summarizes the interference information for different NAICS receivers.

NAICS may be related to interference rejection type receivers which include LMMSE-I RC (Linear MMSE-IRC), E-LMMSE-IRC (Enhanced Linear MMSE-I RC), and W-LMMSE-I RC (Widely Linear MMSE-IRC). In another example, NAICS may be related to maximum likelihood type receivers which include ML (Maximum likelihood receiver), R-ML (Reduced complexity maximum likelihood receiver), and Iterative (R)-ML (Iterative maximum likelihood receiver or Iterative reduced complexity maximum likelihood receiver). For further example, NAICS may be related to interference cancellation type receivers which include L-CWIC (Linear Code word interference cancellation receiver), ML-CWIC (Maximum likelihood Code word interference cancellation receiver), and SLIC (Symbol level interference cancellation type receiver).

Table 1 summarizes information which can be used NAICS for E-LMMSE-IRC, R- ML/SLIC and L-CWIC receivers by way of example only. Interference information E-LMMSE- R-ML/SLIC L-CWIC

IRC

Information MBSFN configuration

for Cell ID/Virtual cell ID

interference Transmission Mode^*

channel PDSCH allocation

estimation Data to RS EPRE, PB

System bandwidth

(CRS-based TM only)

Data to RS EPRE, PA

(CRS-based only)

Number of CRS APs can be used

can be used

(CRS-based TM only)

PMI (TM4 and TM6)

(CRS-based TM only)

Rank (TM3 and TM4)

(CRS-based TM only) can be used nSCID

(DMRS-based TM only)

DMRS APs

(DMRS-based TM only)

Information Modulation type

for CFI

interference MCS

PDSCH nRNTI

demodulati RV

Not needed

on ZP CSI-RS resource Not needed

Number of CRS APs

(DMRS-based TM only)

NZP CSI-RS resource

(DMRS-based TM only)

Where the abbreviations used in the table are:

MBSFN Multicast broadcast single frequency network configuration;

RS EPRE - reference signal energy per resource element

PA/PB - parameters used in the definition of RS EPRE. These may be power offsets. CRS -cell specific reference signal

TM - transmission mode

AP - antenna port

nSCID (scrambling identity)

DMRS-demodulation reference signals

CFI -control format indicator

MCS - modulation and coding scheme

RV - redundancy version

ZP CSI-RS - zero power CSI-RS

NZP CSI-RS- non zero power CSI-RS

Some embodiments may provide NAICS Assistance Information Groups (N-AIGs) to assist the UE in for example cancelling and/or suppressing interference from other cells.

Some embodiments may relate to the signaling procedures.

An N-AIG may be a set of assistance information, which may benefit the NAICS operation in a given scenario. The grouping of N-AIGs may be based on any one or more suitable parameters. By way of example only, the one or more suitable parameters may comprise:

the UE receiver type- different types of advanced receivers may make use of different assistance information.

one or more of the aggressor cell's transmission characteristics - for example transmission mode, transmission scheme, rank, resource allocation, or the like.

A NAICS capable UE may support one or more N-AIGs. Such a UE may be able to indicate its capability to the network (serving cell) to help network in deciding which N-AIGs to transmit.

Each group will have a subset of the information which can be used in NAICS. Some information may be provided in no groups and/or some information in only one group and/or some information may be provided in two or more groups. In some embodiments, each group will be unique.

Reference is made to Figure 9. In Figure 9, six different N-AIGs are shown. It should be appreciated that this is by way of example only and in other embodiments, more or less than six different N-AIGs may be provided.

The N-AIGs may be divided into, for example, two categories based on for example transmission mode or transmission scheme.

It should be appreciated that other embodiments may have more than two categories. The categories may have the same or a different number of groups. Each category may have one or more group. It should be appreciated that some embodiments may use any other suitable parameter to define the two or more categories.

It should be appreciated that in some embodiments, different categories may be associated with different parameters. For example in some embodiments, one or more categories may be based on one parameter and one or more other categories may be based on another parameter.

It should be appreciated that the one or more parameters may be any one or more of the above mentioned parameters.

In the embodiment of Figure 9, one category is a CRS based transmission mode/scheme and the other category is a DMRS based transmission mode/scheme. In this example, there are three groups in each category.

In the example shown in Figure 9, all six groups may be used by ELMMSE-IRC receivers, the SLIC receivers may only benefit from four of the groups and CW-IC may only support two groups. This indicates if a particular AIG is one from which the UE may benefit from, in some embodiments. This may be dependent on the receiver type. In some embodiments, there may be a mapping such as shown in Figure 9 between the UE's capabilities and the AIGs.

It should be appreciated that the types of UE receiver are by way of example only and any other suitable receiver may alternatively or additionally be used.

It should be appreciated that in some embodiments, there may only be one type of receiver or there may be more than one type of receiver.

In embodiments, one or more of the groups are used instead of a full set of information. This means that the amount of signaling may be reduced. Additionally as there are defined groups, signaling of which groups are required and/or are being provided may be reduced.

Other examples of categorization are information for interference channel estimation and information for interference PDSCH demodulation; information enabling symbol based receivers and information enabling interference decoding based receivers; and UE specific C_RNTI information grouped according to predefined criteria. One or more of the above options may be used in some embodiments. Other grouping of information may be alternatively or additionally used.

One example of signaling is shown in Figure 7.

In step S1 , a NAICS capable UE 8 indicates to its serving cell 2 which N-AIGs it supports. In the context of the example of Figure 9, the UE would indicate which of the six groups it supports. This may be dependent on the capabilities of the UE.

In step S2, the serving (victim) cell 2 sends, e.g. over X2 interface, to the interfering (aggressor) cell 4, the list of N-AIGs (assistance information groups) from which the victim UEs 8 in the serving cell 2 would benefit. Different assistance information may be utilized by different receiver architectures. Hence a particular UE may know what type of N-AIGs it requires.

In step S3, the interfering cell (eNodeB) 4 sends an acknowledgement of N-AIG activation to the serving cell 2. This may indicate which, if any of the N-AIGs, it shall transmit. It should be appreciated that the interfering cell may transmit all of the requested N- AIGs, some of the requested N-AIGs or none of the request N-AIGS. The interfering cell may alternatively or additionally select a non- requested N-AIG for transmission.

As a part of this message, the eNB 4 may alternatively or additionally indicate a specific RNTI(s) (referred to as a NAICS-RNTI). In some embodiments, the NAICS-RNTI may be predetermined.

In some embodiments, there may be a separate NAICS-RNTI for each N-AIG. Alternatively or additionally, a NAICS-RNTI may correspond to multiple N-AIGs.

In some embodiments, the serving cell 2 may signal the NAICS-RNTI to the NAICS- capable UEs in the cell, in step S4.

In some embodiments, the interfering cell 4 and the serving cell 2 may reside or be in the same eNB, and in this case the inter-eNB signaling is not needed. The procedure over the air may be the same, with interfering and serving cells signaling as shown in Figure 7.

The interfering eNB 4 may in step S6, start transmitting assistance (control) information corresponding to the requested one or more N-AIGs and/or one or more N-AIGs which the eNB may alternatively determine should be transmitted.

Alternatively or additionally the serving eNB may send interfering control information according to the N-AIG format in step S5.

In some embodiments two or more interfering eNBs may transmit N-AIGs at the same time or at different times. A NAICS UE may monitor N-AIGs from two or more cells, in some embodiments.

The following focuses on the UE to eNB process of some embodiments. The UE may inform an eNodeB of the NAICS assistance information groups (N-AIGs) that are supported by the UE and/or which the UE wants to be enabled by the network. The eNodeB may be an interfering or serving cell / eNodeB.

The UE may receive from an acknowledgement, indicating which N-AIGs are activated in aggressor cell(s), from the serving cell.

The serving cell may indicate the NAICS-RNTIs of the aggressor cell(s) to the NAICS capable UEs. The serving cell may alternatively or additionally indicate the specifics of the enabled N-AIGs which are represented as DCI formats.

The UE may receive the NAICS assistance signaling from the aggressor cell in form of

NAICS DCI. The signaling information may be grouped into one or more DCIs, hence representing one or more AIGs. The following focuses on the eNB procedure of some embodiments. The serving cell /eNB receives from the victim UEs the information about the N-AIGs a given UE supports. The serving eNB sends over X2 to other interfering eNBs the AIG requested by served NAICS UEs. The network may ignore the UEs indications, partially follow or completely follow the UEs indication of the N-AIGs.

The interfering eNBs may send acknowledgement NAICS activation N-AIG messages to serving eNBs. As a part of this message, the interfering eNB may indicate to the serving eNB which of the N-AIGs, if any, the interfering eNB will transmit. As a part of these messages, the interfering eNB 4 may alternatively or additionally indicate specific RNTI(s). Alternatively, the NAICS-RNTI may be predetermined. Alternatively or additionally, the serving eNB may signal the NAICS-RNTI to the NAICS-capable UEs in the cell.

The interfering eNBs may construct N-AIG specific assistance (control) information in form of NAICS DCI message(s) or any other suitable message. The interference information may be grouped into any suitable way, such as previously discussed.

In the some embodiments, the interfering NAICS_DCI messages (i.e. NAICS assistance information) may be sent in the common search space of the control channel of the aggressor cell.

Reference is made to Figure 8, which shows a signaling flow for the UMTS/HSPA network architecture. It should be appreciated that at least some of the aspects discussed in relation to the LTE implementation may be applicable here and vice versa in some embodiments.

In step T2, a RNC sends to the interfering (aggressor) NB 4 a message enabling the NAICS transmission. The message may include the RNTI to be used in the NAICS assistance information transmission provided by the interfering NB 4. The message may also contain information of what kind of assistance should be transmitted. N-AIGs may be used in this embodiment.

Different assistance information may be utilized by different receiver architectures. A particular UE may know what type of assistance it requires. The type of needed and/or useful assistance information may be provided by the UE to the RNC in a capability message in step T1 .

The RNC may provide the indication of the type of useful NAICS information in step T2 to the interfering NB 4 per interfered UE. This may be provided in a message such as a radio link setup request message when introducing the interfering NB 4 into the active set of a NAICS capable UE. The UE may be in soft handover between interfering NB 4 and serving NB 2. It should be appreciated that any other message may alternatively or additionally used to the request message. The serving cell 2 and interfering cell 4 may belong to the same Node B. In this case, the signaling may be similar. In such an embodiment the message may be a radio link addition request message or any other suitable message. The RNC-to-Node B messaging termination point may be the same Node B, but different cells would be addressed within that Node B.

The interfering NB 4 sends a response message in step T3 to the RNC. This may implicitly acknowledge the NAICS activation. As a part of this message, the eNB 4 may alternatively or additionally indicate a specific RNTI(s). Alternatively or additionally, the NAICS-RNTI may be predetermined or set by the RNC. The RNC may set the NAICS-RNTI in the request message enabling NAICS assistance.

In step T4, the RNC may signal the NAICS-RNTI to the NAICS-capable UEs in the cell.

In step T5, the serving node 2 sends data which is scheduled to the UE.

In step T6, the interfering NB 4 starts transmitting control information corresponding to the requested assistance information, corresponding to the data which is scheduled to the interfering UE in a given TTI.

Steps T8 and T10 correspond to steps T6 and steps T7 and T9 correspond to step

T5.

The timeline of steps T6, T8, and T10 on the one hand and steps T5, T7, and T9 can be independent or generally at the same time. Getting the same information in the same time (that is data and assistance, i.e. T5 and T6, T7 and T8, T9 and T10) may maximize the IC capability.

Alternatively or additionally the serving eNB may send interfering control information. The UE informs its capabilities related to network assisted interference cancellation to the RNC using RRC protocol, possibly including the type of NAICS assistance information it is able to benefit from.

The following discusses the UE process of some embodiments. The UE receives information related to the interfering cell's NAICS assistance information transmission (e.g. type of assistance information, and/or RNTI used by the assistance information delivery) from the RNC using for example the RRC protocol.

The UE may receive the signaling from the aggressor NB over a physical code channel or any other suitable channel. The signaling may comprise one or more of the following: message identifying information, for example using the RNTI provided by the RNC to the UE; information related to the interfering signal (data transmission of the interfering Node B to at least one of the UEs it is serving), such as for example one or more of used (relative) transmit power, used modulation, used set of codes and/or used transport block size. The UE may use the received information of the interference to cancel and/or suppress that interference from the wanted signal transmitted by its serving NB.

The network procedure of some embodiments will now be described. The RNC receives the UE capability information. The RNC informs the interfering NB (cell) of the NAIC capable UE, and optionally provides the NAIC RNTI and/or information regarding the UE's capabilities for the type of assistance information the UE is able to benefit from. The may be done using NBAP (node B application part) protocol or any other suitable protocol.

The interfering cell may provide a response message to the received message using the NBAP protocol or any other suitable protocol.

The RNC may provide the UE with information related to the interfering cell's NAICS assistance information (e.g. type of assistance information, RNTI used by the assistance information delivery and/or any other suitable information). This may be using RRC protocol or any other suitable protocol.

The interfering NB may construct the NAICS assistance information related to the data transmission it is scheduling to at least one of the UEs it is serving. The interference information can be grouped in one or more ways. For example, one or more of the following groupings may be used:

a. Information about the (relative) transmit power of the data

b. Information related to the used HS(high speed)-PDSCH channelization codes used to transmit the data

c. Information related to the used modulation scheme on the HS-PDSCH channelization code(s)

d. Information related to the transport block size transmitted on HS-PDSCH channelization code(s)

One or more of the above information may be transmitted.

The NAICS assistance information may be transmitted using a physical channel on a channelization code by the interfering Node B or on any other suitable channel.

Some methods of some embodiments have been described. It should be appreciated that one or more steps may be carried out in a different order and/or combined with one or more other steps. In some embodiments, one or more steps may be omitted. In some embodiments, one or more additional steps may be provided.

One or more of the steps performed in the RNC and/or NB and/or eNB may be carried out by the control apparatus of Figure 4.

One or more of the steps performed by the UE may be carried out by the one or more processors in conjunction with one or more memories in the apparatus of Figure 3.

Some embodiments may provide one or more of the following advantages. N-AIGs may enable savings in terms of signaled information as different N-AIGs may implicitly refer to different information characteristics. Grouping information in N-AIGs may facilitate enabling only specific NAICS assistance information depending on the interference existing at a particular time in the network, hence keeping the overhead in the network under control.

From the UE point of view, grouping of NAI may simplify operation as the UE does not need to blindly detect the information and/or by avoiding excessive signaling overhead.

It should be appreciated that the example of groupings have been given by way of example only and other embodiments may alternatively or additionally provide one or more other embodiments.

It should be appreciated that although embodiments have been described in the context of HSPA and LTE, this is by way of example only and other embodiments may be used in the context of any other standard or system.

Reference has been made to some examples of channels. It should be appreciated that this is by way of example and in other embodiments, different channels may be used.

It should be appreciated that embodiments may be used with any suitable wireless access node such as a base station or wireless access point. eNB and NB are some examples of base stations.

An appropriately adapted computer program code product or products may be used for implementing the embodiments, when loaded on an appropriate data processing apparatus, for example for determining geographical boundary based operations and/or other control operations. The program code product for providing the operation may be stored on, provided and embodied by means of an appropriate carrier medium. An appropriate computer program can be embodied on a computer readable record medium. A possibility is to download the program code product via a data network. In general, the various embodiments may be implemented in hardware or special purpose circuits, software, logic or any combination thereof. Embodiments of the inventions may thus be practiced in various components such as integrated circuit modules. The design of integrated circuits is by and large a highly automated process. Complex and powerful software tools are available for converting a logic level design into a semiconductor circuit design ready to be etched and formed on a semiconductor substrate.

It is also noted herein that while the above described exemplifying embodiments of the invention, there are several variations and modifications which may be made to the disclosed solution without departing from the scope of the present invention.

Claims

1 . A method comprising:

receiving in a user equipment from at least one cell, at least one group of network assistance information, the group or each group comprising a subset of network assistance information; and

using said at least one group of assistance information to reduce interference from at least one interfering cell.

2. A method as claimed in claim 1 , comprising providing information indicating which one or more of a plurality of groups of network assistance information are supported by said user equipment.

3. A method as claimed in claim 2, comprising providing said information to a serving cell with which said user equipment is associated.

4. A method as claimed in any preceding claim, comprising receiving decoding information for decoding said received group of network assistance.

5. A method as claimed in any preceding claim, comprising receiving said at least one group of network assistance information via at least one downlink control channel.

6. A method as claimed in any preceding claim, comprising receiving said at least one group of network assistance information from at least one of a serving cell and said at least one interfering cell.

7. A method comprising:

causing transmission to a user equipment, of at least one group of network assistance information, the or each group comprising a subset of network assistance information for use by the user equipment to reduce interference from at least one interfering cell.

8. A method as claimed in claim 7, comprising receiving a request from a serving cell requesting the transmitting of said at least one group of network assistance information.

9. A method as claimed in claim 7 or 8, comprising receiving user equipment information indicating which one or more groups of network assistance information are supported by said user equipment,

10. A method as claimed in claim 9, comprising receiving said user equipment information from a serving cell of said user equipment.

1 1 . A method as claimed in claim 9 or 10, comprising determining which one or more groups of network assistance information are to be transmitted to said user equipment in dependence on one or more of said user equipment information and characteristics of said at least one interfering cell.

12. A method as claimed in any of claims 7 to 1 1 , wherein said causing the transmitting comprises causing said at least one group of network assistance information to be signalled to said user equipment.

13. A method as claimed in any of claims 7 to 12, comprising providing decoding information for decoding at least one group of network assistance information

14. A method as claimed in claim 13, comprising providing said decoding information to a serving cell of said user equipment.

15. A method comprising:

receiving user equipment information indicating which one or more groups of network assistance information are supported by said user equipment, the or each group comprising a subset of network assistance information for use by the user equipment to reduce interference from at least one interfering cell.

16. A method as claimed in claim 15, comprising causing said user equipment information or information dependent on said user equipment information to be provided to said at least one interfering cell.

17. A method as claimed in claim 15 or 16, comprising receiving decoding information for decoding at least one group of network assistance information.

18. A method as claimed in any of claims 15 to 17, comprising causing the transmitting of decoding information for decoding at least one group of network assistance information, to said user equipment.

19. A method as claimed in any preceding claim, wherein said at least one group of network assistance is dependent on a category or capability of said user equipment.

20. A method as claimed in any preceding claim, wherein said at least one group of network assistance is dependent on a type of receiver used by said user equipment.

21 A method as claimed in any preceding claim, wherein at least one group of network assistance is dependent on characteristics of at least one interfering cell

22. A method as claimed in claim 21 , wherein said characteristics of said at least one interfering cell comprise one or more of: transmission characteristics; transmission mode; transmission scheme; information about the relative transmission power of the data compared to reference signals; precoding matrix indicator; rank; and resource allocation.

23. A method as claimed in any preceding claim, wherein a plurality of groups of network assistance information are usable by said user equipment.

24. A method as claimed in claim 4, 13 or 17, or any claim appended thereto, wherein said decoding information comprises a temporary identifier associated with at least one group of network assistance information.

25. A method as claimed in claim 24, wherein a different temporary identifier is associated with each group of network assistance information.

26. A method as claimed in claim 24, wherein a temporary identifier is associated with a plurality of groups of network assistance information.

27. A method as claimed in any of claims 24 to 26, wherein said decoding information comprises identity information associated with an interfering cell.

28. A computer program comprising computer executable instructions which when run perform the method of any one of the preceding claims.

29. An apparatus in a user equipment comprising at least one processor and at least one memory including computer code for one or more programs, the at least one memory and the computer code configured, with the at least one processor, to cause the apparatus at least to: receive from at least one cell, at least one group of network assistance information, the or each group comprising a subset of network assistance information; and

use said at least one group of assistance information to reduce interference from at least one interfering cell.

30. An apparatus comprising at least one processor and at least one memory including computer code for one or more programs, the at least one memory and the computer code configured, with the at least one processor, to cause the apparatus at least to:

cause transmission to a user equipment, of at least one group of network assistance information, the or each group comprising a subset of network assistance information for use by the user equipment to reduce interference from at least one interfering cell.

31 . An apparatus comprising at least one processor and at least one memory including computer code for one or more programs, the at least one memory and the computer code configured, with the at least one processor, to cause the apparatus at least to:

receive user equipment information indicating which one or more groups of network assistance information are supported by said user equipment, the or each group comprising a subset of network assistance information for use by the user equipment to reduce interference from at least one interfering cell.

32. An apparatus as claimed in any of claims 29 to 31 , wherein at least one group of network assistance is dependent on a category or capability of said user equipment.

33. An apparatus as claimed in any of claims 29 to 32, wherein the at least one group of network assistance is dependent on a type of receiver used by said user equipment.

34. An apparatus as claimed in any of claims 29 to 33, wherein at least one group of network assistance is dependent on characteristics of at least one interfering cell.

35. An apparatus as claimed in claim 34, wherein said characteristics of said at least one interfering cell comprise one or more of: transmission characteristics; transmission mode; transmission scheme; information about the relative transmission power of the data compared to reference signals; precoding matrix indicator; rank; and resource allocation.

36. An apparatus as claimed in any of claims 29 to 35, wherein a plurality of groups of network assistance information are usable by said user equipment.

37. An apparatus as claimed in any of claims 29 to 35, wherein decoding information is at least one of provided and received, said decoding information comprising a temporary identifier associated with at least one group of network assistance information.