RU2471314C2 - Noise control with requests for noise reduction and noise indicators - Google Patents

Abstract

FIELD: information technologies.

SUBSTANCE: in one of aspects requests for reduction of noise and noise indicators may be used to control noise to provide for operation in scenarios with prevailing influence of noise sources. In one version a terminal may receive from the first basic station a request for noise reduction, in which it is requested to reduce noise on the specified frequency and time resources. The terminal may also receive a noise indicator, which transmits the level of noise, to which the second basic station is exposed. The terminal may determine its transfer capacity, being based on the request for reduction of noise and on the noise indicator. For instance, the terminal may determine the initial capacity of transfer, being based on the request for reduction of noise (or noise indicator) and may correct the initial capacity of transfer, being based on the noise indicator (or the request for noise reduction) to produce its transfer capacity. The terminal may send data to a service basic station at a certain capacity of transfer.

EFFECT: reduced noise in a wire communication network.

15 cl, 10 dwg

Description

This application claims priority on the filing date of provisional application for US patent No. 61/047 063, entitled "INTERACTIONS OF RESOURCE UTILIZATION MESSAGES (RUM) AND OTHER SECTOR INTERFERENCE (OSI) INDICATIONS", registered April 22, 2008, and provisional application for US patent No. 61/108 429, entitled “OUT-OF-CLUSTER INTERFERENCE ESTIMATION AND CLUSTER NULL PILOTS”, registered October 24, 2008, both are assigned to the assignee of this application and are presented here by reference.

I. The technical field to which the invention relates.

The present disclosure relates generally to communications, and more specifically to techniques for suppressing interference in a wireless communication network.

II. State of the art

Wireless networks are widely used to provide various communication information such as voice, video, packet data, messages, broadcasting, etc. These wireless networks can be multiple access networks that can support multiple users who share available network resources. Examples of such multiple access networks include code division multiple access (CDMA) networks, time division multiple access (TDMA) networks, frequency division multiple access (FDMA) networks, orthogonal FDMA networks (OFDMA) and FDMA networks single carrier (SC-FDMA).

A wireless communication network may include multiple base stations that can communicate with multiple terminals. A terminal may communicate with a base station via a downlink and an uplink. The downlink (or forward link) refers to the communication line from the base station to the terminal, and the uplink (or reverse link) refers to the communication line from the terminal to the base station. The base station may receive uplink data from the terminal. Data transmission from the terminal may be interfered with by transmissions from other terminals communicating with neighboring base stations. Interference from other terminals can degrade performance. Therefore, in the prior art there is a need for a method for controlling interference in a wireless network.

SUMMARY OF THE INVENTION

The techniques for managing interference in a wireless network are described. In one aspect, interference mitigation requests and interference indicators can be used to control interference to operate in scenarios with a predominant influence of interference sources. Interference Reduction Request is a message that can be sent for a request to reduce interference on certain time-frequency resources to ensure data transmission on these resources. Interference Indicator - A message indicating the level of interference detected by the base station. The interference indicator may transmit the measured interference value or the result of coarse quantization of the measured interference, for example, into two or three levels, which may indicate low, high or very high interference levels. Separate interference indicators can be generated and transmitted for various time-frequency resources. The interference mitigation request may be sent for a particular scheduling case, for example, in a scenario of a predominant interference effect. An interference indicator may be sent periodically and may not be associated with any particular planning case.

In one embodiment, the terminal may receive a noise reduction request from the first base station in which it is asked to reduce interference on said time-frequency resources. The terminal may also receive an interference indicator in which the level of interference to which the second base station is exposed is transmitted. The terminal may determine its transmit power based on the interference mitigation request and the interference indicator, as described below. A terminal may transmit data to a serving base station at a given determined transmit power. The terminal may also determine whether or not to transmit to the second base station on pre-assigned resources, based on the decision to consider or ignore the interference indicator. The pre-assigned resources may be used by the second base station to determine controlled interference or uncontrolled interference in the second base station. In one design, the serving base station may receive an interference mitigation request sent by the first base station in which it is requested to reduce interference on said time-frequency resources. The serving base station may also receive an interference indicator in which the interference level to which the second base station is exposed is transmitted. The serving base station may schedule a terminal to transmit data on the specified time-frequency resources based on the interference mitigation request and the interference indicator. A serving base station may send a response message containing a predicted interference level due to a terminal scheduled on said time-frequency resources to the first base station.

In one design, the base station may send a request to reduce interference (for example, via radio communication to one or more interfering terminals and / or via a reverse connection to one or more other base stations), in which they are asked to reduce interference on said time-frequency resources . The base station may also send an interference indicator (for example, over the air and / or through a reverse connection) in which the level of interference detected by the base station is transmitted. The base station can determine whether or not to send an interference indicator based on uncontrolled interference in the base station, which can be estimated based on the reception power in the base station for pre-assigned resources and / or on response messages containing predicted interference levels from the terminals, served by other base stations. Various aspects and features of the disclosure are described in more detail below.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a wireless network.

FIG. 2 shows uplink data transmission with interference suppression.

FIG. 3 shows exemplary downlink and uplink transmissions.

FIG. 4 shows a process performed by a terminal.

FIG. 5 shows a terminal device.

FIG. 6 shows a process performed by a serving base station.

FIG. 7 shows a device of a serving base station.

FIG. 8 shows a process performed by a neighboring base station.

FIG. 9 shows a device of an adjacent base station.

FIG. 10 shows a block diagram of a terminal and two base stations.

DETAILED DESCRIPTION

The described techniques can be used for various wireless communication networks, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA and other networks.

The terms “network” and “system” are often used interchangeably. A CDMA network may implement a radio access technology such as Universal Terrestrial Radio Access (UTRA), cdma 2000, etc. UTRA includes Broadband CDMA (WCDMA) and other CDMA options. cdma2000 covers the IS-2000, IS-95 and IS-856 standards. A TDMA network may implement a radio access technology such as a Global System for Mobile Communications (GSM). An OFDMA network may implement radio access technology such as evolutionary UTRA (E-UTRA), ultra broadband mobile transmission (UMB), IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, Flash-OFDM®, etc. . UTRA and E-UTRA are part of the Universal Mobile Communications System (UMTS). The 3GPP Long Term Evolution System (LTE) is a planned release of UMTS that uses E-UTRA. UTRA, E-UTRA, UMTS, LTE, LTE-A and GSM are described in documents from an organization called the 3rd Generation Partnership Project (3GPP). Cdma 2000 and UMB are described in documents from an organization called the “3rd Generation 2 Partnership Project” (3GPP2). The described techniques can be used for the above wireless networks and radio access technologies, as well as for other wireless networks and radio access technologies.

FIG. 1 shows a wireless communication network 100, which may include a plurality of base stations and other network entities. For simplicity, FIG. 1, only two base stations 120 and 122 and one network controller 130 are shown. A base station may be a station that communicates with terminals, and it may also be referred to as node B, evolutionary node B (eNB), access point, etc. Each base station may provide a communications area in a specific geographic area. In 3GPP, the term “cell” may refer to a service area of a base station and / or a subsystem of a base station serving this service area. In 3GPP2, the term “sector” or “cell sector” may refer to a coverage area of a base station and / or a subsystem of a base station serving this coverage area. For clarity, the 3GPP cell concept is used in the description below.

The base station may provide a communication area for a macrocell, pico cell, femto cell, etc. A macrocell can serve a relatively large geographic area (for example, several kilometers in radius) and can provide unlimited access for terminals that are subscribed to services. A pico cell can serve a relatively small geographic area and can provide unlimited access for terminals that have a subscription to services. A femto cell can serve a relatively small geographic area (for example, a house) and can provide limited access for terminals connected to a given femto cell (for example, for terminals of users living in a house). A macrocell base station may be referred to as a macro base station. A base station for a pico cell may be referred to as a pico base station. A base station for a femto cell may be referred to as a femto base station or a home base station. Base stations of various types may have different transmit power levels, different coverage areas and different interference effects in the wireless network 100. For example, macro base stations may have a high transmit power level (for example, 20 watts), while pico and femto base stations may have lower transmit power (e.g. 1 watt). Wireless network 100 may also include relay stations. A relay station is a station that receives data transmission and / or other information from a station previous on a data transmission route and sends data transmission and / or other information to a station that follows a data transmission route. A network controller 130 may connect to a plurality of base stations and provide coordination and control of these base stations. Network controller 130 may communicate with base stations 120 and 122 via a reverse connection, as shown in FIG. 1. Base stations 120 and 122 may also communicate with each other, for example, directly or indirectly via a wireless or wired communication line.

The terminals may be dispersed throughout the wireless network 100, and each terminal may be stationary or mobile. For simplicity, only two terminals 110 and 112 are shown in FIG. 1. The terminal may also be referred to as an access terminal (AP), user equipment (UE), mobile station (MS), subscriber unit, station, etc. The terminal may be a cell phone, a personal digital assistant (PDA), a wireless modem, a wireless device, a handheld device, a laptop, a cordless telephone, a wireless local area station (WLL), etc. The terminal can communicate with macrobase stations, pico-base stations, femto-base stations, etc. In FIG. 1, terminal 110 may communicate with a serving base station 120 and may interfere with a neighboring base station 122. A serving base station is a base station determined to serve a terminal in a downlink and / or uplink. Terminal 112 may communicate with base station 122 or some other base station and may interfere with base station 120. Terminal 110 may be an interfering terminal for neighboring base station 122, and terminal 112 may be an interfering terminal for serving base station 120.

The terminal may communicate with the serving base station in the scenario of the predominant influence of interference. In the downlink, the terminal may be subject to high interference from one or more interfering base stations. In the uplink, the serving base station may be subject to high interference from one or more interfering terminals. Due to the increased range, a predominant interference effect scenario may occur, which is a scenario in which a terminal communicates with a base station with lower path loss and lower “geometry” among the plurality of base stations detected by the terminal. For example, a terminal may communicate with a pico base station with lower path loss and lower “geometry” and may be affected by high interference from a macro base station. It may be necessary to reduce interference in a wireless network to provide a given data rate for the terminal. Due to the limited connection, a predominant interference effect scenario may also appear, which is a scenario in which the terminal cannot connect to a powerful limited access base station and can then connect to a weaker power base station with unlimited access. For example, a terminal cannot connect to a femto base station, can connect to a macro base station, and can then be affected by high interference from a femto base station.

In one aspect, interference mitigation requests and interference indicators can be used to control interference to provide scenarios for the predominant effect of interference. Interference reduction requests and interference indicators can be generated using the base stations in various ways, and they can lead to different reactions of the terminals and base stations, as described below. Combinations of interference mitigation requests and interference indicators can provide more efficient interference management. For example, interference mitigation requests may be more efficient in suppressing interference for an uneven data stream, data with a Quality of Service (QoS) requirement, etc. Interference indicators may be more effective for other types of data.

FIG. 2 shows an embodiment of an uplink data transmission circuit 200 with interference suppression through interference mitigation requests. Terminal 110 may have data for transmission to serving base station 120 and may send a resource request. In the resource request, you can specify the priority of the request, the amount of data to be transmitted by the terminal 110, etc. Serving base station 120 may receive a resource request and may send a transmission request to terminal 110 in which the terminal is requested to transmit on specific time-frequency resources, which may be referred to as predetermined resources. Serving base station 120 may also send an interference mitigation request asking interfering terminals to reduce interference on predetermined resources. Serving base station 120 may send an interference mitigation request (i) as a unicast message only to interfering terminals in neighboring cells or (ii) as a broadcast message to all interfering terminals. Each interfering terminal may reduce interference on said resources, (i) avoiding or negating transmission on said resources, (ii) reducing its transmit power on said resources, or (iii) spatially directing its transmissions away from serving base station 120.

Terminal 110 may receive a transmission request from serving base station 120 and may also receive interference mitigation requests from neighboring base stations, only one of which is shown in FIG. 2. Terminal 110 may determine the transmit power P _{TX_terminal} that can be used on these resources based on interference mitigation requests and interference indicators from neighboring base stations, as described below. Terminal 110 may then transmit a power selection pilot at a power level P _pdp , where P _pdp may be equal to P _{TX_terminal} or a scaled value of P _{TX_terminal} .

In general, transmit power can be set using transmit power level, power spectral density (PSD), etc. The transmit power level may be the total transmit power that can be used for transmission. PSD may be transmit power per unit frequency. The transmit power level and PSD may be equal in magnitude for a fixed frequency range and may differ when the frequency range is variable. For example, a given transmit power level may result in a predetermined PSD for a given range and may result in half of the PSD when the frequency range is doubled. As used herein, the term “transmit power” may refer to the level of transmit power and / or PSD, depending on the context in which the term is used and the desired result.

Serving base station 120 may receive power selection pilots from terminal 110 as well as interfering terminals. Serving base station 120 may evaluate the quality of the received signal on these resources based on the received pilot signals, and may select a modulation and coding scheme (MCS) for terminal 110 based on the quality of the received signal. Serving base station 120 may generate and send a destination or grant message, which may include selected MCS, assigned resources, transmit power to use for assigned resources, etc. Assigned resources may contain all or a subset of these resources. Terminal 110 may receive a destination message, process the packet in accordance with the selected MCS, and send a packet transmission on the assigned resources. Serving base station 120 may receive a packet transmission from terminal 110, decode the received transmission, determine acknowledgment information (ACK) based on the decoding result, and send ACK information to terminal 110.

FIG. 2 shows an example uplink data transmission with interference mitigation through interference mitigation requests. Interference reduction requests can also be used in other ways to reduce interference.

Interference Reduction Request is a message that can be sent for a request to reduce interference on certain time-frequency resources to ensure data transmission on these resources. The interference mitigation request may also be referred to as a resource utilization message (RUM). Base station 120 may send a radio interference mitigation request to one or more interfering terminals and / or via a reverse connection to one or more neighboring base stations. Base station 120 may send a noise reduction request to ensure data transmission in a scenario of the predominant effect of interference, to improve the fairness of cells, etc. For example, base station 120 may perform one or more of the following:

1) send a radio interference mitigation request to the interfering terminals in neighboring cells and / or through the reverse connection to neighboring base stations serving the interfering terminals before scheduling the terminal 110 to provide an acceptable amount of interference during transmissions of the terminal 110,

2) send a request to reduce interference through a reverse connection to neighboring base stations, prior to scheduling terminal 110, to transmit to neighboring base stations an extended notification of high interference that terminal 110 can create to neighboring base stations, and

3) send a radio interference mitigation request to interfering terminals in neighboring cells and / or through a reverse connection to neighboring base stations whenever the terminals served by base station 120 are in adverse conditions and cannot meet QoS requirements or equal access criteria.

Scenario 1 can be used to reduce interference on certain time-frequency resources that can be assigned to a terminal to be scheduled by base station 120. If the interference reduction request is sent over the air, then interfering terminals in neighboring cells can reduce their transmit power on these resources . If the interference mitigation request is sent via the reverse connection, then neighboring base stations may not plan their terminals on these resources or may plan their terminals for lower transmit power on these resources.

Scenario 2 can be used to alert neighboring base stations of potential high interference due to a terminal planned by base station 120. Neighboring base stations may not plan their terminals on these resources.

Scenario 3 can be used to reduce interference at certain time-frequency resources, which can then be used for endangered terminals served by base station 120. The interference mitigation request may allow base station 120 to be less interfered with at these resources and may thus improve the quality of the received signal and QoS endured in adverse terminal conditions.

Base station 120 may also send interference mitigation requests in other scenarios to reduce interference on these resources. Base station 120 may send a mitigation request in a unicast message to a specific interfering terminal, in a multicast message to a group of terminals (e.g., terminals in a specific cell), or in a broadcast message to all terminals in neighboring cells.

The interference mitigation request may include various types of information that may be useful for managing interference. In one design, the interference mitigation request may include one or more of the following:

• time-frequency resources where interference is required to be reduced,

• priority level of the terminal or data to be planned on the indicated resources,

• target interference level for the base station sending the request,

• the proposed maximum transmit power for interfering terminals on the indicated resources, and

• the predicted level of interference that may be generated by the terminal scheduled on these resources.

Information on the time-frequency resources on which it is necessary to reduce interference, i.e. about these resources can be provided in different ways. In one design, these resources can be explicitly transmitted using the interference mitigation request. In another implementation, these resources can be implicitly transmitted using the interference mitigation request. For example, a noise reduction request may be sent on certain frequency resources at a specific time. These resources may cover (i) certain frequency resources associated with the frequency resources used to transmit the interference mitigation request, and (ii) a specific time interval determined by when the interference mitigation request is sent. These resources can also be transferred in other ways. These resources can also be determined using any time-frequency characteristic and any degree of detail.

The priority level can be defined in different ways and based on various indicators. For example, the priority level can be determined based on relative throughput or fairness indicators (for example, for the best possible data), latency, absolute priority (for example, determined based on QoS requirements), etc.

The target interference level may indicate the maximum amount of interference that can be created by the interfering terminal for base station 120. The target interference level can be set by the total interference power, interference to thermal noise ratio (IoT), etc. IoT is the ratio of PSD interference to PSD thermal noise. In one design, the target interference level can be explicitly achieved using a noise reduction request. In another design, the target interference level can be implicitly transmitted through the transmit power of the interference mitigation request if it is sent over the air. For example, the transmit power of the interference mitigation request can be set as follows:

where I _target is the target interference level at base station 120,

P _REF is the reference level, and

P _{TX_RUM} is the transmit power of the interference mitigation request.

The values in equation (1) are given in logarithmic units, for example, dBm, dBm / hertz or dB. As shown in equation (1), the transmit power of the interference mitigation request may be inversely proportional to the target interference level. The interference mitigation request can be sent with a higher transmit power for a lower target interference level, and it can then reach further interfering terminals. The transmit power of the interference mitigation request can also be determined based on other parameters, such as the received power of terminal 110 at base station 120.

The interfering terminal can estimate the path loss from the base station 120 to this terminal, for example, based on a pilot received from the base station 120. The interfering terminal can then determine its transmit power so that interference to the base station 120 were equal to or below the target interference level, as described below.

The proposed maximum transmit power for interfering terminals can be transmitted in different ways. In one design, the proposed maximum transmit power can be explicitly transmitted using a noise reduction request, for example, in the form of a specific transmit power level, or a specific receive power level, or a specific PSD. Each interfering terminal may then limit its transmit power accordingly. The predicted level of interference that could be created by the terminal planned on the indicated resources can be set in the form of the total interference power, IoT, etc. The predicted interference level may be the actual amount of interference that could be caused by the planned terminal, or it could be the upper limit of the amount of interference that could be generated.

The interference mitigation request may also include other and / or additional information. For example, the interference mitigation request may identify a specific interfering terminal or a group of interfering terminals that are asked to reduce interference on said resources. The interference mitigation request may also include (i) the target signal-to-noise ratio (SNR) or the target speed (for example, instead of the target interference level), (ii) a measure of the service improvement performance / quality that can be achieved if the target interference / SNR / speed is provided on the indicated resources (i.e., if the interfering terminals take into account the interference mitigation request), (iii) the transmit power (interfering terminal) or the received interfering (from the interfering terminal), which correspond to part of the total necessary improvement of the effective (it may help to create a disturbance to the terminal to choose among different power levels based on the impact on its own performance) and (iv) other similar indicators.

Interference Indicator - A message indicating the level of interference detected by the base station. In one design, the interference indicator may comprise one or more of the following:

• an indicator of interference from other sectors (OSI), which transmit the level of interference detected by the base station,

• an overload indicator indicating whether or not the base station is overloaded, and

• High Interference Indicator (HII), which provides advance notification of high interference that the base station can create to neighboring base stations by scheduling terminals at the cell boundary on the indicated resources.

Interference indicators can be used to control uplink interference to provide a tighter IoT distribution at base stations. This can provide a more accurate prediction of speed and improved energy potential of the communication line. In one design, the interference indicator can be used for the entire frequency range of the system. In another design, the system frequency range can be divided into multiple subbands, and the interference indicator can be applied to one subband. The base station may also periodically send interference indicators, and each interference indicator can be applied for a specific length of time. In general, an interference indicator can be used for a specific time-frequency resource, which can cover any frequency resources and any length of time. Base station 120 may determine an interference indicator based on interference measured by base station 120, for example, on specific time-frequency resources. The measured interference can be set using IoT or some other indicator. Base station 120 may filter the measured interference by time and / or frequency to improve measurement accuracy. Base station 120 may compare the measured interference with one or more interference thresholds and may set an interference indicator based on the comparison result. In one design, a single interference threshold can be used, and the interference indicator can be set as follows:

where I _meas - measured by the base station 120 interference, and

I _threshold - interference threshold value.

In another design, two interference thresholds can be used, and the interference indicator can be set as follows:

where I _{high_threshold} and I _{low_threshold} are two interference thresholds.

In general, an interference indicator may comprise any number of bits for transmitting any number of interference levels. An appropriate number of thresholds can be used to provide the necessary quantization of the measured interference. The interference indicator may also cover any characteristic and any degree of granularity of time-frequency resources.

Interference indicators can be used by base stations to control the high interference that base stations experience. Base station 120 may send an interference indicator (eg, an OSI indicator and / or congestion indicator) to indicate the high interference that base station 120 is experiencing at certain time-frequency resources. Base station 120 may send an interference indicator by radio to interfering terminals and / or through a reverse connection to neighboring base stations serving interfering terminals. In response to the interference indicator, interfering terminals can adjust their transmit power so that interference detected by base station 120 is reduced to an acceptable level. This interaction between the base station 120 and the interfering terminals and / or their serving base stations may provide feedback feedback control at the base station 120. This feedback control may be more robust against link unbalance due to calibration errors, uncorrelated fading in the downlink and uplink and / or other sources of static or dynamic imbalance between the downlink and the uplink. Link imbalance refers to various channel conditions in the downlink and uplink.

Base station 120 may decide not to transmit interference indicators for time-frequency resources that do not require interference management. This may occur if base station 120 does not plan any terminals on time-frequency resources, for example, due to a limited amount or lack of data for uplink transmission, interference mitigation requests received for given resources, loss in contention contest etc. Base station 120 may also transmit interference indicators for time-frequency resources, but may use a higher threshold value (s) when generating interference indicators.

Base station 120 may send interference indicators to interfering terminals in neighboring cells. Some terminals and / or base stations serving them may take into account / be guided by interference indicators, and these terminals may then create “controlled” interference for base station 120. Other terminals and / or base stations serving them may reject / ignore interference indicators, and these terminals may then cause “uncontrolled” interference to base station 120. Examples of such terminals / serving base stations are terminals / base stations that cannot receive interference indicators from base station 120, or terminals / base stations that have received a request to reduce interference at certain time-frequency resources. The terms “controllable” and “uncontrolled” refer to the ability of a base station to control interference through interference indicators. Total interference at base station 120 may include both controlled interference from terminals that take into account interference indicators and uncontrolled interference from terminals that ignore interference indicators. Base station 120 may determine that uncontrolled interference on certain time-frequency resources is the predominant component of total interference on these resources in base station 120 or more of an interference threshold. Base station 120 may then decide not to transmit interference indicators for these time-frequency resources, since interference indicators may not help reduce high interference at base station 120 and may instead lead to an unnecessary decrease in transmit power of request-sensitive terminals reduce interference. Thus, it may be necessary to be able to distinguish between controlled and uncontrolled interference at base station 120. In one design, base station 120 may assign time-frequency resources that can be used for interference measurements. These resources may be referred to as zero pilot resources, pre-assigned resources, interference measurement resources, etc. Base station 120 may have one set of resources with zero pilot signal for the entire frequency range of the system or different sets of resources with zero pilot signal for different subbands, etc. Different non-overlapping resources with zero pilot can be assigned to different base stations.

In one design, terminals that take into account interference indicators from base station 120 do not transmit a signal on resources with a zero pilot signal to base station 120. These terminals can provide this by puncturing / deleting any data transmission, control information and / or pilot signal mapped to resources with a zero pilot signal. Terminals that ignore interference indicators can transmit on resources with zero pilot in the usual way. Base station 120 may estimate uncontrolled interference by measuring the reception power for resources with a zero pilot signal, and may filter the measurement result to improve accuracy. Base station 120 may also measure reception power for other resources and may filter the measurement result to estimate total interference. Base station 120 may determine controlled interference by subtracting uncontrolled interference from total interference.

In another design, terminals that take into account interference indicators from base station 120 may transmit on zero pilot resources to base station 120 in a conventional manner. Terminals that ignore interference indicators may not transmit on resources with a zero pilot signal. Base station 120 may estimate controlled interference based on reception power for resources with zero pilot, estimate total interference based on reception power for other resources, and determine uncontrolled interference by subtracting controlled interference from total interference.

The interference from terminals served by base stations of different power classes can also be distinguished using resources with a zero pilot signal. For example, different zero pilot resources can be reserved for different power classes at each base station. In one design, terminals served by base stations of a given power class A may not transmit on resources with zero pilot for class A power. Terminals served by base stations of other power classes may transmit on resources with zero pilot for class A power. For example, terminals served by macrobase stations may not transmit on resources with a zero pilot signal for macrobase stations, and terminals served by pico base stations may not transmit on resources with a zero pilot signal for pico base stations. The interference due to terminals served by base stations of other power classes can be determined based on the receive power for resources with zero pilot for class A power. In another design, terminals served by Class A power base stations can transmit on resources with zero pilot for class A power. The interference due to terminals served by power class A base stations can then be determined based on the receive power for resources with zero pilot for class A power.

FIG. 3 shows downlink transmissions using base stations 120 and 122 and uplink transmissions using terminal 110 to transmit data on the uplink with reduced interference. Each base station can periodically transmit interference indicators 310, transmitting the level of interference to which this base station is exposed. Serving base station 120 may be affected by high interference from interfering terminals in other cells and may send a noise reduction request 320 for the indicated resources before scheduling terminal 110. Interfering terminals may reduce their transmit power on these resources. Terminal 110 may send data 330 on designated resources, which may contain all or a subset of these resources. Terminal 110 may gouge its data and pilot on resources 340 with a zero pilot signal from neighboring base station 122, whose interference indicator considers terminal 110.

Terminal 110 or its serving base station 120 may use open-loop prediction to determine the transmit power of terminal 110 for a given uplink assignment or at certain time-frequency resources. In non-feedback prediction, the transmit power of the terminal is determined by predicting the amount of interference in a neighboring base station. Terminal 110 may communicate with serving base station 120 and may interfere with neighboring base station 122, which may be an interfering base station. The neighboring base station 122 may send an interference mitigation request that terminal 110 may take into account. The transmit power of terminal 110 may then be set to match the target interference level for base station 122.

In one design, terminal 110 may determine its transmit power based on non-feedback prediction, as follows:

where I _target is the target interference level in the interfering base station,

PL _IBS - losses in the transmission path from the interfering base station to the terminal,

K _backoff is the power loss coefficient, and

P _{TX_terminal} - transmit power of the terminal.

The values in equation (4) are indicated in logarithmic units, for example, in dBm, dBm / hertz or dB. As shown in equation (4), the transmit power of the terminal 110 can be proportional to both the target interference level and the path loss for the interfering base station. Higher transmit power can be used with a higher target interference level and / or with large losses in the transmission path. The power loss coefficient can be used to improve non-feedback prediction in equation (4). Serving base station 120 may also determine the transmit power of terminal 110 based on various parameters, such as the receive power of terminal 110 in base station 120, channel difference (ChanDiff) between base station 120 and the interfering base station, and power loss coefficient. ChanDiff can be set as follows:

ChanDiff = PL _IBS -PL _SBS , (5)

where PL _SBS is the path loss from the serving base station to the terminal.

Terminal 110 may determine the path loss for each base station based on the pilot or reference signal received from that base station, and may average the path loss over time to obtain long-term path loss. Terminal 110 may determine a ChanDiff for the interfering base station based on long-term path loss for serving base station 120 and long-term path loss for the interfering base station. Terminal 110 may send ChanDiff in a pilot measurement report to serving base station 120.

In one design, serving base station 120 may determine the transmit power of terminal 110 based on open-loop prediction, as follows:

P _TX _ _terminal = I _target + ChanDiff + PL _SBS -K _backoff , (6)

As shown in equation (6), the transmit power of the terminal 110 can be determined using the serving base station 120, based on the target interference level for the interfering base station, on ChanDiff, information about which is transmitted by the terminal 110, on the path loss determined by the serving base station 120 based on a pilot received from terminal 110 and a power loss coefficient. The non-feedback prediction in equation (6) can be based mainly on the results of observations of the downlink using the terminal 110, without taking into account uplink fading or other sources of link imbalance. To increase the accuracy of forecasting without feedback, the power loss coefficient can be adjusted using the feedback method, based on interference indicators, to eliminate imbalance in the communication line and / or other sources of interference.

Serving base station 120 may use various target values to calculate the transmit power of terminal 110. In one design, the transmit power of terminal 110 can be calculated based on the target power of the total amount of interference for the interfering base station, which can be normalized by thermal interference. In another design, the transmit power of terminal 110 may be calculated based on a given IoT for an interfering base station. The target IoT can be calculated using the average target IoT, maximum target IoT, etc. In yet another design, the transmit power of terminal 110 can be calculated based on a targeted increase in interference with respect to the current interference level in the interfering base station that can be generated for serving base station 120.

Terminal 110 may receive interference mitigation requests from neighboring base stations. Terminal 110 may determine whether to consider or ignore interference mitigation requests. In one design, terminal 110 may consider all interference mitigation requests that it can successfully decode.

In another design, terminal 110 may consider interference mitigation requests that meet one or more criteria. For example, terminal 110 may take into account interference mitigation requests from each neighboring base station with ChanDiff that exceeds the threshold ChanDiff, with a carrier to thermal noise ratio (CoT) that exceeds the threshold CoT, with a carrier to interference ratio (C / I), which exceeds the C / I threshold, with the number of resources that are determined using the interference mitigation request not exceeding the resource quantity threshold, or with some other indicator of the interference mitigation request that exceeds a certain threshold th value. Terminal 110 may not be a strong source of interference for neighboring base stations whose interference mitigation requests are received with very little power at terminal 110 or whose specified resources are much larger than resources assigned to terminal 110, in which case the interference created by terminal 110 may be narrowband compared to the given resources.

In yet another design, terminal 110 may consider interference mitigation requests that (i) are successfully decoded and / or meet one or more criteria, and (ii) have a higher priority level than the priority level of terminal 110. The priority level of terminal 110 can be determined using terminal 110, for example, based on the QoS requirements of the data to be transmitted on said resources and / or other metrics. The priority level of terminal 110 can also be determined using a serving base station 120 (for example, based on the relative throughput or fairness of terminal 110, latency, or QoS requirements of terminal 110, etc.) and can be sent to terminal 110 via an assignment message.

In yet another design, terminal 110 may account for or ignore interference mitigation requests based on the current resource assignment to terminal 110. For example, terminal 110 may ignore interference mitigation requests if its assigned resources are less than a certain assignment value. This design may be useful for certain types of data, such as (i) data for VoIP, which may have strict latency or QoS requirements, (ii) data that is likely to cause small and / or narrowband interference, (iii) data that is sent in subsequent HARQ transmissions, which may be large due to resources already being used to transmit previous HARQ transmissions, and (iv) other data.

In yet another design, terminal 110 may consider or ignore interference mitigation requests based on the transmit power or the received C / I ratio of terminal 110. Terminal 110 may ignore interference mitigation requests if its transmit power is below the transmit power threshold or if its received ratio The C / I at the serving base station 120 is below the threshold value of the C / I ratio. Thresholds can be set based on various factors, such as (i) QoS requirements and / or assignment value for terminal 110, (ii) priority level or power of received interference mitigation requests, (iii) information from interference mitigation requests and / or ( iv) other information. This design can guarantee a certain minimum level of service for terminal 110 by limiting the amount of interference from neighboring base stations.

Terminal 110 may receive interference indicators from neighboring base stations. Terminal 110 may determine whether interference indicators should be considered or ignored. In one design, terminal 110 may consider all interference indicators that it can successfully decode. In another design, terminal 110 may consider interference indicators that meet one or more criteria. For example, terminal 110 may take into account interference indicators from each neighboring base station with ChanDiff exceeding the threshold ChanDiff, with CoT exceeding the CoT threshold, with C / I exceeding the C / I threshold, or with some other indicator of the neighboring base station, exceeding a certain threshold value. In yet another design, terminal 110 may ignore interference indicators from pico base stations if terminal 110 is being served by a macro base station. A macro base station may serve multiple terminals (which may be referred to as macro terminals), and may allocate less resources for each macro terminal. In contrast, a pico base station may serve few terminals (which may be referred to as pico terminals) and may allocate more resources for each pico terminal. Macroterminals may thus be disadvantaged with respect to pico terminals. This disadvantage can be compensated by allowing macro terminals to ignore interference indicators from pico-base stations. A macro base station may reserve some resources for a pico base station, if it is necessary to enable the pico base station to serve its terminals on the uplink in the presence of high interference from macro terminals. In general, terminals served by base stations of a particular power class can be allowed to ignore interference indicators from base stations of one or more other power classes.

In yet another design, terminal 110 may account for interference indicators from macrobase stations with a higher weight or higher priority if terminal 110 is served by a pico base station. More resources can be assigned to pico terminals, on average, and the advantage of pico terminals relative to macro terminals can be compensated for in accordance with this design. In general, terminals served by base stations of a particular power class can take into account interference indicators from base stations of one or more other power classes with a higher weight or higher priority.

Terminal 110 may take into account an interference indicator from a macro base station with a higher weight or higher priority in different ways. In one design, terminal 110 may adjust its transmit power with a larger step in response to an interference indicator. In another design, terminal 110 may adjust ChanDiff for a macro base station, for example, so that the response of terminal 110 is similar to the reaction of a macro terminal with a lower ChanDiff without any adjustments. In yet another design, terminal 110 may use higher probabilities and / or may assume higher levels of metrics in stochastic / probabilistic algorithms to adjust transmit power based on interference indicators.

In yet another design, terminal 110 may ignore interference indicators from the femto base station if terminal 110 is not served by the femto base station. In yet another design, terminal 110 may ignore interference indicators from a base station with a small negative ChanDiff value, where a small value can be quantified by a threshold. A small negative ChanDiff value may indicate that terminal 110 will be involved in reducing interference with the base station through resource reservation.

Terminal 110 may receive interference mitigation requests and / or interference indicators from neighboring base stations. Terminal 110 may determine whether to consider or ignore each interference mitigation request and each interference indicator, as described above.

Terminal 110 may only take into account interference mitigation requests or take into account only interference indicators, or take into account both.

Terminal 110 can only take into account interference mitigation requests and can then determine its transmit power based on interference mitigation requests. Terminal 110 may determine a target interference level for each interference mitigation request based on the contents of the request or the reception power of the request, as described above.

Terminal 110 may then determine its transmit power for each interference mitigation request based on the target interference level for this interference mitigation request, for example, as shown in equation (4). Terminal 110 may select the lowest transmit power among the transmit powers calculated for all interference mitigation requests. This may allow terminal 110 to meet the interference targets of all neighboring base stations.

Terminal 110 can only take into account interference indicators and can then determine its transmit power directly or indirectly based on interference indicators. For clarity, the following description assumes that each interference indicator has a value of “0” or “1”, which can be determined as shown in equation (2).

In one design, terminal 110 may adjust its transmit power based on the interference indicator as follows:

where P _{TX_terminal} (n) is the transmit power of the terminal in the time interval n,

P _up and P _down are the steps of increasing and decreasing, respectively, the transmit power.

In another design, terminal 110 may adjust the power shift based on the interference indicator, as follows:

where ΔP (n) is the power shift in the time interval n, and

ΔP _up and ΔP _down are the values of the steps of increasing and decreasing, respectively, the power shift.

Terminal 110 may then determine its transmit power as follows:

P _{TX_terminal} (n) = P _ref (n) + ΔP (n) (9)

where P _ref (n) is the reference power level in the time interval n. The reference power level may be the transmit power for the reference signal or pilot signal and may be adjusted using closed-loop power control to provide the target C / I for serving base station 120. The transmit power of terminal 110 can then be shifted from the reference power level by a power shift .

In yet another design, terminal 110 may adjust the maximum transmit power level and / or minimum transmit power level based on the interference indicator, for example, in a similar manner as shown in equation (7). Terminal 110 may then limit its transmit power so that it is within the maximum and minimum transmit power levels.

In yet another _design , terminal 110 may adjust the power loss coefficient K _backoff based on an interference indicator, for example, as shown in equation (8). The terminal 110 may then determine its transmit power using a power loss coefficient, for example, as shown in equation (4).

In the above embodiments, terminal 110 may correct power-related values (e.g., transmit power, power shift, maximum and / or minimum transmit power level or power loss coefficient) in a specific manner based on the interference indicator. In this case, each interference indicator may lead to a correction of the power-related value either up or down, depending on whether the interference indicator is “1” or “0”. In other implementations, terminal 110 may adjust the power-related value in a probabilistic manner based on the interference indicator. Terminal 110 may select a random value of x evenly distributed between 0 and 1.0, and may then adjust the power-related value based on the random value. For example, terminal 110 may adjust its transmit power in a probabilistic manner, as follows:

where Pr _up is the probability of increasing transmission power,

Pr _down is the probability of a decrease in transmit power, and

“InfInd” stands for interference indicator.

Pr _up and Pr _down can have fixed values or they can be transmitted by the base station. Pr _up and Pr _down can also be calculated using terminal 110 based on the ChanDiff value and / or current transmit power received by CoT or received C / I. Terminal 110 may also adjust other power related values in a probabilistic manner.

Terminal 110 may receive interference indicators from one or more neighboring base stations. In one design, terminal 110 may identify the most powerful neighboring base station with the smallest ChanDiff. Terminal 110 may then adjust its transmit power based on an interference indicator only from the most powerful neighboring base station. In another design, terminal 110 may adjust its transmit power based on interference indicators from all base stations in the selected set. This set may include (i) M most powerful neighboring base stations, where M> 1, (ii) neighboring base stations with ChanDiff exceeding the threshold ChanDiff, (iii) neighboring base stations with path losses exceeding the threshold path loss, (iv) neighboring base stations, which includes a list of neighboring stations that the serving base station 120 can transmit, or (v) one or more neighboring base stations selected in other ways. Terminal 110 may adjust its transmit power in different ways based on interference indicators from a plurality of neighboring base stations. In one design, terminal 110 may reduce its transmit power if any neighboring base station is subject to high interference. In another design, terminal 110 may determine a transmit power adjustment for each neighboring base station and may then combine the corrections for all neighboring base stations to obtain an adjustment for the total transmit power. Terminal 110 may also adjust its transmit power based on interference indicators from multiple neighboring base stations in other ways.

Terminal 110 may adjust its transmit power differently based on interference indicators, as described above. Terminal 110 may also adjust one or more of the values supported within it based on interference indicators. Terminal 110 may transmit its transmit power, power shift, maximum and / or minimum transmit power level, power loss coefficient, internal values and / or other values that can be adjusted based on interference indicators to serving base station 120. Serving base station 120 may use the transmitted information to determine the transmit power of terminal 110 and may transmit transmit power in the destination message. Terminal 110 may take into account both interference mitigation requests and interference indicators, and may then determine its transmit power based on interference reduction requests and interference indicators.

In one design, terminal 110 may determine whether or not to transmit to it based on interference mitigation requests. If the decision is made to transmit, then the transmit power of the terminal 110 can be determined in different ways. In a first embodiment, the transmit power of terminal 110 can be assigned using a serving base station 120, for example, in the form of transmit power

P _{TX_terminal} or Power Shift AP (n). The assigned transmit power can be adjusted based on interference indicators received from neighboring base stations. In a second embodiment, the initial transmit power of terminal 110 may be determined based on open-loop prediction, for example, as shown in equation (4). The initial transmit power can be adjusted based on interference indicators received from neighboring base stations. In a third embodiment, the transmit power of terminal 110 may be initially determined based on one or more variables that may be supported by terminal 110, and may be adjusted based on interference indicators from neighboring base stations.

In another design, the initial transmit power of terminal 110 may be determined based on interference mitigation requests, for example, as shown in equation (4). The initial transmit power can be adjusted based on interference indicators from the same base stations and / or other base stations, for example, based on any of the designs described above.

In yet another design, the initial transmit power of terminal 110 can be determined based on interference indicators from neighboring base stations, non-feedback prediction, and / or explicit assignment from serving base station 120. The initial transmit power can be adjusted based on interference mitigation requests.

In yet another design, the maximum and / or minimum transmit power levels for terminal 110 may be determined based on interference mitigation requests. The transmit power of the terminal 110 can be determined based on interference indicators from neighboring base stations, forecasting without feedback and / or on an explicit assignment from the serving base station 120. The transmit power of the terminal 110 can then be limited so that it is within the maximum and minimum transmit power levels. The maximum and / or minimum levels of transmit power can also be adjusted based on subsequent interference indicators from the same and / or other base stations.

Terminal 110 may collect information such as parameters sent in interference mitigation requests received by terminal 110, values computed by terminal 110 based on interference mitigation requests, terminal transmit power 110, maximum and / or minimum transmit power levels for terminal 110, internal values determined based on interference indicators, etc. Terminal 110 may send the collected information to serving base station 120 via a physical channel and / or in-band transmissions. Serving base station 120 may use the information to determine the transmit power of terminal 110 in a future uplink assignment.

Terminal 110 may transmit zero pilot signals to all neighboring base stations whose interference indicators are taken into account by terminal 110. In the uplink, the zero pilot signal is the absence of terminal transmission on pre-assigned time-frequency resources. If the transmit power of terminal 110 is reset or adjusted based on interference mitigation requests, then null pilots can help neighboring base stations further adjust the interference they experience through interference indicators.

Serving base station 120 may receive interference mitigation requests through a reverse connection from one or more neighboring base stations. Reverse link interference mitigation requests may transmit (i) advance scheduling notification from neighboring base stations, (ii) priority information and fairness information for neighboring base stations, (iii) target interference levels for said resources at neighboring base stations, and / or (iv) other information. Serving base station 120 may decide whether to consider or reject each interference mitigation request based on various factors such as priority level of interference mitigation request, ChanDiff value, and resource assignment value for terminals to be scheduled by serving base station 120 on said resources, power terminal transfers, received C / I ratio of terminals, etc. Serving base station 120 may decide to consider or reject each interference mitigation request based on any of the above versions for terminal 110. Serving base station 120 may send a response message through a reverse connection to each neighboring base station to indicate its decision to consider or ignore a noise reduction request from this neighboring base station.

Serving base station 120 may also transmit the predicted levels of interference that it may create for each neighboring base station at the indicated resources by scheduling its terminals. This information can be divided into controlled interference and uncontrolled interference, which can be estimated as described above. This information can be sent in a response message or in a separate message that can be sent at a different speed and / or using other triggering conditions than the response message. Neighboring base station 122 may use information about controlled and uncontrolled interference to determine whether or not to send interference indicators. For example, neighboring base station 122 may decide not to send an interference indicator for certain time-frequency resources if uncontrolled interference on these resources is a predominant component or greater than the interference threshold.

Serving base station 120 may receive interference indicators via a reverse connection from one or more neighboring base stations. Serving base station 120 may determine whether to consider or ignore interference indicators from neighboring base stations when it schedules terminal 110. For example, serving base station 120 may decide to consider or ignore interference indicators from neighboring base station 122 based on the ChanDiff value terminal 110 with respect to neighboring base station 122, power classes of serving base station 120 and neighboring base station 122, type of connection (limited or unlimited) serving and neighboring base stations, etc. The serving base station 120 may schedule its terminals based on interference mitigation requests and / or interference indicators that the serving base station 120 will take into account. In one design, the serving base station 120 may determine whether or not terminal 110 to schedule on these resources based on requests reduce interference on the reverse connection. Serving base station 120 may then determine the transmit power of terminal 110 differently if terminal 110 is scheduled. In the first design, the transmit power of the terminal 110 can be determined through open-loop prediction, for example, as shown in equation (6), and can be further adjusted based on interference indicators from neighboring base stations. In a second embodiment, the transmit power of terminal 110 can be determined based on one or more variables supported by serving base station 120 for terminal 110, and can be adjusted based on interference indicators from neighboring base stations. In a third embodiment, the transmit power of terminal 110 can be determined based on one or more variables that terminal 110 transmits to serving base station 120. The transmitted variable (s) can be maintained at terminal 110 and can be adjusted based on interference indicators from neighboring base stations.

In another design, base station 120 may determine the transmit power of terminal 110 through other mechanisms, such as feedback information from terminal 110, interference indicators from neighboring base stations, non-feedback prediction, etc. Base station 120 may then adjust the transmit power of terminal 110 based on reverse link interference mitigation requests, for example, in accordance with any of the above embodiments for terminal 110.

Base station 120 may send interference mitigation requests on a reverse connection to neighboring base stations. In one design, reverse link interference mitigation requests may carry information with a predicted interference level that terminals served by base station 120 may create to other base stations on said resources. Predicted interference levels can be determined based on open-loop prediction and in accordance with interference mitigation requests received by base station 120 from neighboring base stations. Predicted interference levels can be divided into controlled and uncontrolled interference levels. In another design, reverse link interference mitigation requests may transmit target interference levels for interfering terminals, which may be scheduled by neighboring base stations on said resources.

Base station 120 may also receive information with a predicted interference level that neighboring base stations can create for base station 120 by scheduling its terminals on these resources. Base station 120 may use this information along with interference measurements to which it is exposed on these resources to determine whether or not interference indicators should be transmitted. These interference indicators can, in turn, be used by terminals in other cells or base stations serving them to improve forecasting without feedback and to eliminate imbalances in communication lines or other sources of interference.

Base station 120 may also receive target interference levels for terminals from neighboring base stations, which may be scheduled by base station 120 on these resources. Base station 120 may determine the transmit power of its terminals on these resources based on non-feedback prediction and in accordance with target interference levels from neighboring base stations. Base station 120 may determine predicted interference levels due to its terminals at neighboring base stations based on the transmit power of these terminals. Predicted interference levels can be divided into controlled and uncontrolled interference levels. Base station 120 may then send response messages carrying predicted interference levels to neighboring base stations.

FIG. 4 shows the design of a process 400 performed by a terminal, for example, terminal 110 in FIG. 1. The terminal may receive a noise reduction request from a first base station, which is asked to reduce interference on said time-frequency resources (step 412). The terminal may also receive an interference indicator transmitting the level of interference to which the second base station is exposed (step 414). The first and second base stations may be different base stations or the same base station. The terminal may determine its transmit power based on the interference mitigation request and the interference indicator (block 416).

The interference indicator may comprise (i) an OSI indicator transmitting the interference to which the second base station is exposed, (ii) an overload indicator that transmits information about whether the second base station is overloaded, (iii) a high interference indicator providing advance notification of high interference due to the terminals served by the second base station, and / or (iv) some other indicator of interference or load in the second base station.

In one design, the terminal can determine whether to consider or ignore the interference mitigation request based on the result of decoding the interference mitigation request, the priority level of the interference mitigation request, the priority level of the terminal, the path loss from the first base station to the terminal, and the path loss from the serving base station to the terminal, the receiving power or quality of the received signal of the first base station, the amount of resource allocation for the terminal, the transmit power of the terminal and / or others goy information. The terminal may determine its transmit power based on the interference mitigation request if it is decided to consider the interference mitigation request. In one design, the terminal may determine, account for, or ignore the interference indicator based on the result of decoding the interference indicator, path loss from the second base station to the terminal, path loss from the serving base station to the terminal, reception power, or signal quality received by the second base station, power classes of the serving base station and second base station, type of connection (e.g., limited or unlimited) of the serving base station and second base howling station and / or other information. The terminal can determine its transmit power based on the interference indicator, if they decide to consider the interference indicator. In one design, a terminal may ignore an interference indicator if it is received from a base station of a first power class (e.g., a pico base station) and if the terminal is served by a base station of a second power class (e.g., a macro base station). The terminal may take into account the interference indicator with a higher weight or with a higher priority if it is received from a base station of a second power class (for example, from a macro base station) and if the terminal is served by a base station of a first power class (for example, a pico base station).

The terminal may determine its transmit power differently at step 416. In one design, the terminal may determine a target interference level for these resources in a first base station based on a request to reduce interference. The terminal may determine the path loss from the first base station to the terminal. The terminal may then determine its transmit power based on the target interference level and path loss, for example, as shown in equation (4). The terminal may also determine a power loss coefficient based on an interference indicator, and may determine its transmit power based on an additional power loss coefficient.

In another design, the terminal may adjust its transmit power for the preceding time interval based on the interference indicator to obtain its transmit power for the current time interval, for example, as shown in equation (7). In yet another design, the terminal may adjust the power offset for the preceding time interval based on the interference indicator to obtain a power offset for the current time interval. The terminal may then determine its transmit power based on the power offset for the current time interval and at the reference power level, for example, as shown in equations (8) and (9).

In yet another design, the terminal may determine the initial transmit power based on the interference mitigation request, and may adjust the initial transmit power based on the interference indicator to obtain its transmit power. In yet another design, the terminal may determine the initial transmit power based on the interference indicator, and may adjust the initial transmit power based on the interference mitigation request to obtain its transmit power. In yet another design, the terminal may determine the maximum transmit power level and / or the minimum transmit power level based on the interference reduction request and / or the interference indicator. The terminal may determine the initial transmit power based on the interference indicator and / or the interference mitigation request, and may limit the initial transmit power based on its maximum and / or minimum transmit power levels to obtain its transmit power. The terminal may also determine its transmit power in other ways.

The terminal may transmit data to the serving base station at a specific transmit power (block 418). The terminal may determine whether or not to transmit on the pre-assigned resources for the second base station, based on the decision to consider or ignore the interference indicator (step 420). The pre-assigned resources may be zero pilot resources used by the second base station to determine controlled interference or uncontrolled interference in the second base station.

FIG. 5 shows a design of a terminal device 500. The device 500 includes a module 512 for receiving, from the first base station, a noise reduction request that asks to reduce interference on said time-frequency resources, module 514 for receiving an interference indicator transmitting the level of interference to which the second base station is exposed, module 516 for determining terminal transmit power, based on the interference reduction request and the interference indicator, a module 518 for transmitting data to a serving base station at a specific transmit power and a module 520 for determining whether or not to the second base station to transmit on pre-assigned resources, based on the decision to consider or ignore the interference indicator.

FIG. 6 shows a design of a process 600 performed by a serving base station. The serving base station may receive an interference mitigation request sent by the first base station in which it is requested to reduce interference on said time-frequency resources (block 612). The serving base station may also receive an interference indicator transmitting the level of interference to which the second base station is exposed (block 614). The first and second base stations may be different base stations or the same base station. The serving base station may schedule a terminal for transmitting data on the indicated time-frequency resources based on the interference reduction request and the interference indicator (block 616). In one design, the serving base station may determine, account for, or ignore the interference mitigation request based on the priority level of the interference mitigation request, path loss from the first base station to the terminal, path loss from the serving base station to the terminal, resource assignment value for the terminal, the transmit power of the terminal, the quality of the received signal of the terminal in the serving base station and / or other information. The serving base station may then schedule the terminal based on the interference mitigation request if it is decided to consider the interference mitigation request.

In one design, the serving base station may determine, account for, or ignore the interference indicator based on the path loss from the second base station to the terminal, the path loss from the serving base station to the terminal, power classes of the serving base station and second base station, types connecting the serving base station and the second base station and / or other information. The serving base station may schedule the terminal based on the interference indicator if it is determined that the interference indicator should be taken into account.

In one design, at 616, the serving base station may determine the initial transmit power based on the interference reduction request, at least one variable supported by the serving base station for the terminal, and / or the information that the terminal transmits to the serving base station. The serving base station may then adjust the initial transmit power based on the interference indicator to obtain the transmit power of the terminal. In another embodiment, the serving base station may determine the initial transmit power based on the interference indicator, at least one variable supported by the serving base station for the terminal, and / or information that the terminal transmits to the serving base station. The serving base station may then adjust the initial transmit power based on the interference mitigation request to obtain the transmit power of the terminal. The serving base station may also determine the transmit power of the terminal in other ways. The serving base station may send a response message to the first base station containing the predicted interference level due to the terminal scheduled on the indicated time-frequency resources (step 618).

FIG. 7 shows a design of an apparatus 700 of a serving base station. The device 700 includes a module 712 for receiving, at a serving base station, an interference mitigation request sent by a first base station requesting to reduce interference at said time-frequency resources, a module 714 for receiving an interference indicator transmitting an interference level at a serving base station, which the second base station is exposed, a module 716 for scheduling a terminal for transmitting data on said time-frequency resources based on a noise reduction request and an interference indicator, and a module 718 for transmitting Get to the first base station a response message containing the predicted level of interference due to the terminal scheduled on the indicated time-frequency resources.

FIG. 8 shows the design of a process 800 performed by a base station to reduce interference. The base station may send an interference mitigation request asking to reduce interference on said time-frequency resources (block 812). The base station may send a radio interference mitigation request to at least one interfering terminal in at least one neighboring cell. Each interfering terminal may adjust its transmit power based on the interference mitigation request. Alternatively or additionally, the base station may send a mitigation request via a reverse connection to at least one neighboring base station. Each neighboring base station can plan its terminals based on a mitigation request.

The interference mitigation request may transmit the indicated time-frequency resources, the priority level of the terminal or the data to be scheduled on the indicated resources, the target interference level for the indicated resources on the base station, the predicted interference level on the indicated resources due to the terminal, which will be scheduled on the indicated resources, and / or other information. In one design, for radio transmission, the base station may determine the transmit power of the interference mitigation request based on the target interference level for the specified time-frequency resources in the base station, for example, as shown in equation (1). The base station may then send a noise reduction request with a certain transmit power.

The base station may also send an interference indicator transmitting the level of interference detected by the base station (block 814). The base station may send a radio interference indicator to terminals in neighboring cells. Each terminal can adjust its transmit power based on the interference indicator. Alternatively or additionally, the base station may send an interference indicator via a reverse connection to at least one neighboring base station. Each neighboring base station can control the transmit power of its terminals based on the interference indicator.

The base station may determine whether or not to send an interference indicator based on uncontrolled interference in the base station. In one design, the base station can measure the reception power at the pre-assigned resources used by the base station to determine uncontrolled interference or controlled interference, depending on whether the terminal displays interference indicators from the base station on the pre-assigned resources. The base station may then estimate the uncontrolled interference in the base station based on the reception power on the pre-assigned resources. In another design, the base station may receive interference mitigation requests from neighboring base stations, and from the interference mitigation requests may determine predicted interference levels at the base station due to terminals in neighboring cells. The base station may estimate uncontrolled interference at the base station based on predicted interference levels.

FIG. 9 shows a design of a base station device 900. The device 900 includes a module 912 for transmitting a noise reduction request that asks to reduce interference on said time-frequency resources in a base station, and a module 914 for transmitting an interference indicator transmitting a level of interference detected by the base station. The modules in FIG. 5, 7 and 9 may comprise processors, electronic devices, hardware devices, electronic components, logic circuits, memory devices, program codes, firmware codes, etc., or any combination thereof.

FIG. 10 shows a block diagram of a design of terminal 110, serving base station 120 and neighboring base station 122. At serving base station 120, transmit processor 1014a may receive data from data source 1012a, control information (e.g., interference mitigation requests, interference indicators, etc.). ) from the controller / processor 1030a and scheduling information (e.g., assignment / grant messages) from the scheduling unit 1034a. Processor 1014a may process (eg, encode and modulate) data and other information to obtain data symbols and control symbols, respectively. Processor 1014a may also generate pilot symbols. Processor 1014a may process data, control, and pilot symbols (e.g., for OFDM, CDMA, etc.) and provide output samples. Transmitter (PRDT) 1016a may result in a specific form (e.g., convert to analog, amplify, filter, and upconvert) the output samples and generate a downlink signal that can be transmitted through antenna 1020a.

The adjacent base station 122 may also process data, control information and scheduling information for terminals served by the base station 122. Data, control and scheduling information and a pilot signal can be processed using a transmit processor 1014b, brought to a specific form using a transmitter 1016b, and transmitted through the antenna 1020b. At terminal 110, an antenna 1052 may receive downlink signals from base stations 120 and 122 and other base stations. The receiver (PRMN) 1054 can lead to a certain type (for example, filter, amplify, convert with decreasing frequency and digitize) the signal received from the antenna 1052 and provide input samples. Receiving processor 1056 can process input samples (e.g., for OFDM, CDMA, etc.) and provide detected symbols. The processor 1056 may further process (eg, demodulate and decode) the detected symbols, provide decoded data for the terminal 110 to the data receiver 1058, and provide decoded control information and scheduling information to the controller / processor 1070.

On the uplink, a transmit processor 1082 can receive and process data from a data source 1080 and control information (eg, resource requests) from a controller / processor 1070 and provide output samples. Transmitter 1084 can produce output samples in a specific form and generate an uplink signal that can be transmitted through antenna 1052. At each base station, uplink signals from terminal 110 and other terminals can be received using antenna 1020 and brought to a specific view using the receiver 1042 and processed by the receiving processor 1044. The processor 1044 can provide decoded data to the data receiver 1046 and decoded control information to the controller / processor 1030.

Controllers / processors 1030a, 1030b, and 1070 can control the operation of base stations 120 and 122 and terminal 110, respectively. Processor 1070 and / or other modules in terminal 110 may execute or control process 400 in FIG. 4 and / or other processes of the described techniques. A processor 1030 and / or other modules in each base station may execute or control process 600 in FIG. 6, process 800 in FIG. 8 and / or other processes of the described techniques. Memory units 1032a, 1032b, and 1072 may store data and program codes for base stations 120 and 122 and terminal 110, respectively. Scheduling units 1034a and 1034b may schedule terminals to communicate with base stations 120 and 122, respectively, and may assign resources to scheduled terminals.

Professionals should understand that information and signals can be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referenced throughout the above description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination of them.

Those skilled in the art will further recognize that the various illustrative logical blocks, modules, circuits, and algorithm steps described in connection with this disclosure may be embodied as electronic hardware, software, or a combination thereof. To clearly show this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality. Whether such functionality as hardware or software is embodied depends on the particular application and performance restrictions imposed on the entire system. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present disclosure.

The various illustrative logical blocks, modules, and circuits described in connection with this disclosure may be implemented or implemented using universal processors, digital signal processing processors (DSPs), specialized integrated circuits (ASLs), user programmable gate arrays (FPGAs), or other programmable logic devices, discrete circuits or transistor logic circuits, discrete hardware components, or any combination thereof designed to perform the described functions. A universal processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor can also be implemented as a combination of computing devices, for example, as a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors together with a DSP core, or any other similar configuration.

The steps of a method or algorithm described in connection with this disclosure may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. The program module can be located in random access memory (RAM), flash memory, read-only memory (ROM), erasable programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), in registers, on a hard disk, removable disk, on a compact disk (CD-ROM) or on a storage medium of any other form known from the prior art. An exemplary storage medium is associated with the processor in such a way that the processor can read information from it and write information to it. Alternatively, the storage medium may be an integral part of the processor. The processor and the storage medium may reside in the LIS. LIS can be in the user terminal. Alternatively, the processor and the storage medium may reside as discrete components in a user terminal.

In one or more exemplary embodiments, the functions described may be performed in hardware, software, firmware, or any combination thereof. When implemented in software, functions can be stored or transmitted as one or more instructions or code on a computer-readable medium. Computer-readable media includes both computer storage media and communication media, including any medium that facilitates moving a computer program from one place to another. Storage media can be any available media that can be accessed by a universal or special computer. By way of example, and not by way of limitation, such a computer-readable medium may comprise an OP, ROM, EEPROM, CD-ROM or other optical disk storage device, magnetic disk storage device or other magnetic storage device, or any other medium that may be used to transfer or store the necessary program code, tools in the form of commands or data structures, and which can be accessed by a universal computer or a special computer, or a universal processor or th processor. In addition, any connection must be called computer-readable media. For example, if the software is transferred from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair cable, digital subscriber line (DSL) or wireless technologies such as infrared, radio and microwave, then a coaxial cable, fiber optic cable , twisted pair, DSL or wireless technologies such as infrared, radio and microwaves include media definition. The magnetic disk and optical disk, as used in this work, include a compact disk (CD-ROM), a laser disk, an optical disk, a digital versatile disk (DVD), a floppy disk and a blu-ray disk, and magnetic disks usually reproduce data magnetically, while optical discs reproduce data optically with a laser. Computer-readable media also includes combinations of the above. The previous description of the disclosure is provided to enable any person skilled in the art to make or use this disclosure. Various modifications to this disclosure will be readily apparent to those skilled in the art, and the universal principles defined in this paper can be applied to other varieties without departing from the scope or form of the disclosure. Thus, this disclosure is not limited to the described examples and implementations, but should unite the widest area of use, compatible with the disclosed principles and new features.

Claims (15)

1. A wireless communication method, comprising the steps of:
receive from the first base station a request to reduce interference, which is requested to reduce interference on a given frequency-time resources;
receiving an interference indicator transmitting a level of interference observed by the second base station; and
determining the transmit power of the terminal based on the interference mitigation request and the interference indicator. 2. The method according to claim 1, in which the determination of the transmit power of the terminal comprises the steps of:
determine whether to accept or reject the interference mitigation request based on at least one of the result of decoding the interference mitigation request, priority level of the interference mitigation request, terminal priority level, path loss from the first base station to the terminal, loss in the transmission path from the serving base station to the terminal, reception power or received signal quality of the first base station,
resource assignment values for the terminal and terminal transmit power, and
determining the transmit power of the terminal based on the interference mitigation request, if acceptance of the interference mitigation request is determined. 3. The method according to claim 1, in which the determination of the transmit power of the terminal comprises the steps of:
determining a target interference level for said predetermined time-frequency resources in the first base station based on the interference reduction request,
determining losses in the transmission path from the first base station to the terminal, and
determine the transmit power of the terminal based on the target level of interference and loss in the transmission path. 4. The method according to claim 1, in which the determination of the transmit power of the terminal comprises the steps of:
determining at least one of a maximum transmission power level and a minimum transmission power level based on at least one of a noise reduction request and an interference indicator,
determining the initial transmit power based on the interference indicator or the interference reduction request, and
limit the initial transmit power based on at least one of the maximum and minimum transmit power levels to obtain the transmit power of the terminal. 5. A machine-readable medium on which computer-executable instructions for prescribing, when executed, at least one computer to implement the method according to any one of claims 1 to 4, are embodied. 6. A device for wireless communication, comprising:
means for receiving from the first base station a request to reduce interference, which is requested to reduce interference on predetermined time-frequency resources;
means for receiving an interference indicator transmitting a level of interference observed by a second base station; and
means for determining transmission power of the terminal based on the interference reduction request and the interference indicator. 7. The device according to claim 6, in which the means for determining the transmit power of the terminal contains
means for determining whether to accept or reject the interference mitigation request,
means for determining whether to accept or reject the interference indicator, and
means for determining a transmit power of the terminal based on the interference mitigation request, if the acceptance of the interference mitigation request is determined, and based on the interference indicator, if the adoption of the interference indicator is determined. 8. The device according to claim 6, further comprising:
means for transmitting data to a serving base station at said determined transmit power; and
means for determining whether or not to transmit at the assigned resources for the second base station based on the decision to accept or reject the interference indicator, and these assigned resources are used by the second base station to determine controlled interference or uncontrolled interference in the second base station. 9. A wireless communication method, comprising the steps of:
receiving, at the serving base station, an interference mitigation request sent by a first base station which is requested to reduce interference on predetermined time-frequency resources;
receive in the serving base station an interference indicator transmitting the level of interference observed by the second base station; and
scheduling a terminal for transmitting data on these predetermined time-frequency resources based on a noise reduction request and an interference indicator. 10. The method of claim 9, further comprising determining whether to accept or reject the interference mitigation request based on at least one of a priority level of the interference mitigation request, transmission path loss from the first base station to terminal, losses in the transmission path from the serving base station to the terminal, resource assignment values for the terminal, terminal transmit power and received signal quality of the terminal in the serving base station, while planning the terminal is performed based on the interference mitigation request, if acceptance of the interference mitigation request is determined. 11. The method according to claim 9, further comprising determining whether to accept or reject the interference indicator based on at least one of a loss in the transmission path from the second base station to the terminal, losses in the transmission path from the serving base station to the terminal, the power classes of the serving base station and the second base station, and the binding types of the serving base station and the second base station, with terminal planning being performed based on an interference indicator, if The adoption of the interference indicator is now supported. 12. A device for wireless communication, comprising:
means for receiving, at the serving base station, a noise reduction request sent by a first base station which is requested to reduce interference on predetermined time-frequency resources;
means for receiving, at the serving base station, an interference indicator transmitting the level of interference observed by the second base station; and
means for scheduling a terminal for transmitting data on these predetermined time-frequency resources based on a noise reduction request and an interference indicator. 13. The device according to item 12, in which the means for planning the terminal contains
means for determining whether to accept or reject the interference mitigation request,
means for determining whether to accept or reject the interference indicator, and
means for scheduling the terminal based on the interference mitigation request, if the acceptance of the interference mitigation request is determined, and based on the interference indicator, if the adoption of the interference indicator is determined. 14. A wireless communication method, comprising the steps of:
send a request to reduce interference, which is requested to reduce
interference at predetermined time-frequency resources in the base station; and send an interference indicator transmitting the interference level,
observed by the base station. 15. A device for wireless communication, comprising:
means for transmitting a noise reduction request that is requested to reduce interference on predetermined time-frequency resources in a base station; and
means for transmitting an interference indicator transmitting a level of interference observed by a base station.

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