RU2450483C2 - Control of interface in wireless communications system using hybrid repeated time use - Google Patents

Abstract

FIELD: information technologies.

SUBSTANCE: noise generated during wireless communications may be controlled with the help of hybrid repeated time use. The method and the device determine one or several patterns of repeated time use by appropriate one or several points of access with arbitrary placement. The second pattern of repeated time use is selected, which creates less noise with the specified one or more patterns of repeated time use. Signals are sent according to the second pattern of repeated time use from the second point of access with arbitrary placement into an associated access terminal.

EFFECT: reduced noise.

28 cl, 23 dwg

Description

Priority 35 U.S.C. §119

[0001] This application claims the priority of provisional patent application US No. 60/990541, filed November 27, 2007; provisional patent application US No. 60/990547, filed November 27, 2007; provisional application for US patent No. 60/990559, filed November 27, 2007; provisional application for US patent No. 60/990513, filed November 27, 2007; provisional application for US patent No. 60/990564, filed November 27, 2007; and provisional application for US patent No. 60/990570, filed November 27, 2007, the contents of which are incorporated herein by reference in their entirety.

FIELD OF THE INVENTION

[0002] This application relates to wireless communications and, more specifically, but without limitation, to improving communication performance.

INTRODUCTION

[0003] Wireless communication systems are widely deployed to provide multiple users with various types of communication (eg, voice, data, multimedia services, etc.). With the rapidly growing demand for high-speed and multimedia services, tasks arise associated with the implementation of effective and reliable communication systems with improved performance.

[0004] To complement conventional base stations of a mobile telephone network, base stations with a small coverage area (for example, installed in a user's home) can be deployed to provide more reliable wireless coverage in rooms for mobile devices. Such base stations with a small coverage area are known as access points, base stations, home nodes-B or femtocells. Typically, such base stations with a small coverage area are connected to the Internet or to the mobile operator’s network via a DSL router or cable modem.

[0005] Since the radio frequency (RF) coverage of base stations with a small coverage area may not be optimized by the mobile operator and the deployment of such base stations may be ad-hoc, problems with RF interference may occur. Moreover, for base stations with a small coverage area, soft handover may not be supported. Finally, the mobile station may not receive permission to exchange data with the access point that has the best RF signal due to the requirement of limited association (i.e., a closed subscriber group). Thus, there is a need for improved interference management for wireless networks.

SUMMARY OF THE INVENTION

[0006] This document relates to interference management using hybrid time reuse. By identifying interfering time reuse patterns, the optimal time reuse pattern for the access point can be tuned. In one illustrative embodiment of the invention, the communication method includes determining patterns of time reuse of neighboring unplanned access points and the offset of the control channel macro access points. The optimal time reuse pattern is selected based on maximizing the signal-to-noise ratio of the associated access terminal.

[0007] In another illustrative embodiment, the communication device includes an interference controller configured to determine time reuse patterns of neighboring unplanned access points, the signal-to-noise ratio of the access terminals being maximized.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] These and other selected aspects will be disclosed in the following detailed description, the appended claims, and the accompanying drawings, in which:

[0009] figure 1 shows a simplified block diagram illustrating selected aspects of a communication system;

[0010] figure 2 shows a simplified block diagram illustrating selected aspects of the components of an illustrative communication system;

[0011] in FIG. shows a flowchart for selected aspects of operations that may be performed to control interference;

[0012] figure 4 shows a simplified block diagram of a wireless communication system;

[0013] FIG. 5A shows a simplified block diagram of a wireless communication system including femto nodes;

[0014] FIG. 5B is a simplified diagram of an arrangement of femto nodes and access terminals illustrating negative geometric features;

[0015] FIG. 6 is a simplified diagram illustrating coverage areas for wireless communications;

[0016] FIG. 7 is a flowchart for several selected aspects of operations that can be performed to control interference using a beam and a controlled zero position of the radiation pattern;

[0017] FIG. 8 is a flowchart for several selected aspects of operations that can be performed to control interference using optimized reduced overhead power levels;

[0018] FIG. 9 is a flowchart for several selected aspects of operations that can be performed to control interference using optimized reduced overhead power levels;

[0019] FIG. 10 is a flowchart for several selected aspects of operations that can be performed to control interference using frequency selective transmission to counteract overload and negative geometric features;

[0020] FIGS. 11A-11B show a flowchart for several selected aspects of operations that can be performed to control interference by adaptively adjusting noise figure and path loss;

[0021] FIG. 12 is a flowchart for several selected aspects of operations that can be performed to control interference using a sub-frame time reuse technique;

[0022] FIG. 13 is a slot diagram illustrating time sharing by femto nodes, which can be used to control interference using a hybrid sub-frame time reuse technique;

[0023] FIG. 14 is a flowchart for several selected aspects of operations that can be performed to control interference by using hybrid sub-frame time reuse;

[0024] FIG. 15 is a simplified block diagram of several selected aspects of communication system components;

[0025] FIGS. 16-21 show simplified block diagrams of several selected aspects of devices configured to control interference using the methods described herein.

[0026] In accordance with the generally accepted approach, the various elements illustrated in the figures may not be drawn to scale. Accordingly, the dimensions of the various elements can be increased or decreased arbitrarily for clarity. In addition, some figures may be simplified for clarity. Thus, the figures may not contain all components of the illustrated hardware (eg, device) or method. The same reference numerals can be used to denote the same elements throughout the description and in all figures.

DETAILED DESCRIPTION

[0027] Various aspects of the present disclosure are described below. It should be noted that the principles and embodiments described herein may be implemented in various forms, and any particular structure, function, or combination thereof disclosed herein is illustrative. Based on the information contained herein, one skilled in the art should recognize that any aspect disclosed herein may be implemented independently of any other aspect and that two or more such aspects may be combined in various ways. For example, hardware may be implemented or the method may be implemented using any number of aspects disclosed herein. In addition, such hardware may be implemented or such a method may be implemented using other structures, other functionality, or a combination thereof in addition to or instead of one or more of the aspects disclosed herein. Moreover, an aspect may comprise at least one element of a claim.

[0028] In some aspects, the principles set forth herein can be used in networks that provide large-scale coverage (eg, wide area cellular networks, such as 3G networks, commonly referred to as macrocell networks) and finer coverage (eg, network environment households or buildings). When moving an access terminal (AP) through such a network, the access terminal can be served at certain locations by access nodes (UEs) that provide macro coverage, while at other locations, the access terminal can be served by access nodes that provide finer coverage. In some aspects, finer-coated units can be used to provide increased productivity, indoor coverage, and various services (for example, to provide more reliable customer service). As used herein, nodes providing coverage over relatively large areas may be referred to as macro nodes. Nodes that provide coverage for relatively small areas (such as households) can be called femto nodes. Nodes that cover areas smaller than macroregions and larger than femto regions can be called pico nodes (for example, providing coverage in an office building).

[0029] A cell associated with a macro node, a femto node, or a pico node may be referred to as a macro cell, femto cell, or pico cell, respectively. In some embodiments, each cell may be further associated with (eg, divided into) one or more sectors.

[0030] In various applications to refer to a macro node, femto node, or pico node. For example, a macro node can be configured as or called an access node, base station, access point, eNodeB, macro cell, etc. In the same way, a femto node can be configured as or called a home NodeB, home eNodeB, access point, base station, femtocell, etc.

[0031] FIG. 1 shows selected aspects of a communication system 100 in which distributed nodes (eg, access points 102, 104, and 106) provide wireless connectivity to other nodes (eg, access terminals 108, 110, and 112), which can be installed in or associated with an associated geographic area. In some aspects, access points 102, 104, and 106 may communicate with one or more network nodes (eg, a centralized network controller, such as network node 114) to facilitate connectivity to a wide area network.

[0032] Restrictions may be imposed on an access point, such as access point 104, such that only certain access terminals (eg, access terminal 110) have the right to access the access point, or other restrictions may be imposed on the access point . In this case, the limited access point and / or its associated access terminals (e.g., access terminal 110) may interfere with other nodes in the system 100, such as, for example, an unlimited access point (e.g., macro access point 102), its associated access terminals ( for example, access terminal 108), another restricted access point (eg, access point 106) or its associated access terminals (eg, access terminal 112). For example, the closest access point for a given access terminal may not be a serving access point for this access terminal. Accordingly, transmissions of this access terminal may interfere with reception of the access terminal. As discussed herein, frequency reuse, frequency selective transmission, interference cancellation, and an intelligent antenna (e.g., beamforming and controlling the minimum beam pattern) and other techniques can be used to mitigate interference.

[0033] Illustrative operations in system 100 will be described in more detail with reference to FIG. 2. For convenience, the operations shown in FIG. 2 (and any operations discussed herein) may be described as being performed by certain components (for example, components of a system 100 or components of a system 300 shown in FIG. 3). However, it should be noted that these operations may be performed by other types of components and may be performed using a different number of components. It should also be noted that one or more of the operations described herein may not be used in a particular embodiment.

[0034] For illustrative purposes, various aspects of the present disclosure will be described in the context of a network node, access point, and access terminal communicating with each other. However, it should be noted that the principles set forth herein may also be applicable to other types of hardware or hardware described using different terminology.

[0035] Figure 3 shows several illustrative components that can be inserted into a network node 114 (eg, a radio network controller), an access point 104, and an access terminal 110 in accordance with the principles set forth herein. It should be noted that the components illustrated for one of these nodes can also be introduced into other nodes of the system 100.

[0036] Network node 114, access point 104, access terminal 110 include transceivers 302, 304, and 306, respectively, for communicating with each other and other nodes. The transceiver 302 includes a transmitter 308 for sending signals and a receiver 310 for receiving signals. The transceiver 304 includes a transmitter 312 for sending signals and a receiver 314 for receiving signals. The transceiver 306 includes a transmitter 316 for sending signals and a receiver 318 for receiving signals.

[0037] In a typical embodiment, the access point 104 communicates with the access terminal 110 through one or more wireless communication lines and the access point 104 communicates with the network node 114 through the transport network. It should be noted that in various embodiments, wired or wireless links may be used between these or other nodes. Thus, transceivers 302, 304, and 306 may include components for both wireless and wired communications.

[0038] The network node 114, access point 104, and access terminal 110 also include various other components that can be used in the interference management disclosed herein. For example, network node 114, access point 104, and terminal 110 may include interference controllers 320, 322, and 324, respectively, to mitigate interference and provide related functions, as disclosed herein. Interference controllers 320, 322, and 324 may include one or more components to perform a certain type of interference control. Network node 114, access point 104, and access terminal 110 may also include communication controllers 326, 238, 330, respectively, for controlling communication with other nodes and providing related functions, as disclosed herein. Network node 114, access point 104, and access terminal 110 may also include timing controllers 326, 238, 330, respectively, for controlling communications with other nodes and providing related functions, as disclosed herein. Other components shown in FIG. 3 will be discussed below.

[0039] For illustrative purposes, interference controllers 320, 322 are shown as containing multiple controller components. However, in practice, a particular embodiment may not use all of these components. For example, the controller component 338 or 340 related to the hybrid automatic retransmission request (HARQ) may provide functions related to HARQ interlacing operations, as disclosed herein. The profile component 342 or 340 of the controller may provide functions related to operations associated with the transmit power or receive attenuation profile, as disclosed herein. The component 346 or 348 of the controller related to the time slots may provide functions related to operations with the time slots, as disclosed herein. The antenna component 350 or 352 of the controller may provide functions related to the operations of the smart antenna (eg, beamforming and / or controlling the minimum position of the radiation pattern) as disclosed herein. The controller component 354 or 356 related to reception noise may provide functions related to operations with adaptive adjustment of noise figure and path loss, as disclosed herein. Transmit power component 358 or 360 of the controller may provide functions related to transmit power operations, as disclosed herein. The time reuse component 362 or 364 of the controller may provide functions related to time reuse operations, as disclosed herein.

[0040] FIG. 2 illustrates how a network node 114, an access point 104, and an access terminal 110 can communicate with each other to provide interference control (eg, mitigation). In some aspects, these operations may be performed on the uplink and / or downlink to mitigate interference. In general, one or more of the techniques shown in FIG. 2 may be used in particular embodiments described below with reference to FIGS. 7-14. Thus, for clarity, when describing particular embodiments, these techniques may not be described in detail.

[0041] As represented by block 202, a network node 114 (eg, an interference controller 320) may optionally determine one or more interference control parameters for the access point 104 and / or access terminal 110. Such parameters may be presented in various forms. For example, in some embodiments, the network node 114 may determine types of interference control information. Examples of such parameters will be described in more detail below with reference to FIGS. 7-14.

[0042] In some aspects, when determining interference parameters, it may be determined how to allocate one or more resources. For example, in the operations indicated in block 402, it can be determined how the allocated resource (e.g., frequency spectrum, etc.) can be divided for partial reuse. In addition, when determining partial reuse parameters, it can be determined which part of the allocated resource (for example, HARQ repeats) can be used by each access point from a set of access points (for example, restricted access points).

[0043] In some aspects, the network node 114 may determine, based on the received information, a parameter that indicates whether interference may occur on the uplink or downlink, and, if so, indicates the level of such interference. Such information can be received from various nodes in the system (for example, from access points and / or access terminals) and in various ways (for example, through a transport network, over the air, etc.).

[0044] For example, in some cases, one or more access points (eg, access point 104) may monitor the uplink and / or downlink and send an indication of interference detected in the uplink and / or downlink to the network node 114 (eg , periodically or in response to a request). As an example of the first option, the access point 104 can calculate the signal strength for its received signals from neighboring access terminals that are not associated (for example, are not served) with the access point 104 (for example, access terminals 108 and 112), and reports this to network node 114.

[0045] In some cases, each access point in the system may generate a load indication when it experiences a relatively high load. Such an indication may take the form, for example, a 1xEV-DO busy bit, a channel for transmitting non-serving cell comparative power (RGCH) information to 3GPP, or any other suitable form. In a standard scenario, an access point can send this information to its associated access terminal via a downlink. However, such information can also be sent to network node 114 (for example, via a transport network).

[0046] In some cases, one or more access terminals (eg, access terminal 110) may monitor downlink signals and provide information based on such tracking. Access terminal 110 can send such information to access point 104 (which can then redirect information to network node 114) or to network node 114 (via access point 104) Other access terminals in the system can send information to network node 114 in a similar way.

[0047] In some cases, the access terminal 110 may generate measurement messages (eg, periodically). In some approaches, such a measurement message may indicate from which access point the access terminal 110 receives signals, an indication of the signal strength associated with the signals from each access point (e.g., Ec / Io), propagation path loss to each access point, or which or other relevant information. In some cases, the measurement message may include information related to any download indication received by the downlink access terminal 110.

[0048] Then, the network node 114 may use information from one or more measurement messages to determine whether the access point 104 and / or access terminal 110 is relatively close to another node (eg, to another access point or access terminal). In addition, the network node 114 may use this information to determine if the access point 104 and / or the access terminal 110 interferes with any other node. For example, a network node 114 may determine the intensity of a received signal at a node based on the transmit power at a node that transmits loss path signals between these nodes.

[0049] In some cases, access terminal 110 may generate information that indicates a signal to noise ratio (eg, signal to noise ratio, SINR) in a downlink. Such information may include, for example, a channel quality indicator (CQI), a data rate control indicator (DRC), or some other suitable information. In some cases, this information may be sent to access point 104, and access point 104 may forward this information to network node 114 for use in interference control operations. In some approaches, the network node 114 may use such information to determine if there is interference in the downlink, or to determine if the interference in the downlink is increasing or decreasing.

[0050] As more similarly described below, in some cases, interference-related information can be used to determine how to reduce interference. As one example, CQI or other suitable information may be received for each HARQ cycle, with the subsequent determination of which of the HARQ cycles is associated with the lowest interference level. A similar technique can also be applied to other partial reuse methods.

[0051] It should be noted that the network node 114 may determine the parameters in various other ways. For example, in some cases, the network node 114 may randomly select one or more parameters.

[0052] As indicated in block 204, the network node 114 (eg, a communication controller 326) sends certain interference control parameters to the access point 104. As described below, in some cases, the access point 104 uses these parameters, and in some cases, the access point 104 sends these parameters to the access terminal 110.

[0053] In some cases, the network node 114 may control interference in the system by determining the interference control parameters to be used by two or more nodes (eg, access points and / or access terminals) in the system. For example, in the case of a partial reuse scheme, the network node 114 may send various (e.g., mutually exclusive) interference control parameters to neighboring access points (e.g., access points that are close enough to each other to cause mutual interference). As a specific example, network node 114 may allocate a first HARQ cycle to access point 104, and a second HARQ cycle to allocate to access point 106. In this case, the communication made by one limited access point may not cause significant interference to the communication made by the other limited access point.

[0054] As shown in block 206, the access point 104 (eg, the interference controller 322) determines the interference control parameters that it can use or which it can send to the access terminal 110. In cases where the network node 114 determines the interference control parameters for the access point 104, this determination operation may consist in receiving the set parameters and / or retrieving the set parameters (for example, from the data memory).

[0055] In some cases, the access point 104 itself determines the interference control parameters. These parameters may be similar to those discussed above in the description of block 202. In addition, these parameters may be determined in a manner similar to the method discussed above in the description of block 202. For example, access point 104 may receive information (eg, measurement messages, CQI , DRC) from access terminal 110. In addition, the access point 104 may monitor the ascending and / or descending line in order to determine the presence of interference in this line. Access point 104 may also randomly select a parameter.

[0056] In some cases, the access point 104 may cooperate with other access points to determine the interference control parameter. For example, in some cases, the access point 104 may communicate with the access point 106 to determine which parameters are used by the access point 106 (and select other parameters) or to coordinate the use of different (eg, mutually exclusive) parameters. In some cases, the access point 104 may determine whether it will interfere with another node (for example, based on the CQI feedback, which indicates that the resource is using another node) and, if so, determine its interference control parameters so that reduce possible interference.

[0057] As shown in block 208, the access point 104 (eg, communication controller 328) may send interference control parameters or other relevant information to the access terminal 110. In some cases, this information may relate to power control (e.g., determine uplink transmit power).

[0058] As shown in blocks 210 and 212, the access point 104 may transmit to the access terminal 110 on the downlink, and the access terminal 110 may transmit to the access point 104 on the uplink. Thus, the access point 104 can use its interference control parameters for downlink transmission and / or for uplink reception. Similarly, access terminal 110 may consider these interference control parameters when receiving on the downlink or transmitting on the uplink.

[0059] In some embodiments, an access terminal 110 (eg, an interference controller 306) may determine one or more interference control parameters. Such parameters may be used by access terminal 110 and / or may be sent (e.g., by communication controller 330) to access point 104 (e.g., for use in uplink operations).

[0060] FIG. 4 shows a wireless communication system 400 configured to support multiple users in which the principles set forth herein may be implemented. System 400 provides communications for multiple cells 402, such as, for example, macro cells 402A-402G, with each cell being served by a corresponding access node 404 (eg, access nodes 404A-404G). As shown in FIG. 4, access terminals 406 (e.g., access terminals 406A-406L) can be scattered a given time at various locations throughout the system. Each access terminal 406 can currently communicate with one or more downlink (DL) access nodes (also called forward link (FL)) and / or uplink (UL) access nodes 404 (also called reverse link (RL)) , depending on, for example, whether the access terminal 406 is active and whether it is in a soft switching state. Wireless communications system 400 can provide service to a wide geographic area. For example, macro cells 402A-402G may cover several neighboring quarters.

[0061] As already mentioned, nodes or local access points that provide coverage for a relatively small area (eg, households) may be referred to as femto nodes. FIG. 5A shows an illustrative communications system 500 in which one or more femto nodes are deployed within a network environment. In particular, system 500 includes a plurality of femto nodes 510 (e.g., femto nodes 510A and 510B) installed in a relatively small scale network environment (e.g., in one or more user households 530). Each femto node 510 may be connected to a wide area network 530 (e.g., the Internet) and a core network 550 of a mobile operator via a DSL router, cable modem, wireless line or other means of connection (not shown). As discussed below, each femto node 510 may be configured to service associated access terminals 520 (e.g., access terminal 520A) and, optionally, unassociated (foreign) access terminals 520 (e.g., access terminal 520F). In other words, access to the femto nodes 510 may be limited, whereby this access terminal 520 may be served by a set of designated home femto nodes 510, but may not be served by unassigned foreign femto nodes 510 (e.g., neighbor femto node 510).

[0062] FIG. 5B shows in more detail negative geometries for multiple femto nodes and access terminals in a network environment. In particular, the femto node 510A and the femto node 510B are respectively deployed in neighboring households of users 530A and 530B. Access terminals 520A-520C are allowed to associate and communicate with the femto node 510A, but not with the femto node 510B. Similarly, the terminal 520D and the access terminal 520E are allowed to associate and communicate with the femto node 510B, but not with the femto node 510A. The terminal 520F and the access terminal 520G are not allowed to associate and communicate with either the femto node 510B or the femto node 510A. The terminal 520F and the access terminal 520G may associate and communicate with the macro cell access node 560 (Fig. 5A) or another femto node in another household (not shown).

[0063] When arbitrarily deploying femto nodes 510 with limited association (ie, the access point may not be allowed to associate with the nearest femto node providing the best signal quality), interference and negative geometry are common. Solutions to the negative geometry problem are discussed below.

[0064] FIG. 6 shows an example of a coverage map 600 where several tracking areas 602 (or routing areas, or location areas) are defined, each of which includes several macro coverage areas 604. Meanwhile, coverage areas associated with tracking areas 602A, 602B, and 602C are indicated by wide lines, and macrocoating areas 604 are represented by hexagons. The tracking areas 602 also include areas 606. In this example, each of the femto coating areas 606 (e.g., the femto coating area 606C) is depicted inside the macro coating area 604 (e.g., macro coating area 604B). It should be noted that the femto coating area 606 may not lie within the macro coating area 604. In practice, a given tracking area 602 or macrocoating area 604 can be defined with a large number of femto coating areas 606. In addition, within the tracking area 602 or the macrocoating area 604, one or more picocoating areas (not shown) can be defined.

[0065] As shown in FIGS. 5A-5B, the owner of the femto node 510 can subscribe to a mobile service, such as a 3G mobile service, provided through a mobile operator’s core network 550. In addition, the access terminal 520 may be configured to operate both in a macro network environment and in a smaller network environment (eg, household scale). In other words, depending on the current position of the access terminal 520, the access terminal 520 may be served by an access node 560 of a mobile network 550 with macro cells or one of a plurality of femto nodes 510 (e.g., femto nodes 510A and 510B that are located in the corresponding user household 530). For example, when a subscriber is outside his home, he is served by a regular macro access node (for example, node 560), and when a subscriber is at home, he is served by a femto node (for example, node 510A). It should be noted that the femto node 520 may be backward compatible with existing access terminals 520.

[0066] Femtocell 510 may be deployed on a single frequency or, alternatively, on multiple frequencies. Depending on the specific configuration, one frequency or one or more of the many frequencies may overlap with one or more frequencies used by the macro node (for example, node 560).

[0067] In some embodiments, the access terminal 520 may be configured to connect to a preferred femto node (eg, a home femto node of an associated access terminal 520), if such a connection is possible. For example, if the access terminal 520 is within the user's household 530, it may be desirable for the access terminal 520 to communicate only with the home femto node 510.

[0068] In some embodiments, if the access terminal 520 operates within the macrocell network 550 but is not located in its most preferred network (for example, as recorded in the preferred roaming list), the access terminal 520 may continue to search for the most preferred network (for example, home femtocell 510), using reselection of the best system (BSR), which may include periodic scanning of available systems to determine if the best systems are currently available, followed by associated oia with such preferred systems. When performing a search, access terminal 520 may restrict the search to a specific frequency band or channel. For example, a search for the most preferred system may be repeated periodically. After discovering the preferred femto node 510, the access terminal 520 selects the femto node 510 for permanent connection within its coverage area.

[0069] In some embodiments, restrictions may be imposed on the femto node. For example, a given femto node can provide only certain services only to certain access terminals. When a so-called limited (or closed) association is deployed, this access terminal can only be served by a mobile network with macro cells and a specific set of femto nodes (for example, femto nodes 510, which are located inside the corresponding user's household 530). In some embodiments, the implementation of the node may be limited in such a way that it does not provide at least one node, at least one of the following: signaling, data access, registration, call or service.

[0070] In some embodiments, a restricted or foreign femto node (which may also be called a home NodeB of a closed subscriber group) provides services to a limited set of access terminals. This set can be expanded temporarily or permanently. In some embodiments, a Closed Subscriber Group (CSG) may be defined as a set of access nodes (eg, femto nodes) that share a common access control list of access terminals. A channel on which all femto nodes (or all restricted femto nodes) in a given area operate can be called a femto channel.

[0071] Various relationships may exist between this femto node and this access terminal. For example, from the point of view of the access terminal, an open femto node can be considered as a femto node without association restrictions. Restricted femto nodes can be femto nodes that are subject to certain restrictions (for example, restrictions on association and / or registration). A home femto node may be a femto node for which the access terminal is authorized to perform access and work. The guest femtocell may be a femtocell for which the access terminal is temporarily authorized to perform access and work. A restricted or foreign femtocell may be a femtocell for which the access terminal does not have authorization to perform access and work, except, possibly, in emergency situations (for example, calling 911).

[0072] From the point of view of a restricted or foreign femto node, the associated or home access terminal may be an access terminal that is authorized to access the restricted femto node. The guest access terminal may be an access terminal with temporary access to a limited femto node. An unassociated (alien) access terminal may be an access terminal that does not have permission to gain access to a limited femto node, with the possible exception of emergency situations, such as calling 911 (for example, an access terminal that does not have authority or permission to register with limited femto node).

[0073] For simplicity, various functions are described herein in the context of a femto node. However, it should be noted that pico nodes can provide similar or similar functions for a larger coverage area. For example, a pico node may be limited, a home pico node may be defined for a given access terminal, and the like.

[0074] A multiple access wireless communication system may simultaneously support communication for multiple wireless access terminals. As indicated above, each terminal can communicate with one or more base stations using transmissions on the downlink (straight line) and uplink (return line). The downlink is the communication line from the base stations to the terminals, and the uplink is the communication line from the terminals to the base stations. Such a communication line can be established using a system with one input and one output, a system with multiple inputs and multiple outputs (MIMO), or systems of a different type.

[0075] The MIMO system uses multiple (N _T ) transmit antennas and multiple (N _R ) receive antennas for data transmission. A MIMO channel formed by N _T transmit antennas and N _R receive antennas can be decomposed into N _S independent channels, which are also called spatial channels, where N _S ≤min {N _T , N _R }. Each of the N _S independent channels corresponds to a dimension. A MIMO system can provide increased performance (for example, higher throughput and / or increased reliability) if additional dimensions created by multiple transmit and receive antennas are used.

[0076] The MIMO system may support time division duplex ("TDD") and frequency division duplex ("FDD"). In a TDD system, forward and reverse link transmissions are in the same frequency domain, so the reversibility principle makes it possible to estimate a downlink (straight line) channel from an uplink (reverse line) channel. This allows the access point to determine the gain in the transmission with the formation of the beam downlink, if the access point has many antennas.

[0077] As already indicated, in the arbitrary deployment of base stations with an association restriction (ie, the mobile station is not allowed to associate with the nearest base station with which it can establish the most reliable connection), interference and negative geometry are common. In one illustrative embodiment, the spatial structure of which is shown in FIG. 5B, the femtocell 510A and the femtocell 510B are deployed in neighboring households. Access terminals 520A-520C are allowed to associate and communicate with the femto node 510A, but not with the femto node 510B. Similarly, access terminals 520D-520E are allowed to associate and communicate with the femto node 510B, but not with the femto node 510A. Access terminals 520F-520G are not allowed to associate and communicate with any of the femto nodes 510A-510B. Access terminals 520F-520G may be associated with macro access node 560 (Fig. 5A) or with another femto node in another household (not shown). Accordingly, such a negative geometry with respect to access-enabled femto nodes and neighboring access terminals can lead to interference and jamming in the uplink and downlink.

[0078] SILENCING THE Ascending Line

[0079] For example, suppose that L _A3 (dB) and L _A5 (dB) are path loss, between the femto node 510A and the access terminal 520C and the access terminal 520D, respectively. In particular, L _A3 may be much larger than L _A5. Thus, when the access terminal 520D transmits to its home femto node 510B, it creates excessive interference (or drowns) the femto node 510A, effectively blocking the reception of access terminals 520A-C in the femto node 510A. In such an uplink jamming situation, even if the access terminal 520C transmits with a maximum Tx power of P _3max , the received C / I for the access terminal in the femto node 510A can be characterized as follows:

C / I (AT 520C in the femto node 510A) = P _3max -L _A3 - (P ₅ -L _A5 ) (dB)

[0080] In some illustrative embodiments, depending on the transmit power P ₅ , the C / I of the access terminal 520C in the femto node 510A can be a very large negative number due to the large value of L _A3 . This geometric configuration is called the extremely negative geometry of the ascending line.

[0081] SILENCING THE DOWNLINE

[0082] Similarly, in one illustrative embodiment, L _B5 can significantly exceed L _A5 . This means that when the femto node 510A transmits an access terminal 520A, this can create extremely strong interference (or jamming) in the access terminal 520D, effectively blocking the reception of the femto node 510B in the access terminal 520D. In such a downlink jamming situation, the received C / I for the femto node 510B in the access terminal 520D can be characterized as follows:

C / I (femtocells B in AT 5) = P _B -L _B5 - (P _A -L _A5 ) (dB)

[0083] The C / I of the femto node 510B in the access terminal 520C can be a very large negative number due to the large value of L _B3 . This geometric configuration is called the extremely negative downlink geometry.

[0084] The practical options discussed below can solve the problem of negative geometry without the need to modify the operation of existing access terminals. Thus, in the present exemplary embodiment, it is desirable to reduce interference caused by negative geometry by modifying processes in the femto node, rather than in the access terminals. Accordingly, the problem of the negative geometry of the ascending line and the descending line is solved using the illustrative embodiment described below.

[0085] With reference to FIG. 7, as well as to FIGS. 5A-5B, operations related to controlling the position of the beam and controlling the position of the minimum radiation pattern to solve the problem associated with jamming and negative geometry will be described in detail. The present illustrative embodiment uses methods and hardware to prevent jamming and effects associated with negative geometry using beam position control and beam minimum position control at an arbitrary location of a restricted access base station.

[0086] In an illustrative scenario for deploying a femto node, adjacent signals (required or interference) may be Ricean in nature, which implies a strong directional component and uniform attenuation over the frequency band (due to a small spread of delays and multiple reflection paths inside the building). Particularly in the case of jamming, sectorization can provide the desired method of counteracting the strong Ricean interference component.

[0087] As shown in block 702, the femto node 702 continuously listens (ie, receives in accordance with various receiver configurations described herein) in order to detect transmission from access terminals 520. As shown in branch block 704, the femto node 510 determines whether the access attempt (eg, transmission) by the access terminal is directed to the femto node 510. If the detected access terminal access attempt is directed to a specific femto node 510, then, as shown in block 706, there is no the need to reduce interference, since the access terminal is an access terminal associated with a home femto node.

[0088] As shown in branch block 708, further the femto node 510 compares the characteristics (eg, power level) of an access attempt to determine whether the characteristic exceeds a threshold level that causes interference in the home femto node. If the attempt to gain access does not exceed the interference threshold, then, as shown in block 706, there is no need to reduce interference, since the characteristic of the attempt to gain access by the home femto node 510 leads to acceptable interference.

[0089] As shown in block 710, if the home femto node 510 receives a strong enough signal (for example, exceeding the interference threshold) to gain access or some other strong uplink signal from an unassociated access terminal 520, the home femto node 510 uses a shaping beam ( i.e. directional transmission and reception) of an antenna for orienting the direction of the signals or the absence of signals (eg, zero of the diagram) in the direction of the unassociated access terminal 520 in the downlink and uplink.

[0090] For example, beamforming (ie, controlling the direction of the beam) can be accomplished using the sectorized or directional (eg, switching of the beam) antenna configurations described herein for beamforming and / or minimum transmission or beam signal and / or minimum reception signal. In particular, interference cancellation can be performed for the received radio frequency (RF) signal, thereby reducing problems at the receiver, such as overloading the input stages and reducing the sensitivity of analog-to-digital conversion, which is a consequence of jamming femto nodes. In addition, the sectorized or directional configuration of the antennas allows you to save the same directional component for the uplink and downlink, for use in both directions of transmission.

[0091] As shown in block 712, downlink and pilot signal transmissions, as well as traffic channel transmissions, if any, are performed in accordance with beamforming, so that a minimum amount is directed toward a neighboring unassociated terminal energy. The direction of the transmission signal away from the unassociated access terminal reduces the effects of negative geometry for the unassociated access terminal.

[0092] As shown in block 714, the minimum radiation patterns are oriented towards the nearest unassociated access terminal 520 using the antenna configuration (eg, sectorized antennas, or controlling the direction of the minimum radiation patterns using an adaptive phased array antenna) described herein. Thus, when the associated access terminal 520 tries to contact the home femto node 510, the access attempt signal of the associated access terminal, as well as other traffic (e.g., voice / data) will not be drowned out by strong transmission signals from neighboring unassociated access terminals having negative geometry.

[0093] For example, if the access point uses two separate antennas, then the access point can monitor the characteristics of the access attempt signals from the access terminal on both antennas. If a strong uplink signal is detected on one of the antennas from an unassociated access terminal, the access point can disable the transmission function (control of the beam direction) and disable the reception function (control the direction of the minimum of the diagram) on this antenna.

[0094] As shown in block 716, the femto node 510 periodically (eg, once per second) disables sectorization of the minimum of the diagram in the receiving direction to determine, as shown in block 702, whether the unassociated access terminal 520 with a strong signal has moved or stopped transmitting. If, as shown in block 704, the strong unwanted signal disappears, the femto node 510 can disable the minimum sectorization of the diagram and continue to work with omnidirectional transmission and reception, as shown in block 706. If the strong unwanted signal is still present or has moved and exceeds the threshold value, as shown in block 708, the femto node 510 can adjust the receive and transmit sectorization by orienting the zero position of the radiation pattern, as shown in block 710, in the direction of the undesired unassociated erminala 520 access.

[0095] The example described above with reference to FIG. 5B shows a femto node 510A that orientates a chart zero during sectorization towards an unassociated access terminal 520D while the unassociated access terminal 520D is in an active connection state with the femto node 510B. When the unassociated access terminal 520D enters standby mode, the femtocell 510A returns to omnidirectional transmission and reception.

[0096] During periods of zero orientation of sectorization in a particular direction, if the associated access terminal 520 is in that direction, it may experience a malfunction. Accordingly, in the illustrative embodiment, the femto node 510 sends zero sectorization (i) only while the unwanted unassociated access terminal 520 with a strong signal is active and (ii) only if the unwanted transmission from the unassociated access terminal 520 exceeds a high threshold signal strength at the receiver, as determined in block 708, which indicates that the signal to attempt access from the desired associated access terminals cannot be decoded in the femto node 510. Referring to FIG. 5B, It should be noted that the femto node 510B may not orient the sectorization zero towards the unassociated access terminal 520A, since the signal from the unassociated access terminal 520A is not very strong. If the femto node 510B orientates the sectorization zero towards the unassociated access terminal 520A, this will interrupt the operation of the desired associated access terminal 520E.

[0097] In general, if the access point cannot determine the direction of interference from the unassociated access terminal (for example, in the case of very strong jamming, saturating the access point receiver), it may try to use different directions to orient the beam and the zero of the diagram to maximize the quality of the received signal from the associated access terminal.

[0098] With reference to FIG. 8, as well as to FIGS. 5A-5B, a detailed description will be given of operations related to the use of optimizing transmission power over service channels to solve jamming and negative geometry problems. The present illustrative embodiment uses methods and hardware to prevent jamming and negative geometry effects using optimized power levels in the service channels during arbitrary deployment of base stations.

[0099] In the General case, the transmission power level on the service channels and the total transmission power of the femto node is determined based on the desired range of the femto node. To allow access terminals to access the femto node at a location where the access terminal is muffled by a neighboring femto node that refuses to associate, overhead channels (e.g., common control channels such as a pilot channel, a synchronization channel, and a broadcast / call channel) subjected to temporary multiplexing. For this, various timelines and time multiplexing methods can be used. In addition, overhead channels can only be switched on periodically, for example at the cyclic slot index of the associated access terminals, so that the associated access terminals can receive call messages. In yet another configuration, the femto node may not perform signaling at all.

[0100] However, during an active voice call or data transfer, there may be no waiting periods that allow a neighboring femto node to temporarily multiplex the service channels of the muted due to the presence of negative geometry. Accordingly, an illustrative embodiment describes a method for optimizing the transmission power of overhead signals (e.g., pilot channels, synchronization channels, and broadcast / call channels) in the case of an active call in the femto node when temporary overhead multiplexing is not practical.

[0101] For example, in 1xRTT and WCDMA networks, level settings for overhead channels (eg, pilot channels, call channels, synchronization channels) are tuned for specific performance based on geometry and coverage constraints. In addition, the deployment of femto nodes has significant differences compared to the deployment of access nodes with macrocells. Such differences include:

1. Due to the limited coverage size, the maximum values of losses on the propagation path are much lower for areas (eg, cells) served by femto nodes, compared with areas (eg, cells) served by access nodes with macro cells (eg 80 dB maximum losses on a path propagation compared to 140 dB in the deployment option with macro cells);

2. The number of simultaneously active access terminals is less in cells served by femto nodes than in cells served by access nodes with macro cells (1-2 users compared to 20-40 users);

3. As discussed above, due to restrictions on associations with femto nodes, negative placement geometry may be common when deploying femto nodes, as opposed to deploying access nodes with macro cells.

[0102] These differences can lead to very different optimal power setting parameters for the service channels for femto nodes 510. Since the femto node 510 typically has zero to several active terminals 520, it would be desirable to keep the service channels at a minimum power level to reduce interference to neighboring cells. served by femto nodes 510 and access nodes 560 with macrocells (i.e., joint work on channels is assumed). For example, in one illustrative embodiment, the emphasis is on optimizing the pilot channel, the analysis is also applicable to other service channels.

[0103] In the illustrative embodiment, the optimal traffic-to-pilot (T2P) value is determined for the case where a single voice call is determined, as well as the default pilot strength setting, Ecp _DEFAULT . When downlink (forward link) power control code changes the traffic-to-pilot ratio, the pilot power is adjusted in such a way as to maintain the lowest value of the total transmit power and interference caused by the neighboring femto node.

[0104] For example, the access terminal 520A at the boundary of the home femto node 510A and the neighboring femto node 510B have equal path loss for both femto nodes 510, and the neighboring femto node 510 transmits at full power, thereby interfering, Ior_max. In the present example, assuming that the home femto node transmits a pilot channel with a certain power level, Ecp, the pilot signal to noise ratio (SNR) can be written as follows: Ecp / Ior_max. In accordance with the present exemplary embodiment, it is desired to find the optimum Ecp setting that will result in the lowest total transmit power from the home femto node 510A.

[0105] As shown in block 802, the gain Ecp level in the pilot channel is initialized with the Ecp _DEFAULT value. Thus, the default Ecp value (Ecp _DEFAULT ) can be determined based on reasonable differential load and path loss expected in femto networks.

[0106] As shown in block 804, a traffic call (eg, voice call) is established between the home femto node 510A and the access terminal 520A with the power used in the traffic channel designated as Ect. In one illustrative embodiment, the value of Ect is determined by controlling the power of the downlink (straight line), as shown in branch block 806. Downlink (straight line) power control is used to maintain the required quality of service (for example, the required packet error rate, PER). The downlink (straight line) power control can either indicate a decrease in Ect, as shown in block 808, or indicate an increase in Ect, as shown in block 810, or indicate no change in Ect.

[0107] As shown in block 812, the determination of the level of packet errors (PER) is used to identify adequate signal quality. In general, if Ecp is very low, then the channel quality estimate will be degraded, resulting in a very large Ect. With increasing Ecp, channel quality estimation will improve, and the required Ect will decrease. However, if Ecp becomes very large, then the channel quality estimate will exceed the required value, which will not lead to a further decrease in Ect. Accordingly, if the PER is inadequate, downlink (straight line) power control adjusts the Ect.

[0108] Since the interference generated by other femto nodes must be minimized, it is necessary to obtain an optimal value of Ecp, which leads to a minimum (Ect + Ecp). As shown in block 814, determine Ecp _OPTIMAL , where:

In another, the optimal Ecp value was found that minimizes the total transmit power, where

Ect = f (Ecp)

(the function f (.) can be determined using stand-alone modeling or tests).

Then, as shown in block 816, the optimal value of Ect is determined as

Ect _OPTIMAL = f (Ecp _OPTIMAL )

[0109] As shown in block 818, the T2P _OPTIMAL is determined as follows:

[0110] In another illustrative embodiment, the simulation can be performed to find Ecp _OPTIMAL and Ect _OPTIMAL for the usual types of channels expected in cells of femto nodes, using, for example, models with uniform either Rayleigh or Rays fading, with a low Doppler effect, which can be tracked using power management. D of one illustrative embodiment, these optimal values depend on the differential value of the specific losses on the propagation path from the access terminal to the neighboring femto node and on the interference power received from the neighboring femto node (for example, if the mobile terminal has losses on the propagation path to the neighboring femto node by 3 dB less compared to the home femto node, then the optimal values of Ecp and Ect should be increased by 3 dB).

[0111] On the other hand, in an alternative illustrative embodiment, if a neighboring femto node transmits halfway from Ior_max, then the optimal Ecp and Ect values should be reduced by 3 dB. However, it should be noted that a very frequent change in Ecp value is not practical, since it determines the boundaries of femtocell redirection. Thus, as already mentioned, the default Ecp value (Ecp _DEFAULT ) can be determined based on the reasonable differential load and path loss expected in femto networks.

[0112] As shown in Fig. 9, in order to maintain an optimal mode of operation in cases with differential load and path loss values exceeding the expected values, in one illustrative embodiment, the following algorithm can be used for each of the many calls arising between the femto node and multiple associated access terminals.

[0113] As shown in block 902, the gain Ecp level in the pilot channel initializes the Ecp _DEFAULT value for analyzing each voice call. Thus, the default Ecp value (Ecp _DEFAULT ) can be determined based on reasonable differential load and path loss expected in femto networks.

[0114] As shown in block 904, the process is repeated for each call established between the home femto node 510A and the associated access terminals 520 with the power used in the traffic channel designated as Ect. In one illustrative embodiment, the value of Ect is determined by controlling the power of the downlink (straight line), as shown in block 906 branches. Downlink (straight line) power control is used to maintain the required quality of service (e.g., packet error rate, PER). The downlink (straight line) power control can either indicate a decrease in Ect, as shown in block 908, or indicate an increase in Ect, as shown in block 910, or indicate no change in Ect.

[0115] As shown in branch block 912, packet error rate determination (PER) is used to identify adequate signal quality. Accordingly, if the PER is inadequate, downlink (straight line) power control adjusts the Ect.

[0116] As shown in block 918, T2P _FILTERED (eg, Ect _FILTERED / Ecp _FILTERED ) is monitored during a call. The purpose of T2P filtering is to eliminate small scale fluctuations in the calculation of T2P. For example, a moving average filter can be used to filter Ect and Ecp values to calculate Ect _FILTERED and Ecp _FILTERED, respectively.

[0117] As shown in branch block 920, a T2P _FILTERED value analysis is _performed . If T2P _FILTERED > T2P _OPTIMAL + Δ ₁ , then, as shown in block 922, Ecp is increased to:

[0118] As shown in block 924, a T2P _FILTERED value analysis is _performed . If T2P _FILTERED <T2P _OPTIMAL -Δ ₂ , then, as shown in block 926, Ecp is reduced to:

[0119] T2P _OPTIMAL depends on the specific traffic configuration (speed, coding, etc.). For example, if two users make voice calls using vocoders at the same speed, they will have the same T2P _OPTIMAL values. However, if there is another user performing the data transfer (for example, 1xRTT data transfer at 153 kb / s), this will require a different T2P _OPTIMAL . After determining T2P _OPTIMAL for a given user (based on the type of traffic), the algorithm automatically adjusts Ecp. Such an algorithm is defined for one user. In the case of many users, the algorithm can give different Ecp values for each user. However, service channels are common to all users, and we can only have one installation for Ecp. Thus, the algorithm can be generalized to the case of multiple users. For example, the “optimal” Ecp _i for each user (i = 1, ..., N) in the system can be found as described above, and then the real Ecp can be displayed as max (Ecp ₁ , ..., Ecp _N ). Another possibility is to find the optimal Ecp, such that the total transmission power of overhead information and traffic for all users is minimized. This leads to a modification of the calculations shown in block 814:

For users from 1 to N in the femtocell. The purpose of T2P filtering is to eliminate small scale fluctuations in the calculation of T2P. For example, a moving average filter can be used to filter Ect and Ecp values to calculate Ect _FILTERED and Ecp _FILTERED, respectively.

[0120] An optimal T2P can be obtained by simulation, and after the T2P output, an Ect trim (which is part of the 3G standard operations) can be determined using power control. Then Ecp is adjusted to achieve / support T2P. In particular, two algorithms can be performed together: 1) a power control algorithm that adjusts the Ect; 2) Ect tuning is described in this document.

[0121] In the above algorithm, Δ1 and Δ2 are hysteresis parameters used to prevent rapid fluctuations of Ecp. In addition, to prevent drastic changes in Ecp, the above equations can be modified in one illustrative embodiment to effect Ecp correction more slowly. Other overhead channels (e.g., call channel, synchronization channel) can be adjusted based on the power level of the pilot signal (i.e. their relative power level in relation to the power level of the pilot signal can be kept constant).

[0122] Thus, illustrative embodiments have been described to reduce the transmission power of service signals (eg, pilot channel, synchronization channel, and broadcast / call channel) when there is an active call in the femto node by determining the optimal power level of service signals. An exemplary embodiment has been described using a pilot channel as an illustrative channel. However, this analysis can also be applied to any service channel.

[0123] Below, with reference to FIG. 10 and FIGS. 5A-5B, operations related to the use of frequency selective transmission to solve problems associated with jamming and negative geometry are described in more detail. As noted, due to the arbitrary deployment of the femto nodes, the received SINR for the associated access terminal can be very low due to interference during transmission carried out by the neighboring femto node. Such interference degrades the efficiency of the control channel and the traffic channel of the access terminal and, as a result, can lead to an interruption in operation or to a decrease in the number of services. The illustrative embodiments disclosed herein are aimed at improving the performance of an access terminal in a high interference area without having to replace existing access terminals.

[0124] In the general case, in an illustrative embodiment, frequency selectivity is specifically introduced for downlink transmissions by orthogonalizing the waveform during transmission with respect to adjacent femto nodes to minimize interference. As an example, each femto node 510 selects a transmission pulse shape by reading a channel from available waveforms, for example, from three waveforms of a 3-tap channel, with each set of coefficients from a given row, for example a 3x3 DFT matrix. In this case, for a given access point, each transmitted waveform will be filtered by a 3-tap FIR (in addition to the normal filtering of the main band) with pulse filter responses selected from one of the following three waveforms:

where exp (jx) = cos (x) + j sin (x) .

[0125] An alternative choice is two impulse responses with coefficients of 2x2 DFT (N = 2). The selection of the transmission filter is retained for a period after which the femto node 510 can re-select based on the reading of the channel.

[0126] With reference to FIG. 10, a method for controlling interference when selecting a transmission waveform in a wireless communication system is described. As presented in block 1002, a set of N transmit waveforms is assigned to the femto node 510 for use in downlink transmissions. In one illustrative embodiment, the channel waveform may be formed from N-tap channel filter coefficients with each set of coefficients obtained from a particular row in an NxN DFT matrix.

[0127] As shown in block 1004, the femto node 510 selects a default waveform upon initialization (eg, power on) according to a specific selection process (eg, randomization, randomly defined network, etc.). The default waveform from a set of N transmit waveforms (downlink). The default waveform is initially set as the preferred transmit waveform, TxWave _PREFERED .

[0128] As shown in block 1004, upon initiation of the cell, the femto node 510 transmits in a downlink using a preferred waveform of the transmission. A call is established by an associated access terminal 520, which includes channel quality indicators (e.g., Channel Quality Indicator (CQI), data rate control (DRC)) determined by the access terminal 520 and sent directly to the femto node 510 in an uplink.

[0129] As shown in block 1008, the femto node initiates a waveform testing cycle for a T_test_waveform time period until all possible waveforms are tested. As shown in block 1010, the femto node 510 communicates with the associated access terminal 520 using the current waveform. The associated access terminal receives downlink transmissions and generates a channel quality indication in response to signal quality. The channel quality indication is sent in an uplink (return line) to the femto node 510.

[0130] As shown in block 1012, the femto node displays an uplink for determining channel quality using the current waveform based on the received channel quality indication. Femtocell 510 can either generate a table of waveforms and corresponding channel quality indicators, or compare the current channel quality indicator with any previous channel quality indicators and a stored waveform indicator.

[0131] As shown in block 1014, waveform testing proceeds to the next assigned waveform for continuous evaluation. The exemplary waveform selection process is repeated until the possible waveforms are involved in the downlink transmission and the quality indication of the corresponding channel in the uplink is received. As shown in block 1016, a preferred waveform based on determining the channel quality is then selected as the preferred transmission waveform that provides the best channel quality in the presence of interference due to the negative geometry associated with deployments of other arbitrary base stations.

[0132] As shown in block 1018, the preferred waveform may be periodically updated based on various factors including specific time periods, end of call, threshold for channel degradation, or other channel conditions known to those skilled in the art. When determining the update, the processing returns to channel quality estimation of various possible transmission waveforms.

[0133] In the present exemplary embodiment, interference due to the high energy of adjacent interference is controlled by the orthogonality of the Fourier series on the predominant signal energy during convolution, at the cost of creating intrinsic noise through ISI and thus limiting performance with good geometry. Additional gain could be obtained by using the MMSE equalizer due to the different frequency coloring of the pulse responses for the desired signals and interference signals. Such a mechanism is real in the configuration of the femto node, since the delay spread is much smaller than the interval of one elementary signal.

[0134] With reference to FIGS. 11A-11B and FIGS. 5A-5B, an operation related to using noise figure adjustment and path loss adjustment to solve problems associated with jamming and negative geometry is described in detail. This illustrative embodiment uses methods and devices to prevent jamming and to solve problems associated with jamming and negative geometry, using adaptive adjustment of noise figure and path loss.

[0135] Typically, the femto nodes are connected to the Internet 540 and the backbone network 550 of the mobile operator via a broadband connection (eg, a DSL router or cable modem). Since the RF coverage of the femto nodes 510 is not manually optimized by the mobile carrier backbone 550 and deployment is typically done ad-hoc, serious problems associated with RF interference may occur if suitable interference suppression methods are not used.

[0136] In networks with macrocells, access terminals 520 and macrocell access nodes 560 are designed to operate in a specific dynamic area. In the cells formed by the femto nodes 510, the home femto node 510 and the associated access terminal 520 may have a random spatial arrangement relative to the neighbors, thereby creating very high signal levels outside the sensitivity range of the respective receivers. On the downlink (straight line), such a configuration may introduce saturation of the receiver of the associated access terminal and degrade demodulation performance. On the return line, such a configuration can create a very high noise excess (RoT), which is known to create instability in the home femto node 510. Thus, the maximum and minimum transmit power levels and receiver noise figure values must be adjusted according to the home femto node 510 Such a situation is shown in Fig. 5B with reference to the home femtocell 510A and the associated access terminal 520A.

[0137] Femto nodes 510B may cause noise in both the UL uplink (reverse link) and the DL (downlink) cell downlink served by the macro cell access node 560. For example, a femto node 510B, installed, for example, near the window of a household 530, can cause significant interference on the DL downlink in an access terminal 520F located outside the house (i.e., an unassociated access terminal) that is not served by a femto node 510B. Also on the UL uplink, an associated access terminal 520, which is served by a particular home femto node 510, can cause significant interference at macro cell access nodes 560.

[0138] On the UL uplink, unassociated access terminals 520F that are served by macro cell access nodes 560 can cause significant interference to the home femto node 510A.

[0139] As noted, femto nodes 510 can also cause significant interference with each other as a result of arbitrary placement. For example, in a neighboring household 530, a femto node 510 installed near a wall separating two households 530 can cause significant interference with a neighboring femto node 510 in a nearby household 530. In this case, it may not be necessary that the strongest signal (in in terms of RF signal strength) from the femto node 510 to the access terminal 520, refers to the home femto node of the associated access terminal due to the association restrictions described above. Such a scenario is illustrated in FIG. 5B, where on the DL downlink, the femto node 510A can cause significant interference (eg, low SINR) in the access terminal 520D. Also on the UL uplink, an unassociated access terminal 520D can cause significant interference (e.g., high RoT) in a foreign femto node 510A.

[0140] For example, in the uplink of a CDMA wireless network, system stability and load are typically determined by the following parameter: thermal noise excess (RoT), also known as noise excess, in the femto node. The excess of thermal noise (RoT) indicates the relationship between the total power received from all sources in the femto node and thermal noise:

RoT = (Ioc + Ior + No) / No ,

Where

Ior : total received power received in the femto node from all wireless devices for which the given femto node is in their active set,

Ioc : total received power received in the femto node from all wireless devices for which the given femto node is not in their active set,

No : thermal noise dispersion including the noise figure (NF) of the femto node.

[0141] RoT control is required for stable operation of the UL uplink system. Typically, RoT should be around 5 dB or higher. High RoT values can lead to significant performance degradation. For example, in FIG. 5B, for two neighboring cells formed by femto nodes 510A and 510B, a high RoT caused by access terminal 520D in femto node 510A results in poor performance of the associated access terminal 520C. There is one specific scenario for the occurrence of interference when the neighboring access terminal 520D has pulsed traffic on the UL uplink and shows very high power levels (for example, very close) in the femto node 510A. Therefore, during a burst of pulses transmitted at a high speed on the UL uplink from the access terminal 520D, RoT in the femto node 510A gives 20 dB. Moreover, the UL uplink power control mechanism in CDMA systems (e.g. CDMA2000, WCDMA, 1xEV-DO) is designed to deal with this type of interference scenario. However, due to the very high dispersion in RoT, this mechanism may take some time for the femto node 510A to overcome the interference in the associated access terminal caused by the unassociated access terminal 520D by power control. Meanwhile, the signal-to-noise ratio (SIR) of the associated access terminal 520C falls below the required levels, resulting in subsequent packet errors on the UL uplink going from the associated access terminal 520C to the home femto node 510A.

[0142] In order to minimize an unexpected drop in the SIR in the desired scenario, in one embodiment, the size of the UL uplink power control step during transmission from the home femto node 510A to the associated access terminal 510C can be increased. However, there are usual upper limits on the size of the power control stage imposed by communication standards, since other disturbances in the system may occur if the system operates with a very high size of the power control stage. Thus, it is desirable to control the RoT level in the femto node 510.

[0143] In order to prevent unexpected jumps in RoT due to an unexpected increase in interference caused by non-associated access terminals (eg, interference caused by a non-associated access terminal 520D at the femto node 510A), the noise figure NF can be increased or the received signals can be attenuated by adding some path loss component propagation (PL) in the UL uplink. However, such an operation is performed in a femto node with high levels of interference. For example, in the scenario shown in FIG. 5B, if both the femto nodes 510A and 510B increase the noise figure NF or weaken it by the same amount, the result will be higher transmit power levels on the UL uplink for both access terminals 520C and 520D. As a result, the problem of high RoT arising in the femto node 510A is not solved.

[0144] According to an exemplary embodiment, the femto node showing high RoT, the femto node 510A in the present scenario increases its noise figure NF or attenuation until the femto node ceases to show high RoT, the femto node 510B in this scenario maintains its noise figure NF provided that it does not create a high level of noise outside the cell. Thus, a method is provided for adjusting the noise figure NF or attenuation when there is a high level of interference outside the cell in a particular femto node. According to an exemplary embodiment, for interference management in a RoT wireless communication system in a given time slot, n can be expressed as follows:

RoT (n) = [Ioc (n) + Ior (n) + No (n)] / No (n)

and

where Ec _i represents the total received energy per user i .

[0145] With reference to FIGS. 11A-11B, a method for controlling interference in a wireless communication system using adaptive adjustment of noise and loss factors along the propagation path for adaptively adjusting propagation path loss for RoT control is described. It should be noted that the tuning factor can be applied either to attenuation in the UL uplink, or to the noise figure NF in the femto node.

[0146] As shown in block 1104, the operations described herein may occur periodically, as, for example, in the case of the next slot n times. For example, in each slot n, the femto node 510 may perform the following method to provide interference control in a communication system. As shown in block 1104, various signals are measured and levels are calculated. In particular, as shown in block 1106, the thermal noise coefficient No (n) is measured in the femto node 510. The thermal noise coefficient No (n) is a dispersion of thermal noise including the noise coefficient (NF) of the femto node.

[0147] As shown in block 1108, the strength of the total received signal Io (n) is measured. The strength of the total received signal Io (n) represents the total received power received in the femto node from all wireless devices for which this femto node is in their active set, and from all wireless devices for which this femto node is not in their active set. As shown in block 1112, the interference Ior level inside the cell (associated access terminal) is calculated, which is the total received power received at the femto node from all wireless devices for which the given femto node is in their active set. The calculated interference level within the cell can be expressed as:

[0148] As shown in block 1110, the ratio of the energy of the received elementary pilot signal Ecp (n) to the interference and noise Nt (n) from all wireless devices for which the femto node is in their active set is measured.

[0149] As shown in block 1114, the interference level outside the cell (unassociated access terminal) Ioc (n) , which is the total received power received at the femto node from all wireless devices for which this femto node is not in their active set, is calculated. The calculated interference level outside the cell can be expressed as:

Ioc (n) = Io (n) -Ior (n) -No (n)

[0150] As shown in block 1116, the ratio of the level of interference received from outside the cell to the No (n) thermal noise coefficient and the ratio of the maximum energy of the filtered received elementary pilot signal Ecp (n) to the interference-plus-noise Nt (n) are calculated for access terminals within a cell. As shown in block 1118, the signal-to-noise ratio of the access terminal, measured as the energy ratio of the received elementary pilot signal Ecp (n) to interference and noise Nt (n) for all access terminals within the cell, for example, using filtering, is filtered with infinite impulse response (IIR) in the dB domain. The maximum filtered value for access terminals for which the femto node is in their active set can be expressed as follows:

[0151] As shown in block 1120, the signal-to-noise ratio is calculated for the level of externally received interference cell Ioc and thermal noise coefficient No (n). The signal-to-noise ratio is also further filtered, for example, using filtering with a finite impulse response (FIR) in the dB domain. The calculated signal-to-noise ratio outside the cell (unassociated terminal) can be expressed as follows:

[0152] As shown in block 1122, for access terminals within the cell, excess received interference from outside the cell is determined outside the allowable (target) amount with which the communication system can actually work, and the ratio of the maximum excess energy of the received elementary pilot signal to interference and noise . As shown in block 1124, the excess amount for the ratio of the energy of the received elementary pilot signal to interference and noise can be expressed as follows:

with the above allowable threshold value EcpNt_target , expressed in units of dB.

[0153] As shown in block 1126, the amount of excess for the Ioc_excess interference level received from outside the cell can be expressed as follows:

with the above acceptable threshold value Ioc_target , expressed in units of dB.

[0154] As shown in block 1128, the amount of additional path loss (PL_adjust) to be used is calculated. As shown in block 1130, possible adjustments for path propagation loss are determined. Possible adjustments can be expressed as:

Regarding determining the values of possible adjustments, possible values can be based on various characteristics or rules. For example, different points can be expressed as:

(1) PL_cand ₁ and PL_cand ₂ are designed to quickly adjust PL based on high Ecp / Nt and Ioc values that exceed a high threshold value.

(2) In the case of both Ecp / Nt and Ioc there are lower tolerance limits, PL_cand _{3 is} designed to slowly reduce (attenuate) PL so that it is not high unnecessarily.

(3) If there is only one active user in a cell, then there may be no reason to restrict Ioc, since the RoT control mechanism can already control the RoT level. Therefore, in this case, when the system has only one user, Ioc_target can be set to a very large value.

[0155] As shown in block 1132, the corresponding propagation path loss (PL_adjust) can be applied according to the upper and lower adjustment limits for PL propagation path loss, expressed as:

(PL_cand> PL_adjust_max)

PL_adjust (n) = PL_adjust_max

(PL_cand> 0)

PL_adjust (n) = PL_cand

(PL_cand≤0)

PL_adjust (n) = 0

[0156] As shown in block 1134, attenuation (or noise factors) in the UL uplink is increased by PL_adjust (n). It should be noted that in a real implementation, hardware limitations may require quantization of PL_adjust (n) for possible closest installations.

[0157] With reference to FIG. 12, as well as to FIGS. 5A-5B, operations related to reusing a subframe time to solve a jamming and negative geometry problem will be described in detail. The present exemplary embodiment uses methods and hardware to prevent jamming and negative geometry effects using reuse of subframe time.

[0158] In one illustrative embodiment, if the radio interface allows the use of time division multiplexing, transmissions can be scheduled so as to eliminate time slots with negative geometry. For example, the femto node 510B may communicate with the associated access terminal 520D during the time interval when the femto node 510A is silent. Similarly, the associated access terminal 520C can communicate with the femto node 510A during the time interval when the silence of the unassociated access terminal 520D is scheduled for the femto node 510B. Such methods, using synchronization and scheduling approaches, have found application in systems that allow the use of time-sharing scheduling, such as 1xEVDO. For example, since the 1xEVDO control channels use time multiplexing, neighboring femto nodes 510 can apply time reuse of these control channels.

[0159] However, as discussed below, this does not apply to radio interface technologies that do not allow the use of time division scheduling and multiplexing operations, for example, technologies using CDM control channels, including 1xRTT, WCDMA and HSPA.

[0160] In one illustrative embodiment, sub-frame time reuse is applicable to technologies where hybrid time reuse cannot be applied. In many cellular technologies, such as cdma2000 and WCDMA, the base station continuously transmits on the pilot channel and other CDM control channels (e.g., synchronization, call, broadcast, etc.) channels that are used by access terminals for various purposes, including initial scanning and access, standby tracking and channel estimation. Such continuous transmission over the pilot channel and overhead channels from the femto nodes can lead to downlink jamming described above, even if the jamming source does not have active traffic.

[0161] In one illustrative embodiment, the first step is to overcome interruption situations where the pilot channel and service channels (eg, synchronization and call channels) of the desired femto node 510 cannot be received at access terminal 530. For example, cdma2000 frame divided into sixteen power control groups (PCG). To enable reception of a pilot signal, a portion of the transmission on the pilot channel and the service channels is gated.

[0162] As shown in FIG. 5B, the femto node 510A transmitting to the associated access terminals 520A-C transmits such gated frames (for example, traffic is not transmitted in a straight line during gating periods). In the unassociated access terminal 520D during the gating period of the femto node 510A, the carrier / interference ratio, C / I, for transmissions from the femto node 510B is significantly improved, which makes it possible to receive the pilot and synchronization channels from the 510B femto node in terminal 520D despite the presence of negative geometry at access terminal 520D.

[0163] In one illustrative embodiment, the gating periods are planned so that they do not intersect with each other. So, the femto node 510A and the femto node 510B can use disjoint subframes (or power control groups). In one illustrative embodiment, by gating (i.e., not transmitting traffic in a straight line), for example, 1/2, 2/3, or 3/4 of a subframe, a time reuse pattern of 2, 3, or 4 can be created. If Since the pilot channel and service channels have significant redundancy, for receiving a pilot channel, as well as for decoding service channels, this will be 3-6 dB of the line budget for the pilot channel and service channels. However, this can be easily compensated by increasing the transmission power of the femto node 510, since with this deployment of the femto node 510, the placement is not limited to the transmission power.

[0164] In addition to the pilot channel and overhead channels, the same gating method can be applied to transmissions on voice or data channels. In one illustrative embodiment, the femto node 510 gates a portion of each frame transmission. If, for example, the disconnected part (for example, 1/2) is less than the channel coding rate used for transmission, for example, in the cdma2000 direct voice packet transmission standard format (RC3) uses a convolutional code with a speed of 1/4, access terminal 520 will be able to decode the packet, even when gating half the packet. In order to avoid the need to know the geometry and plan for non-overlapping gating intervals, the following describes a method for preventing jamming and effects associated with negative geometry using reuse of subframe times.

[0165] FIG. 12 shows an illustrative embodiment for managing interference in a wireless communication system using sub-frame time reuse. As shown in block 1202, gating sequences (or patterns) are identified, each gating sequence gating, for example, either eleven of sixteen power control groups (PCGs) to obtain a 5/16 reuse factor, or eight of sixteen PCGs to obtain a reuse factor use 2.

[0166] Gating sequences can be selected in such a way as to minimize cross-correlation between pairs of gating sequences from femto nodes 510, which are potential sources of interference. As shown in block 1204, each femto node 510 selects one of the gate sequences. Although the femto node 510 may try to select a gating sequence that does not overlap with neighboring femto nodes, in the general case, the selection does not necessarily lead to non-overlapping options. However, the present illustrative embodiment provides a mechanism by which nonoverlapping sequences can be identified and selected.

[0167] As shown in block 1206, the access terminal 520 establishes an active connection with the femto node 510. In response to establishing a connection, the access terminal 520 provides “fast” downlink power control feedback on each subframe, which allows the femto node 510 to select the desired non-overlapping gating sequence.

[0168] In particular, as shown in block 1208, the femto node 510B transmits a sequence of frames over, for example, a voice / data channel to an access terminal 520D with no gating of all power control groups (PCGs). As shown in block 1210, since a neighboring femto node 510A, which is a potential source of interference, is already communicating with access terminals 520A-C using gating technology of subframes, access terminal 520D will observe interference on a subset of subframes when performing gated transmission by neighboring femto node 510A - an interference source . Moreover, the access terminal 520D will also observe another subset of the subframes without interference from a neighboring femto node 510A when the femto node 510A performs gating on this subset of the subframes.

[0169] During the subframes where the femto node 510A does not perform gating, the access terminal 520D will observe, for example, low Eb / No. As shown in block 1212, the downlink power control feedback from the access terminal 520D indicates that the femto node 510B should increase transmission power for specific subframes. Similarly, during subframes where the femto node 510A does not perform gating, the access terminal 520D will observe a high Eb / No, and the downlink power control feedback from the access terminal 520D indicates that the femto node 510B should reduce the transmit power for specific subframes .

[0170] As shown in block 1214, the downlink (down) power control of the subframes provided by the access terminal 520D to the femto node 510B indicates which subframes transmitted by the neighboring femto node 510A are the source of interference gated and for which subframes there is no gating. Accordingly, such an indication allows the femto node 510B to select a gating sequence (pattern) that does not overlap (is complementary) with the gating sequence (pattern) selected by the neighboring femto node 510A - a source of interference. Thus, an illustrative embodiment makes it possible to establish the fact of using a gating sequence (pattern) selected by a neighboring femto node 510A as a source of interference.

[0171] Depending on the technology used, other considerations may further determine the types of gating sequences (patterns) best suited for use in gating technology of subframes. Moreover, since existing access terminals cannot determine whether gating on a downward (straight) line is used, other considerations may be used to use the selection of gating sequences (patterns) in which shortened “off” periods are interspersed with shortened “on” periods . Taking such considerations into account can reduce the impact on the methods for estimating downlink (forward) channels and evaluating feedback on the quality of channels used in existing access terminals. So, for example, when eight out of sixteen gates are gated, there may be good reasons for choosing alternating gated and non-gated subframes.

[0172] In another illustrative embodiment, when selecting a gating sequence, various considerations may be used for deployment options in which neighboring femto nodes 510 are not synchronized. Such a situation may occur, for example, if the WCDMA femto nodes 510 are not synchronized. In one illustrative embodiment of unsynchronized femto nodes 510, instead of using alternating gated / non-gated subframes, it may be appropriate to adjacent all or most of the gated / non-gated subframes. For example, in the case of a WCDMA system with fifteen subframes for 10 ms, or thirty subframes for 20 ms, it may be appropriate for each femto node 510 to gate nine consecutive subframes of fifteen and not to gate six consecutive subframes. Alternatively, when using a 20 ms frame, the femto node 510 can gate sixteen consecutive subframes of fifteen and not gate fourteen consecutive subframes.

[0173] In an alternative illustrative embodiment, other methods for overcoming such a situation and improving downlink C / I use femto nodes 510 configured to gate transmission on the pilot channel and service channels, if there are no associated terminals, and include a pilot channel and service channels periodically and / or at very low power only during periods when the associated access terminals 520 can scan to search for the femto node 510.

[0174] With reference to FIGS. 13-14, as well as FIGS. 5A-5B, operations related to hybrid time reuse will be described in detail to solve the problem of jamming and negative geometry. The present exemplary embodiment uses methods and hardware to prevent jamming and negative geometry effects using hybrid time reuse technology.

[0175] In the illustrative embodiment, if the radio interface allows time division multiplexing (eg, 1xEV-DO), transmissions can be scheduled so as to eliminate time slots with negative geometry. For example, the femto node 510B may communicate with the associated access terminal 520D during a time interval when the femto node 510A does not transmit. Similarly, the associated access terminal 520C can communicate with the femto node 510A during the time interval when the femto node 510B is scheduled to not transmit the access terminal 520D.

[0176] In an illustrative embodiment of the hybrid time reuse method, the downlink transmission is time divided into three distinct groups:

1) the period of transmission on the synchronous control channel (SCC),

2) HARQ limited cycle transmission period,

3) the transmission period of the unlimited HARQ cycle.

[0177] FIG. 13 is an illustrative timing diagram for a downlink including three different time periods during each cycle period of a synchronous control channel (SCC) of 256 time slots. In one illustrative embodiment, based on dividing the time of resources during the “unlimited HARQ cycle,” three different femto channels are defined. As described in more detail below, it is desirable that neighboring femto nodes 510 select different femto channels so that they do not interfere with other neighboring femto nodes 510 (i.e., each femto node 510 selects a primary femto channel different from that selected by neighboring femto node 510). In the absence of interference from a neighboring femto node, multiple femto channels (in addition to the main femto channel) by one femto node 510 can be used. An illustrative embodiment using hybrid time reuse is described in detail below.

[0178] FIG. 14 illustrates a method for managing interference in a wireless communication system using hybrid time reuse in accordance with an illustrative embodiment. As shown in block 1402, upon power-up or other synchronization of the femto node 510, the femto node 510 performs temporary synchronization with a macrocell network (for example, a macro cell access node 560). As shown in block 1404, during temporal synchronization by the macrocell access node 560, the femto node 510 performs an offset measurement (MSCCO) of the secondary synchronization channel (SCC) using the macro cell access node 560 and neighboring femto nodes 510. Based on this measurement, the femto node 510 identifies the preferred HARQ cycle with the least interference, as shown in block 1406. The preferred slot offset (PSO) is determined from the identified preferred HARQ cycle.

[0179] As shown in block 1408, the primary femto channel is selected. For example, an illustrative selection process may be performed according to the following algorithm:

If mod (PSO-MSCCO, 4) = 1, then femtochannel 1 is selected as the primary femtochannel.

If mod (PSO-MSCCO, 4) = 2, then femtochannel 2 is selected as the primary femtochannel.

If mod (PSO-MSCCO, 4) = 3, then femtochannel 3 is selected as the primary femtochannel.

[0180] After determining the femto channel, the femto node 510 can transmit traffic in a downlink (straight line). Transmissions by femto nodes 510 are time limited to reduce interference from transmissions of macro cells and other femto nodes. The femto node transmission protocol for various macro cell transmission periods, the SCC transmission period, the HARQ limited cycle transmission period, and the unlimited HARQ cycle transmission period are described below.

[0181] As shown in block 1410 and FIG. 13, an SCC transmission period 1302 is determined at the beginning of each SCC cycle 1304 (eg, 256 slots) to enable SCC offset transmission (eg, the first 32 slots in each SCC cycle). In one illustrative embodiment, two sub-periods 1306 and 1308 are determined based on the HARQ cycle: preferred slot offset and non-preferred slot offset.

[0182] In a preferred slot offset (PSO) HARQ cycle, the femto node 510 transmits SCC information. This makes it possible to reliably transmit control channel information and allows access terminals 520 to connect and disconnect from the femto node 510. During the HARQ cycle with non-preferred slot offsets, the femto nodes 510 do not transmit traffic in a downward (straight) line so that a minimum amount of interference to neighboring macrocells is created and neighboring femto nodes transmitting via SCC. With these offset slots for the pilot channel and the MAC channel, part of the downlink power is used, which allows these channels to function successfully.

[0183] As shown in block 1412 and FIG. 13, during the limited HARQ cycle transmission period, the femto node 510 is allowed to transmit downlink (forward) line traffic in the HARQ cycle with PSO, while delay-sensitive traffic is given absolute priority over other types of traffic. As shown in FIG. 13, the limited HARQ cycle transmission period allows transmission for any femto node, so that delay-sensitive traffic (such as VoIP) does not experience excessive delays. In one example, during the limited HARQ cycle transmission period, if the requested DRC is zero, then a single-user packet of 38.4 kb / s may be used. If the DRC is null or erased, compatible types of user packets may be used, such as a 38.4 kb / s single-user packet (SUP) or 256/512/1024 bit multi-user packet (MUP) (similar to the mapping case for an erased DRC).

[0184] In one illustrative embodiment, downlink traffic can also be transmitted in a HARQ MSCCO cycle. In one embodiment, neighboring femto nodes 510 may also use this cycle (i.e., there is no offset against interference). During the HARQ cycle with other slot offsets, the femto nodes do not transmit downlink (forward) traffic (time reuse), however, a portion of the downlink power can be allocated to the pilot channel and MAC channel to ensure the successful operation of these channels.

[0185] As shown in block 1414 and FIG. 13, during the transmission period of an unlimited HARQ cycle, the femto node is allowed to transmit downlink traffic in all four HARQ cycles. At the beginning of the period, the power of the downlink may slowly increase to enable the speed prediction node of the access terminal to function. In one illustrative embodiment, a DRC length of 1 slot may be used to further increase the slew rate of DRC values. Due to the conservative behavior of the prediction node, if at the beginning of the transmission period of the unlimited HARQ cycle, the mobile device requests zero DRC, the femto node 510 can transmit compatible packet types (multiuser packet or 38.4 kb / s single-user packet). In addition, the femto node downlink scheduler can continue to track previously requested DRC values and maintain DRC values from the last transmission period and HARQ early completion statistics to decide what data rate can be decoded by access terminal 520

[00186] The principles disclosed herein may be implemented in a node (eg, a device) using various components to communicate with at least one other node. On Fig shows several components of the samples that can be used to facilitate communication between nodes. Essentially, FIG. 15 shows a wireless device 1510 (e.g., an access point) and a wireless device 1550 (e.g., an access terminal) of a MIMO system 1500. At device 1510, traffic data for multiple data streams is provided from a data source 1512 to a data processor (“TX”) 1514.

[00187] In some embodiments, each data stream is transmitted through a respective transmit antenna. TX data processor 1514 formats, codes, and interleaves the traffic data for each data stream based on the particular coding scheme selected for that data stream to provide encoded data.

[00188] The coded data for each data stream may be multiplexed using OFDM techniques using pilot data. Pilot data is usually a known data pattern that is processed in a known manner and can be used in the receiver system to estimate the channel response. Then, the multiplexed pilot and encoded data for each data stream is modulated (i.e., mapped into symbols) based on a particular modulation scheme (e.g., BPSK, QSPK, M-PSK or M-QAM) selected for such a data stream to provide modulation characters. The data rate, coding, and modulation of data for each data stream may be determined by instructions executed by processor 1530. Data memory 1532 may store program codes, data, and other information used by processor 1530 or other components of device 1510.

[00189] Modulation symbols for all data streams are then provided to the TX MIMO processor 1520, which may perform additional processing of the modulation symbols (eg, for OFDM). Then, the TX MIMO processor 1520 provides N _T modulation symbol streams to N _T transceivers ("XCVRs") 1522A-1522T. In some embodiments, TX MIMO processor 1520 applies weighting to beamforming to the symbols of the data streams and to the antennas through which the symbols are transmitted.

[00190] Each transceiver 1522 receives and processes a respective symbol stream to provide one or more analog signals, and further condition (eg amplifies, filters, and upconverts) the analog signals to provide modulated signals suitable for transmission over MIMO channels. Then, N _T modulated signals from transceivers 1522A-1522T are transmitted through N _T antennas 1524A-1524T, respectively.

[00191] At device 1550, the transmitted modulated signals are received using N _R antennas 1552A-1552R and received signals from each antenna 1522 are provided to a respective transceiver ("XCVR") 1554A-1554R. Each transceiver performs conditioning (for example, filters, amplifies, and downconverts) the corresponding received signals, digitizes the conditioned signals to provide samples, and further processes the samples to provide a corresponding “received” symbol stream.

[00192] Then, the receiving ("RX") data processor 1560 receives and processes the N _R received symbol streams from N _R transceivers 1554 based on the processing method for a particular receiver to provide N _T “detected” symbol streams. Then, the RX data processor 1560 performs demodulation, deinterleaving, and decoding of each detected symbol stream to recover traffic data for the data stream. The processing by the RX data processor 1560 is complementary to the processing performed by the TX MIMO processor 1520 and the TX data processor 1514 in the device 1510.

[00193] The processor 1570 periodically determines which precoding matrix to use (see description below). The processor 1570 creates a return line message containing a portion of the matrix index and a portion of the rank value. Data memory 1572 may store program, code, data, and other information used by processor 1570 or other components of device 1550.

[00194] The reverse link message may contain various types of information regarding the communication link and / or the received data stream. The reverse link message is then processed by TX data processor 1538, which also receives traffic data for multiple data streams from data source 1536, is modulated by modulator 1580, conditioned by transceivers 1554A-1554R, and transmitted back to device 1510.

[00195] At device 1510, the modulated signals from device 1550 are transmitted using antennas 1524, conditioned by transceivers 1522, demodulated by a demodulator ("DEMOD") 1540, and processed by the RX data processor 1542 to extract the reverse link message transmitted by device 1550. Then, processor 1530 determines which precoding matrix to use to determine beamforming weights, then processes the extracted message.

[00196] FIG. 15 also shows that communication components may include one or more components that perform interference control operations, as described herein. For example, the interference control component 1590 ("INTER.") May interact with a processor 1530 and / or other components of a device 1510 to send / receive signals to / from another device (eg, device 1550), as disclosed herein. Similarly, the interference control component 1592 interacts with the processor 1570 and / or other components of the device 1550 to send / receive signals to / from another device (e.g., device 1510). It should be noted that for each device 1510 and 1550, the functionality of two or more of the described components can be provided by one component. For example, one processing component may provide the functionality of the interference control component 1590 and processor 1530, and one processing component may provide the functionality of the interference control component 1592 and processor 1570.

[00197] The principles disclosed herein may be implemented in various types of communication systems and / or system components. In some embodiments, the principles disclosed herein can be applied in a multiple access system capable of communicating with multiple users by sharing available system resources (e.g., by determining one or more bandwidths, transmit power, encoding, interleaving, etc. d.). For example, the principles disclosed herein may apply to any one or a combination of the following methods: Code Division Multiple Access ("CDMA"), Code Division Multiple Access ("MCCDMA"), Broadband CDMA ("W-CDMA" ), high speed packet access systems ("HSPA" "HSPA +"), time division multiple access systems ("TDMA"), frequency division multiple access systems ("FDMA"), single carrier frequency division multiple access systems ("SC-FD MA "), orthogonal frequency diversity multiple access (" OFDMA ") systems or other multiple access techniques. Wireless communication systems using the methods described herein can be developed to implement one or more standards, such as IS-95, cdma2000, IS-856, W-CDMA, TDSCDMA and other standards. A CDMA network may implement a radio method such as Universal Terrestrial Radio Access ("UTRA)", cdma2000, or some other method. UTRA includes W-CDMA and low chip rate ("LCR"). The cdma2000 method covers IS-2000, IS-95, and IS-856 standards. A TDMA network may implement a radio method, such as the global digital standard for mobile cellular ("GSM"). An OFDMA network may implement a radio method such as Advanced UTRA ("E-UTRA"), IEEE 802.11, IEEE 802.16, IEEE 802.20, Flash-OFDM®, etc. UTRA, E-UTRA and GSM are part of the universal mobile telecommunications system ("UMTS"). The principles disclosed in this document can be implemented in the 3GPP system of long-term development ("LTE"), the system of ultra-mobile broadband access ("UMB"), other types of systems. LTE is an implementation of UMTS that uses E-UTRA. Although some embodiments of the present disclosure can be described using 3 GPP terminology, it should be noted that the methods described herein can be applied to 3GPP methods (Rel99, Rel5, Rel6, Rel7), as well as 3GPP2 methods (1xRTT, 1xEV-DO Re 10, RevA, RevB) and other methods.

[00198] The principles disclosed herein can be implemented (eg, implemented or implemented using) in a variety of devices (eg, nodes). In some embodiments, a node (eg, a wireless node) implemented in accordance with the principles disclosed herein may comprise an access point or access terminal.

[00199] For example, an access terminal may comprise, be implemented in, or known as a user equipment, subscriber station, subscriber unit, mobile station, mobile device, mobile node, remote station, remote terminal, user terminal, user agent, user device, or known by some other terms. In some embodiments, the access terminal may comprise a cell phone, a cordless telephone, a session initiation protocol ("SIP") telephone, a wireless local loop ("WLL") station, a personal digital assistant ("PDA"), a portable device with the ability a wireless connection or some other suitable processing device connected to a wireless modem. Therefore, one or more of the embodiments disclosed herein may be implemented in a telephone (e.g., cell phone or smartphone), computer (e.g. laptop), portable communications device, portable computing device (e.g., handheld personal computer), entertainment device (e.g., music device, video device or satellite radio), global positioning system device, or any other suitable device that is configured to Connectivity through a wireless environment.

[00200] An access point may comprise, may be implemented as, or may be known as a NodeB, an eNodeB, a radio network controller ("RNC"), a base station ("BS"), a radio base station ("RBS"), a base station controller ( "BSC"), base transceiver station ("BTS"), transceiver function ("TF"), radio transceiver, radio router, basic service set ("BSS"), advanced service set ("ESS") or may be known by other similar terms.

[00201] In some embodiments, a node (eg, an access point) may comprise an access node for a communication system. Such an access node may provide, for example, the ability to connect to a network (for example, a wide area network such as the Internet or a cellular network) via a wired or wireless communication line with the network. Therefore, the access node may provide an opportunity to another node (for example, an access terminal) to access a network or some other functional means. In addition, it should be noted that one or both of the nodes can be portable or, in some cases, relatively non-portable.

[00202] It should also be noted that the wireless node may be able to transmit and / or receive information in a non-wireless manner (for example, via a wired connection). Thus, the receiver and transmitter, as described herein, may include appropriate communication interface components (e.g., electrical or optical interface components) to provide communication with a non-wireless medium.

[00203] A wireless node may communicate through one or more wireless communication lines that are based or otherwise supported by any suitable wireless communication method. For example, in some embodiments, a wireless node may be associated with a network. In some embodiments, the network may comprise a local area network or a wide area network. A wireless device may support or otherwise use one or more of a variety of wireless communication methods, protocols or standards, such as those described herein (e.g., CDMA, TDMA, OFDM, OFDMA, WiMAX, Wi-Fi, etc.). Similarly, a wireless node may support or otherwise use one or more of a plurality of appropriate modulation or multiplexing. Thus, a wireless node may include appropriate components (eg, radio interfaces) for establishing and communicating via one or more wireless communication lines using the above or other wireless communication methods. For example, a wireless node may comprise a wireless transceiver with associated receiver and transmitter components, which may include various components (eg, signal generators and signal processors) that facilitate communication through a wireless medium.

[00204] The components described in this work can be implemented in numerous ways. Turning to FIGS. 16-21, devices 1600, 1700, 1800, 1900, 2000, and 2100 are presented as a series of interconnected functional blocks. In some embodiments, the functionality of these units may be implemented as a processing system including one or more processor components. In some embodiments, the functionality of these units may be implemented using, for example, at least part of one or more integrated circuits (eg, ASICs). As described herein, an integrated circuit may include a processor, software, other related components, or some combination thereof. The functionality of these blocks can also be implemented in some other ways, as described herein.

[00205] The devices 1600,1700,1800,1900, 2000 and 2100 may include one or more modules that can perform one or more of the functions described above with reference to various drawings. In some embodiments, one or more of the components of the interference controller 320 or the interference controller 322 may provide functionality related, for example, to the interference reception / direction tool 1602, the interference comparison / determination / update tool 1606, the service channel power tool 1702, the shape tool 1802 signal for transmission, to channel quality means 1806, interference determining means 1902, propagation path loss means 1906, strobe sequences means 2002, re-patterning means 2102 Using means 2106 and the synchronization / offset / timing. In some embodiments, the communication controller 326 or the communication controller 328 may provide functionality related, for example, to transmit / receive means 1604, 1704, 1804, 1904, 2004, and 2104.

[00206] It should be borne in mind that any reference to an element in this document using a designation such as "first", "second", etc., as a rule, does not limit the number and order of such elements. Rather, such a designation may be used herein as a common method for distinguishing between two or more elements or examples of an element. Thus, reference to the first and second elements does not mean that only two elements can be used here or that the first element must precede the second element in some way. In addition, other than indicated otherwise, a set of elements may contain one or more elements.

[00207] It will be apparent to those skilled in the art that information and signals may be represented using any of a variety of different techniques. For example, data, instructions, commands, information, signals, bits, symbols and chips that may be referred to throughout the description above may be represented by voltage, current, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof .

[00208] Those skilled in the art should also bear in mind that any of the various illustrative logical blocks, modules, processors, tools, circuits, and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware (for example, a digital implementation, an analog implementation, or a combination of two that can be developed using a source encoding method or some other method), various forms of code development program ki containing instructions (which may be referred to herein as “software” or “software module” for convenience) or a combination of both. To more clearly illustrate such interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and steps are typically described above in terms of their functionality. Such functionalities are implemented either in the form of hardware or software, depending on the specific application and development-related restrictions imposed on the entire system. Specialists in this field can implement the desired functionality in various ways for each specific application, but such solutions should not be interpreted as a departure from the scope of the present disclosure.

[00209] Various illustrative logic blocks, circuit modules described in connection with the embodiments disclosed herein may be implemented or implemented using integrated circuits (“ICs”) of an access point access terminal. An IC may include a general purpose processor, digital signal processor (DSP), application specific integrated circuit (ASIC), programmable gate array (FPGA) or other programmable logic device, logic element on discrete components or transistor logic, discrete hardware components, electrical components, optical components, mechanical components, or a combination thereof, designed to perform the functions described herein and may execute codes or instructions to torye are within the IC, outside the IC, or both inside and outside the IC. A general purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, for example, a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

[00210] It should be borne in mind that any particular order or hierarchy of steps in any disclosed process is an example of an illustrative approach. Based on the preferences of the development, it should be borne in mind that a special order or hierarchy of stages in the processes can be transformed, while remaining within the scope of this disclosure. The claims that accompany the method represent the elements of the various steps in an illustrative manner and are not intended to limit the particular order or hierarchy presented.

[00211] The functions described may be implemented in hardware, software, firmware, or any combination thereof. When implemented in software, functions can be stored or transmitted through a computer-readable medium in the form of one or more instructions or code. A computer-readable medium includes both a computer storage medium and a communication medium including any medium that facilitates transferring a computer program from one place to another. A storage medium may be any available medium that can be accessed by a computer. By way of example, and not limitation, such a computer-readable medium may comprise RAM, ROM, EEPROM, CD-ROM or other optical disk drive, magnetic disk drive, or other magnetic storage devices, or any other medium that can be used for transferring or storing the desired program code in the form of instructions or data structures that can be accessed by a computer. Also, any communication is called a computer-readable medium. For example, if 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 using 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 are included in the definition of the environment. A magnetic disk and disk, as used herein, includes a compact disc (CD), a laser disc, an optical disc, a universal digital disc (DVD), a floppy disk and a blu-ray disc, where magnetic discs typically reproduce data in a magnetic way, while optical disks reproduce data in an optical way using a laser. Combinations of the above should also be included within the scope of a computer-readable medium. Finally, it should be borne in mind that a computer-readable medium can be implemented in any suitable computer program product.

[00212] The above description of the disclosed embodiments is provided to enable any person skilled in the art to create or use the present disclosure. Various modifications are apparent to those skilled in the art in these embodiments, and the generic principles defined herein can be applied to other embodiments without departing from the scope of the present disclosure. Thus, the present disclosure is not intended to limit the embodiments shown herein, but is intended to provide the broadest possible scope consistent with the principles and new features disclosed herein.

Claims (28)

1. A method for controlling interference in a wireless communication system, comprising:
determining one or more patterns of time reuse at the corresponding one or more unplanned access points;
selecting a second time reuse pattern that creates less interference for one or more time reuse patterns, the second time reuse pattern corresponding to alternating HARQ offsets of the secondary macrocell synchronization channel; and
transmitting signals according to a second time reuse pattern from a second unplanned access point to an associated access terminal. 2. The method according to claim 1, in which the determination of one or more patterns of time reuse includes the installation of time synchronization in the second unplanned access point with a macro cell. 3. The method according to claim 2, in which
establishing time synchronization comprises measuring offsets of the secondary synchronization channel used by the macrocell and one or more unplanned access points; and
selecting a second time reuse pattern comprises identifying the HARQ interlace from the offsets of the secondary synchronization channel that shows the least interference, and identifying a preferred slot offset from the identified HARQ interlace. 4. The method of claim 3, further comprising identifying the primary femto channel, at least in part, based on the preferred slot offset. 5. The method according to claim 4, in which the signal transmission comprises transmitting signals on a primary femto channel from a second unplanned access point to an associated access terminal. 6. The method according to claim 3, in which the signal transmission comprises transmitting information identifying offsets of the secondary synchronization channel to an associated access terminal. 7. The method according to claim 1, further comprising transmitting on pilot channels corresponding to one or more time reuse patterns. 8. A device for controlling interference in a wireless communication system, comprising:
an interference controller configured to determine one or more time reuse patterns at the corresponding one or more unplanned access points and select a second time reuse pattern that creates less interference for one or more time reuse patterns, wherein the second time reuse pattern corresponds to alternating HARQ offsets of the secondary macrocell synchronization channel; and
a communication controller configured to transmit signals according to a second time reuse pattern from a second randomly located access point to an associated access terminal. 9. The device of claim 8, in which the determination of one or more reuse patterns comprises establishing time synchronization in a second unplanned access point with a macro cell. 10. The device according to claim 9, in which
establishing time synchronization comprises measuring offsets of the secondary synchronization channel used by the macrocell and one or more unplanned access points; and
selecting a second time reuse pattern comprises identifying the HARQ interlace from the offsets of the secondary synchronization channel that shows the least interference, and identifying a preferred slot offset from the identified HARQ interlace. 11. The device of claim 10, wherein the interference controller is further configured to identify the primary femto channel, at least in part, based on the preferred slot offset. 12. The device according to claim 11, in which the signal transmission comprises transmitting signals on the primary femto channel from the second unplanned access point to the associated access terminal. 13. The device of claim 10, wherein the signal transmission comprises transmitting information identifying offsets of the secondary synchronization channel to the associated access terminal. 14. The device of claim 8, wherein the communication controller is further configured to transmit on pilot channels corresponding to one or more time reuse patterns. 15. A device for controlling interference in a wireless communication system, comprising: means for determining one or more patterns of time reuse at the corresponding one or more unplanned access points;
means for selecting a second time reuse pattern that creates less interference for one or more time reuse patterns, the second time reuse pattern corresponding to alternating HARQ offsets of the secondary macro synchronization channel; and
means for transmitting signals according to a second time reuse pattern from a second unplanned access point to an associated access terminal. 16. The device according to clause 15, wherein the means for determining one or more patterns of time reuse contains means for establishing time synchronization in the second unplanned access point with an arbitrary location with a macro cell. 17. The device according to clause 16, in which:
means for establishing time synchronization comprises means for measuring offsets of the secondary synchronization channel used by the macrocell and one or more unplanned access points; and
means for selecting a second time reuse pattern comprises means for identifying the HARQ interlace from the offsets of the secondary synchronization channel that shows the least interference, and means for identifying the preferred slot offset from the identified HARQ interlace. 18. The apparatus of claim 17, further comprising means for identifying the primary femto channel based at least in part on a preferred slot offset. 19. The device according to p, in which the means for transmitting signals comprises means for transmitting signals on the primary femto channel from the second unplanned access point to the associated access terminal. 20. The device according to 17, in which the means for transmitting signals comprises means for transmitting information identifying the offsets of the secondary synchronization channel to the associated access terminal. 21. The device according to clause 15, further comprising means for transmitting on pilot channels corresponding to one or more time reuse patterns. 22. A computer-readable medium containing computer-executable instructions to cause a computer to implement a method for controlling interference in a wireless communication system, comprising the steps of:
determining one or more time reuse patterns at the respective one or more unplanned access points;
selecting a second time reuse pattern that causes the least interference to one or more unplanned access points, the second time reuse pattern corresponding to alternating HARQ offsets of the secondary macro-cell synchronization channel; and
transmit signals according to a second time reuse pattern from a second unplanned access point to an associated access terminal. 23. The computer-readable medium of claim 22, wherein determining one or more time reuse patterns comprises the step of establishing time synchronization in a second unplanned access point with a macro cell. 24. The computer-readable medium of claim 23, wherein the step of establishing time synchronization comprises measuring offsets of the secondary synchronization channel used by the macro cell and one or more unplanned access points; and
selecting a second time reuse pattern comprises identifying the HARQ interlace from the offsets of the secondary synchronization channel that shows the least interference, and identifying a preferred slot offset from the identified HARQ interlace. 25. The computer-readable medium of claim 24, further comprising identifying the primary femto channel, at least in part, based on a preferred slot offset. 26. The computer-readable medium of claim 25, wherein the signal transmission comprises transmitting signals via a primary femto channel from a second unplanned access point with arbitrary placement to an associated access terminal. 27. The computer-readable medium of claim 24, wherein the signal transmission comprises transmitting information for identifying offsets of the secondary synchronization channel to an associated access terminal. 28. The computer-readable medium of claim 22, further comprising transmitting on pilot channels corresponding to one or more time reuse patterns.

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