US20140204787A1 - Method and arrangement in a telecommunication system - Google Patents
Method and arrangement in a telecommunication system Download PDFInfo
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- US20140204787A1 US20140204787A1 US14/219,263 US201414219263A US2014204787A1 US 20140204787 A1 US20140204787 A1 US 20140204787A1 US 201414219263 A US201414219263 A US 201414219263A US 2014204787 A1 US2014204787 A1 US 2014204787A1
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L5/00—Arrangements affording multiple use of the transmission path
- H04L5/003—Arrangements for allocating sub-channels of the transmission path
- H04L5/0058—Allocation criteria
- H04L5/0073—Allocation arrangements that take into account other cell interferences
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L5/00—Arrangements affording multiple use of the transmission path
- H04L5/0001—Arrangements for dividing the transmission path
- H04L5/0028—Variable division
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W24/00—Supervisory, monitoring or testing arrangements
- H04W24/08—Testing, supervising or monitoring using real traffic
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W72/00—Local resource management
- H04W72/50—Allocation or scheduling criteria for wireless resources
- H04W72/54—Allocation or scheduling criteria for wireless resources based on quality criteria
- H04W72/541—Allocation or scheduling criteria for wireless resources based on quality criteria using the level of interference
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W16/00—Network planning, e.g. coverage or traffic planning tools; Network deployment, e.g. resource partitioning or cells structures
- H04W16/02—Resource partitioning among network components, e.g. reuse partitioning
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W16/00—Network planning, e.g. coverage or traffic planning tools; Network deployment, e.g. resource partitioning or cells structures
- H04W16/02—Resource partitioning among network components, e.g. reuse partitioning
- H04W16/10—Dynamic resource partitioning
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W72/00—Local resource management
- H04W72/50—Allocation or scheduling criteria for wireless resources
- H04W72/51—Allocation or scheduling criteria for wireless resources based on terminal or device properties
Definitions
- the technology relates to wireless telecommunication systems, and in particular to resource allocation in wireless telecommunication systems.
- Many wireless telecommunication systems are cellular. That is, the coverage area is divided into cells, and each mobile device, or other user equipment, communicates with a base station in the cell in which it is located. In order to achieve such communication, a communication resource must be allocated to the mobile device.
- the available communication resources include the available communication bandwidth and the available time.
- TDMA Time Division Multiple Access
- FDMA Frequency Division Multiple Access
- TDMA time division multiple access
- FDMA frequency division multiple access
- One issue in cellular wireless telecommunication systems concerns interference. That is, where for example a mobile device is located between a base station to which it is transmitting and another base station that is also receiving signals transmitted on the same frequency, there is a danger that the signals transmitted from that mobile device will erroneously be received, and/or will cause interference at the other base station.
- One way to solve this issue is to allocate the available transmission frequencies to different cells, in such a way as to reduce the probability of such interference. For example, if a transmission frequency is allocated for use by mobile devices within a particular cell of the system, then it may advantageously not be allocated for use by mobile devices within any other cell that neighbours that particular cell. This step reduces the probability that the signals transmitted from that mobile device will erroneously be received, or will cause interference at any other base station that is receiving signals on that transmission frequency.
- transmission times in different cells are controlled in such a way as to reduce the probability of interference with transmissions in neighbouring cells.
- one example embodiment provides a method of controlling a cellular wireless telecommunication system, in which data is transmitted in frames, and wherein, for a first cell of said system, there is semi-statically defined at the same time position in a plurality of consecutive time intervals a low interference time period for transmissions in the first cell, each of said time intervals comprising an equal number of frames, and the low interference time period being a time period during which neighbouring cells are configured to minimize interference in the first cell;
- FIG. 1 illustrates a wireless communication network according to an aspect.
- FIG. 2 illustrates a division of a network coverage area into cells in the network.
- FIG. 3 is a flow chart, illustrating a method according to an aspect.
- FIG. 4 is a flow chart, illustrating a second method according to an aspect.
- FIG. 5 is a timing diagram, illustrating operation of a first network in accordance with the method of FIG. 4 .
- FIG. 6 is a timing diagram, illustrating operation of a second network in accordance with the method of FIG. 4 .
- FIG. 1 shows a wireless communication network, in which there are a number of base stations 10 , 12 , 14 , located within a coverage area of the network such that they can provide mobile communication services to user equipments active within the coverage area.
- FIG. 2 shows four such user equipments, in the form of mobile phones 20 , 22 , 24 , 26 , but it will be appreciated that any suitable type of user equipment can be used in the network.
- the base stations 10 , 12 , 14 have connections to a core network (not shown) of the wireless communication network, and each have radio transceiver circuitry for communicating with the user equipments.
- the coverage area of the network is divided into cells, as described in more detail below, with each base station providing service to the user equipments located within the corresponding cell.
- the user equipments are similarly conventional, and also have radio transceiver circuitry, for communicating with the base stations.
- the description is provided with reference to an example wireless communication network operating on the OFDMA (Orthogonal Frequency Division Multiple Access) principle, in which the whole of the available frequency bandwidth is used in each of the cells.
- This available bandwidth is divided into sub-channels, and one or more of these sub-channels can be allocated for communications with any particular user equipment.
- FIG. 1 shows only a small number of base stations and user equipments, it will be appreciated that a practical network is likely to include large numbers of base stations and user equipments.
- FIG. 2 illustrates schematically the division of the coverage area into cells. More specifically, FIG. 2 shows a part of the network coverage area being divided into three cells 100 , 120 , 140 , served respectively by the base stations 10 , 12 , 14 .
- the base stations are not shown in FIG. 2 although it will be recognized that one common arrangement involves the definition of each cell in the area surrounding the respective base station. It will also be recognized that the division shown in FIG. 2 is purely illustrative, and that the shape of cells is not regular as shown in FIG. 2 , but rather is defined by the radio frequency properties of the environment, and the signal strengths employed by the base stations, as well as by the positions of other surrounding base stations.
- Each user equipment can be instructed by its serving base station to make measurements relating to the signals transmitted by that serving base station and by other base stations.
- One of the purposes of such measurements is to allow the network to determine the nearby cells that should be considered to be neighbouring cells, it being recognized that the arrangement of base stations and cells will likely be less regular in practice than that shown in FIG. 2 .
- the cells 100 , 120 , 140 define the areas served respectively by the base stations 10 , 12 , 14 . That is, a mobile device within the cell 100 will have a connection to the base station 10 , etc.
- the cells are subdivided, and the service provided to a user equipment depends on the part of the cell in which it is located.
- FIG. 3 is a flow chart, illustrating a method for determining a part of the serving cell in which a user equipment is located.
- step 160 the user equipment measures the strength of signals received from its serving cell. Techniques for measuring signal strength are well known to the person skilled in the art, and will not be described further. An illustrative example refers to a user equipment that is located within the cell 100 , and so in step 160 the user equipment measures the strength of signals received from the cell 100 .
- step 162 the user equipment measures the strength of signals received from the neighbouring cells. Again, techniques for determining the neighbour cell list, and for making the signal strength measurements, are well known to the person skilled in the art, and will not be described further. In the case of the user equipment that is located within the cell 100 , in step 160 the user equipment measures the strength of signals received from the cells 120 and 140 , as well as other neighbouring cells not shown in detail in FIG. 2 .
- step 164 a comparison is made, for example within the base station 10 or elsewhere in the network, between the signal strength measurements made in steps 160 and 162 . Based on these comparison results, the cell 100 is logically subdivided into regions, and the location of the user equipment within one of those regions is determined
- FIG. 2 shows a part of the logical subdivision of the cell 100 , based on the comparison of the signal strength measurements.
- the user equipment is determined to be in an interior region 101 of the cell 100 , and the user equipment (UE) is referred to as an interior UE.
- some threshold value such as 3 dB
- the user equipment is determined to be in an exterior region of the cell 100 , and the user equipment is referred to as an exterior UE.
- the exterior UE is determined to be in the exterior region 102 that borders the neighbouring cell 120 .
- the exterior UE is determined to be in the exterior region 104 that borders the neighbouring cell 140 .
- the exterior UE is determined to be in the exterior region 103 that borders both of the neighbouring cells 120 , 140 .
- Similar exterior regions 106 , 107 are defined, with the exterior region 106 bordering the neighbouring cell 120 and one other neighbouring cell not shown in detail in FIG. 2 , and the exterior region 107 bordering the neighbouring cell 140 and a different neighbouring cell not shown in detail in FIG. 2 .
- Other exterior regions are also defined, bordering other neighbouring cells, but are not shown in FIG. 2 .
- any user equipment in the interior region 101 can be regarded as an interior device, while other user equipments can be regarded as exterior devices.
- exterior devices in the regions 106 , 102 and 103 that border the first neighbouring cell 120 can be regarded as having a higher risk of interference with that first neighbouring cell
- exterior devices in the regions 103 , 104 and 107 that border the second neighbouring cell 140 can be regarded as having a higher risk of interference with that second neighbouring cell
- exterior devices in the region 103 that borders the first and second neighbouring cells 120 , 140 can be regarded as having a higher risk of interference both with the first and with the second neighbouring cell.
- FIG. 4 is a further flow chart, illustrating a further method whereby a degree of coordination is achieved between the cells.
- step 180 the timing of the transmissions from one or more neighbouring cells is determined, relative to the timing of the transmissions from the cell under consideration. This determination may be made in the base station serving that cell, or may be made elsewhere in the network and communicated explicitly or implicitly to the cell, as required.
- each of the base stations starts the transmission of a new frame of data simultaneously. Therefore, in this case, it can readily be determined that there is no time difference between the transmissions from each base station.
- each base station instructs the devices within its cell to make measurements relating to the timing of the transmissions from the neighbouring cells, relative to the timing of its own transmissions.
- the relative timings can be determined with reference to the system frame numbers of the respective transmissions.
- These measurements can be made at regular periodic intervals, or when initiated by the network or the base station in response to a specified condition occurring.
- step 182 there is defined for the cell a first time period, which is advantageously a time period during which there is a lower probability of interference from neighbouring cells. This will be discussed in more detail below.
- step 184 there is defined for that cell one or more second time periods, which correspond to the first time periods defined in neighbouring cells, and during which there may be a higher probability of interference from neighbouring cells. Again, this will be discussed in more detail below.
- TDD time division duplexing
- FDD frequency division duplexing
- each active user equipment may be allocated all of the available sub-channels for some fraction of each frame. In other embodiments, an active user equipment may be allocated only a fraction of the available sub-channels for some fraction of each frame.
- aspects relate primarily to the way in which the fraction of the frame is allocated to a particular user equipment.
- each frame is divided into three sections, each of equal length.
- a first frame transmitted from the cell 100 is divided into sections t A0 -t A1 , t A1 -t A2 , t A2 -t A3 , while a second frame is divided into sections t A3 -t A4 , etc.
- a first frame transmitted from the cell 120 is divided into sections t B0 -t B1 , t B1 -t B2 , t B2 -t B3 , while a second frame is divided into sections t B1 -t B4 , etc, and a first frame transmitted from the cell 140 is divided into sections t C0 -t C1 , t C1 -t C2 , t C2 -t C3 , while a second frame is divided into sections t C3 -t C4 , etc.
- a time period is defined, during which there is a lower probability of interference from neighbouring cells.
- these time periods may be determined by network planning and the relevant base station may be informed which time period to adopt.
- the time period may be determined by the base station on the basis of measurements made by user equipments within the cell.
- the time differences between the serving cell and the neighbouring cells may be determined by knowledge of the network planning in the case of synchronized cells, or may be determined by the base station on the basis of measurements made by user equipments within the cell or by the base station itself.
- the time period is defined at least semi-statically, i.e. on a static or semi-static basis. That is, after the time period has been defined for a cell, it occurs at the same time position for a significant period of time, and in particular for the duration of a large number of frames, for example until measurements suggest that the radio environment has changed, or the timing relations between cells have changed. Again, the radio environment or the timing relations can be monitored using UE measurements or measurements made by the base station itself.
- the cell 100 may adopt the time period t A from t A0 -t A1 as its less interfered time period
- the cell 120 may adopt the time period t B from t B1 -t B2 as its less interfered time period
- the cell 140 may adopt the time period t C from t C2 -t C3 as its less interfered time period.
- these time periods are selected by the different cells such that no time period is adopted as the less interfered time period by any two adjacent cells. Even if this is not possible then, in any event, steps are preferably taken to ensure the maximum average reuse distance between cells that share a time period as the less interfered time period.
- each frame is divided into three sections
- the less interfered time period being equal to one third of one frame
- one or more second time periods are also defined, in which there is a specific risk of interference from one or more respective other cell.
- exterior user equipments in each cell which would tend to have a greater risk of interference with other cells because they are closer to the cell boundaries, are preferably allocated resources during the less interfered time periods.
- exterior user equipments in the cell 100 are preferably allocated resources during the time period t A
- exterior user equipments in the cell 120 are preferably allocated resources during the time period t B
- exterior user equipments in the cell 140 are preferably allocated resources during the time period t C .
- an exterior user equipment may instead be allocated resources outside the less interfered time period of that cell, provided that it avoids the use of a second time period during which there is a particular risk of interference with a specific neighbouring cell.
- the time period t B may be regarded as such a second time period concerning interference from the cell 120 , since exterior user equipments in that cell will preferentially be transmitting during that time period, while the time period t C may be regarded as such a second time period concerning interference from the cell 140 , since exterior user equipments in that cell will preferentially be transmitting during that time period.
- an exterior user equipment in the cell 100 that is in the region 102 bordering the cell 120 if that user equipment cannot be allocated resources in the less interfered time period t A , it can instead be allocated resources during the time period t C , in preference to the time period t B .
- an exterior user equipment in the cell 100 that is in the region 104 bordering the cell 140 if that user equipment cannot be allocated resources in the less interfered time period t A , it can instead be allocated resources during the time period t B , in preference to the time period t C .
- each active user equipment may be allocated all of the available sub-channels for some fraction of each frame. In other embodiments, an active user equipment may be allocated only a fraction of the available sub-channels for some fraction of each frame.
- each frame is divided into three sections, each of equal length, although the frames may be divided in any convenient way.
- a first frame transmitted from the cell 100 is divided into sections t A5 -t A6 , t A6 -t A7 , t A7 -t A8 , while a second frame is divided into sections t A8 -t A9 , etc.
- a first frame transmitted from the cell 120 is divided into sections t B5 -t B6 , t B6 -t B7 , t B7 -t B8 , while a second frame is divided into sections t B8 -t B9 , etc, and a first frame transmitted from the cell 140 is divided into sections t C5 -t C6 , t C6 -t C7 , t C7 -t C8 , while a second frame is divided into sections t C8 -t C9 , etc.
- a time period is defined, during which there is a lower probability of interference from neighbouring cells.
- these time periods may be determined by the cell itself to be the first section of each frame.
- the time period in one cell may be adjusted, based on reported timing measurements relating to other cells, such that the time periods become the same in all cells. This will tend to reduce the number of timing reports that are needed in the network.
- the relative timings of the frames in the different cells are arbitrary, as shown in FIG. 6 and, furthermore, these relative timings may change.
- the time period is defined on a static or semi-static basis. That is, after the time period has been defined, it occurs at the same time position for a significant period of time, and in particular for the duration of a large number of frames, for example until measurements suggest that the radio environment has changed.
- the cell may set its own first time period based on the present conditions, and in particular based on the measurements of the timings in other cells. The cell can monitor the timing relations with the neighbouring cells on the basis of measurements made by the user equipments in the cell, or measurements made by the base station itself
- the cell 100 may adopt the time period t A from t A5 t A6 as its less interfered time period
- the cell 120 may adopt the time period t B from t B5 -t B6 as its less interfered time period
- the cell 140 may adopt the time period t C from t C5 -t C6 as its less interfered time period.
- each frame is divided into three sections, and the less interfered time period is equal to one third of one frame
- each frame or other time interval into a different number of sections, such that the less interfered time period is equal to some different fraction of one frame or time interval.
- one or more second time periods are also defined, in which there is a specific risk of interference from one or more respective other cell.
- exterior user equipments in each cell which would tend to have a greater risk of interference with other cells because they are closer to the cell boundaries, are preferably allocated resources during the less interfered time periods.
- the methods described are applicable to any user equipments that require lower interference, such as interior user equipments having coverage problems or user equipments requiring particularly high data rates.
- exterior user equipments in the cell 100 are preferably allocated resources during the time period t A
- exterior user equipments in the cell 120 are preferably allocated resources during the time period t B
- exterior user equipments in the cell 140 are preferably allocated resources during the time period t C .
- an exterior user equipment in a region bordering one or more particular neighbouring cell should preferably not be allocated resources during respective second time periods corresponding to the less interfered time periods of that one or more neighbouring cell.
- the time period t B may be regarded as such a second time period concerning interference from the cell 120 , since exterior user equipments in that cell will preferentially be transmitting during that time period, while the time period t c may be regarded as such a second time period concerning interference from the cell 140 , since exterior user equipments in that cell will preferentially be transmitting during that time period.
- that user equipment can be allocated resources at any time during the less interfered time period t A , because there is no overlap with the time period t B .
- that user equipment should preferentially be allocated resources in that part of the less interfered time period t A that does not overlap with the time period t C .
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Abstract
Description
- This application is a continuation application claiming priority from U.S. application Ser. No. 12/739,322, filed Apr. 22, 2010, which is the U.S. national phase of International
- Application No. PCT/SE2007/050777, filed 25 Oct. 2007, which designated the U.S., the entire contents of each of which are hereby incorporated by reference.
- The technology relates to wireless telecommunication systems, and in particular to resource allocation in wireless telecommunication systems.
- Many wireless telecommunication systems are cellular. That is, the coverage area is divided into cells, and each mobile device, or other user equipment, communicates with a base station in the cell in which it is located. In order to achieve such communication, a communication resource must be allocated to the mobile device. The available communication resources include the available communication bandwidth and the available time. Thus, in a TDMA (Time Division Multiple Access) system, the available communications channel is allocated to different users at different times, while, in a FDMA (Frequency Division Multiple Access) system, different communications frequencies are allocated to different users.
- Many cellular wireless telecommunication systems use a combination of TDMA and FDMA, in that the communication resource allocated to a user comprises a particular bandwidth allocation during a specified time period.
- One issue in cellular wireless telecommunication systems concerns interference. That is, where for example a mobile device is located between a base station to which it is transmitting and another base station that is also receiving signals transmitted on the same frequency, there is a danger that the signals transmitted from that mobile device will erroneously be received, and/or will cause interference at the other base station.
- One way to solve this issue is to allocate the available transmission frequencies to different cells, in such a way as to reduce the probability of such interference. For example, if a transmission frequency is allocated for use by mobile devices within a particular cell of the system, then it may advantageously not be allocated for use by mobile devices within any other cell that neighbours that particular cell. This step reduces the probability that the signals transmitted from that mobile device will erroneously be received, or will cause interference at any other base station that is receiving signals on that transmission frequency.
- In example aspects, transmission times in different cells are controlled in such a way as to reduce the probability of interference with transmissions in neighbouring cells.
- More specifically, one example embodiment provides a method of controlling a cellular wireless telecommunication system, in which data is transmitted in frames, and wherein, for a first cell of said system, there is semi-statically defined at the same time position in a plurality of consecutive time intervals a low interference time period for transmissions in the first cell, each of said time intervals comprising an equal number of frames, and the low interference time period being a time period during which neighbouring cells are configured to minimize interference in the first cell;
-
- the method comprising, for at least one user equipment served by the first cell:
- receiving signal strength measurements; and
- based on the signal strength measurements, determining whether the user equipment should be scheduled for the low interference time period.
- This has the advantage that the probability of interference may be reduced, and hence that the overall capacity of the cell can be used with high efficiency.
-
FIG. 1 illustrates a wireless communication network according to an aspect. -
FIG. 2 illustrates a division of a network coverage area into cells in the network. -
FIG. 3 is a flow chart, illustrating a method according to an aspect. -
FIG. 4 is a flow chart, illustrating a second method according to an aspect. -
FIG. 5 is a timing diagram, illustrating operation of a first network in accordance with the method ofFIG. 4 . -
FIG. 6 is a timing diagram, illustrating operation of a second network in accordance with the method ofFIG. 4 . -
FIG. 1 shows a wireless communication network, in which there are a number ofbase stations FIG. 2 shows four such user equipments, in the form ofmobile phones - As is conventional, the
base stations - The user equipments are similarly conventional, and also have radio transceiver circuitry, for communicating with the base stations.
- The description is provided with reference to an example wireless communication network operating on the OFDMA (Orthogonal Frequency Division Multiple Access) principle, in which the whole of the available frequency bandwidth is used in each of the cells. This available bandwidth is divided into sub-channels, and one or more of these sub-channels can be allocated for communications with any particular user equipment.
- Although
FIG. 1 shows only a small number of base stations and user equipments, it will be appreciated that a practical network is likely to include large numbers of base stations and user equipments. -
FIG. 2 illustrates schematically the division of the coverage area into cells. More specifically,FIG. 2 shows a part of the network coverage area being divided into threecells base stations FIG. 2 although it will be recognized that one common arrangement involves the definition of each cell in the area surrounding the respective base station. It will also be recognized that the division shown inFIG. 2 is purely illustrative, and that the shape of cells is not regular as shown inFIG. 2 , but rather is defined by the radio frequency properties of the environment, and the signal strengths employed by the base stations, as well as by the positions of other surrounding base stations. - Each user equipment can be instructed by its serving base station to make measurements relating to the signals transmitted by that serving base station and by other base stations. One of the purposes of such measurements is to allow the network to determine the nearby cells that should be considered to be neighbouring cells, it being recognized that the arrangement of base stations and cells will likely be less regular in practice than that shown in
FIG. 2 . - As is conventional, the
cells base stations cell 100 will have a connection to thebase station 10, etc. In preferred example embodiments, the cells are subdivided, and the service provided to a user equipment depends on the part of the cell in which it is located. -
FIG. 3 is a flow chart, illustrating a method for determining a part of the serving cell in which a user equipment is located. - In
step 160, the user equipment measures the strength of signals received from its serving cell. Techniques for measuring signal strength are well known to the person skilled in the art, and will not be described further. An illustrative example refers to a user equipment that is located within thecell 100, and so instep 160 the user equipment measures the strength of signals received from thecell 100. - In
step 162, the user equipment measures the strength of signals received from the neighbouring cells. Again, techniques for determining the neighbour cell list, and for making the signal strength measurements, are well known to the person skilled in the art, and will not be described further. In the case of the user equipment that is located within thecell 100, instep 160 the user equipment measures the strength of signals received from thecells FIG. 2 . - In
step 164, a comparison is made, for example within thebase station 10 or elsewhere in the network, between the signal strength measurements made insteps cell 100 is logically subdivided into regions, and the location of the user equipment within one of those regions is determined -
FIG. 2 shows a part of the logical subdivision of thecell 100, based on the comparison of the signal strength measurements. - Where the signal strength measured in
step 160, i.e. the signal strength from theserving cell 100, is greater than any of the signal strengths measured instep 162, i.e. the signal strengths from the neighbouring cells, by a margin that exceeds some threshold value, such as 3 dB, then the user equipment is determined to be in aninterior region 101 of thecell 100, and the user equipment (UE) is referred to as an interior UE. - By contrast, where the signal strength from the
serving cell 100 does not exceed all of the signal strengths from the neighbouring cells by a margin that exceeds the threshold value, such as 3 dB, then the user equipment is determined to be in an exterior region of thecell 100, and the user equipment is referred to as an exterior UE. - More specifically, where the signal strength from the
serving cell 100 does not exceed the signal strength from the neighbouringcell 120 by a margin that exceeds the threshold value, but where the signal strength from theserving cell 100 does exceed the signal strength from all of the other neighbouring cells by a margin that exceeds the threshold value, then the exterior UE is determined to be in theexterior region 102 that borders the neighbouringcell 120. - Similarly, where the signal strength from the serving
cell 100 does not exceed the signal strength from the neighbouringcell 140 by a margin that exceeds the threshold value, but where the signal strength from theserving cell 100 does exceed the signal strength from all of the other neighbouring cells by a margin that exceeds the threshold value, then the exterior UE is determined to be in theexterior region 104 that borders the neighbouringcell 140. - Where the signal strength from the serving
cell 100 does not exceed the signal strength from the neighbouringcell 120 by a margin that exceeds the threshold value, and also does not exceed the signal strength from the neighbouringcell 140 by a margin that exceeds the threshold value, but where the signal strength from the servingcell 100 does exceed the signal strength from all of the other neighbouring cells by a margin that exceeds the threshold value, then the exterior UE is determined to be in theexterior region 103 that borders both of the neighbouringcells - Similar
exterior regions exterior region 106 bordering the neighbouringcell 120 and one other neighbouring cell not shown in detail inFIG. 2 , and theexterior region 107 bordering the neighbouringcell 140 and a different neighbouring cell not shown in detail inFIG. 2 . Other exterior regions are also defined, bordering other neighbouring cells, but are not shown inFIG. 2 . - Thus, any user equipment in the
interior region 101 can be regarded as an interior device, while other user equipments can be regarded as exterior devices. Then, exterior devices in theregions neighbouring cell 120 can be regarded as having a higher risk of interference with that first neighbouring cell, while exterior devices in theregions neighbouring cell 140 can be regarded as having a higher risk of interference with that second neighbouring cell, it being noted of course that exterior devices in theregion 103 that borders the first and second neighbouringcells -
FIG. 4 is a further flow chart, illustrating a further method whereby a degree of coordination is achieved between the cells. - In
step 180, the timing of the transmissions from one or more neighbouring cells is determined, relative to the timing of the transmissions from the cell under consideration. This determination may be made in the base station serving that cell, or may be made elsewhere in the network and communicated explicitly or implicitly to the cell, as required. - The methods described herein can be applied either to synchronized networks or to unsynchronized networks. In the case of synchronized networks, each of the base stations starts the transmission of a new frame of data simultaneously. Therefore, in this case, it can readily be determined that there is no time difference between the transmissions from each base station.
- In the case of an unsynchronized network, the frames transmitted by the different base stations begin at times that are effectively random. Therefore, in this case, each base station instructs the devices within its cell to make measurements relating to the timing of the transmissions from the neighbouring cells, relative to the timing of its own transmissions. For example, the relative timings can be determined with reference to the system frame numbers of the respective transmissions.
- These measurements can be made at regular periodic intervals, or when initiated by the network or the base station in response to a specified condition occurring.
- In
step 182, there is defined for the cell a first time period, which is advantageously a time period during which there is a lower probability of interference from neighbouring cells. This will be discussed in more detail below. - In
step 184, there is defined for that cell one or more second time periods, which correspond to the first time periods defined in neighbouring cells, and during which there may be a higher probability of interference from neighbouring cells. Again, this will be discussed in more detail below. - The operation of the method is illustrated, firstly with reference to its application in a synchronized network, in
FIG. 5 . As is well known, communications networks that use time division duplexing (TDD) are usually synchronized, to allow for the possibility that a device will handover from one cell to another and retain the same timings. - Similarly, systems that use frequency division duplexing (FDD) need to be synchronized if they are to allow the transmission of multicast messages. Thus, the system illustrated in
FIG. 5 may arise in such networks but will not arise exclusively in such networks. - In
FIG. 5 , there are shown the timings of transmissions from the threecells - Aspects relate primarily to the way in which the fraction of the frame is allocated to a particular user equipment.
- In this example embodiment, each frame is divided into three sections, each of equal length. Thus, a first frame transmitted from the
cell 100 is divided into sections tA0-tA1, tA1-tA2, tA2-tA3, while a second frame is divided into sections tA3-tA4, etc. Similarly, a first frame transmitted from thecell 120 is divided into sections tB0-tB1, tB1-tB2, tB2-tB3, while a second frame is divided into sections tB1-tB4, etc, and a first frame transmitted from thecell 140 is divided into sections tC0-tC1, tC1-tC2, tC2-tC3, while a second frame is divided into sections tC3-tC4, etc. - Within each of the
cells - In either case, the time period is defined at least semi-statically, i.e. on a static or semi-static basis. That is, after the time period has been defined for a cell, it occurs at the same time position for a significant period of time, and in particular for the duration of a large number of frames, for example until measurements suggest that the radio environment has changed, or the timing relations between cells have changed. Again, the radio environment or the timing relations can be monitored using UE measurements or measurements made by the base station itself.
- For example, as shown in
FIG. 5 , and referring toFIG. 2 , thecell 100 may adopt the time period tA from tA0-tA1 as its less interfered time period, thecell 120 may adopt the time period tB from tB1-tB2 as its less interfered time period, and thecell 140 may adopt the time period tC from tC2-tC3 as its less interfered time period. In this embodiment, there are only three time periods that are available for selection by each of the cells in the system. Preferably, these time periods are selected by the different cells such that no time period is adopted as the less interfered time period by any two adjacent cells. Even if this is not possible then, in any event, steps are preferably taken to ensure the maximum average reuse distance between cells that share a time period as the less interfered time period. - Although the description makes reference to a situation where there is a less interfered time period during each frame, it is also possible to define a time interval that is equal to a plurality of frames, with the less interfered time period then occurring at the same time position in each time interval.
- Further, although an example in which each frame is divided into three sections is described with the less interfered time period being equal to one third of one frame, it is also possible to divide each frame or other time interval into a different number of sections, such that the less interfered time period is equal to some different fraction of one frame or time interval.
- When a first, less interfered, time period has been defined in each cell, one or more second time periods are also defined, in which there is a specific risk of interference from one or more respective other cell.
- Thus, in this case, exterior user equipments in each cell, which would tend to have a greater risk of interference with other cells because they are closer to the cell boundaries, are preferably allocated resources during the less interfered time periods. Specifically, in this example, exterior user equipments in the
cell 100 are preferably allocated resources during the time period tA, exterior user equipments in thecell 120 are preferably allocated resources during the time period tB, and exterior user equipments in thecell 140 are preferably allocated resources during the time period tC. - However, if no such resources are available, an exterior user equipment may instead be allocated resources outside the less interfered time period of that cell, provided that it avoids the use of a second time period during which there is a particular risk of interference with a specific neighbouring cell.
- Thus, considering
cell 100, the time period tB may be regarded as such a second time period concerning interference from thecell 120, since exterior user equipments in that cell will preferentially be transmitting during that time period, while the time period tC may be regarded as such a second time period concerning interference from thecell 140, since exterior user equipments in that cell will preferentially be transmitting during that time period. - Therefore, for an exterior user equipment in the
cell 100 that is in theregion 102 bordering thecell 120, if that user equipment cannot be allocated resources in the less interfered time period tA, it can instead be allocated resources during the time period tC, in preference to the time period tB. Similarly, for an exterior user equipment in thecell 100 that is in theregion 104 bordering thecell 140, if that user equipment cannot be allocated resources in the less interfered time period tA, it can instead be allocated resources during the time period tB, in preference to the time period tC. - As described above, it is exterior user equipments in a cell that are preferentially allocated resources in the less interfered time period defined for that cell. However, alternatively or additionally, other user equipments that require low interference conditions may be preferentially allocated resources in the less interfered time period.
- The operation of the method is further illustrated with reference to its application in an unsynchronized network, in
FIG. 6 . - In
FIG. 6 , there are again shown the timings of transmissions from the threecells - Again, in this example embodiment, each frame is divided into three sections, each of equal length, although the frames may be divided in any convenient way. Thus, a first frame transmitted from the
cell 100 is divided into sections tA5-tA6, tA6-tA7, tA7-tA8, while a second frame is divided into sections tA8-tA9, etc. Similarly, a first frame transmitted from thecell 120 is divided into sections tB5-tB6, tB6-tB7, tB7-tB8, while a second frame is divided into sections tB8-tB9, etc, and a first frame transmitted from thecell 140 is divided into sections tC5-tC6, tC6-tC7, tC7-tC8, while a second frame is divided into sections tC8-tC9, etc. - Within each of the
cells - In an unsynchronized system, the relative timings of the frames in the different cells are arbitrary, as shown in
FIG. 6 and, furthermore, these relative timings may change. In any event, the time period is defined on a static or semi-static basis. That is, after the time period has been defined, it occurs at the same time position for a significant period of time, and in particular for the duration of a large number of frames, for example until measurements suggest that the radio environment has changed. However, the cell may set its own first time period based on the present conditions, and in particular based on the measurements of the timings in other cells. The cell can monitor the timing relations with the neighbouring cells on the basis of measurements made by the user equipments in the cell, or measurements made by the base station itself - For example, as shown in
FIG. 6 , thecell 100 may adopt the time period tA from tA5tA6 as its less interfered time period, thecell 120 may adopt the time period tB from tB5-tB6 as its less interfered time period, and thecell 140 may adopt the time period tC from tC5-tC6 as its less interfered time period. - As before, although the description refers to a situation where there is a less interfered time period during each frame, it is also possible to define a time interval that is equal to a plurality of frames, with the less interfered time period then occurring at the same time position in each time interval.
- Further, although the description refers to an example in which each frame is divided into three sections, and the less interfered time period is equal to one third of one frame, it is also possible to divide each frame or other time interval into a different number of sections, such that the less interfered time period is equal to some different fraction of one frame or time interval.
- When a first, less interfered, time period has been defined in each cell, one or more second time periods are also defined, in which there is a specific risk of interference from one or more respective other cell.
- Thus, in this case, exterior user equipments in each cell, which would tend to have a greater risk of interference with other cells because they are closer to the cell boundaries, are preferably allocated resources during the less interfered time periods. Incidentally, although specific reference is made to the allocation of resources for exterior user equipments, which are likely to cause interference with user equipments in neighbouring cells as well as being more vulnerable to interference from user equipments in neighbouring cells, the methods described are applicable to any user equipments that require lower interference, such as interior user equipments having coverage problems or user equipments requiring particularly high data rates.
- Specifically, in this example, exterior user equipments in the
cell 100 are preferably allocated resources during the time period tA, exterior user equipments in thecell 120 are preferably allocated resources during the time period tB, and exterior user equipments in thecell 140 are preferably allocated resources during the time period tC. - However, this is also subject to the condition that an exterior user equipment in a region bordering one or more particular neighbouring cell should preferably not be allocated resources during respective second time periods corresponding to the less interfered time periods of that one or more neighbouring cell.
- Thus, considering
cell 100, the time period tB may be regarded as such a second time period concerning interference from thecell 120, since exterior user equipments in that cell will preferentially be transmitting during that time period, while the time period tc may be regarded as such a second time period concerning interference from thecell 140, since exterior user equipments in that cell will preferentially be transmitting during that time period. - Therefore, for an exterior user equipment in the
cell 100 that is in theregion 102 bordering thecell 120, that user equipment can be allocated resources at any time during the less interfered time period tA, because there is no overlap with the time period tB. However, for an exterior user equipment in thecell 100 that is in theregion 104 bordering thecell 140, that user equipment should preferentially be allocated resources in that part of the less interfered time period tA that does not overlap with the time period tC. - There is thus disclosed a system for minimizing interference, based on the allocation of resources to user equipments, at times when there is a reduced possibility of such interference, as a result of some predetermined definition of a less interfered time period.
Claims (17)
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US14/219,263 US20140204787A1 (en) | 2007-10-25 | 2014-03-19 | Method and arrangement in a telecommunication system |
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US12/739,322 US8681745B2 (en) | 2007-10-25 | 2007-10-25 | Method and arrangement in a telecommunication system |
PCT/SE2007/050777 WO2009054761A1 (en) | 2007-10-25 | 2007-10-25 | Method and arrangement in a telecommunication system |
US14/219,263 US20140204787A1 (en) | 2007-10-25 | 2014-03-19 | Method and arrangement in a telecommunication system |
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US12/739,322 Continuation US8681745B2 (en) | 2007-10-25 | 2007-10-25 | Method and arrangement in a telecommunication system |
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EP2206251A4 (en) * | 2007-10-25 | 2013-07-10 | Unwired Planet Llc | Method and arrangement in a telecommunication system |
DE102008063612A1 (en) * | 2008-04-15 | 2009-10-22 | Rohde & Schwarz Gmbh & Co. Kg | Method for testing the transmission states of a measuring device |
EP2534912B1 (en) * | 2010-02-12 | 2014-10-22 | Telefonaktiebolaget L M Ericsson (PUBL) | Method and arrangement in a telecommunication network with intercell interference coordination |
CN102300320B (en) * | 2010-06-22 | 2014-04-30 | 上海贝尔股份有限公司 | Inter-cell interference coordination method and device |
US20140023050A1 (en) * | 2012-07-17 | 2014-01-23 | Electronics And Telecommunications Research Institute | Method and apparatus for allocating resources in cellular communication system |
CN104602249B (en) * | 2014-12-05 | 2018-01-19 | 华为技术服务有限公司 | A kind of method and device for determining cell relations |
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US20090052353A1 (en) * | 2007-08-23 | 2009-02-26 | Motorola, Inc. | System and method for transmission timeslot assignment in wireless time division duplex systems |
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US20120243427A1 (en) * | 2008-12-23 | 2012-09-27 | At&T Mobility Ii Llc | Using Mobile Communication Devices To Facilitate Coordinating Use of Resources |
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JPH0494228A (en) * | 1990-08-09 | 1992-03-26 | Matsushita Electric Ind Co Ltd | Dynamic channel allocation method |
CA2113750C (en) * | 1993-04-30 | 1999-08-24 | Hamid Ahmadi | A multiaccess scheme for mobile integrated local area networks |
US5507034A (en) * | 1993-09-01 | 1996-04-09 | Telefonaktiebolaget Lm Ericsson | Channel selection in a cellular communication system |
FI107854B (en) * | 1994-03-21 | 2001-10-15 | Nokia Networks Oy | A method for eliminating interference in a CDMA cellular network |
EP1122895A1 (en) | 2000-02-03 | 2001-08-08 | Motorola, Inc. | Time division duplex cellular communications system with dynamic slot allocation and reduced interference |
US7236793B2 (en) * | 2001-01-31 | 2007-06-26 | Ipr Licensing, Inc. | Queuing far/far service requests in wireless network |
US7149476B2 (en) * | 2003-02-20 | 2006-12-12 | Cingular Wireless Ii, Llc | Precision for interference estimation in unsynchronized wireless networks |
US7146162B2 (en) * | 2003-03-25 | 2006-12-05 | Interdigital Technology Corporation | Method and system for managing resources in wireless communication systems |
CN1859054B (en) * | 2005-04-30 | 2011-05-11 | 华为技术有限公司 | Method for realizing time soft multiple use in radio communication system |
JP2006311417A (en) * | 2005-05-02 | 2006-11-09 | Nec Corp | Transmission scheduling method for mobile terminal and base station |
US20070161376A1 (en) * | 2006-01-11 | 2007-07-12 | Nokia Corporation | Timeslot reuse for a service based interference control |
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EP2206251A4 (en) * | 2007-10-25 | 2013-07-10 | Unwired Planet Llc | Method and arrangement in a telecommunication system |
-
2007
- 2007-10-25 EP EP07835361.2A patent/EP2206251A4/en not_active Withdrawn
- 2007-10-25 US US12/739,322 patent/US8681745B2/en not_active Expired - Fee Related
- 2007-10-25 WO PCT/SE2007/050777 patent/WO2009054761A1/en active Application Filing
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2014
- 2014-03-19 US US14/219,263 patent/US20140204787A1/en not_active Abandoned
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US5375123A (en) * | 1993-02-05 | 1994-12-20 | Telefonakitebolaget L. M. Ericsson | Allocation of channels using interference estimation |
US20090052353A1 (en) * | 2007-08-23 | 2009-02-26 | Motorola, Inc. | System and method for transmission timeslot assignment in wireless time division duplex systems |
US20100159972A1 (en) * | 2008-12-19 | 2010-06-24 | Foundation For Collaboration Sungkyunkwan University | Method and apparatus for effective multi-cell interference control service |
US20120243427A1 (en) * | 2008-12-23 | 2012-09-27 | At&T Mobility Ii Llc | Using Mobile Communication Devices To Facilitate Coordinating Use of Resources |
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US8681745B2 (en) | 2014-03-25 |
EP2206251A4 (en) | 2013-07-10 |
US20100246519A1 (en) | 2010-09-30 |
WO2009054761A1 (en) | 2009-04-30 |
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