WO2010023518A2 - Graduated single frequency network - Google Patents
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- WO2010023518A2 WO2010023518A2 PCT/IB2009/006484 IB2009006484W WO2010023518A2 WO 2010023518 A2 WO2010023518 A2 WO 2010023518A2 IB 2009006484 W IB2009006484 W IB 2009006484W WO 2010023518 A2 WO2010023518 A2 WO 2010023518A2
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- 230000005540 biological transmission Effects 0.000 claims abstract description 143
- 238000000034 method Methods 0.000 claims description 40
- 230000008859 change Effects 0.000 claims description 10
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Classifications
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W4/00—Services specially adapted for wireless communication networks; Facilities therefor
- H04W4/06—Selective distribution of broadcast services, e.g. multimedia broadcast multicast service [MBMS]; Services to user groups; One-way selective calling services
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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
- H04W72/542—Allocation or scheduling criteria for wireless resources based on quality criteria using measured or perceived quality
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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
- H04W16/14—Spectrum sharing arrangements between different networks
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B7/00—Radio transmission systems, i.e. using radiation field
- H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
- H04B7/022—Site diversity; Macro-diversity
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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
- H04W72/30—Resource management for broadcast services
Definitions
- the present invention relates to communications, and in particular to a graduated single frequency network.
- Single frequency network are often employed to broadcast information to users throughout a cellular or like network.
- SFNs Single frequency network
- adjacent base stations will transmit the same information at the same time using the same radio resources.
- the signals transmitted from the different base stations effectively reinforce each other and therefore increase the spectral efficiency of the overall network with respect to the signals being transmitted.
- Increases in spectral efficiency are greatest along cell boundaries where multiple relatively weak signals combine with each other to increase the effective power associated with the transmitted signals.
- the transmitted signals are readily received along the cell boundaries because the effective power of the transmitted signals is increased and the potential for interference is decreased.
- SFNs are not without compromises.
- different channel qualities may occur due to base station locations, cell sizes, interference levels, physical topologies, neighboring transmissions, and the like. If each base station in the SFN of a cellular network has to transmit the same information at the same time using the same resources, the entire SFN must be designed to accommodate those cells or areas having the worst channel quality. Since the areas with the worst channel quality dictate the resources for the entire SFN, those areas with relatively high channel quality are theoretically using more resources than are necessary for broadcasting the data of the SFN. These resources could be better used for supporting traditional voice, data, or other media applications.
- the signals from adjacent transmitters reinforce one another.
- signal quality is improved in the network and especially at or near cell boundaries.
- the present invention provides a graduated single frequency network (GSFN) wherein transmitters in cells throughout a geographic area cooperate to broadcast data to user terminals throughout the geographic area, and adjacent transmitters transmit signals that reinforce one another.
- GSFN graduated single frequency network
- transmitters in certain adjacent cells throughout the geographic area may employ different transmit parameters to provide different transmission signals.
- the transmission signals used to transmit the data may be varied in a graduated fashion throughout the geographic area, wherein when there is a difference in the transmission signals of transmitters in adjacent cells, the difference is configured to allow the transmission signals to reinforce one another despite being different.
- FIGURE 1 is a block representation of a communication environment according to one embodiment of the present invention.
- FIGURE 2 illustrates a cellular network according to one embodiment of the present invention.
- FIGURE 3 illustrates a resource allocation according to a first embodiment of the present invention.
- FIGURE 4 illustrates a resource allocation according to a second embodiment of the present invention.
- FIGURE 5 illustrates a resource allocation according to a third embodiment of the present invention.
- FIGURE 6 illustrates a resource allocation according to a fourth embodiment of the present invention.
- FIGURE 7 illustrates sub-carrier mapping to resource blocks according to a first embodiment of the present invention.
- FIGURE 8 illustrates sub-carrier mapping to resource blocks according to a second embodiment of the present invention.
- FIGURES 9A-9C illustrate constellations for different layers of hierarchical modulation.
- FIGURES 10A-1 OF illustrate the transition from a first layer QPSK modulation to a third layer 64-QAM modulation according to one embodiment of the present invention.
- FIGURE 11 provides a table of exemplary scaling factors according to one embodiment of the present invention.
- FIGURE 12 is a flow diagram illustrating the combination of multiple embodiments of the present invention.
- FIGURE 13 is a block representation of a base station according to one embodiment of the present invention.
- FIGURE 14 is a block representation of a user terminal according to one embodiment of the present invention.
- a single frequency network is effectively a network wherein transmitters in cells throughout a geographic area broadcast data using the same transmission signal at the same time. The signals from adjacent transmitters reinforce one another. As a result of this over-the-air combining, signal quality is improved in the network and especially at or near cell boundaries.
- the present invention provides a graduated single frequency network (GSFN) wherein transmitters in cells throughout a geographic area cooperate to broadcast data to user terminals throughout the geographic area, and adjacent transmitters transmit signals that reinforce one another.
- GSFN graduated single frequency network
- transmitters in certain adjacent cells throughout the geographic area may employ different transmit parameters to provide different transmission signals.
- the transmission signals used to transmit the data may be varied in a graduated fashion throughout the geographic area, wherein when there is a difference in the transmission signals of transmitters in adjacent cells, the difference is configured to allow the transmission signals to reinforce one another despite being different. While transmitters in certain adjacent cells may use different transmission signals to transmit the data, other adjacent cells may use the same transmission signal at any given time. Changes in transmission signals may be controlled based on the channel conditions in the cells throughout the geographic area.
- the transmission signals may continue to vary in a graduated fashion throughout the geographic area based on various criteria, such as the channel conditions in the corresponding cells.
- any differences between the transmission signals from transmitters in any two adjacent cells are proportional to the change in channel quality between the two adjacent cells. Larger changes in channel quality between adjacent cells will result in larger differences between the respective transmission signals, whereas smaller changes in channel quality between adjacent cells will result in smaller different between the respective transmission signals.
- BSC base station controller
- Each cell 12 represents the primary coverage area of a particular base station (BS) 14 that is operating under the control of the BSC 10.
- the base stations 14 are capable of facilitating bi-directional communications through any number of communication technologies with user terminals (UT) 16 that are within communication range of the base stations 14, and thus within a corresponding cell 12.
- Communications throughout the cellular network may support traditional voice and data communications, wherein separate sessions are established with separate user terminals 16 as well as broadcast communications, wherein effectively the same information is broadcast by multiple base stations 14 at the same time.
- the cellular network may support traditional voice calls as well as provide a mechanism for broadcasting radio or television content throughout all or portions of the cellular network.
- a portion of a cellular network 18 is illustrated to include numerous cells 12.
- Each cell 12 in Figure 2 is labeled with a letter ranging from A to H.
- the cells 12 on the left side of Figure 2 are relatively small, and thus have a relatively high channel quality.
- the cells 12 on the right are generally larger and have a relatively lower channel quality.
- the cells 12 generally increase in size as they progress from the left to the right side of Figure 2. Accordingly, the channel quality for the cells 12 tends to decrease as the cells 12 progress from the left side to the right side of Figure 2.
- cells A have the highest channel quality
- cells H have the worst channel quality, wherein the channel quality decreases from cells A to cells B, from cells B to cells C, from cells C to cells D, from cells D to cells E, from cells E to cells F, from cells F to cells G, and from cells G to cells H.
- cells 12 with the same label are considered like cells 12, and cells 12 with different labels are considered different cells 12.
- Certain cells 12 may be adjacent like cells 12 or different cells 12.
- a cell D may be adjacent to other like cells D as well as different cells E.
- the base stations 14 and each of the cells 12 may broadcast the same data to user terminals 16 at the same time.
- the base stations 14 in like cells 12 will transmit the data using the same transmission signals at the same time.
- the transmission signals for different cells 12 may vary from one another, but will be configured to substantially reinforce one another near the boundaries of the adjacent cells 12 (A through H).
- each of the cells A may broadcast data using a first transmission signal
- each of the cells B may broadcast the data using a second transmission signal
- each of the cells C may broadcast the data using a third transmission signal, and so on and so forth, wherein each of the cells 12 within a given series of cells A through H uses the same transmission signal.
- the transmission signals used by the different series of cells A through H are different.
- the difference between the transmission signals used by different cells 12 that are adjacent to one another is relatively small, wherein the different transmission signals substantially reinforce one another despite being different.
- the change in transmission signals between different cells 12 that are adjacent one another is relatively small, the continual and gradual changes in the transmission signals across the cellular network 18 may result in the transmission signals on one side of the cellular network 18 varying significantly from transmission signals used on another side of the cellular network 18.
- the difference between the transmission signals used by cells A and cells B may be relatively small, whereas the difference between the transmission signals used by cells A and cells H may be significant.
- the difference between the transmission signals from adjacent cells may be relatively large, yet the transmission signals from the adjacent cells are configured to reinforce one another as desired.
- any differences between the transmission signals from transmitters in any two adjacent cells may be proportional to the change in actual or presumed channel quality between the two adjacent cells.
- the channel quality for a given cell may be measured on an average, based on the measurements from those users who are receiving the broadcast data, or based simply on the size of the cell 12.
- Channel quality may be measured based on any number of actual or predicted factors from the network, user, or environment perspective. Larger changes in channel quality between adjacent cells 12 will result in larger differences between the respective transmission signals, whereas smaller changes in channel quality between adjacent cells 12 will result in smaller differences between the respective transmission signals.
- the following description references the exemplary cellular network 18 of Figure 2, wherein the differences in channel quality between the different cells 12 are relatively small. As a result, the differences between the corresponding transmission signals are relatively small. However, the concepts of the present invention equally apply to environments where relatively large differences in channel quality between adjacent cells result in relatively large changes in the corresponding transmission signals. The goal is to take measures to have the transmission signals of adjacent cells 12 reinforce each other, even when they are different. [0029] Those skilled in the art will recognize that the transmission of data may employ various encoding, modulation, and like techniques.
- the data to be broadcast may represent audio, video, or other media content, and is deemed not to include supplemental information associated with encoding, such as parity information, checksums, and the like.
- the transmission signals will represent the actual signals being transmitted by the base stations 14 or like transmitters, and may carry information including the data to be broadcast as well as other information, which may include parity information and the like.
- the change in transmission signals across different cells 12 is a function of the encoding rate used by the base stations 14 in the different cells 12.
- a higher encoding rate indicates that less parity information is used to facilitate forward error correction for a set amount of data.
- a lower encoding rate indicates that more parity information is used for forward error correction for the same amount of data.
- Cells 12 associated with higher channel qualities will support higher encoding rates, while cells 12 with lower channel qualities will require lower encoding rates.
- transmission resources may vary depending on communication technology, but are generally related to time, frequency, phase, multiple access codes, amplitude, and the like.
- the transmission signals will be substantially the same, and preferably, a majority of the transmission signals will be the same while a portion of the transmission signals is different.
- the transmission signals of different cells 12 that are adjacent one another will have common signal portions and at least one of the transmission signals of the different cells 12 will have a different signal portion.
- the common signal portions of the transmission signals use the same resources in the same way.
- the different signal portion or portions either use different resources or use the same resources in a different way.
- one of the transmission signals may use more or less resources than the other or use the same resources in a different way, while both of the transmission signals maintain common signal portions wherein the same resources are used in the same way.
- FIG. 3 A particular example of a preferred embodiment is illustrated in Figure 3.
- twelve unique resource blocks (RBs) are available for transmitting information in association with broadcasting certain data.
- the resource blocks are referenced as RB1 through RB12, and may represent any transmission resource or group of transmission resources.
- data D certain data to be broadcast
- parity information PY is generated according to a desired encoding scheme along with the data D, wherein Y corresponds to the incremental parity information associated with a particular encoding layer.
- resource blocks RB1 through RB5 represent the common portion of the transmission signals provided by cells 12 (A through H).
- resource block RB1 carries data D 1
- resource block RB2 carries data D 2
- resource block RB3 carries data D 3
- resource block RB4 carries data D 4
- resource block RB5 carries the parity information P 1 for a first layer of encoding for data D (D 1 , D 2 , D 3 , and D 4 ).
- cells A are assumed to have the highest channel quality of the cells A through H, and are the only cells 12 deemed capable of broadcasting data D using only resource blocks RB1 through RB5.
- Cells B are assumed to have a lower channel quality than cells A 1 and may require additional parity information to facilitate forward error correction.
- an additional resource block RB6 is employed by cells B for transmitting the parity information P2.
- the effective encoding rate for cells A may be 4/5, while the effective encoding rate for cells B may be 2/3.
- the common signal portion for the transmission signals of cells A and cells B are carried by resource blocks RB1 through RB5, while the different signal portion corresponds to the supplemental parity information P 2 that is carried in resource block RB6 in cells B.
- the different series of cells 12 (A through H) will increasingly use more resources.
- cells C will share resource blocks RB1 through RB6 with cells B 1 and use an additional resource block RB7 for transmitting the additional parity information P 3 .
- cells D will share resource blocks RB1 through RB7 with cells C, while also using resource block RB8 for transmitting additional parity information P 4 .
- This process of cells 12 with lower channel quality using additional resources gradually changes across the cellular network 18. Accordingly, different cells 12 that are adjacent one another employ transmission signals that have common signal portions that are used in the same way, while at least one of the different cells 12 employs a different signal portion that is different than the other cell 12. [0034] With reference to Figure 4, the data and parity information may be intermingled among the resource blocks in any fashion desirable by the designer.
- resource blocks RB1 through RB5 have a mixture of data D x and parity information P 1 , wherein the parity information Pi is sufficient for forward error correction of data D at a first layer of encoding. While the data and parity information D 1 ⁇ , Pi are shared in resource blocks RB1 through RB5, the parity information associated with a second layer of encoding is provided in resource block RB6, the parity information associated with a third layer of encoding is provided in resource block RB7, and so on and so forth.
- the resource blocks that are not used for broadcasting data D may be used for other purposes, such as supporting voice sessions, individual messaging or media sessions, and the like. In essence, the resource allocation for broadcasting data D is the same as that illustrated in Figure 4.
- cells A take advantage of unused resource blocks RB7 through RB12 for other data
- cells B take advantage of resource blocks RB8 through RB12 for other data
- cells C take advantage of resource blocks RB9 through RB12 for other data
- cells D take advantage of resource blocks RB10 through RB12 for other data
- cells E take advantage of resource blocks RB11 and RB12 for other data
- cells F take advantage of resource block RB12 for other data.
- certain resource blocks may be left unused to effectively provide spectral spacing and minimize interference between adjacent cells 12.
- the common portions of the transmission signals for different cells 12 that are adjacent one another may reinforce one another while minimizing the interference from other cells 12 that are providing different transmission signals.
- cells D take advantage of resource block RB8 for parity information PA.
- Adjacent cells E also use resource block RB8 for transmitting parity information P4.
- cells C and B do not need to use resource block RB8 for transmitting parity information when broadcasting data D.
- cells C will avoid using resource block RB8 in a manner that would potentially interfere with cells B transmitting other data or cells D transmitting parity information P4.
- blanking certain resource blocks RB may be beneficial in certain applications, the use of such blanking techniques is not necessary for practicing the present invention. Further, the blanked resource blocks may be used to transmit unicast data.
- steps are taken to reduce the interfering impact on the data begin broadcast, such as reducing the transmit power associated with transmitting the unicast data relative to transmitting the broadcast data.
- steps are taken to reduce the interfering impact on the data begin broadcast, such as reducing the transmit power associated with transmitting the unicast data relative to transmitting the broadcast data.
- cells F are deemed to have the lowest channel quality, while cells E and cells G have similar channel quality, and cells D and cells H have similar channel quality.
- additional resource blocks RB are used for each successive group of cells A through F. Moving from cells F to cells H through cells G, resource blocks are removed. As such, the resource blocks are allocated based on channel conditions and allow the overall change of the transmission signals from the various cells 12 to track the channel qualities of the respective cells 12.
- the resource blocks for adjacent ones of like and different cells 12 are used in the same fashion at the same time, such that the common portions of the transmission signals will reinforce one another.
- the extent to which the transmission signal changes may be a function of the effective encoding rate, wherein when additional information, including parity information, is required for transmission of the data D 1 additional resources are invoked.
- additional information including parity information
- fewer resources may be invoked while maintaining a common portion of the transmission signals.
- the present invention is particularly beneficial in orthogonal frequency division multiple access (OFDM) architectures, where information is modulated on a plurality of relatively low bandwidth sub-carriers during any given time slot.
- OFDM orthogonal frequency division multiple access
- FIG. 7 a time-frequency mapping of sub-carriers in an OFDM environment is illustrated.
- each circle represents a sub- carrier, and each row of sub-carriers represents the available sub-carriers for a given time slot.
- a resource block RB may include a single resource, such as a single sub-carrier during a single time slot, or a group of sub-carriers along one or more time slots.
- the number located within a sub-carrier identifies a corresponding resource block RB.
- resource block RB1 includes the first three sub-carriers in the first four time slots, which are grouped at the top left corner of the time-frequency map.
- the sub-carriers allocated for a given resource block are adjacent one another in both time and frequency.
- the sub-carriers for a given resource block may be intermingled with the sub-carriers of other resource blocks, such that there is a dispersion of sub-carriers throughout the time- frequency spectrum.
- the common portions of different transmission signals will use the same sub-carriers in the same way at the same time.
- a given symbol may be modulated onto a particular sub-carrier in a resource block across any number of cells 12.
- the transmission signal changes across a cellular network 18 by changing the amount of information being transmitted, and thus the amount of resources necessary for transmitting the information.
- the transmission signal changes across a cellular network 18 by gradually transitioning from one modulation layer to another or changing parameters associated with a particular modulation layer.
- quadrature phase-shift keying (QPSK) modulation may be used on one end of the cellular network 18 and may gradually transition into a higher order modulation, such as 16 quadrature amplitude modulation (QAM) or 64-QAM at the other end of the cellular network 18, as channel qualities permit.
- QAM quadrature amplitude modulation
- 64-QAM 64-QAM
- hierarchical modulation is employed in at least certain parts of the cellular network 18, wherein areas that can support higher modulation orders are able to take advantage of the additional resources afforded by such higher orders of modulation.
- FIG. 9A a constellation for QPSK modulation is illustrated. For a given resource at a particular time, one of the available signals Si is selected for a certain set of data. For QPSK, any given symbol S 1 represents a corresponding two bit value (b 0 , b-i). With reference to Figure 9B, a 16-QAM constellation is illustrated.
- each possible symbol value S 2 represents a four bit value (bo, b-i, b 2 , b 3 ).
- the 16-QAM symbols S 2 are generally spaced about the position of a QPSK symbol Si.
- the QPSK symbol Si is a first layer scaling factor Ki from the origin of the constellation (see Figure 9A).
- the 16- QAM symbols S 2 are a second layer scaling factor K 2 from an associated QPSK signal S 1 .
- the QPSK signals are not modulated along with the 16-QAM symbols; however, the relationship is important because the two most significant bits (b Ol b-i) of the 16-QAM symbols effectively correspond to the two bits of a QPSK symbol S 1 .
- each of the four bits (bo, b 1f b 2 , b 3 ) may be recovered.
- the receiver is only able to determine which quadrant a symbol resides in, the receiver is effectively only receiving QPSK symbols, and thus will only be able to recover bits bo and b 1 . Since the full 16-QAM symbol cannot be resolved, the least significant bits b 2 , b 3 are lost.
- Network designers can take advantage of these characteristics by mapping higher priority data to the most significant bits b 0 , b 1 and lower priority data to the least significant bits b 2) b 3 .
- each of the bits bo, b-i, b2, b 3 can be recovered, and when only the quadrant in which a symbol resides can be recovered, only the most significant bits b Ol bi of the lower layer are recovered. This process can be extended to higher modulation orders, as illustrated in Figure 9C.
- a 64-QAM constellation has 64 symbols S3 associated with a scaling factor K 3 , which is effectively a measure of the distance between associated 64-QAM symbols S 3 with the relative position of 16-QAM symbols S 2 .
- K 3 the scaling factor
- each symbol corresponds to 6 bits (b Ol bi, b 2 , b 3 , b 4 , bs).
- bits b 4 and bs may be associated with an even lower priority layer or channel, and only when the 64-QAM symbols may be fully resolved will bits B 4 and B 5 be able to be recovered.
- the receiver can only effectively resolve 16-QAM symbols S2, only bits bo, bi, b2, and b 3 can be recovered. If the receiver can only effectively resolve QPSK symbols S 1 , then only bits bo and bi can be recovered.
- the scaling factor Kx corresponds to the modulation layer and is a distance to a reference origin of symbols associated with a lower modulation layer.
- the transmission signals used for broadcasting data may gradually transition from one modulation order to another across the cellular network 18. This gradual changing of the modulation order may systematically transition from a first modulation layer to a second modulation layer by gradually increasing or decreasing the scaling factors Kx.
- the selected QPSK symbol is represented by Ki Si.
- the transition from QPSK modulation to 16-QAM modulation is initiated as shown in Figure 10B.
- the scaling value for the 16-QAM symbols may be relatively small, such that the second order 16-QAM symbols S 2 are very close to where the first order QPSK symbols Si would have been located.
- the QPSK symbols in cells H and the corresponding 16-QAM symbols in cells G will effectively reinforce one another.
- cells F may continue to use the second order 16-QAM modulation as shown in Figure 1OC; however, the second layer scaling factor K 2 is increased such that the 16-QAM symbols in any given quadrant will move away from each other and the location where the corresponding QPSK symbol
- the second layer 16-QAM symbols S 2 will be easier to resolve as the second layer scaling factor K 2 increases. Further, corresponding 16-QAM symbols in cells F and G will continue to substantially reinforce one another.
- the 16-QAM constellation used in cells E is illustrated. Notably, the second order 16-QAM modulation is used; however, the second layer scaling factor K 2 is increased over the second layer scaling factor K 2 that used in cells F.
- the constellation for cells D is illustrated in Figure 1OE. Like the transition from cells H to cells G, the transition from cells E to cells D involves implementation of a higher modulation layer.
- the third layer scaling factor K 3 is relatively small when the third layer 64-QAM modulation is first introduced in the cellular network 18. As such, the third layer 64-QAM symbols S 3 transmitted in cells D will tend to reinforce the second order 16-QAM symbols S 2 transmitted in cells E. With reference to Figure 10F, the constellation for cells C is illustrated. The 64-QAM modulation remains in effect; however, the third layer scaling factor K 3 is increased relative to the third layer scaling factor K 3 used in cells D. As such, the 64-QAM modulation symbols will be easier to resolve, yet continue to reinforce corresponding symbols in cells D.
- This gradual progression from one modulation order to another and varying the corresponding scaling values to effect a gradual transition from one modulation order to another across the cellular network 18 will continue as desired based on various criteria, such as channel quality.
- the common portion of the transmission signal that continues across different cells 12 that are adjacent one another is the lowest or one of the lower level modulation layers.
- broadcast data may be transmitted on a lower modulation layer across a portion of or the entire cellular network 18, while higher modulation layers may be used to carry other data for unicast, multi-cast, or limited broadcast purposes.
- the portion of the transmission signal that changes will relate to the higher modulation orders.
- adjacent cells 12 should transmit symbols that roughly correspond to each other in their respective modulation layers, whether the modulation layers are the same or different.
- the above example provides a relatively aggressive transition from first layer QPSK modulation in cells H to 64-QAM modulation in cells C. In practice, such transitions among different cells 12 that are adjacent one another are preferably more gradual.
- Figure 11 provides a table illustrating the first and second layer scaling factors K-i, K 2 for transitioning from a first layer QPSK modulation in cells H wherein the first layer scaling factor is 2, to a second layer 16-QAM modulation having a first layer scaling factor Ki of 1.85 and a second layer scaling factor K 2 of 0.8.
- the scaling factors Kx are selected based on channel conditions, and are preferably made available to the user terminals 16 to assist with demodulation and recovery of the transmitted information.
- the concepts of the first and second embodiments may be combined.
- the use of different encoding rates and associated resources of the first embodiment may be combined with the hierarchical modulation of the second embodiment.
- the technique is best illustrated through example. To emphasize the potential gradualness of the transition in the transmitted signal across the cellular network 18, assume that there are a series of cells A through M, wherein cells A have the highest channel quality, and cells M have the lowest channel quality. With reference to Figure 12, assume that cells M employ layer 1 QPSK modulation wherein the first layer scaling factor Ki is 2. Further assume that cells M employ an encoding rate of 1/3, which requires the use of 12 resource blocks.
- Cells L have a slightly better channel quality than cells M, and as such cells L continue to employ layer 1 QPSK modulation having a first layer scaling factor K 1 of 2; however, the encoding rate increases to 4/11 and the required number of resource blocks decreases to 11 relative to that of cells M.
- the number of allocated resource blocks will continue to drop and the encoding rate will continue to increase while modulation stays at the first layer QPSK modulation.
- cells G may have a relatively high encoding rate of 4/5 and only employ 8 resource blocks, while continuing to use layer 1 QPSK modulation having a first layer scaling factor Ki of 2.
- the modulation order changes to 16-QAM.
- the encoding rate may decrease. Although only 8 resource blocks are used, the use of the second layer 16-QAM modulation provides a higher effective transmission rate, which may be used to support the decreased encoding rate.
- the first layer scaling factor Ki is 2 and the second layer scaling factor K 2 is only 0.2. Cells E will increase the encoding rate and decrease the number of resource blocks used for the transmission signal; however, the second layer scaling factor K 2 will increase to 0.5. As such, the corresponding symbols transmitted in cells E and cells F for the transmission signal will continue to reinforce one another.
- a GSFN architecture is provided to support broadcasting data across all or a portion of the cellular network 18, wherein the transmission signal provided by different cells 12 across the cellular network 18 may differ from one another to address existing channel conditions while substantially reinforcing one another in a similar fashion to that of a traditional single frequency network.
- the channel conditions may be measured manually, by the user terminals 16, or by the base stations 14.
- the transmission plan for the GSFN may be calculated based on these channel conditions by the base stations 14 in an individual or cooperative manner, or by a central authority that may instruct each of the base stations 14 to employ the appropriate transmission parameters to ensure the base stations 14 are transmitting the appropriate transmission signals relative to one another. Since the transmission signals for the GSFN vary across the cellular network 18 and may include different information, use different resources, and employ different modulation layers, corresponding control information may need to be transmitted to the user terminals 16.
- the control information may be specific to a particular cell 12 or group of cells 12, and may be provided to the user terminals 16 in any number of ways.
- the control information may be embedded in all or certain resource blocks, and the control information may identify the data stream to which it belongs and an order in which to process the information in a particular resource block.
- control information may be embedded in the different modulation layers, wherein the control information in a given modulation layer would correspond to that particular modulation layer or higher modulation layers.
- the user terminal 16 may use information determined from a separate source to determine an appropriate control region to use.
- the GSFN may provide multiple control regions from which the user terminal 16 may select. For example, different control regions may be transmitted with control information.
- On a reserved time-frequency resource each base station 14 that belongs to a particular control region will transmit a corresponding sequence.
- the user terminal 16 will select one of the appropriate sequences transmitted from the different base stations 14 based on the sequence received with the strongest signal strength.
- the control information in the control region associated with the highest signal strength is the control information used by the user terminal 16.
- the user terminal 16 may blindly detect resource blocks that go together by trying different combinations, wherein the number of combinations to try may be limited in a defined manner. The user terminal 16 does not need to re-try all different combinations after an appropriate combination is determined, and may continue to use the same combination for some predetermined period of time. This method may be combined with other signaling methods to reduce the overhead associated with the other signaling schemes.
- the control information for the broadcasting provided by the GSFN may be transmitted to each user terminal 16 using unicast techniques, wherein the control information is individually sent to each of the available user terminals 16. This is in contrast to the above examples wherein the control information is effectively broadcast along with the data being broadcast.
- the control information may be broadcast using the same resources by the different base stations 14.
- a base station 14 configured according to one embodiment of the present invention is illustrated.
- the base station 14 may support any type of wireless communication technology, such as traditional cellular technologies employing OFDM, code division multiple access (CDMA), and time division multiple access (TDMA) and local wireless technologies such as those set forth in the IEEE 802.11 standards. Accordingly, the base station 14 may act as any wireless access point that supports wireless communications.
- the base stations 14 will preferably be able to support traditional individual or unicast sessions with individual user terminals 16 that are within communication range while cooperating to broadcast the same data across the entire cellular network 18 as described above.
- the base station 14 generally includes a control system 20, a baseband processor 22, transmit circuitry 24, receive circuitry 26, one more antennas 28, and a network interface 30.
- the receive circuitry 26 receives radio frequency signals bearing information from one or more remote transmitters provided by user terminals 16.
- a low noise amplifier and a filter cooperate to amplify and remove broadband interference from the signal for processing.
- Downconversion and digitization circuitry (not shown) will then downconvert the filtered, received signal to an intermediate or baseband frequency signal, which is then digitized into one or more digital streams.
- the baseband processor 22 processes the digitized received signal to extract the information or data bits conveyed in the received signal. This processing typically comprises demodulation, decoding, and error correction operations. As such, the baseband processor 22 is generally implemented in one or more digital signal processors (DSPs).
- DSPs digital signal processors
- the received information is then sent toward the core network via the network interface 30 or transmitted toward another user terminal 16 serviced by the base station 14.
- the network interface 30 will typically interact with the core network via the base station controller 10.
- the baseband processor 22 receives digitized data, which may represent voice, data, or control information, from the network interface 30 under the control of control system 20, which encodes the data for transmission.
- the encoded data is output to the transmit circuitry 24, where it is used by a modulator to modulate a carrier signal that is at a desired transmit frequency or frequencies.
- a power amplifier (not shown) will amplify the modulated carrier signal to a level appropriate for transmission, and deliver the modulated carrier signal to one or more of the antennas 28 through a matching network.
- a fixed or mobile user terminal 16 configured according to one embodiment of the present invention is illustrated.
- the user terminal 16 will support a communication technology that is compatible with the base stations 14.
- the user terminal 16 will include a control system 32, a baseband processor 34, transmit circuitry 36, receive circuitry 38, one or more antennas 40, and user interface circuitry 42.
- the receive circuitry 38 receives radio frequency signals bearing information from one or more remote transmitters provided by base stations 14.
- a low noise amplifier and a filter cooperate to amplify and remove broadband interference from the signal for processing.
- Downconversion and digitization circuitry (not shown) will then downconvert the filtered, received signal to an intermediate or baseband frequency signal, which is then digitized into one or more digital streams.
- the baseband processor 34 processes the digitized received signal to extract the information or data bits conveyed in the received signal. This processing typically comprises demodulation, decoding, and error correction operations.
- the baseband processor 34 is generally implemented in one or more digital signal processors (DSPs).
- DSPs digital signal processors
- the baseband processor 34 receives digitized data, which may represent voice, data, or control information, from the control system 32, which it encodes for transmission.
- the encoded data is output to the transmit circuitry 36, where it is used by a modulator to modulate a carrier signal that is at a desired transmit frequency or frequencies.
- a power amplifier (not shown) will amplify the modulated carrier signal to a level appropriate for transmission, and deliver the modulated carrier signal to the one or more antennas 40 through a matching network.
- modulation and processing techniques available to those skilled in the art are applicable to the present invention.
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Abstract
Description
Claims
Priority Applications (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP09809390.9A EP2345271A4 (en) | 2008-08-25 | 2009-08-07 | Graduated single frequency network |
CN200980142484.0A CN102204314B (en) | 2008-08-25 | 2009-08-07 | Method for providing gradual single frequency network |
GB1104963A GB2475460A (en) | 2008-08-25 | 2009-08-07 | Graduated single frequency network |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
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US12/197,942 | 2008-08-25 | ||
US12/197,942 US8229441B2 (en) | 2007-08-24 | 2008-08-25 | Graduated single frequency network |
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WO2010023518A2 true WO2010023518A2 (en) | 2010-03-04 |
WO2010023518A3 WO2010023518A3 (en) | 2010-07-29 |
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Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
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PCT/IB2009/006484 WO2010023518A2 (en) | 2008-08-25 | 2009-08-07 | Graduated single frequency network |
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US (1) | US8229441B2 (en) |
EP (1) | EP2345271A4 (en) |
CN (1) | CN102204314B (en) |
GB (1) | GB2475460A (en) |
WO (1) | WO2010023518A2 (en) |
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US8351367B2 (en) * | 2008-04-24 | 2013-01-08 | Marvell World Trade Ltd. | Signaling of unused resources |
CN101800616B (en) * | 2009-02-10 | 2012-11-21 | 富士通株式会社 | Data relay device, communication device and method |
JP2013239761A (en) * | 2012-05-11 | 2013-11-28 | Hitachi Ltd | Radio communication system and radio station |
DE102014100595A1 (en) * | 2014-01-20 | 2015-07-23 | Intel IP Corporation | A communication terminal and method for determining a power scaling factor |
US10735143B2 (en) * | 2017-11-07 | 2020-08-04 | Huawei Technologies Co., Ltd. | System and method for bit mapping in multiple access |
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US8477673B2 (en) | 2006-06-09 | 2013-07-02 | Qualcomm Incorporated | Cell specific retransmission of single frequency network MBMS data |
CN100551111C (en) * | 2006-08-08 | 2009-10-14 | 中兴通讯股份有限公司 | Single frequency network planning method based on orthogonal frequency division multiplexi |
-
2008
- 2008-08-25 US US12/197,942 patent/US8229441B2/en active Active
-
2009
- 2009-08-07 CN CN200980142484.0A patent/CN102204314B/en active Active
- 2009-08-07 GB GB1104963A patent/GB2475460A/en not_active Withdrawn
- 2009-08-07 EP EP09809390.9A patent/EP2345271A4/en not_active Withdrawn
- 2009-08-07 WO PCT/IB2009/006484 patent/WO2010023518A2/en active Application Filing
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US20050265280A1 (en) | 2004-05-25 | 2005-12-01 | Samsung Electronics Co., Ltd. | OFDM symbol transmission method and apparatus for providing sector diversity in a mobile communication system, and a system using the same |
WO2007039494A1 (en) | 2005-09-30 | 2007-04-12 | Siemens Aktiengesellschaft | Method for improving service performance of a trunk broadcasting service in a mobile communication system |
WO2008020736A2 (en) | 2006-08-18 | 2008-02-21 | Lg Electronics Inc. | Broadcast and multicast services (bcmcs) for orthogonal frequency division multiplexing (ofdm)-based mobile broadband wireless cellular systems |
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Also Published As
Publication number | Publication date |
---|---|
WO2010023518A3 (en) | 2010-07-29 |
CN102204314A (en) | 2011-09-28 |
CN102204314B (en) | 2014-03-26 |
US20090291700A1 (en) | 2009-11-26 |
GB2475460A (en) | 2011-05-18 |
US8229441B2 (en) | 2012-07-24 |
EP2345271A2 (en) | 2011-07-20 |
GB201104963D0 (en) | 2011-05-11 |
EP2345271A4 (en) | 2016-05-25 |
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