Classifications

• • 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
  • H04L5/0014—Three-dimensional division
  • H04L5/0023—Time-frequency-space
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L1/00—Arrangements for detecting or preventing errors in the information received
  • H04L1/02—Arrangements for detecting or preventing errors in the information received by diversity reception
  • H04L1/06—Arrangements for detecting or preventing errors in the information received by diversity reception using space diversity
  • H04L1/0618—Space-time coding
  • H04L1/0625—Transmitter arrangements
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L1/00—Arrangements for detecting or preventing errors in the information received
  • H04L1/02—Arrangements for detecting or preventing errors in the information received by diversity reception
  • H04L1/06—Arrangements for detecting or preventing errors in the information received by diversity reception using space diversity
  • H04L1/0618—Space-time coding
  • H04L1/0637—Properties of the code
  • H04L1/0668—Orthogonal systems, e.g. using Alamouti codes

Definitions

• the present invention relates generally to a method and a device for determining a shifting parameter to be used by a telecommunication device for transferring symbols.
• the present invention is in the field of coding and decoding schemes used in the context of MIMO (Multiple Input Multiple Output) communications especially used in conjunction of OFDM or OFDMA-like transmission schemes.
• MIMO Multiple Input Multiple Output
• Orthogonal Frequency-Division Multiplexing is based upon the principle of frequency-division multiplexing (FDM) and is implemented as a digital modulation scheme.
• the bit stream to be transmitted is split into several parallel bit streams, typically dozens to thousands.
• the available frequency spectrum is divided into several sub-channels, and each low-rate bit stream is transmitted over one subchannel by modulating a sub-carrier using a standard modulation scheme, for example PSK, QAM, etc.
• the sub-carrier frequencies are chosen so that the modulated data streams are orthogonal to each other, meaning that cross talk between the subchannels is eliminated.
• OFDM orthogonal advantage of OFDM is its ability to cope with severe channel conditions, for example, multipath and narrowband interference, without complex equalization filters.
• Channel equalization is simplified by using many slowly modulated narrowband signals instead of one rapidly modulated wideband signal.
• DFT spread OFDM Single Carrier Frequency- Division Multiple Access
• SC-FDMA Single Carrier Frequency- Division Multiple Access
• Alamouti code In a first implementation of Alamouti code, two transmit antennas (FirstAnt and SecondAnt) are used for transferring two symbols a and b in two time slots (Tl and T2). At time Tl antenna FirstAnt transmits symbol a when antenna SecondAnt transmits symbol b. At time T2 antenna FirstAnt transmits symbol -b* when antenna SecondAnt transmits symbol a*, where "*" denotes the complex conjugate.
• This Alamouti code let us call it classical Alamouti in time, has the advantage to offer simple coding and decoding, the increased diversity leading to better performance. It is to be noted that the throughput is not increased.
• the optimal MAP for Maximum A Posteriori decoding is very simple, it does not imply matrix inversion, log enumeration or sphere decoding as long as the channel does not vary between Tl and T2 and as long as the channel can be characterized by a simple multiplication. It is naturally well combined with OFDM or OFDM-like modulation schemes.
• OSFBC Orthogonal Space Frequency Block Code
• OFDMA OFDMA-like modulation schemes
• OFDMA-like modulations we denote for example some frequency- domain implementation of a single carrier scheme, in which preferably, but not strictly necessarily, a cyclic prefix has been added, like for example the described DFT-spread OFDM.
• the advantage is the use of only one modulation slot, which can be advantageous from the multiplexing point of view, and may lead to better performance in case of very fast variations of the channel like high Doppler.
• Alamouti codes due to their simple implementation and good performance are very attractive schemes to be used in MIMO transmission. When applied to SC-FDMA like modulation schemes, these codes do not have the valuable feature to produce signals with the low variation envelope property for each antenna, the envelope being the modulus of the complex envelope.
• WO 2008/098672 it has been proposed a method of radio data emission, by an emitter comprising at least two transmit antennas.
• the signal transmitted on a first antenna being considered in the frequency domain as resulting from a DFT of size K leading to the emission of a symbol on each of the K sub-carriers allocated to the emitter on the first antenna.
• the use of above mentioned technique is not adapted into systems wherein the sub-carriers allocated to the telecommunication device are not consecutive.
• the present invention aims at providing a telecommunication system in which it is possible to use above mentioned technique in a system wherein the sub-carriers allocated to the telecommunication device are not consecutive.
• X* means the complex conjugate of X
• p-l-k is taken modulo K with K even
• p even characterized in that the method comprises the steps of:
• the sub-carriers are grouped in at least two clusters, each cluster being separated from another cluster by at least one sub-carrier not allocated to the telecommunication device,
• the present invention concerns also a device for determining a shifting parameter p to be used by a telecommunication device for mapping symbols on sub- carriers, the telecommunication device comprising at least two transmit antennas, the symbols being transferred through each antenna of the telecommunication device on at least an even number K, strictly greater than two, of sub-carriers allocated to the telecommunication device,
• the sub- carriers are grouped in at least two clusters, each cluster being separated from another cluster by at least one sub-carrier not allocated to the telecommunication device,
• the sub-carrier resource allocation is more flexible and can be adapted to cases wherein the communication conditions are good in discontinuous frequency bands.
• the present invention ensures that the signal transferred on one transmit antenna has the same PAPR as the one transmitted on the other transmit antenna. Finally, the performances of the system are kept at a good level.
• the £-th allocated sub-carrier on which symbols Xt and are mapped on first and respectively second transmit antennas, and the (p- ⁇ -k)mo ⁇ K -th allocated sub-carrier on which symbols are mapped on first and respectively second transmit antennas are paired and the shifting parameter p is determined so as to minimize the number of sub-carriers comprised between the most distanced paired sub-carriers.
• the subcarrier equally distanced from the extreme sub-carriers allocated to the telecommunication device is determined and the shifting parameter p is determined according to the fact that the mean is or not a sub- carrier allocated to the telecommunication device.
• the k-th allocated sub-carrier on which symbols Xt and are mapped on first and respectively second transmit antennas, and the (p-l-k)modK -th allocated sub-carrier on which symbols X (p - ⁇ - k)mod ⁇ and (_ ⁇ P ⁇ - k)mo ⁇ ⁇ * k are mapped on first and respectively second transmit antennas are paired and parameter/? is determined as following: if the mean is a sub- carrier allocated to the telecommunication device, the shifting parameter/? is equal to the number of sub-carriers allocated to the telecommunication device and comprised in the first cluster or is equal to the sum of the number of sub-carriers allocated to the telecommunication device and comprised in at least two clusters.
• the k- ⁇ h allocated sub-carrier on which symbols Xk and are mapped on first and respectively second transmit antennas, and the (p- ⁇ -k)mo ⁇ K -th allocated sub-carrier on which symbols are mapped on first and respectively second transmit antennas are paired and the shifting parameter p is determined so as to minimize the number of sub-carriers paired with sub-carriers mapped in different clusters.
• a cost function J(/?) which is equal to the number of sub-carriers allocated to the mobile station which are paired to a sub-carrier of another cluster is computed for each possible value of the shifting parameter and the shifting parameter value/? is determined as the value of/? which corresponds to the minimum value of J(/?).
• the maximum distance between two paired sub-carriers is determined for each possible value of the shifting parameter and the value of the shifting parameter/? among the values of/? which minimize J(/?) is the one which corresponds to the lowest maximum distance between two paired sub-carriers.
• the determination of the shifting parameter is executed by a base station of a wireless cellular telecommunication network and the telecommunication device is a mobile station handled by the base station.
• information representative of the sub-carriers allocated to the mobile station are transferred to the mobile station.
• the mobile station is able to determine itself the shifting parameter p.
• the signalling between the base station and the mobile station is reduced.
• information representative of the determined shifting parameter are transferred to the mobile station.
• the base station de maps symbols on sub- carriers allocated to the mobile station using the shifting parameter determined for the mobile station.
• the determination of the a shifting parameter/? is executed by a mobile station of a wireless cellular telecommunication network.
• the present invention concerns a computer program which can be directly loadable into a programmable device, comprising instructions or portions of code for implementing the steps of the method according to the invention, when said computer program is executed on a programmable device.
• Fig. 1 represents a wireless cellular telecommunication network in which the present invention is implemented ;
• Fig. 2 is a diagram representing the architecture of a base station in which the present invention is implemented ;
• Fig. 3 is a diagram representing the architecture of a mobile station in which the present invention is implemented ;
• Fig. 4 illustrates the architecture of the encoder comprised in a mobile station according to a particular embodiment of the invention in frequency domain
• Fig. 5 illustrates the architecture of the decoder of a base station having several receive antennas according to a particular embodiment of the invention ;
• Fig. 6 discloses an example of an algorithm executed by a base station according to a first mode of realisation of the present invention
• Fig. 7 discloses an example of an algorithm executed by a base station according to a second mode of realisation of the present invention when each cluster comprises an even number of sub-carriers;
• Fig. 8 discloses an example of an algorithm executed by a base station according to a third mode of realisation of the present invention
• Fig. 9 represents an example of mapping of symbols on sub-carriers according to the first mode of realisation of the present invention ;
• Fig. 10 represents an example of mapping of symbols on sub-carriers according to the second mode of realisation of the present invention
• Fig. 11 represents a table of cost function values and maximum distance values between sub-carriers which are associated ;
• Fig. 12 represents an example of mapping of symbols on sub-carriers according to the third mode of realisation of the present invention ;
• Fig. 13 discloses an example of an algorithm for mapping symbols using the shifting parameter determined according to the present invention
• Fig. 14 discloses an example of an algorithm for de-mapping symbols using the shifting parameter determined according to the present invention.
• Fig. 1 represents a wireless cellular telecommunication network in which the present invention is implemented.
• the present invention will be described in an example wherein the telecommunication system is a wireless cellular telecommunication system.
• the present invention is also applicable to wireless or wired telecommunication systems like Local Area Networks.
• the base station and mobile station are emitters and/or receivers.
• Fig. 1 one base station BS of a wireless cellular telecommunication network and a mobile station MS are shown.
• the shifting parameter p is determined by a base station.
• the shifting parameter is determined by the mobile station from clusters of sub-carriers which are allocated to it by the base station.
• the base station BS is a base station of a wireless cellular telecommunication network comprising plural base stations.
• the wireless cellular telecommunication network may have a more important number of mobile stations MS to communicate with the base station BS.
• the base station BS may be named a node or an access point.
• the mobile station MS may be a personal computer, a peripheral device like a set top box, or a phone.
• a shifting parameter p to b e used by a telecommunication device for mapping symbols on sub-carriers is determined.
• the telecommunication device comprises at least two transmit antennas, the symbols being transferred through each antenna of the telecommunication device on at least an even number K, strictly greater than two, of sub-carriers allocated to the telecommunication device.
• X* means the complex conjugate of X
• p-l-k is taken modulo K K and/? even.
• Sub-carriers allocated to the telecommunication device are grouped in at least two clusters, each cluster being separated from another cluster by at least one sub- carrier not allocated to the telecommunication device.
• the shifting parameter p is determined as being even and according to clusters of sub-carriers allocated to the telecommunication device.
• Fig. 2 is a diagram representing the architecture of a base station in which the present invention is implemented.
• the base station BS has, for example, an architecture based on components connected together by a bus 201 and a processor 200 controlled by the program as disclosed in Figs. 6, 7 or 8, 13 and/or 14.
• the base station BS may have an architecture based on dedicated integrated circuits.
• the bus 201 links the processor 200 to a read only memory ROM 202, a random access memory RAM 203, a wireless interface 205 and a network interface 206.
• the memory 203 contains registers intended to receive variables and the instructions of the program related to the algorithm as disclosed in Figs. 6, 7 or 8, 13 and/or 14.
• the processor 200 controls the operation of the network interface 206 and of the wireless interface 205.
• the read only memory 202 contains instructions of the program related to the algorithm as disclosed in Figs. 6, 7 or 8, 13 and/or 14, which are transferred, when the base station BS is powered on, to the random access memory 203.
• the base station BS may be connected to a telecommunication network through the network interface 206.
• the network interface 206 is a DSL (Digital Subscriber Line) modem, or an ISDN (Integrated Services Digital Network) interface, etc.
• the wireless interface 205 comprises means for transferring information representative of the sub-carriers allocated to the mobile station MS.
• the wireless interface 205 comprises means for transferring information representative of the shifting parameter determined for the mobile station MS and to be used by the mobile station MS for mapping and/or de-mapping symbols on allocated sub-carriers.
• the wireless interface 205 comprises an encoder as disclosed in Fig. 4 and/or a decoder as disclosed in Fig. 5.
• Fig. 3 is a diagram representing the architecture of a mobile station in which the present invention is implemented.
• the mobile station MS has, for example, an architecture based on components connected together by a bus 301 and a processor 300 controlled by the program as disclosed in Figs. 6, 7 or 8, 13 and/or 14.
• the mobile station MS may have an architecture based on dedicated integrated circuits.
• the bus 301 links the processor 300 to a read only memory ROM 302, a random access memory RAM 303 and a wireless interface 305.
• the memory 303 contains registers intended to receive variables and the instructions of the program related to the algorithm as disclosed in Figs. 6, 7 or 8, 13 and/or 14.
• the processor 300 controls the operation of the wireless interface 305.
• the read only memory 302 contains instructions of the program related to the algorithm as disclosed in Figs. 13 and/or 14, which are transferred, when the mobile station MS is powered on, to the random access memory 303.
• the wireless interface 305 comprises means for mapping data on sub-carriers comprised in the clusters of sub-carriers allocated to the mobile station MS according to the shifting parameter determined for the mobile station MS by the base station BS or by the mobile station MS from clusters of sub-carriers allocated to the mobile station MS and means for de-mapping symbols.
• the wireless interface 305 comprises an encoder as disclosed in Fig. 4 and/or a decoder as disclosed in Fig. 5.
• Fig. 4 illustrates the architecture of the encoder according to a particular embodiment of the invention in frequency domain.
• Data to be transmitted are coded and organized as symbols by the coding and modulation module 40 giving a set of symbols X n . Then the signal is spread in the frequency domain by the DFT (Discrete Fourier Transform) module 41.
• the DFT module is replaced by a Fast Fourier Transform module or any other processing module.
• DFT module may not be needed.
• the symbols spread in the frequency domain are mapped on sub-carriers comprised in the allocated frequency band by a frequency mapping module 42 which maps data to be transferred on sub-carriers.
• the frequency mapping module 42 comprises zero insertion and/or frequency shaping capabilities.
• the frequency mapping module 42 maps symbols on the frequency band allocated to the mobile station MS. As the sub-carriers are not allocated in a contiguous sub-band, the frequency band is separated into several clusters. The frequency mapping module 42 maps symbols on the different clusters of the frequency band allocated to the mobile station MS.
• the frequency mapping module 42 shows an example wherein M ⁇ symbols are mapped on K sub-carriers of two clusters.
• a first cluster comprises the sub-carriers noted « 0 to Mo-I and a second cluster comprises the sub-carriers noted n ⁇ to Mi-I .
• M 1 are generally even.
• the symbols outputted by the frequency mapping module 42 are transformed back in the time domain by the IDFT (Inverse Discrete Fourier Transform) module 43.
• IDFT Inverse Discrete Fourier Transform
• An optional cyclic prefix insertion module 44 can be applied before transmission through a first antenna of the mobile station MS.
• a second antenna of the mobile station MS is fed by data computed by the space frequency block code computation module 45 according to the shifting parameter p determined for the mobile station MS, leading to a new branch having a frequency mapping module 46 identical to the frequency mapping module 42, an IDFT module 47 and an optional cyclic prefix insertion module 48 as the IDFT module 43 and cyclic prefix insertion module 44 respectively.
• the space frequency block code computation module 45 is connected to the output of the DFT module 41.
• Fig. 5 illustrates the architecture of the decoder of a device having several receive antennas according to a particular embodiment of the invention.
• Several signals 57 are received from the receive antennas.
• the synchronization module 50 synchronizes all these received signals 57.
• the optional cyclic prefix removal modules 511 to 5 Ii remove the cyclic prefix if used, in parallel to all the synchronized signals.
• the DFT modules 52i to 52 L execute a DFT on the synchronized signals on which the cyclic prefix has been removed or not.
• the DFT module is replaced by a Fast Fourier Transform module or any other processing module.
• L modules, possibly one complex module, of channel estimation 531 to 53 L will work on the L signals and feeding one decoder module54 comprising K two by two elementary space frequency block decoders serially processing the pairs of sub- carriers.
• An inverse DFT module 55 before a classical channel decoding module 56 treats the resulting signal.
• IDFT module 55 may not be needed. In other variants, it may be replaced with other processing modules.
• Fig. 6 discloses an example of an algorithm for determining the shifting parameter for a mobile station according to a first mode of realisation of the present invention.
• the present algorithm will be described when it is executed by the processor 200 of the base station BS.
• the same algorithm may also be executed by the processor 300 of the mobile station MS when information indicating the clusters of sub-carriers are received from the base station BS by the mobile station MS.
• the present algorithm is executed each time clusters of sub-carriers are allocated to a mobile station MS handled by the base station BS.
• the processor 200 gets the index « 0 of the first sub-carrier allocated to the mobile station MS.
• the first sub-carrier allocated to the mobile station MS is the first sub-carrier of the first cluster CLo allocated to the mobile station MS and comprising MQ sub-carriers.
• the processor 200 gets the index of the last sub-carrier allocated to the mobile station MS.
• the index of the last sub-carrier allocated to the mobile station MS is equal to HNC- I plus MN C - I minus one, where Nc is the number of clusters allocated to the mobile station MS, ⁇ NC - I is the index of the first sub-carrier of the last cluster comprising M JVC-1 sub-carriers
• the processor 200 determines the index noted ⁇ equidistant of the sub-carrier which is sensibly equidistant from the first and last sub-carrier allocated to the mobile station MS according to the following formula :
• the processor 200 checks if ⁇ equidistant is the index of a sub- carrier allocated to the mobile station MS.
• ⁇ equidistant is the index of a sub-carrier allocated to the mobile station MS. If ⁇ equidistant is the index of a sub-carrier allocated to the mobile station MS, the processor 200 moves to step S605. Otherwise, the processor 200 moves to step S604.
• the processor 200 determines the shifting parameter p to be used for the mobile station MS using the following formula:
• ⁇ equidistant and which comprises sub-carriers which have an index lower than ⁇ equidistant- M 1 are generally even, p is selected as the closest even integer inferior or equal to
• the processor 200 interrupts the present algorithm.
• the processor 200 determines the shifting parameter /? to be used for the mobile station using the following formula:
• Fig. 9 represents an example of mapping of symbols on sub-carriers according to the first mode of realisation of the present invention.
• the frequency band comprises fifteen sub-carriers noted 0 to 14 in the column 920. Ten of the sub-carriers are allocated to the mobile station MS. The sub-carriers allocated to the mobile station MS are indicated by grey rectangles in the column 921. The allocated sub-carriers belong to three clusters. The sub-carriers 0 and 1 belong to the cluster CLo, the sub-carriers 3 to 8 belong to the cluster CLi and the sub-carriers 12 and 13 belong to the cluster CL 2 .
• the processor 200 determines that the index noted ⁇ equidistant is equal to 7.
• the processor 200 determines at step S605 the shifting parameter/? as equal to 6.
• the emitter comprises two transmit antennas which transfer K equals ten symbols on sub-carriers of the frequency band allocated to the mobile station MS.
• the symbols Xo to Xg shown in the column 922 are transferred through a first antenna.
• the line 900 comprises the sub-carrier 0 on which the couple of symbols (Xo, - X5*) is mapped.
• the line 906 comprises the sub-carrier 5 on which the couple of symbols (X5, Xo*) is mapped. Same symbols Xo and X5 are mapped on the sub-carriers 0 and 6, the sub-carriers 0 and 6 are paired.
• the line 901 comprises the sub-carrier 1 on which the couple of symbols (X 1 , X 4 *) is mapped.
• the line 905 comprises the sub-carrier 5 on which the couple of symbols (X 4 , -Xi *) is mapped. Same symbols Xi and X 4 are mapped on the sub- carriers 1 and 5.
• the line 903 comprises the sub-carrier 3 on which the couple of symbols (X 2 , - X3*) is mapped.
• the line 904 comprises the sub-carrier 4 on which the couple of symbols (X3, X 2 *) is mapped. Same symbols X 2 and X3 are mapped on the sub-carriers 903 and 904.
• the line 907 comprises the sub-carrier 7 on which the couple of symbols (X 6 , - Xg*) is mapped.
• the line 913 comprises the sub-carrier 13 on which the couple of symbols (Xg, Xe*) is mapped. Same symbols Xe and Xg are mapped on the sub-carriers 7 and 13.
• the line 908 comprises the sub-carrier 8 on which the couple of symbols (X 7 , X8*) is mapped.
• the line 912 comprises the sub-carrier 12 on which the couple of symbols (Xs, -X 7 *) is mapped. Same symbols X 6 and X> are mapped on the sub- carriers 8 and 12.
• Fig. 7 discloses an example of an algorithm for determining the shifting parameter for a mobile station according to a second mode of realisation of the present invention when each cluster comprises an even number of sub-carrier.
• the present algorithm will be described when it is executed by the processor 200 of the base station BS.
• the same algorithm may also be executed by the processor 300 of the mobile station MS when information indicating the clusters of sub-carriers are received for the base station BS by the mobile station MS.
• the present algorithm is executed each time clusters of sub-carriers are allocated to a mobile station MS handled by the base station BS.
• the processor 200 gets the index no of the first sub-carrier allocated to the mobile station MS.
• the first sub-carrier allocated to the mobile station MS is the first sub-carrier of the first cluster CLo allocated to the mobile station MS and comprising Mo sub-carriers.
• the processor 200 gets the index of the last sub-carrier allocated to the mobile station MS.
• the index of the last sub-carrier allocated to the mobile station MS is equal to HNC-I plus MN C -I minus 1, where Nc is the number of clusters allocated to the mobile station MS, ⁇ NC - I is the index of the first sub-carrier of the last cluster comprising MN C -I sub-carriers
• the processor 200 determines the index noted ⁇ equidistant of the sub-carrier which is sensibly equidistant from the first and last sub-carrier allocated to the mobile station MS according to the following formula :
• ⁇ equidistant ceil( ( « NC - I +A/ NC - I -1+ « O )/2) where "ceil(x)" denotes the closest integer superior or equal to x.
• the processor 200 checks if ⁇ equidistant is the index of a sub- carrier allocated to the mobile station MS.
• ⁇ equidistant is the index of a sub-carrier allocated to the mobile station MS. Otherwise, the processor 200 moves to step S704.
• the processor 200 determines the shifting parameter p to be used for the mobile station using the following formula: Compute TM, where q is the index of the cluster CL q which is the closest
• ⁇ equidistant- p is selected as the closest even integer inferior or equal to V M 1 ⁇ .
• M 1 are
• the processor 200 interrupts the present algorithm.
• the processor 200 checks if ⁇ equidistant is the index of a sub-carrier comprised in the cluster CL 0 .
• step S706 If ⁇ equidistant is the index of a sub-carrier comprised in the cluster CLo, the 10 processor 200 moves to step S706. Otherwise, the processor 200 moves to step S707.
• step S706 the processor 200 sets the value of the shifting parameter /? to be used for the mobile station MS as equal to Mo, which must be even. Otherwise, p is set to the greatest even integer inferior to this value.
• the processor 200 interrupts the present algorithm.
• step S708 the processor 200 checks if maxi is lower or equal to max 2 . If maxi is lower or equal to max 2 , the processor 200 moves to step S709. Otherwise, the processor 200 moves to step S710.
• the processor 200 computes the shifting parameter/? to be used for 25 the mobile station MS using the following formula: q- ⁇
• the processor 200 computes the shifting parameter/? to be used for the mobile station MS using the following formula:
• the processor 200 interrupts the present algorithm.
• the maximum distance between paired sub-carriers is minimized and the shifting parameter p is chosen as to be equal to a sum of the number of sub-carriers comprised in at least one cluster.
• Fig. 10 represents an example of mapping of symbols on sub-carriers according to the second mode of realisation of the present invention.
• the frequency band comprises ten sub-carriers noted 0 to 9 in the column 1020. Eight of the sub-carriers are allocated to the mobile station MS. The sub-carriers allocated to the mobile station MS are indicated by grey rectangles in the column 1021. The allocated sub-carriers belong to two clusters. The sub-carriers 0 to 5 belong to the cluster CL 0 , the sub-carriers 7 and 8 belong to the cluster CLi. According to the example of the Fig. 10, the processor 200 determines that the index noted ⁇ equidistant is equal to 4.
• the processor 200 moves from step S703 to step S705 and determines at step S706 the shifting parameter/? as equal to 6.
• the emitter comprises two transmit antennas which transfer K equals eight symbols on sub-carriers of the frequency band allocated to the mobile station MS.
• the symbols Xo to X ⁇ shown in the column 1022 are transferred through a first antenna.
• the line 1000 comprises the sub-carrier 0 on which the couple of symbols (Xo, - X5*) is mapped.
• the line 1005 comprises the sub-carrier 5 on which the couple of symbols (X5, Xo*) is mapped. Same symbols Xo and X5 are mapped on the sub-carriers 0 and 5. No impairment exists for the sub-carriers 0 and 5. As no impairment occurs, the decoding of the received symbols Xo and X5 at the receiver side is possible.
• the line 1001 comprises the sub-carrier 1 on which the couple of symbols (X 1 , X 4 *) is mapped.
• the line 1004 comprises the sub-carrier 4 on which the couple of symbols (X 4 , -Xi *) is mapped. Same symbols Xi and X 4 are mapped on the sub- carriers 1 and 4.
• the line 1002 comprises the sub-carrier 2 on which the couple of symbols (X 2 , - X3*) is mapped.
• the line 1003 comprises the sub-carrier 3 on which the couple of symbols (X3, X 2 *) is mapped. Same symbols X 2 and X3 are mapped on the sub-carriers 2 and 3 No impairment exists for the sub-carriers 2 and 3.
• the line 1007 comprises the sub-carrier 7 on which the couple of symbols (X 6 , - X 7 *) is mapped.
• the line 1008 comprises the sub-carrier 8 on which the couple of symbols (X 7 , X 6 *) is mapped. Same symbols X 6 and X 7 are mapped on the sub-carriers 7 and 8.
• Fig. 8 discloses an example of an algorithm for determining the shifting parameter for a mobile station according to a third mode of realisation of the present invention.
• the present algorithm will be described when it is executed by the processor 200 of the base station BS.
• the same algorithm may also be executed by the processor 300 of the mobile station MS when information indicating the clusters of sub-carriers are received for the base station BS by the mobile station MS.
• the present algorithm is executed each time clusters of sub-carriers are allocated to a mobile station MS handled by the base station BS.
• the processor 200 gets the number K of sub-carriers allocated to the mobile station MS.
• step S801 the processor 200 sets the variable/? to null value.
• the processor 200 computes a cost function J(p) which is equal to the number of sub-carriers allocated to the mobile station which are paired to a sub-carrier of another cluster using the current value of/? as shifting parameter.
• the processor 200 computes a variable O(p) which is equal to the maximum distance between two paired sub-carriers.
• the processor 200 increments p by two.
• the processor 200 checks if/? is equal to K. If/? is not equal to K, the processor 200 returns to step S802.
• the processor 200 checks all the possible values of/? with/? even.
• Fig. 11 represents a table of cost function values and maximum distance values between sub-carriers which are associated.
• the table of the Fig. 11 shows the different values of J(/?) and D(/?) when the sub-carriers allocated to the mobile station MS are as the one disclosed in the Fig. 12.
• step S806 the processor 200 selects the minimum value of J(/?) comprised in the table of the Fig. 11.
• step S807 the processor 200 checks if the minimum value of J(/?) is obtained with more than one value of p. If the minimum value of J(/?) is obtained with more than one value of/?, the processor 200 moves to step S809. Otherwise, the processor 200 moves to step S808.
• the processor 200 selects the value of the shifting parameter /? as the value of/? which corresponds to the minimum value of J(/?).
• the processor 200 interrupts the present algorithm.
• the processor 200 selects the value of the shifting parameter /? among the values of/? which correspond to the minimum value of J(/?) as one of the values of/? which corresponds to the lowest D(/?).
• the processor 200 interrupts the present algorithm.
• Fig. 12 represents an example of mapping of symbols on sub-carriers according to the third mode of realisation of the present invention.
• the frequency band comprises fifteen sub-carriers noted 0 to 14 in the column 1220. Ten of the sub-carriers are allocated to the mobile station MS. The sub-carriers allocated to the mobile station MS are indicated by grey rectangles in the column 1221. The allocated sub-carriers belong to three clusters. The sub-carriers 0 and 1 belong to the cluster CL 0 , the sub-carriers 3 to 8 belong to the cluster CLi and the sub-carriers 12 and 13 belong to the cluster CL 2 .
• the line 1200 comprises the sub-carrier 0 on which the couple of symbols (Xo, - X 7 *) is mapped.
• the line 1208 comprises the sub-carrier 8 on which the couple of symbols (X 7 , Xo*) is mapped. Same symbols Xo and X 7 are mapped on the sub-carriers 0 and 8, the sub-carriers 0 and 8 are then paired. No impairment exists for the sub- carriers 0 and 8. As no impairment occurs, the decoding of the received symbols Xo and X ⁇ at the receiver side is possible.
• the line 1201 comprises the sub-carrier 1 on which the couple of symbols (X 1 , Xe*) is mapped.
• the line 1207 comprises the sub-carrier 7 on which the couple of symbols (X 6 , -Xi *) is mapped. Same symbols Xi and Xe are mapped on the sub- carriers 1 and 7.
• the line 1203 comprises the sub-carrier 3 on which the couple of symbols (X 2 , - X5*) is mapped.
• the line 1206 comprises the sub-carrier 6 on which the couple of symbols (X5, X 2 *) is mapped. Same symbols X 2 and X5 are mapped on the sub-carriers 3 and 6.
• the line 1204 comprises the sub-carrier 4 on which the couple of symbols (X3, X 4 *) is mapped.
• the line 1205 comprises the sub-carrier 5 on which the couple of symbols (X 4 , -X3*) is mapped. Same symbols X3 and X 4 are mapped on the sub- carriers 5 and 6.
• the line 1212 comprises the sub-carrier 12 on which the couple of symbols (Xs, -X9*) is mapped.
• the line 1213 comprises the sub-carrier 13 on which the couple of symbols (Xs, -X9*) is mapped. Same symbols Xs and Xg are mapped on the sub- carriers 12 and 13.
• Fig. 13 discloses an example of an algorithm for mapping symbols using the shifting parameter determined according to the present invention.
• the present algorithm is executed when symbols are transmitted by the base station BS and/or by the mobile station MS.
• the present algorithm will be disclosed when it is executed by the mobile station MS.
• the mobile station MS receives information representative of the sub-carriers allocated to the mobile station MS.
• the mobile station MS receives information representative of the shifting parameter/? determined for the mobile station MS.
• the symbols to be transferred are mapped on the allocated sub-carriers according to the received shifting parameter and transferred to the base station BS.
• Fig. 14 discloses an example of an algorithm for de-mapping symbols using the shifting parameter determined according to the present invention.
• the present algorithm is executed when symbols are received by the base station BS and/or by the mobile station MS.
• the present algorithm will be disclosed when it is executed by the base station BS.
• the processor 300 obtains information representative of the sub- carriers allocated to the mobile station MS the base station BS handles.
• the processor 300 obtains information representative of the shifting parameter p determined for the mobile station MS the base station BS handles.
• Information representative of the shifting parameter p determined for each mobile station MS the base station BS handles is as the one determined according to the algorithm disclosed in the Fig. 6, 7 or 8.
• the received symbols are de-mapped on the allocated sub- carriers according to the received shifting parameters.

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• 2009
  • 2009-03-20 EP EP09155717A patent/EP2230788A1/en not_active Withdrawn
• 2010
  • 2010-03-12 US US13/255,698 patent/US8913569B2/en active Active
  • 2010-03-12 WO PCT/EP2010/053150 patent/WO2010105973A1/en not_active Ceased
  • 2010-03-12 JP JP2012500192A patent/JP5589055B2/ja active Active
  • 2010-03-12 EP EP10707921.2A patent/EP2409442B1/en not_active Not-in-force
  • 2010-03-12 CN CN201080012529.5A patent/CN102356587B/zh not_active Expired - Fee Related

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