Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04J—MULTIPLEX COMMUNICATION
  • H04J4/00—Combined time-division and frequency-division multiplex systems
• • 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
  • H04L1/004—Arrangements for detecting or preventing errors in the information received by using forward error control
  • H04L1/0056—Systems characterized by the type of code used
  • H04L1/0071—Use of interleaving
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L27/00—Modulated-carrier systems
  • H04L27/26—Systems using multi-frequency codes
  • H04L27/2601—Multicarrier modulation systems
  • H04L27/2602—Signal structure
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04J—MULTIPLEX COMMUNICATION
  • H04J7/00—Multiplex systems in which the amplitudes or durations of the signals in individual channels are characteristic of those channels

Definitions

• This invention relates to communication systems and methods, and more particularly to such systems and methods using FEC blocks.
• the OFDMA PHY uses a two-dimensional allocation method (in the frequency and the time domains) in order to allocate slots for transmission.
• FIG. 1 An example for a possible transmission frame can be seen in Fig. 1, wherein different bursts in the DL are shown in different shades of gray. The same method may be used in the UL as well.
• Each burst may contain several FEC blocks; a FEC block is the basic entity, which is processed, in the encoding chain.
• a possible encoding chain using the convolutional encoder, uses a bit Interleaver as one of the chain processing elements or any other FEC encoding needs Interleaver which may appear in the byte level or/and symbol level or/and bit level as for example we have in DVB-T.
• bit Interleaver definition is given in the standard and follows the following definitions, for example 802.16d OFDMA: — P 1 —
• All encoded data bits shall be interleaved by a block interleaver with a block size corresponding to the number of coded bits per the encoded block size N cbps as set in 8.4.9.2.
• the interleaver is defined by a two-step permutation. The first ensures that adjacent coded bits are mapped onto nonadjacent subcarriers. The second permutation insures that adjacent coded bits are mapped alternately onto less or more significant bits of the constellation, thus avoiding long runs of lowly reliable bits.
• N cpc be the number of coded bits per subcarrier, i.e., 2, 4 or 6 for QPSK, 16-QAM or 64-QAM, respectively.
• s N cpc /2.
• k be the index of the coded bit before the first permutation
• m k bethe index of that coded bit after the first and before the second permutation
• lety' k be the index after the second permutation, just prior to modulation mapping
• d be the modulo used for the permutation.
• the second permutation is defined by the formula:
• the de-intef leaver which performs the inverse operation, is also defined by two permutations, within a received block of N ebfS bits, let/ be the index of a received bit before the first permutation: rri j be the index of that bit after the first and before the second permutation; and let A / be the index of that bit after the second permutation, just prior to delivering the block to the decoder.
• the first permutation is defined by the formula:
• the second permutation is defined by the formula:
• the first permutation in the de-interleaver is the inverse of the second permutation in the interleaver, and conversely.
• This Interleaver and the OFDMA permutations in the different modes such as PUSC, FUSC, OFUSC, AMC - these are different ways to scatter or/and grouping of the subcarriers in time or/and in frequency in the transmitted frame) can be improve the results with a very small minimal distance between the interleaved bits .
• Figs. 1 - 4 illustrate an example for a possible transmission frame
• FIG. 5 - 7 detail, in table format, data to be used in preferred embodiments of the invention
• FIG. 8 - 10 detail methods for implementing the invention - S -
• Figs. 1 - 2 illustrate an example for a possible transmission frame. Different bursts in the DL are shown in different shades of gray or are enclosed within rectangles therein.
• a bi-dimensional transmission is detailed in the time/frequency space, with frequency axis 11 indicating subchannels, and time axis including the stages downlink (DL) 12 and uplink (UL) 13.
• the frame includes a preamble 21, DL and UL map 22, bursts 23, 24, 25, 26, 27 and 28.
• Table 1 (Fig. 5) illustrates examples of embodiments of the present invention, wherein the parameter d is devised as a result of manipulating the "d" parameter of the formula per modulation and encoded block.
• the Table shows such an example that apply to the current 802.16d ( 2004 ) for the "d" parameter, this optimization results in a high minimal-distance between the interleaved bits, and an improved performance of the link.
• This extra optimization per FEC block will improve the system in case of burst errors which hit part of the FEC block that may caused by other cell, sectors interferers or by separate or combination of frequency/time fading which may create a frequency selective fading (holes) which are moving in time relative to the Doppler caused by the speed of the mobile or any other reasons .
• This Multi-parameter d or any scattered spread parameter can be applied to another level , for example for symbol , byte and bit interleaves which may optimize for different FEC method like block code RS, TPC, LDPC etc., or covolutional codes like CC, CTC etc.
• An improvement in the above invention may include a closed loop method: When mobile or fixed user detects that the scattered parameter are not good for the location of the scattered subcarrier hits by interference that randomly hit sequence of adjacent bits in the block code that reduce the code capability, the Mobile when detect this situation can ask the base for a parameter change which will break the sequence.
• any repetition code, ARQ code or HARQ may change the scattered parameter by selecting for each transmission a different set of scattered parameters, which effectively will give the new system and method desirable frequency hopping and time hopping results in two level of diversity.
• the OFDMA PHY defined: For example, within the IEEE802.16d/e standard and DVB-RCT ETSI standard uses a two-dimensional allocation method (in the frequency and the time domains) in order to allocate slots for transmission, an example for a possible transmission frame can be seen in Figs. 3 - 4.
• a bi-dimensional transmission is detailed in the time/frequency space, with frequency axis 11 indicating subchannels, and time axis including the stages downlink (DL) 12 and uplink (UL) 13.
• the frame includes a preamble 21, DL and UL map 22, bursts 23, 24, 25, 26, 27 and 28.
• Each burst may contain several FEC blocks; a FEC block is the basic entity, which is processed, in the encoding chain.
• a possible encoding chain using the convolutional encoder, uses a bit Interleaver as one of the chain processing elements or any other FEC encoding needs Interleaver which may appear in the byte level or/and symbol level or/and bit level as, for example, we have in DVB-T.
• bit Interleaver definition is given in the standard and follows the following definitions for example 802.16d OFDKIA as detailed above.
• the invention may be used in a system such as CDMA, SC, OFDM, OFDMA, etc.
• parameter d used for all blocks
• the bit Interleaver may use more than one constant parameter (named "d", and it equals for example 16 in 802.16), in order to perform its inner permutations.
• the present invention implements this new innovative concept by manipulating the "d" parameter of the formula per modulation and encoded block, the following table shows such an example that apply to the current 802.16d (2004) for the "d" parameter.
• Yet another method will be to optimize each transmission type (depending on the mode used, modulation, and number of slots) with its own unique parameter achieving optimal performance for each transmission' type.
• This extra optimization per FEC block will improve the system in case of burst errors which hit part of the FEC block that may caused by other cell, sectors interferers or by separate or combination of frequency/time fading which may create a frequency selective fading (holes) which are moving in time relative to the Doppler caused by the speed of the mobile or any other reasons .
• This Multi-parameter d or any scattered spread parameter can be applied to other level like symbol, byte and bit interleaves which may optimize for different FEC method like block code RS, TPC, LDPC etc. or covolutional codes like CC, CTC etc.
• the method includes ( See Fig . 8 ) :
• An improvement for the above invention could be close loop method when mobile or fixed user detects that the scattered parameter are not good for the location of the scattered subcarrier hits by interference that randomly hit sequence of adjacent bits in the block code that reduce the code capability.
• the Mobile when detect this situation can ask the base for parameter change which will break the sequence for example we can have two different d per FEC block.
• the method includes (See Fig. 9):
• the base may base answer, if possible, with a parameter change which will break the sequence.
• any repetition code, ARQ code or HARQ may change the scattered parameter by selecting, for each transmission, a different set of scattered parameter ARQ can combined CL Scattering by incorporate scattered parameter number as part of the ARQ ACK/NACK which effectively will give us controlled close loop frequency hopping and time hopping results in two level of diversity.
• the method includes (See Fig. 10):
• OLL Open Loop
• Yet another method will be to optimize each transmission type (depending on the mode used, modulation and transmission slot format) with its own unique parameter, achieving optimal performance for each transmission type.

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• Engineering & Computer Science (AREA)
• Computer Networks & Wireless Communication (AREA)
• Signal Processing (AREA)
• Mobile Radio Communication Systems (AREA)
• Error Detection And Correction (AREA)
• Detection And Prevention Of Errors In Transmission (AREA)
• Digital Transmission Methods That Use Modulated Carrier Waves (AREA)

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• 2006
  • 2006-03-26 EP EP06711343A patent/EP1966919A4/de not_active Withdrawn
  • 2006-03-26 WO PCT/IL2006/000374 patent/WO2006100683A2/en not_active Ceased
  • 2006-03-26 JP JP2008502562A patent/JP2008537860A/ja active Pending
  • 2006-03-26 KR KR1020077024494A patent/KR20080016541A/ko not_active Ceased

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