WO2001039408A1 - Transmission gap interference measurement - Google Patents
Transmission gap interference measurement Download PDFInfo
- Publication number
- WO2001039408A1 WO2001039408A1 PCT/EP2000/011659 EP0011659W WO0139408A1 WO 2001039408 A1 WO2001039408 A1 WO 2001039408A1 EP 0011659 W EP0011659 W EP 0011659W WO 0139408 A1 WO0139408 A1 WO 0139408A1
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- WO
- WIPO (PCT)
- Prior art keywords
- signal
- data
- control channel
- interference
- transmission gap
- Prior art date
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- 230000005540 biological transmission Effects 0.000 title claims abstract description 48
- 238000005259 measurement Methods 0.000 title description 9
- 230000006854 communication Effects 0.000 claims abstract description 60
- 238000004891 communication Methods 0.000 claims abstract description 60
- 238000000034 method Methods 0.000 claims abstract description 20
- 238000005070 sampling Methods 0.000 claims description 9
- 230000007480 spreading Effects 0.000 claims description 9
- 108010003272 Hyaluronate lyase Proteins 0.000 claims description 3
- 230000010267 cellular communication Effects 0.000 abstract description 7
- 238000001228 spectrum Methods 0.000 description 25
- 230000001413 cellular effect Effects 0.000 description 8
- 238000013459 approach Methods 0.000 description 7
- 238000010586 diagram Methods 0.000 description 6
- 230000001419 dependent effect Effects 0.000 description 4
- 238000000691 measurement method Methods 0.000 description 3
- 230000008901 benefit Effects 0.000 description 2
- 230000001427 coherent effect Effects 0.000 description 2
- 238000010276 construction Methods 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 238000012545 processing Methods 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000007175 bidirectional communication Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 230000002265 prevention Effects 0.000 description 1
- 230000003252 repetitive effect Effects 0.000 description 1
- 230000004044 response Effects 0.000 description 1
- 230000001360 synchronised effect Effects 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B7/00—Radio transmission systems, i.e. using radiation field
- H04B7/14—Relay systems
- H04B7/15—Active relay systems
- H04B7/204—Multiple access
- H04B7/216—Code division or spread-spectrum multiple access [CDMA, SSMA]
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W24/00—Supervisory, monitoring or testing arrangements
- H04W24/10—Scheduling measurement reports ; Arrangements for measurement reports
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B17/00—Monitoring; Testing
- H04B17/30—Monitoring; Testing of propagation channels
- H04B17/309—Measuring or estimating channel quality parameters
- H04B17/336—Signal-to-interference ratio [SIR] or carrier-to-interference ratio [CIR]
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/69—Spread spectrum techniques
- H04B1/707—Spread spectrum techniques using direct sequence modulation
- H04B1/7097—Interference-related aspects
- H04B1/7103—Interference-related aspects the interference being multiple access interference
Definitions
- the present invention relates generally to radio-signal communication and, more particularly, to systems and methods for determining the signal to interference ratio in a code-division-multiple-access (CDMA) cellular communication system
- CDMA code-division-multiple-access
- a "cellular" communication system includes multiple communication cells (a.k.a.., regional zones) arranged adjacent one another to cover a larger regional area. Each cell limits the number of possible simultaneous communications to the number of channels provided m the cell. The size of the cell is defined through receivers and transmitters (a. k.a.., transceivers) located within base stations that provide the communication channels through which the mobile radios communicate. Accordingly, a mobile radio communicates m a cellular system by determining the nearest base station and then establishing a radio communication link with that base station
- the prevention of interference from and to other radio communication links is an important concern.
- this concern is addressed through the use of an accurate method for determining with the nearest base station and by controlling the transmission power levels used in maintaining the communication If the nearest base station is not accurately selected or changes without a timely update, the communication can overlap and interfere with other communications in the system Similarly, if the transmission power used m maintaining the radio link within a given cell is not properly controlled at relatively low level, the excessive transmissions can cause intolerable levels of interference
- the mobile stations select the nearest base station by monito ⁇ ng a control channel transmitted from each base station for its signal strength and selecting the nearest base station by compa ⁇ ng these channel reception levels for the best signal quality
- the transmission power is controlled at minimum levels by using algorithms at the base station and/or the mobile radio and, in some systems, also by passing control information between the base station and the mobile radio du ⁇ ng the communication.
- va ⁇ ous approaches have been proposed for determining the SIR in DSSS CDMA cellular communication systems
- Two such approaches respectively include measu ⁇ ng the reception level by dedicating otherwise unused orthogonal variable spreading factor (OVSF) codes or by using designated pe ⁇ ods in the channelization codes defined by each cellular system OVSF codes are used by the base station transmitter to spread the signal through the bandwidth and by the receiver to despread and demodulate the received signal
- OVSF orthogonal variable spreading factor
- the present invention is directed to signal quality and SIR measurement in connection with the operation of direct-sequence-spread-spectrum (DSSS) code-division- multiple-access (CDMA) communication systems and in a manner that overcomes the above- mentioned concerns.
- DSSS direct-sequence-spread-spectrum
- CDMA code-division- multiple-access
- Va ⁇ ous example embodiments of the present invention are directed to overcoming the above-mentioned concerns.
- a control channel e.g., used for data transmission by the base station
- a transmission gap in the control channel corresponds to an interval in each CDMA access slot when data is not being transmitted the control channel and where the traffic of other users can be detected.
- This traffic is the interference factor "I" in the SIR and, therefore, can be used with the measured signal reception level to compute the SIR.
- a signal-receiving method for use in a DSSS CDMA communication includes: locating a first control channel that is multiplexed with another channel in a received communication signal; selecting a transmission gap in the first control channel where data for other control information is being transmitted in place of the first control channel; measu ⁇ ng interference from other radio links in the transmission gap; and determining a signal quality for the received communication signal as a function of the measured interference
- the present invention is directed to the 3GPP system that uses a p ⁇ mary control channel, referred to as PCCPCH (p ⁇ mary common control physical channel), for transmitting data from the base stations.
- PCCPCH p ⁇ mary common control physical channel
- the PCCPCH has a pe ⁇ od of 256 chips in which data is not transmitted.
- a "chip” (or sometimes “chip interval”) refers to a duration of the bit pulse in the waveform used to spread the signal in the modulation stage.
- the base stations multiplex the PCCPCH and another set of channels (p ⁇ mary and secondary SCH channels), by gapping data in the PCCPCH channel for a chip interval (e g , 256 chips) per slot to permit transmission of data for the SCH channels
- this transmission gap is used by the mobile radio to measure the interference factor for the SIR
- Other example embodiments of the present invention are directed to specific methods and arrangements involving use of such a transmission gap in a control channel
- FIG 1 is an illustration of an approach for multiplexing control channels in an example CDMA communication system, with one of the channels including a transmission gap for measurement of interference, according to one aspect of the present invention
- FIG. 2 is block diagram illustrating the functional operation of spreading/modulation from a base station, according to a conventional CDMA cellular communication system.
- FIG 3 is a block diagram of a spread spectrum communication device, according to an example embodiment of the present invention.
- FIG 4 is a block diagram of a rake receiver m a spread spectrum communication device, according to the present invention.
- FIG 5 shows a rake finger in a rake receiver, according to the present invention.
- FIG 6 depicts a pseudo-noise generator for use in a rake receiver according to the present invention While the invention is amenable to va ⁇ ous modifications and alternative forms, specifics thereof have been shown by way of example in the drawings and will be desc ⁇ bed in detail. It should be understood, however, that the intention is not to limit the invention to the particular embodiments desc ⁇ bed On the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spi ⁇ t and scope of the invention as defined by the appended claims.
- the present invention is believed to be applicable to code-division-multiple- access (CDMA) communications systems which require or benefit from measu ⁇ ng interference from other signals sha ⁇ ng the same channel.
- the invention has been found to be particularly beneficial in direct-sequence, spread-spectrum (DSSS) CDMA cellular systems that multiplex multiple control channels by including a transmission gap in one of the control channels for transmission of data for another one of the control channels.
- DSSS direct-sequence, spread-spectrum
- the 3GPP system is one such system including base stations adapted to multiplex the data in the p ⁇ mary common control physical control channel (PCCPCH) with data in another set of channels, referred to as the p ⁇ mary and secondary synchronization channels (SCH). While the present invention is not necessa ⁇ ly limited to this type of system, an appreciation of the present invention is presented by way of example embodiments directed thereto.
- PCCPCH p ⁇ mary common control physical control channel
- SCH p ⁇ mary and
- FIG. 1 illustrates the internal operation of a base station directing data from two control channel paths 12 and 14 to a multiplexer 16, and a mobile directing data from a demultiplexer 16' to corresponding control paths 12' and 14'.
- the upper control channel depicts a first control channel including a transmission gap du ⁇ ng which data for the first control channel is not transmitted.
- the multiplexer 16 is adapted to pass data from the lower control channel path du ⁇ ng this transmission gap. From the multiplexer 16, the data is combined with other information before being upconverted for transmission by the base station.
- the data m these two control channel paths are decoded in essentially the reverse order of the encoding of the base station.
- the upper control channel 12 of FIG.1 corresponds to the PCCPCH, including its 256 chip transmission gap du ⁇ ng which PCCPCH data is not transmitted, and the lower control channel 14 path corresponds to a summation of data from the p ⁇ mary and secondary SCH as transmitted du ⁇ ng this 256 chip gap in the PCCPCH.
- SIR signal to interference ration
- FIG 2 depicts the multiplexing operation in FIG 1 for the 3GPP system using a block diagram showing the functional operation of the spreading/modulation of the va ⁇ ous channels, including the PCCPCH and P/S SCH, as depicted m 3GPP TS25.213, Version 2.3.0 (page 18)
- the arrangement of FIG 2 includes a circuit 30 for spreading/ modulation for the downlink DPCH channels, a circuit 34 for spreading and modulation for the SCH and
- PCCPCH channels PCCPCH channels
- summer 36 adapted to combine the outputs of circuits 34 and 36 into an output signal at 38
- the spreading/ modulation circuit 30 includes signal mixing circuits 40-1, 40- 2, 40-N, which mix the data from each of the input DPCH channels with the approp ⁇ ate OVSF spreading code
- the outputs of the signal mixing circuits are fed to blocks 44 and 46 for development of the I and Q components before processing at complex-va ⁇ able transformer 48 and being summed at block 50
- the output at block 50 is then code- multiplexed using designated PN codes as inputs to a mixer 54
- the spreading and modulation circuit 34 for the SCH and PCCPCH channels includes signal mixing circuits 60, 62, and 64, which mix the data from the PCCPCH and the p ⁇ mary and secondary SCH channels using designated PN codes as inputs to mixer stages 66, 68 and 70.
- the outputs of the mixer stages 66, 68 and 70 are processed for development of the I and Q components, with the Q components being processed by complex-va ⁇ able transformers 72, 74 and 76 and the I and Q components summed at blocks 78, 80 and 82.
- These data are then code-multiplexed using PN codes as inputs to a mixers 84, 86 and 88.
- the data at this stage in the p ⁇ mary and secondary SCH channels are summed at summer 90, and the sum is then time multiplexed with spread data in the PCCPCH using multiplexer 92
- the multiplexer 92 is adapted as desc ⁇ bed above in connection with the multiplexer 16 of FIG 1 In this manner, the p ⁇ mary and secondary SCH channels are code multiplexed and transmitted simultaneously du ⁇ ng the first 256 chips of each slot, which leaves the above-discussed transmission gap for interference measurement at the receiving end, as illustrated and desc ⁇ bed in connection with FIG 1
- FIG 3 is a block diagram of an example spread spectrum communication device 101 adapted to perform the interference measurements according to the present invention
- the spread spectrum communication device 101 is used m a DSSS CDMA cellular system, wherein a symbol to be transmitted to the spread spectrum communication device 101 is spread by a pseudo-noise (PN) reference sequence with a chip rate that is substantially greater than a symbol rate of the symbol, so as to form a spread spectrum signal
- PN pseudo-noise
- Such a spread spectrum signal is modulated onto a earner for transmission as desc ⁇ bed, for example, in TIA/EIN Inte ⁇ m Standard TIA EIA/IS-95-A.
- the spread spectrum communication device 101 receives a modulated spread spectrum signal s(t). In the spread spectrum communication device 101, received multipath components of the transmitted modulated spread spectrum signal s(t) are resolved at sub-chip resolution
- the spread spectrum communication device 101 includes a receiver front-end 102 coupled to an antenna 103 receiving the modulated spread spectrum signal s(t).
- the front end 102 includes a front end block 104 for filte ⁇ ng and amplifying the received signal s(t), and a earner demodulator in the form of a mixer 105 coupled to a local oscillator 106 for demodulating the received signal s(t).
- the spread spectrum communication device 101 can be a unidirectional device only receiving the signal s(t), or as in most applications, the device 101 is a bi -directional communication device.
- the spread spectrum communication device 101 also includes a transmitter branch 107 of which a power amplifier 108 is shown.
- the transmitter branch 107 is adapted to generate a spread spectrum signal as desc ⁇ bed in the above-mentioned TIA/EIA Interim Standard document.
- the mixer 105 provides a demodulated spread spectrum signal, in the form of quadrature base band signals sl(t) and sQ(t), to a sampler 109 for obtaining quadrature base band samples sI(nTs) and sQ(nTs) from the signals sl(t) and sQ(t), t being time, n being an integer, and 1/Ts being a sampling rate exceeding the chip rate of the received signal s(t).
- the spread spectrum device 101 can retneve the symbols or the bits intended for it by conelating the samples with a locally generated pseudo-noise sequence which is the same as the pseudo-noise reference with which the symbol was transmitted.
- the spread spectrum communication device 101 includes a rake receiver 110 and a conventional channel estimator 111.
- the channel estimator 111 estimates channel characte ⁇ stics of the multipath components intended for it from the samples sI(nTs) and sQ(nts), at the sub-chip resolution, and provides information to branches of the rake receiver 110, which samples to process (from the stream of samples sI(nTs) and sQ(nTs)) such information being indicated in FIG. 3 with a bold arrow
- the channel characte ⁇ stics are represented by correlation results, and within chip intervals the channel estimator 111 determines local maximums of such correlation results and corresponding sample positions.
- the rake receiver 110 of FIG. 3 is further adapted to measure the interference dunng the chip interval corresponding to the transmission gap in the PCCPCH. This can be achieved using one of vanous approaches including the example approach discussed below in connection with FIG. 4 In this example application, the measured interference is passed the processor 113 which, using the signal strength of the received signal, computes the SIR.
- the spread spectrum communication device lOlfurther comp ⁇ ses a symbol detector 112, and a processor 113 coupled to the rake receiver 110, the channel estimator 111. and the symbol detector 112
- a symbol detector 112 coupled to the rake receiver 110, the channel estimator 111. and the symbol detector 112
- FIG 4 is a block diagram of the rake receiver 110 in the spread spectrum communication device 101, according to the present invention
- the rake receiver 110 comp ⁇ ses a plurality of receiver branches, k+1 rake fingers where k is an integer Shown are rake fingers 120, 121, 122 and 123
- the respective rake fingers 1, 2, , k provide output signals Rj, R , , R to a diversity combiner 124 which diversity combines them to form a multipath received diversity combined signal S
- the processor 113 can control power to the individual rake fingers and thereby switch off power to unused rake fingers using power control lines pi, p2, and p3.
- the bold arrows indicate information from the channel estimator 111.
- the information includes synchronization information to synchronize pseudorandom sequences to be supplied to the rake fingers 120, 121, 122, 123 with the pseudorandom reference sequence implicitly being present in the received signal s(t).
- synchronization is determined using a reference sequence that is repetitive after 2 15 chips.
- the rake finger 123 provides an output signal R k+ ⁇ that is used by a conventional IIR filter 125 to estimate the interference (output "I")
- a switch 126 is controlled in synchronism with the PCCPCH so that the output signal R ⁇ + ⁇ is coupled to the IIR filter 125 du ⁇ ng a significant portion, or the entirety, of the transmission gap
- the output signal R + i is coupled to the IJR filter 125 for the entire 256 chip transmission gap duration
- the IIR filter 125 output the interference "I" to the processor 113 for determining the SIR as discussed above in connection the FIG 3
- FIG 5 shows an example construction of the rake finger 120, which is the same as the construction of the rake fingers 120, 121 and 122 of FIG 4
- the rake finger 120 comp ⁇ ses a down-sampler 130, receiving down-sampling information DSI from the channel estimator 111, instructing the down-sampler 111 which samples are to be removed from the input sample stream si (nTs) and sQ (nTs), so as to select multipath components with a sub- chip resolution
- the rake finger 120 further comp ⁇ ses a data de-spreader 131, a local pseudo-noise reference generator 132, a phase estimator 133, and a coherent combiner 134, outputs of the data de-spreader 133 and the phase estimator 133 being coherently combined in the coherent combiner 134.
- the rake receiver 123 of FIG 4 can be constructed in a similar manner as that shown for the rake finger 120 of FIG 5, with the exception that the rake finger 123 does not require a phase estimation block, such as phase estimator 133 of the rake finger 120
- rake receiver 123 of FIG 4 corresponds to the illustrated rake fmger 120 of FIG 5 with the removal of the phase estimator 133 and connections 135 and 136
- FIG. 6 depicts the pseudo-noise generator 132 for use in rake fingers (e.g., 120) of the rake receiver 110
- the pseudo-noise generator 132 comp ⁇ ses a pseudo noise code generator 140 providing in-phase and quadrature pseudo noise codes PNi and PN Q , and a Walsh code generator 141 providing a so-called Walsh code WLS
- the pseudo-noise generator 132 further provides a dump signal DMP for controlling reading out of the data de- spreader 131 and the phase estimator 133.
- the pseudo-noise generator 132 is synchronized by the channel estimator 111 so as to synchronize the locally generated pseudo-noise reference sequence to the pseudo-noise reference sequence in the received signal, intended for the rake receiver 110.
- the rake receiver 110 can process signals generated in a narrow-band DSSS CDMA system, such as desc ⁇ bed in the IS-95-A system.
- the present invention provides an accurate method and arrangement of measu ⁇ ng the traffic interference in certain types of CDMA cellular communication systems.
- Embodiments of the present invention have the advantage of being implemented in straight-forward manner and without requi ⁇ ng burdensome maintenance of additional codes While the present invention has been desc ⁇ bed with reference to particular example embodiments, those skilled in the art will recognize that many changes may be made thereto.
- va ⁇ ous blocks depicted in the figures represent functional aspects that can be implemented using discrete, semi-programmable, fully-programmable signal processing technology, and va ⁇ ous combinations thereof
- va ⁇ ous receiver blocks used to exemplify particular operations are provided merely as examples and are not intended to limit the invention, other receiver arrangements can also be used
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Abstract
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Priority Applications (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2001540956A JP2003516027A (en) | 1999-11-23 | 2000-11-22 | Measuring transmission gap interference |
EP00981297A EP1147629A1 (en) | 1999-11-23 | 2000-11-22 | Transmission gap interference measurement |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US09/447,541 | 1999-11-23 | ||
US09/447,541 US6747969B1 (en) | 1999-11-23 | 1999-11-23 | Transmission gap interference measurement |
Publications (1)
Publication Number | Publication Date |
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WO2001039408A1 true WO2001039408A1 (en) | 2001-05-31 |
Family
ID=23776772
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
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PCT/EP2000/011659 WO2001039408A1 (en) | 1999-11-23 | 2000-11-22 | Transmission gap interference measurement |
Country Status (6)
Country | Link |
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US (1) | US6747969B1 (en) |
EP (1) | EP1147629A1 (en) |
JP (1) | JP2003516027A (en) |
KR (1) | KR100733637B1 (en) |
CN (1) | CN1218518C (en) |
WO (1) | WO2001039408A1 (en) |
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1999
- 1999-11-23 US US09/447,541 patent/US6747969B1/en not_active Expired - Fee Related
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2000
- 2000-11-22 JP JP2001540956A patent/JP2003516027A/en active Pending
- 2000-11-22 EP EP00981297A patent/EP1147629A1/en not_active Withdrawn
- 2000-11-22 CN CN00805312XA patent/CN1218518C/en not_active Expired - Fee Related
- 2000-11-22 KR KR1020017009140A patent/KR100733637B1/en not_active IP Right Cessation
- 2000-11-22 WO PCT/EP2000/011659 patent/WO2001039408A1/en active IP Right Grant
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US8837431B2 (en) | 2002-04-05 | 2014-09-16 | Intel Corporation | HS-DSCH inter-node B cell change |
US8130721B2 (en) | 2002-04-05 | 2012-03-06 | Interdigital Technology Corporation | HS-DSCH inter-node B cell change |
US8085726B2 (en) | 2002-04-05 | 2011-12-27 | Interdigital Technology Corporation | High speed downlink shared channel cell change |
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US7706405B2 (en) | 2002-09-12 | 2010-04-27 | Interdigital Technology Corporation | System for efficient recovery of Node-B buffered data following MAC layer reset |
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EP1710927A3 (en) * | 2002-11-06 | 2008-10-01 | QUALCOMM Incorporated | Noise and channel estimation using low spreadindg factors |
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Also Published As
Publication number | Publication date |
---|---|
KR100733637B1 (en) | 2007-06-28 |
US6747969B1 (en) | 2004-06-08 |
KR20010101615A (en) | 2001-11-14 |
JP2003516027A (en) | 2003-05-07 |
CN1344448A (en) | 2002-04-10 |
CN1218518C (en) | 2005-09-07 |
EP1147629A1 (en) | 2001-10-24 |
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