AU4210697A

AU4210697A – Transmitting and receiving method and radio system
– Google Patents

AU4210697A – Transmitting and receiving method and radio system
– Google Patents
Transmitting and receiving method and radio system

Info

Publication number
AU4210697A

AU4210697A
AU42106/97A
AU4210697A
AU4210697A
AU 4210697 A
AU4210697 A
AU 4210697A
AU 42106/97 A
AU42106/97 A
AU 42106/97A
AU 4210697 A
AU4210697 A
AU 4210697A
AU 4210697 A
AU4210697 A
AU 4210697A
Authority
AU
Australia
Prior art keywords
subcarriers
signals
signal
radio system
detected
Prior art date
1996-09-05
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)

Granted

Application number
AU42106/97A
Other versions

AU723045B2
(en

Inventor
Hannu Hakkinen
Ari Hottinen
Mikko Kokkonen
Risto Wichman
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)

Nokia Oyj

Original Assignee
Nokia Telecommunications Oy
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
1996-09-05
Filing date
1997-09-05
Publication date
1998-03-26

1997-09-05
Application filed by Nokia Telecommunications Oy
filed
Critical
Nokia Telecommunications Oy

1998-03-26
Publication of AU4210697A
publication
Critical
patent/AU4210697A/en

2000-08-17
Application granted
granted
Critical

2000-08-17
Publication of AU723045B2
publication
Critical
patent/AU723045B2/en

2017-09-05
Anticipated expiration
legal-status
Critical

Status
Ceased
legal-status
Critical
Current

Links

Espacenet

Global Dossier

Discuss

Classifications

H—ELECTRICITY

H04—ELECTRIC COMMUNICATION TECHNIQUE

H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION

H04L25/00—Baseband systems

H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines

H04L25/03—Shaping networks in transmitter or receiver, e.g. adaptive shaping networks

H04L25/03006—Arrangements for removing intersymbol interference

H04L25/03178—Arrangements involving sequence estimation techniques

H04L25/03331—Arrangements for the joint estimation of multiple sequences

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

H04B1/713—Spread spectrum techniques using frequency hopping

H04B1/715—Interference-related aspects

H—ELECTRICITY

H04—ELECTRIC COMMUNICATION TECHNIQUE

H04J—MULTIPLEX COMMUNICATION

H04J11/00—Orthogonal multiplex systems, e.g. using WALSH codes

H04J11/0023—Interference mitigation or co-ordination

H04J11/0026—Interference mitigation or co-ordination of multi-user interference

H04J11/0036—Interference mitigation or co-ordination of multi-user interference at the receiver

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

H04L5/0016—Time-frequency-code

H—ELECTRICITY

H04—ELECTRIC COMMUNICATION TECHNIQUE

H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION

H04L5/00—Arrangements affording multiple use of the transmission path

H04L5/003—Arrangements for allocating sub-channels of the transmission path

H04L5/0037—Inter-user or inter-terminal allocation

H04L5/0041—Frequency-non-contiguous

H—ELECTRICITY

H04—ELECTRIC COMMUNICATION TECHNIQUE

H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION

H04L25/00—Baseband systems

H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines

H04L25/03—Shaping networks in transmitter or receiver, e.g. adaptive shaping networks

H04L25/03006—Arrangements for removing intersymbol interference

H04L2025/0335—Arrangements for removing intersymbol interference characterised by the type of transmission

H04L2025/03375—Passband transmission

H04L2025/03414—Multicarrier

H—ELECTRICITY

H04—ELECTRIC COMMUNICATION TECHNIQUE

H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION

H04L25/00—Baseband systems

H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines

H04L25/0202—Channel estimation

H04L25/0204—Channel estimation of multiple channels

H—ELECTRICITY

H04—ELECTRIC COMMUNICATION TECHNIQUE

H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION

H04L25/00—Baseband systems

H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines

H04L25/0202—Channel estimation

H04L25/0224—Channel estimation using sounding signals

H04L25/0228—Channel estimation using sounding signals with direct estimation from sounding signals

Abstract

The invention relates to a transmitting and receiving method and a radio system. In a transmitter the signals to be transmitted are spread coded in means and modulated by subcarriers in means. In a receiver (R) the signals are demodulated in means and submitted to multiuser detection in means by using the subcarriers to limit the number of detectable signals in the means. The receiver uses multiuser detection for reducing multiple access interference and correcting frequency-selective fading.

Description

TRANSMITTING AND RECEIVING METHOD AND RADIO SYSTEM
FIELD OF THE INVENTION
The invention relates to a transmitting and receiving method used in a digital radio system comprising at least one base station and subscriber ter- minal communicating with one another by transmitting and receiving signals.
The invention also relates to a radio system comprising at least one base station and subscriber terminal with a transmitter and receiver arranged to transmit and receive digital signals.
DESCRIPTION OF THE PRIOR ART In the CDMA method (Code Division Multiple Access), a narrowband user data signal is multiplied to a relatively broad band by a spreading code having a considerably higher frequency than the data signal. Upon multiplication, the data signal is spread to the entire band in use. All users use the same frequency band for simultaneous transmission. The objective is to select mutually substantially orthogonal spreading codes, i.e. codes that have minimal mutual correlation.
In a CDMA receiver implemented in a conventional manner, a data signal is returned in the receiver to the original band by multiplying it again with the same spreading code as at the transmission stage. The signals of other users impede the detection of the desired signal by distorting the received signal. This interference, caused by users to each other, is called multiple access interference.
In the OFDMA method (Orthogonal Frequency Division Multiple Access) the spread-coded symbol train of a transmission signal is modulated by subcarriers which are preferably distributed to a wide frequency band. OFDMA modulation is typically carried out by inverse Fourier transformation.
Multipath propagation causes distortion or crosstalk on radio system channels. In the CDMA system this can be detected in that a signal originally spread-coded with orthogonal spreading codes is no longer orthogonal upon arrival at a receiver, there being crosstalk between signals of different channels. In the OFDMA system, subcarriers attenuate frequency-selectively, impairing detection. In the CDMA system, crosstalk is adjusted by using interference cancellation. In the OFDMA system, frequency-selective attenuation is compensated for by error correction. However, the complexity of all methods eliminating crosstalk gener-

ated by multipath propagation increases faster than the amount of information/ the bit string to be processed. Consequently, known methods cannot remove this problem.
SUMMARY OF THE INVENTION It is the object of the present invention to implement a method and a radio system in which the amount of information to be processed can be limited thus allowing better elimination of various disturbances.
This is achieved with the method described in the preamble, characterized in that upon transmission the signals are spread-coded and modu- lated by subcarriers in accordance with the OFDMA/CDMA methods, and upon reception the signals are demodulated and multiuser-detected by selecting the signals to be detected in the multiuser detection using the sub- carriers and consequently reducing the number of signals in the multiuser detection. The radio system of the invention is characterized in that the transmitter comprises means for spread coding and means for modulating the transmission signals by subcarriers in accordance with the OFDMA/CDMA methods, and the receiver comprises demodulation means arranged to select a detectable signal on the basis of subcarriers, and means for multiuser de- tection of the received signals.
The method of the invention provides considerable advantages. The method of the invention enables good tolerance of interference caused by channel isolation and signal multipath, propagation by means of a simple receiver implementation.
DESCRIPTION OF THE DRAWINGS
In the following the invention will be described in more detail with reference to the examples according to the attached drawings, in which Figure 1 shows a radio system, Figure 2 shows subcarrier frequency hopping, and Figure 3 shows the structure of a transmitter and a receiver.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The solution of the invention is particularly applicable to the OFDMA CDMA radio system without, however, being restricted to it.
Figure 1 shows a typical digital radio system comprising a base sta-

tion 1 , subscriber terminals 2 to 4, and a base station controller 5. The base station 1 communicates with the subscriber terminals 2 to 4 using signals 6 to 8. The base station 1 communicates with the base station controller 5 via a digital transmission link 9. Usually the subscriber terminal 2 to 4 is a mobile telephone. The signals 6 to 8 between the base station 1 and the subscriber terminals 2 to 4 comprise digitized information: speech or data generated by subscribers, or control information generated by the radio system
Let us now have a closer look at the method of the invention, the solution of which is based on the CDMA/OFDMA method. The CDMA/OFDMA method is preferably used in communication between a base station and subscriber terminals in a digital radio system. In the method the spread coding of a transmission signal according to the CDMA method and the signal modulation by subcarriers according to the OFDMA method are preferably combined, and the signals are then demodulated and multiuser-detected in a receiver. It is preferable to combine multiuser detection with the CDMA/OFDMA method since this enables separation of the signal components generated in multipath propagation and, consequently, restriction of the number of detectable signals, which in turn enables reduction of crosstalk caused by multipath propagation.
In the method of the invention, the signals are spread according to CDMA by e.g. multiplying each symbol pertaining to the data to be transmitted and comprising a bit or a bit combination with a spreading code V having a higher frequency than the data. The spreading codes V are preferably e.g. Walsh/Hadamard codes, substantially orthogonal with respect to one another, i.e. having minimal mutual correlation. The spread-coded symbols are prefera- bly combined by summing into a continuous spread-coded symbol string. This can be expressed mathematically as follows:
U = 2 ,F, = , «, ,…, «„, . ,], (1)
/=1 where Ns is the length of the spreading code V„ and b, represents transmission bits by a mapping b, € [-1 , 1].
A received OFDMA signal can be expressed as:
y(nt. ) = (-1)”∑ ∑ H.’u/’ 2^ + N(t). (2)
1-0 i-O

where /w +1 = /„ + ^ , T = Ts + σ, σ is safety time, N is the total number of subcarriers, Ts is symbol duration time, N(t) is noise summed in a signal, and f0 is the frequency of the lowest subcarrier. We can see that the set [H/w’j is a discrete Fourier transformation (DFT) of the signal set . According

to prior art, the CDMA/OFDMA radio system subcarriers are generated from a signal to be transmitted by e.g. discrete inverse Fourier transformation. DFT consequently generates a filter bank, each filter being adapted to a multiplexed subcarrier. DFT transformation is preferably implemented in accordance with prior art as fast Fourier transformation, i.e. as FFT transformation. Thus, an OFDMA signal can be generated by inverse FFT transformation. When a safety time σ, which is longer than the channel impulse response, is preferably reserved between each symbol, the symbols are not mixed in reception since the channel properties change slowly compared with the symbol duration time. The CDMA/OFDMA method has been described in more detail e.g. in the publication: Performance of CDMA/OFDMA for Mobile Communication System, Khaled Fazel, IEEE ICUP’93, pp. 975 to 979, 1993, which is incorporated herein by reference.
Upon reception, a CDMA/OFDMA signal according to the invention is OFDMA demodulated, preferably as FFT transformation, and multiuser- detected by using the following solution of principle:
x = gnH-‘y = R’ y, (3)
where x denotes the symbols/bits of the transmitted signal, H”1 is the inverse matrix of the cross-correlation matrix of the spreading codes V, y is a received signal at e.g. the output of an adapted filter, R”1 is a normalized cross-correlation matrix, and y is a normalized output of an adapted filter, commonly used in receivers to correct the signal distortions caused by a channel.
An optimal receiver can be approximated by various methods. In CDMA systems, various methods are used for multiuser detection (MUD). The most common methods include linear multiuser detection, a decorrelating detector and a multi-stage detector. These methods have been described in more detail in the following references: Varanasi, Aazhang: Multistage detection for asynchronous code division multiple access communications, IEEE Transactions on Communications, vol. 38, pp. 509 to 519, Apr 1990; Lupas,

Verdu: Linear multiuser detectors for synchronous code-division multiple access channels, IEEE Transactions on Information Theory, vol. 35, No. 1 , pp. 123 to 136, Jan 1989; and Lupas, Verdu: Near-far resistance of multiuser detectors in asynchronous channels, IEEE Transactions on Communications, vol. 38, Apr 1990. However, many operations requiring computing capacity, such as matrix inversion operations, are associated with these methods, too.
Another way to solve the problems caused by multiuser interference is to use interference cancellation (IC). In IC-type solutions, users are detected one by one, often in the order of magnitude by removing the effect of the sig- nals of detected users from the received transmission before the next user is detected. Patent publication EP 491668, in which a procedure of the above type is applied to a CDMA cellular radio system, is incorporated as a reference by way of example of such a solution. Interference cancellation methods are computationally more efficient than MUD-type algorithms, but their perform- ance is lower particularly under difficult reception conditions, such as in multipath fading where signal levels are often weak. These methods are best suited for lowering interference originating from the user cell, and thus for improving system capacity.
In the method of the invention, multiuser detection is performed so as to reduce multiple access interference and/or correct frequency-selective fading, resulting in improved detection quality.
In the solution of the invention, the received signals are also grouped or separated from one another according to subcarriers. A subcarrier set has been allocated to each signal, or user. This allows a desired signal set to be selected for multiuser detection or only one signal to be separated for detection. This way subcarriers serve to reduce the number of signals in multiuser detection. This also means that signals are not separated according to spreading codes, but all used spreading codes are allocated to all users.
In the solution of the invention, a prior art maximum likelihood (ML) multiuser detection, or a multiuser detection method based on the like, disassembles the spread coding, generates estimates from the received signal by using a channel estimate, and compares these with a real received signal. Bit or symbol decisions are made in accordance with the most compatible estimate. The channel estimate is generated in a known manner from e.g. a pilot or reference signal, reference data comprising predetermined symbols, or from one or more directly detectable signals.

In the solution of the invention, subcarriers are selected from the frequency band non-uniformly. This is advantageous since undesirable fading situations can be avoided particularly in 2-way channels. Furthermore, the solution of the invention is particularly advantageous when used in the downlink direction of a radio system with the base station spread coding and modulating the signal and the subscriber terminal multiuser-detecting the signal transmitted from the base station. An advantage of this solution is, for example, that in reception the signals can be grouped so as to detect only some of them. All received signals are detected at the base station any way, and thus subcarrier grouping would be quite useless. However, such a solution reduces the computing performed at the subscriber terminal and consequently the necessary computing capacity and energy consumption.
In the method of the invention, subcarriers are hopped by changing the frequency of the modulating subcarrier of each spread-coded signal in a predetermined manner. This allows the signals to be separated from one another upon reception preferably according to the way in which subcarrier frequency hopping takes place, i.e. according to the hopping sequence. The primary purpose of such a procedure is to multiplex different base stations to the same band. In the method of the invention, subcarrier frequency hopping is implemented by evenly utilizing substantially the entire frequency band. This improves evenly the fading tolerance of all signals.
In the method of the invention, subcarrier frequency hopping is implemented orthogonally by one carrier at a time being available to only one transmitted signal. This can be easily implemented within the range of one cell. This allows signal collisions to be minimized in reception.
Referring now to Figure 2, which shows subcarrier frequency hopping at the output of an OFDMA modulator. The y-axis represents frequency and the x-axis time. In Figure 2, possible subcarrier frequencies d to c16 are uniform, while subcarriers 20 to 23 are per se preferably non-uniform. As a result of hopping, the frequencies of the subcarriers 20 to 23 change for all signals when moving from one instant t1 to t3 to another. Additionally, the subcarriers 20 to 23 are evenly distributed to the frequency band at the interval d to c16. Reference is now made to the block diagram of a transmitter and receiver in Figure 3. The transmitter TR comprises a series-parallel converter

30, spread coding means 31 , a multiplexer 32, modulation means 33, and an antenna 34. The receiver R comprises an antenna 34, demodulation means 35, and multiuser detection means 36. The transmitter TR and the receiver R implement the inventive method. On the transmitter the data is conveyed as e.g. a bit string to the series-parallel converter 30, which converts series-mode data into parallel-mode. Let us assume that the series-parallel converter 30 has generated a parallel-mode N-bit block of data. These data are spread coded by a spreading sequence of length M in the means 31 whose outputs are summed in the multiplexer 32 into a substantially continuous data flow. The summed sequence is modulated with K subcarriers by the means 33, which is preferably an OFDMA modulator. M < K is true for K subcarriers. The sum signal modulated by the subcarriers is transmitted in accordance with prior art via the antenna 34. As the receiver antenna 34 receives signals, the means 35 disas- semble the subcarrier modulation of the desired signal or signals by FFT transformation. The means 36 submit the demodulated signal to multiuser detection in accordance with prior art. The means 35 group or separate the signals based on the modulation and consequently select the desired signal or signals to detection. Let us study another example of the inventive solution. In this example the invention is applied to the downlink direction of a radio system, i.e. the transmission direction from a base station to a subscriber terminal. The base station modulates a transmission signal by subcarriers and transmits the generated multicarrier signal on a band width providing sufficient diversity against selective fading. Typically there are dozens or hundreds of subcarriers in use. Eight carriers are reserved for each channel/signal, for example. Signal information is also usually error protected and interleaved in some manner, although it is not essential to the invention. The information to be transmitted is divided in e.g. 8-bit groups and spread-coded by e.g. 8 orthogonal spreading codes which are preferably Walsh-Hadamard sequences. The spread-coded signals are summed and these 8 sum signals are coupled to subcarrier modulators in which the signals are modulated to subcarriers. If frequency hopping is used, the subcarrier modulator also hops the frequency of the subcarrier of each signal in a predetermined manner. One channel preferably only comprises one signal and one subcarrier. In this case each channel uses e.g. each 10th OFDMA signal for the transfer of an 8-bit group time divisionally. In multiuser detection taking place in a multisymbol detector, detection for 8 parallel bits/symbols is provided by the detected signals and the estimated channel response. At this stage known interference cancellation and multi access detection methods can be utilized, since the originally orthogonal spreading codes are no longer orthogonal because of multipath propagation. Crosstalk can be reduced when channel response and spreading codes are known. Crosstalk occurs between channels inside a cell only because of multipath propagation. However, it is negligible because of the relatively long symbol duration. In the solution of the invention, subcarrier modulation is preferably carried out as linear modulation, such as phase and amplitude modulation. The solution of the invention can be implemented by ASIC or VLSI circuits, particularly as regards digital signal processing. The functions to be performed are preferably implemented by microprocessor technology-based software. Although the invention is described in the above with reference to the example in accordance with the accompanying drawings, it will be appreciated that the invention is not to be so limited, but the it may be modified in a variety of ways within the scope of the inventive idea disclosed in the ap- pended claims. Claims (20) 1. A transmitting and receiving method used in a digital radio system comprising at least one base station (1) and subscriber terminal (2 to 4) communicating with one another by transmitting and receiving signals (6 to 8), characterized in that upon transmission the signals (6 to 8) are spread-coded and modulated by subcarriers (20 to 23) in accordance with the OFDMA/CDMA methods, and upon reception the signals (6 to 8) are demodulated and multiuser-detected by selecting the signals to be detected in the multiuser detection using the subcarriers (20 to 23) and consequently re- ducing the number of signals in the multiuser detection. 2. A method as claimed in claim 1, characterized in that upon reception, as multiple access interference and frequency-selective fading cause signal (6 to 8) quality to change, multiuser detection is performed on the detectable signals to reduce multiple access interference and/or correct selec- tive fading. 3. A method as claimed in claim 1, characterized in that upon reception, a predetermined group of signals is selected to be detected on the basis of the subcarriers (20 to 23). 4. A method as claimed in claim 1, characterized in that upon reception, only one signal is selected to be detected on the basis of the subcarriers (20 to 23). 5. A method as claimed in claim 1, characterized in that as the subcarriers (20 to 23) reserve a given frequency band, the subcarriers are selected non-uniformly from the frequency band. 6. A method as claimed in claim ^characterized in that the method is used particularly in the downlink direction of a radio system with the base station (1) spread coding and modulating the signal (6 to 8) and the subscriber terminal (2 to 4) multiuser-detecting the signal (6 to 8). 7. A method as claimed in claim 1, characterized in that upon modulation, the subcarriers (20 to 23) are hopped by changing the modulating subcarrier (20 to 23) of each spread-coded signal (6 to 8) in a predetermined manner. 8. A method as claimed in claim 7, characterized in that the frequency hopping of the subcarriers (20 to 23) is implemented by evenly util- izing substantially the entire frequency band. 9. A method as claimed in claim 7, characterized in that the frequency hopping of the subcarriers (20 to 23) is implemented orthogonally by one carrier at a time being available to only one transmitted signal. 10. A method as claimed in claim 7, characterized in that the single signal or the several signals to be detected upon reception are chosen by means of the hop sequence of the subcarriers (20 to 23). 11. A radio system comprising at least one base station (1) and subscriber terminal (2 to 4) with a transmitter (TR) and receiver (R) arranged to transmit and receive digital signals (6 to 8), c h a r a c t e r i z e d in that the transmitter (TR) comprises means (31) for spread coding and means (33) for modulating the transmission signals (6 to 8) by subcarriers (20 to 23) in accordance with the OFDMA/CDMA methods, and the receiver (R) comprises demodulation means (35) arranged to select a detectable signal on the basis of subcarriers (20 to 23), and means (36) for multiuser detection of the received signals. 12. A radio system as claimed in claim 11, characterized in that the receiver (R) is arranged to perform multiuser detection for reducing multiple access interference and/or correcting selective fading as signal quality in the channel changes because of multiple access interference and fre- quency-selective fading. 13. A radio system as claimed in claim 11, characterized in that the demodulation means (35) are arranged to select a predetermined group of signals to be detected on the basis of the subcarriers (20 to 23). 14. A radio system as claimed in claim 11, characterized in that the demodulation means (35) are arranged to select only one signal to be detected on the basis of the subcarriers. (20 to 23). 15. A radio system as claimed in claim 11, characterized in that as the subcarriers (20 to 23) reserve a given frequency band, the modulation means (33) are arranged to select the modulating subcarriers (20 to 23) non-uniformly from the frequency band. 16. A radio system as claimed in claim 11, characterized in that the base station (1) is the transmitter (TR) and the subscriber terminal (2 to 4) is the receiver (R). 17. A radio system as claimed in claim 11, characterized in that the modulation means (33) are arranged to hop the subcarriers (20 to 23) by changing the subcarrier (20 to 23) modulating each spread-coded signal in a predetermined manner. 18. A radio system as claimed in claim 17, characterized in that as the subcarriers (20 to 23) reserve a given frequency band, the modulation means (33) are arranged to hop the subcarriers (20 to 23) by evenly util- izing substantially the entire frequency band. 19. A radio system as claimed in claim 17, characterized in that the modulation means (33) are arranged to hop the subcarriers (20 to 23) orthogonally by one subcarrier (20 to 23) at a time being available to only one transmitted signal. 20. A radio system as claimed in claim 17, characterized in that the demodulation means (35) are arranged to select one or more signals for detection by means of the hop sequence of the subcarriers (20 to 23). AU42106/97A 1996-09-05 1997-09-05 Transmitting and receiving method and radio system Ceased AU723045B2 (en) Applications Claiming Priority (3) Application Number Priority Date Filing Date Title FI963479A FI102577B1 (en) 1996-09-05 1996-09-05 Transmission and reception procedure and radio system FI963479 1996-09-05 PCT/FI1997/000525 WO1998010542A2 (en) 1996-09-05 1997-09-05 Transmitting and receiving method and radio system Publications (2) Publication Number Publication Date AU4210697A true AU4210697A (en) 1998-03-26 AU723045B2 AU723045B2 (en) 2000-08-17 Family ID=8546608 Family Applications (1) Application Number Title Priority Date Filing Date AU42106/97A Ceased AU723045B2 (en) 1996-09-05 1997-09-05 Transmitting and receiving method and radio system Country Status (11) Country Link US (1) US6282185B1 (en) EP (1) EP0872060B1 (en) JP (1) JPH11514827A (en) CN (1) CN1148902C (en) AT (1) ATE289139T1 (en) AU (1) AU723045B2 (en) DE (1) DE69732478T2 (en) ES (1) ES2235248T3 (en) FI (1) FI102577B1 (en) NO (1) NO982013L (en) WO (1) WO1998010542A2 (en) Families Citing this family (51) * Cited by examiner, † Cited by third party Publication number Priority date Publication date Assignee Title DE19647833B4 (en) * 1996-11-19 2005-07-07 Deutsches Zentrum für Luft- und Raumfahrt e.V. Method for simultaneous radio transmission of digital data between a plurality of subscriber stations and a base station FI103235B1 (en) 1997-06-26 1999-05-14 Nokia Telecommunications Oy Interference suppression method in OFDM radio receiver US6904078B1 (en) 1998-04-23 2005-06-07 Ntt Docomo, Inc. CDMA receiver and CDMA transmitter/receiver US7020071B2 (en) * 1998-11-25 2006-03-28 Lucent Technologies Inc. Methods and apparatus for wireless communication using orthogonal frequency division multiplexing JP3715141B2 (en) * 1999-07-13 2005-11-09 松下電器産業株式会社 Communication terminal device EP1085689B1 (en) * 1999-09-13 2003-05-21 Mitsubishi Electric Information Technology Centre Europe B.V. Assignment of spreading sequences in an MCCDMA system JP3522619B2 (en) * 2000-01-05 2004-04-26 株式会社エヌ・ティ・ティ・ドコモ Transmitter in multi-carrier CDMA transmission system JP3911378B2 (en) 2000-02-16 2007-05-09 松下電器産業株式会社 Communication terminal device and communication method JP2001285927A (en) * 2000-03-29 2001-10-12 Matsushita Electric Ind Co Ltd Communication terminal and wireless communication method US6961364B1 (en) * 2000-04-18 2005-11-01 Flarion Technologies, Inc. Base station identification in orthogonal frequency division multiplexing based spread spectrum multiple access systems US9130810B2 (en) * 2000-09-13 2015-09-08 Qualcomm Incorporated OFDM communications methods and apparatus US6870808B1 (en) 2000-10-18 2005-03-22 Adaptix, Inc. Channel allocation in broadband orthogonal frequency-division multiple-access/space-division multiple-access networks JP4031707B2 (en) * 2000-12-15 2008-01-09 アダプティックス インコーポレイテッド Multi-carrier communication with group-based subcarrier allocation US6947748B2 (en) 2000-12-15 2005-09-20 Adaptix, Inc. OFDMA with adaptive subcarrier-cluster configuration and selective loading US6882619B1 (en) * 2001-02-21 2005-04-19 At&T Corp. Interference suppressing OFDM method for wireless communications US7158474B1 (en) * 2001-02-21 2007-01-02 At&T Corp. Interference suppressing OFDM system for wireless communications US7099374B2 (en) 2001-03-14 2006-08-29 Mercury Computer Systems, Inc. Wireless communication systems and methods for long-code communications for regenerative multiple user detection involving matched-filter outputs US7035201B2 (en) * 2001-04-20 2006-04-25 Mediatek Inc. Programmable transceiver structure of multi-rate OFDM-CDMA for wireless multimedia communications US10931338B2 (en) 2001-04-26 2021-02-23 Genghiscomm Holdings, LLC Coordinated multipoint systems US6975583B2 (en) * 2001-05-14 2005-12-13 Intel Corporation Technique for continuous OFDM modulation JP3628977B2 (en) * 2001-05-16 2005-03-16 松下電器産業株式会社 Radio base station apparatus and communication terminal apparatus AU2002322131A1 (en) * 2001-06-21 2003-01-08 Flarion Technologies, Inc. Method of tone allocation for tone hopping sequences JP4119696B2 (en) 2001-08-10 2008-07-16 松下電器産業株式会社 Transmitting apparatus, receiving apparatus, and wireless communication method JP4171261B2 (en) * 2001-08-27 2008-10-22 松下電器産業株式会社 Wireless communication apparatus and wireless communication method BR0212206A (en) * 2001-08-30 2004-09-21 Ntt Docomo Inc Radio transmission system and process, and transmitting apparatus and receiving apparatus used in the radio transmission system CN100566222C (en) * 2001-09-28 2009-12-02 富士通株式会社 Channel estimating apparatus and method JP3836019B2 (en) 2001-11-21 2006-10-18 松下電器産業株式会社 Reception device, transmission device, and transmission method CN100413232C (en) 2001-11-28 2008-08-20 富士通株式会社 Orthogonal frequency division multiplexing transmission method US7187647B1 (en) 2002-01-23 2007-03-06 At&T Corp. Ultra-wide bandwidth system and method for in-premises wireless networking DE60320956D1 (en) 2002-03-07 2008-06-26 Alvarion Ltd HIERARCHICAL PREAMBLE STRUCTURES FOR OFDMA BASED ON COMPLEMENTARY SEQUENCES US10644916B1 (en) 2002-05-14 2020-05-05 Genghiscomm Holdings, LLC Spreading and precoding in OFDM US7551546B2 (en) * 2002-06-27 2009-06-23 Nortel Networks Limited Dual-mode shared OFDM methods/transmitters, receivers and systems JP2004363721A (en) * 2003-06-02 2004-12-24 Matsushita Electric Ind Co Ltd Wireless communication system and wireless communication method CN1259785C (en) 2003-08-04 2006-06-14 大唐移动通信设备有限公司 Method for obtaining carrier frequency departure of time division synchronous CDMA (TD-SCDMA) user terminal and equipment US8934848B2 (en) 2003-08-06 2015-01-13 Panasonic Intellectual Property Corporation Of America Radio communication device and radio communication method configured for channel quality reporting of selected sub-carrier bands KR100957415B1 (en) 2003-10-31 2010-05-11 삼성전자주식회사 Apparatus for transmitting/receiving a pilot signal for distinguish a base station in a communication using orthogonal frequency division multiplexing scheme and method thereof CN1691562B (en) * 2004-04-19 2010-11-17 北京三星通信技术研究有限公司 CDMA access method based on orthogonal time-frequency domain with variable spread spectrum and frequency hopping US7924909B2 (en) * 2004-06-02 2011-04-12 Telefonaktiebolaget Lm Ericsson (Publ) Method and apparatus for interference cancellation in wireless receivers US11184037B1 (en) 2004-08-02 2021-11-23 Genghiscomm Holdings, LLC Demodulating and decoding carrier interferometry signals US11381285B1 (en) 2004-08-02 2022-07-05 Genghiscomm Holdings, LLC Transmit pre-coding US7715845B2 (en) * 2004-10-14 2010-05-11 Qualcomm Incorporated Tone hopping methods and apparatus US7379446B2 (en) * 2004-10-14 2008-05-27 Qualcomm Incorporated Enhanced beacon signaling method and apparatus US7573851B2 (en) 2004-12-07 2009-08-11 Adaptix, Inc. Method and system for switching antenna and channel assignments in broadband wireless networks US8351405B2 (en) * 2006-07-14 2013-01-08 Qualcomm Incorporated Method and apparatus for signaling beacons in a communication system US20090323610A1 (en) * 2006-09-26 2009-12-31 Koninklijke Philips Electronics, N.V. Bonding adjacent tv bands, sub-carrier allocation, data burst definition and spread ofdma in a physical layer for 802.22 wran communication systems US7852247B2 (en) 2006-12-05 2010-12-14 Texas Instruments Incorporated Mixed-signal filter JP4499762B2 (en) * 2007-05-08 2010-07-07 富士通株式会社 Orthogonal frequency division multiplexing transmission method CN101394390B (en) * 2008-10-20 2011-04-20 北京鑫百灵宽带通信科技有限公司 Spectrum-spread type PDH microwave communication system and method US10637705B1 (en) 2017-05-25 2020-04-28 Genghiscomm Holdings, LLC Peak-to-average-power reduction for OFDM multiple access US10243773B1 (en) 2017-06-30 2019-03-26 Genghiscomm Holdings, LLC Efficient peak-to-average-power reduction for OFDM and MIMO-OFDM WO2020242898A1 (en) 2019-05-26 2020-12-03 Genghiscomm Holdings, LLC Non-orthogonal multiple access Family Cites Families (5) * Cited by examiner, † Cited by third party Publication number Priority date Publication date Assignee Title US5151919A (en) 1990-12-17 1992-09-29 Ericsson-Ge Mobile Communications Holding Inc. Cdma subtractive demodulation US5140610A (en) * 1991-10-08 1992-08-18 The United States Of America As Represented By The Secretary Of The Army FM video data link spectrum spreading US5521937A (en) 1993-10-08 1996-05-28 Interdigital Technology Corporation Multicarrier direct sequence spread system and method US5805583A (en) * 1995-08-25 1998-09-08 Terayon Communication Systems Process for communicating multiple channels of digital data in distributed systems using synchronous code division multiple access US5825835A (en) * 1996-02-23 1998-10-20 L-3 Communications Corporation Multi-user acquisition procedure for multipoint-to-point synchronous CDMA systems 1996 1996-09-05 FI FI963479A patent/FI102577B1/en active 1997 1997-09-05 ES ES97940175T patent/ES2235248T3/en not_active Expired - Lifetime 1997-09-05 US US09/068,169 patent/US6282185B1/en not_active Expired - Lifetime 1997-09-05 AT AT97940175T patent/ATE289139T1/en not_active IP Right Cessation 1997-09-05 DE DE69732478T patent/DE69732478T2/en not_active Expired - Lifetime 1997-09-05 JP JP10512291A patent/JPH11514827A/en active Pending 1997-09-05 EP EP97940175A patent/EP0872060B1/en not_active Expired - Lifetime 1997-09-05 CN CNB971913757A patent/CN1148902C/en not_active Expired - Fee Related 1997-09-05 WO PCT/FI1997/000525 patent/WO1998010542A2/en active IP Right Grant 1997-09-05 AU AU42106/97A patent/AU723045B2/en not_active Ceased 1998 1998-05-04 NO NO982013A patent/NO982013L/en not_active Application Discontinuation Also Published As Publication number Publication date EP0872060A2 (en) 1998-10-21 NO982013D0 (en) 1998-05-04 US6282185B1 (en) 2001-08-28 WO1998010542A3 (en) 1998-04-23 ATE289139T1 (en) 2005-02-15 CN1205142A (en) 1999-01-13 EP0872060B1 (en) 2005-02-09 FI963479A0 (en) 1996-09-05 WO1998010542A2 (en) 1998-03-12 FI963479A (en) 1998-03-06 FI102577B (en) 1998-12-31 JPH11514827A (en) 1999-12-14 ES2235248T3 (en) 2005-07-01 FI102577B1 (en) 1998-12-31 NO982013L (en) 1998-07-06 AU723045B2 (en) 2000-08-17 DE69732478D1 (en) 2005-03-17 CN1148902C (en) 2004-05-05 DE69732478T2 (en) 2006-01-05 Similar Documents Publication Publication Date Title EP0872060B1 (en) 2005-02-09 Transmitting and receiving method and radio system CN1280997C (en) 2006-10-18 Multi-user detection using an adaptive combination of joint detection and successive interference cancellation McCormick et al. 2002 Multicarrier CDMA for future generation mobile communication US8553820B2 (en) 2013-10-08 Groupwise successive interference cancellation for block transmission with reception diversity Hara et al. 1997 Overview of multicarrier CDMA KR100371112B1 (en) 2003-02-06 Transeiver US7787514B2 (en) 2010-08-31 Carrier interferometry coding with applications to cellular and local area networks US7218666B2 (en) 2007-05-15 Method and system for transmission and frequency domain equalization for wideband CDMA system KR100873173B1 (en) 2008-12-10 System and Method for co-channel interference cancellation in cellular OFDM systems WO2003003634A1 (en) 2003-01-09 Multicarrier transmitter, multicarrier receiver, and multicarrier wireless communication method US20050276311A1 (en) 2005-12-15 Mt-cdma using spreading codes with interference-free windows EP0794627B1 (en) 2006-01-11 Spread spectrum communication apparatus JPH11511915A (en) 1999-10-12 Interference cancellation method and receiver CN1883137B (en) 2012-11-21 Fast frequency hopping with a code division multiplexed pilot in an OFDMA system JP4588430B2 (en) 2010-12-01 Method and receiver for communicating ultra-wideband signals using orthogonal frequency division multiplexing modulation KR20060099674A (en) 2006-09-20 Apparatus and method for performance improvement of channel estimation in broadband wireless access system EP1359678B1 (en) 2009-05-20 Code allocation method in an MC-CDMA telecommunication system KR100781044B1 (en) 2007-11-29 The aparatus and method for Channel Estimation For Wirelss Telecommnunication System Bogucka 1996 Transmission and reception of the multicarrier CDMA signals in the 3rd generation mobile communication system CN100492932C (en) 2009-05-27 Multi-user detection using an adaptive combination of joint detection and successive interference cancellation Schnell 1995 Interference calculations for mc-ssma systems in mobile communications KR20100042650A (en) 2010-04-26 Radio transmission device, radio communication system and radio transmission method Mottier et al. 2004 Spreading sequence assignment in the downlink of OFCDM systems using multiple transmit antennas Garia et al. 0 Comparative Study of OFDM and CDMA Technique Jeong et al. 1999 A TDD-CDMA system with pre-phase subcarrier equalizer using asymmetric modulation scheme in duplex channel Legal Events Date Code Title Description 2000-12-14 FGA Letters patent sealed or granted (standard patent) 2003-04-03 MK14 Patent ceased section 143(a) (annual fees not paid) or expired
Download PDF in English