DE102006038825A1 - Radio communication system, network device and method for transmitting data in a radio communication system - Google Patents

Abstract

The invention relates to a method for processing data for transmission in a radio communication system in which symbols to be transmitted (S <SUB> 1 </ SUB>, ..., S <SUB> L </ SUB>) the time domain into the frequency domain, mapped to a subcarrier or to a plurality (L) of at least two subcarriers (F <SUB> 1 </ SUB>, ..., F <SUB> L </ SUB>) and for transmission are transformed back into the time domain, wherein the symbols (S <SUB> 1 </ SUB>, ..., S <SUB> L </ SUB>) are spectrally decomposed before the transformation into the frequency domain in the time domain. In addition, the invention relates to a radio communication system or network device with a control device (C) for processing data for transmission over an uplink, wherein the control device (C) is designed or driven to be transmitted symbols (S <SUB> 1 < / SUB>, ..., S <SUB> L </ SUB>) from the time domain into the frequency domain, to a plurality (L) of at least one subcarrier (F <SUB> 1 </ SUB>, .. ., F <SUB> L </ SUB>) and to transform back into the time domain for transmission and the symbols (S <SUB> 1 </ SUB>, ..., S <SUB> L </ SUB>) before the Spectrally decompose transformation into the frequency domain in the time domain.

Description

The The invention relates to a method for transmitting data in one Radio communication system and a radio communication system and a network device to perform of such a procedure.

Generally Mobile radio systems based on e.g. of the standard GSM (Global System for Mobile Communications) or the UMTS standard (Universal Mobile Telecommunication System). Exemplary of methods of transmission of data in the upward direction (English uplink) from a subscriber-side terminal to a network-side access station is also on the technical specification 3GPP TR 25.814 V1.0.1 (2005-11), 3rd Generation Partnership Project, directed.

When Development in the sense of a long-term development of 3GPP radio access technology, which currently exists becomes UMTS-LTE (LTE: Long Term Evolution) or the so-called Evolved UTRA (UTRA: Universal Terrestrial Radio Access / universal terrestrial radio access). Some of the important aspects of such long-term development include reduced latency, higher Subscriber data rates, improved system capacity and system coverage and reduced costs for the operator of the system.

In the upward direction is doing a transfer over a single carrier proposed, wherein a multiple access scheme is proposed, which as SC-FDMA (Single Carrier-Frequency Division Multiple Access) is a single carrier frequency division multiple access method. Based on traditional time domain transmission techniques the spectral components of single carrier time domain symbols in Type of OFDMA (Orthogonal Frequency Division Multiple Access / Orthogonal Frequency division multiple access) on the participants or their terminals allocated bandwidths. This technique serves to one Peak-to-average ratio (PAR, Engl. Peak-to-Average Ratio) at the transmitter of the terminal of the subscriber. This increases the cell coverage and the Overall Performance and takes care of low requirements for the high-frequency power amplifier of the terminal.

Based 2 is exemplified a data processing according to SC-FDMA. For example, L symbols S are applied to a data input of a device for processing corresponding data. These are applied to a transformation unit DFT for performing a discrete Fourier transformation. The transformation unit DFT outputs output values corresponding to L on L lines. These are applied to an imaging unit MAP for a subcarrier mapping. Output values of this mapping unit MAP are applied to a further transformation unit IFFT for an inverse Fourier transformation whose output values are applied to a processing device CPA for further processing and output. In this procedure, spectral components of L symbols are thus determined for the exemplary transmitted symbol rate of 12 * L ksps by means of the discrete Fourier transformation and then the resulting carriers are mapped to the allocated spectrum. Finally, for example, 2048 samples are obtained using the inverse Fourier transform. However, this procedure is disadvantageous because it requires high complexity if L is not a power of 2.

A The object of the invention is a method and a radio communication system or specify a network device therein, which is a particular Significant reduction in processing complexity of data for in particular an uplink without a particularly significant increase in the peak-to-average ratio (PAR). In particular, this is to be applied under a SC-FDMA scenario become.

These The object is solved by the inventive features of the independent claims. advantageous Embodiments of the invention can be taken from the dependent claims.

According to the invention is a Method for processing data for transmission in a radio communication system, at the to be transmitted Transformed symbols from the time domain into the frequency domain, to a plurality of at least one subcarrier, preferably two or more more subcarriers imaged and for transmission back to the time domain be transformed, the symbols before the transformation in the frequency domain is spectrally decomposed in the time domain. The Symbols are preferably decomposed by means of a binary spectral decomposition.

Preferably, the symbols are split into a plurality of sequences and only subsequently transformed into the frequency domain. The transformed into the frequency domain sequences are doing preferably multiplexed to a serial data stream prior to mapping to the subcarriers. The se rial data stream is preferably formed with a plurality of mutually associated elements equal to the plurality of symbols.

at Such a method is used in a control device of the radio communication system before imaging on the subcarriers preferably a transformation with a transformation template carried out. The transformation becomes, for example, with a transformation matrix with a main diagonal and at least two other diagonals performed nonzero. On a side diagonal in one half below the unit matrix the values are positive and on a secondary diagonal in one half above the Unit matrix, the values are negative. All other matrix elements are preferably set equal to zero.

Also according to the invention a radio communication system having a controller for processing of data for transmission over a Connection, in particular an uplink, wherein the control device is formed or controlled, to be transmitted symbols from the To transform time domain into the frequency domain, to one subcarriers or preferably to a plurality of at least two or more subcarriers and for transmission back to the time domain to transform and transform the symbols before the transformation into Spectrally decompose the frequency domain in the time domain.

Also according to the invention a network device with a control device for processing of data for transmission over a Connection, in particular an uplink, in a radio communication system, wherein the control device is designed or driven to be transmitted Transform symbols from the time domain into the frequency domain, on a subcarrier or preferably to a plurality of at least two or more subcarriers and for transmission back to the time domain to transform and transform the symbols before the transformation into Spectrally decompose the frequency domain in the time domain.

at the radio communication system and the network device is the Control device designed or driven to perform a such preferred method. In particular, they are designed for a mobile communication system based on SC-FDMA.

The Invention will be described in more detail with reference to an embodiment. Show

1 Data processing components and data within such a processing sequence for a preferred uplink SC-FDMA, and

2 Components for performing a method according to the prior art.

In the 1 exemplified a simplified structure of components of a terminal of a radio communication system according to the known UMTS standard, wherein an implementation of the inventive method in radio communication systems according to other standards, such as GSM, in the same way is possible.

The starting point is that transmitted or transmitted symbols S ₁ , S ₂ ,..., S _{L of} a division device SP for splitting the applied sequence into M sequences Sequen Z ₁ , ..., Z _r , ... , Z _{M are} created. These sequences Z ₁ ,..., Z _r ,..., Z _M are each applied to a transformation unit FFT for performing a Fourier transformation. The dimension or size varies. Output values of these Fourier transform units FFT are applied to a multiplexing unit MX for performing serial multiplexing, output values of this multiplexing unit MX being applied to a transformation unit LT for performing a particularly linear transformation. Output values F ₁ , ..., S _L of the linear transformation transformation unit LT are applied to an imaging unit MAP for performing a subcarrier mapping. Their output values are applied to a transformation unit FFT1 for carrying out a Fourier transform of size N. The transformed output values O ₁ ,... O ₂₀₄₈ are applied to a processing unit CPA for performing a cyclic prefix addition. This finally outputs the actual output values O ₁ ,..., O ₂₀₄₀ , O ₁ ,... O _CD at a rate of, for example, 30.72 Msps.

The following is the basis 1 sketched data processing using a formula representation explained in more detail. It is assumed that, for example, in the time domain L symbols S 1 , P 2 , ..., S L = S are to be transmitted as a symbol sequence and a first power value C is determined by C = ceil (log2 (L)) with ceil as the next upper limit function. It is assumed that a running variable b ₁ ..., b _{C is} the C-bit binary representation of L, with b ₁ being the least significant bit (MSB). Then L can be described as the sum of the powers of 2 according to

Furthermore, a position sequence P can be defined as a sequence of positions with the condition b _k = 1. Then P ₁ = 1, P ₂ ,, P _M

Therefore, the symbols S can be split into M sequences according to: 1 st sequence = 1 st 2 ^C-P1 symbols from S, 2 nd sequence = next 2 ^C-P2 symbols from S and so on to the M th sequence = last 2 ^C-PM symbols of S. The first sequence thus consists of the first 2 ^C-1 symbols of the symbol sequence S etc. up to the M-th sequence of the last 2 ^C-PM symbols of the symbol sequence S.

As a result, if the Fourier transforms of each of these M sequences are taken and multiplexed, this results in a serial sequence of L subcarriers Y ₁ , ... Y _L. These L subcarriers Y ₁ , ... Y _L are first passed through a linear transformation and then mapped to the bandwidth allocated for the corresponding terminal. The dimension of these Fourier transforms correspond to the power of 2s: 2 ^C-P1 , 2 ^C-P2, and so on down to 2 ^C-PM .

kann die Symbolabfolge S in die M Sequenzen

gesplittet werden. Als nächstes werden die M Fouriertransformationen der zerlegten Z Sequenzen gebildet gemäß

und in einen seriellen Strom multiplext Y → = {Y →1, Y →2}. With

can the symbol sequence S in the M sequences

be split. Next, the M Fourier transforms of the decomposed Z sequences are formed according to

and multiplexed into a serial stream Y → = {Y → 1 , Y → 2 }.

Therefore can the multiplexed Y sequences as a binary spectral decomposition the time domain symbols.

It should be noted that Y → is a vector of size L, ie equal to the number L of symbols S ₁ , S ₂ ,..., S _{L of} the symbol sequence S.

Thus, with subcarriers F → a matrix T can be formed as an L × L transformation matrix, so that the following applies: F → = {F 1 ... F L } = Y → · T.

Where T is any invertible matrix, including the unit matrix. Finally, the last processing steps are similar to the existing SC-FDMA method. Subcarriers F ₁ ,..., F _L are mapped to the allocated bandwidths and the inverse Fourier transform of the corresponding size or dimension of, in particular, 2048 is performed. That is, for the localized subcarrier allocation, initial values O ₁ , ... O _{2048 are} formed according to O 1 , ..., O 2048 = IFFT {0, 0, ..., F 1 , ..., F L , 0, 0, ..., 0}.

Finally, the cyclic prefix is added with the length CP, so that ultimately the sequence is output O 1 , ..., O 2048 , O 1 , ..., O CP ,

It should be noted that the linear transformation F → = {F ₁ ... F _L } = Y →. T is given here in the sense of a generalization and can also be implemented alternatively by means of equivalent procedures.

Further reduction of the peak-to-average ratio and further improvement of inter-user interference at bandwidth edges may be achieved, for example, by the die, as compared to the template T in the form of a unit matrix

For this template T, the values of the main diagonal and the values of the lower 2 ^C-P1 diagonal are all set to the value "1" and the values of the upper 2 ^C-P1 diagonal are all set to "-1". The remaining elements are set to "0".

By such a procedure, advantages over the known methods can be achieved. According to the known methods, when a discrete Fourier transform of dimension L is used as an even number, the processing complexity is equal to L ² . In contrast, according to the described and preferred method of binary spectral decomposition, the processing complexity is less than or equal to ceil (log2 (L)) · 2 ceil (log2 (L)) ,

For example, L = 511 results in a complexity of 261,121 in the known methods. In the case of binary spectral decomposition, a complexity of only advantageous results 256 · 8 + 128 · 7 + 64 · 6 + 32 · 5 + 16 · 4 + 8 · 3 + 4 · 2 + 2 + 1 = 3587.

at a use in the mathematical laboratory shows a Monte Carlo simulation, that the peak-to-average ratio is approximately the same size for both methods and 16 QAM-modulated Signal (QAM: Quadrature Amplitude Modulation) less than or equal to 8.5 dB within a 99.97% confidence interval.

Claims (14)

Method for processing data for transmission in a radio communication system, in which - symbols (S ₁ ,..., S _L ) to be transmitted are transformed from the time domain into the frequency domain, onto at least one subcarrier (F ₁ ,. F _L ) and transformed back into the time domain for transmission, - wherein the symbols (S ₁ , ..., S _L ) are spectrally decomposed before the transformation into the frequency domain in the time domain. The method of claim 1, wherein the symbols to be transmitted (S _1, ..., S _L) when imaging a plurality (L) of at least two or more subcarriers (F _1, ..., F _L) ready and Transmission are transformed back into the time domain. Method according to Claim 1 or 2, in which the symbols (S ₁ , ..., S _L ) are decomposed by means of a binary spectral decomposition. Method according to claim 1, 2 or 3, wherein the symbols (S ₁ , ..., S _L ) are split to a plurality (M) of sequences (Z ₁ , ..., Z _M ) and subsequently transformed into the frequency domain become. Method according to Claim 4, in which the sequences (Z ₁ ,..., Z _M ) transformed into the frequency domain are compared to at least one such subcarrier (F ₁ ,..., F _L ) to a serial data stream (Y ₁ , ..., Y _L ) are multiplexed. A method according to claim 2 and 5, wherein the serial data stream (Y ₁ , ..., Y _L ) having a plurality (L) of elements associated with each other is equal to the plurality (L) of the symbols (S ₁ , ..., S _L ) is formed. A method as claimed in any preceding claim, wherein in a control device of the radio communication system, prior to mapping to the subcarriers (F ₁ , ..., F _L ), a transformation (F → ° = {F ₁ ... F _L } = Y → · T) with a transformation matrix (T). The method of claim 7, wherein the transformation with a transformation matrix (T) with a main diagonal and at least two further diagonals not equal to zero and all others Matrices elements is performed equal to zero. Method according to Claim 7 or 8, in which the transformation matrix (T) has a multiplicity (L, L) of columns and rows equal to the multiplicity of subcarriers (F ₁ ,..., F _L ) and / or of the symbols to be transmitted ( S ₁ , ..., S _L ) is used. Radio communication system with a control device (C) for processing data for transmission via a connection, wherein the control device (C) is formed and / or controlled, to be transmitted symbols (S ₁ , ..., S _L ) from the time domain in to transform the frequency domain onto a subcarrier or to a multiplicity (L) of at least two subcarriers (F ₁ ,..., F _L ) and to transform it back into the time domain for transmission and the symbols (S ₁ , S _L ) in front of Spectrally decompose transformation into the frequency domain in the time domain. A radio communication system according to claim 10, wherein in that the control device (C) is designed or activated for Carry out A method according to any one of claims 1 to 9. Network device comprising a control device (C) for processing data for transmission via a connection in a radio communication system, wherein the control device (C) is designed or driven to transmit symbols (S ₁ , ..., S _L ) from the time domain in the frequency domain, on a subcarrier or on a multiplicity (L) of at least two subcarriers (F ₁ ,..., F _L ) and to transform back into the time domain for transmission and the symbols (S ₁ ,. S _L ) before the transformation spectrally decompose into the frequency domain in the time domain. A network device according to claim 12, wherein the control device (C) is designed or driven to perform a method according to one of the claims 1 to 9. Radio communication system according to claim 10 or 11 or network device according to claim 12 or 13 for a mobile communication system based on SC-FDMA.