JP3662818B2 - Interference cancellation apparatus, radio terminal apparatus, and interference cancellation method - Google Patents

Description

【０００９】
ただし、n(t)は受信機雑音である。
以後の説明では便宜上、雑音を省略して説明する。
同期回路２０４では、受信信号r(t)に含まれる拡散符号c₁(t)の同期を確立し、その符号を同期回路２０４から２次復調回路２０３に供給する。2次復調回路２０３では、受信信号r(t)と符号ｃ₁(t)との乗算を行い、次の計算によりa₁(t)を得る。
【００１０】
【数２】

【００１１】
ただし、γ_k(t) = c₁(t)×c_k(t), a_k(t) = d_k(t) cos(2πf_ct +θ_k), k = 2,3,〜,Kで、c₁(t)×c₁(t) = 1の関係を使用している。
第１項が希望信号の変調信号で、第２項が、他局信号による雑音成分として寄与する項である。γ_k(t)は希望信号を拡散する符号c₁(t)と、他局信号を拡散する符号c_k(t)との積で、直交していない為、１周期積分してもゼロにならならず広帯域信号のままである。
１次復調器２０２では、a₁(t)を復調してデータd₁(t)を出力する。
【００１２】
【発明が解決しようとする課題】
このように、現在、携帯電話等の通信局数を増やす方法として、スペクトル拡散による符号変調方式が主流となりつつある。しかしながら、スペクトル拡散方式では、複数の他局信号からの干渉を除去する必要があり、この干渉波が、通信局数を制限している。従来は、基地局で干渉波除去に対応しているため大規模のシステム構成になっている。
【００１３】
本発明は、以上の点に鑑み、無線端末に組み込むことを可能とし、容易に他局信号からの干渉信号を除去することを目的とする。また、本発明は、スペクトル拡散通信方式において、雑音として作用する他局の信号成分を除去し、耐雑音特性を向上させ、同時通信局数を増やすことを目的とする。
【００１４】
【課題を解決するための手段】
本発明の第１の解決手段によると、
受信されたスペクトル拡散信号に基づき、希望信号の拡散符号と各局からの搬送波信号を検出する同期回路と、
受信されたスペクトル拡散信号と、前記同期回路により出力された希望信号の拡散符号とを乗算する乗算回路と、
前記乗算回路からの出力と、前記同期回路から出力された各局からの搬送波信号とをそれぞれ乗算する同期検波回路と、
前記同期検波回路からの各乗算結果と希望信号の拡散符号との相関値に基づき、各非希望信号の干渉雑音成分を計算する相関値計算回路と、
各局からの搬送波信号の位相情報からタップ係数を求めるタップ係数制御回路と、
前記相関値計算回路により求められた干渉雑音成分と、タップ係数制御回路により求められたタップ係数とに基づき、合成成分を求める干渉発生部と、
前記相関値計算回路により求められた希望信号についての相関値から、前記干渉発生部により求められた合成成分を減算し、希望受信信号を得る減算回路と
を備えた干渉除去装置を提供する。
【００１５】
本発明の第２の解決手段によると、
スペクトル拡散信号を受信するアンテナと、
前記アンテナで受信した信号を入力する請求項１乃至３のいずれかに記載の干渉除去装置と、
前記干渉除去装置からの出力を復調する復調回路
を備えた無線端末装置を提供する。
本発明の第３の解決手段によると、
受信されたスペクトル拡散信号と希望信号の拡散符号とを乗算した出力と、各局からの搬送波信号とをそれぞれ乗算し、
各乗算結果と希望信号の拡散符号との相関値に基づき、各非希望信号の干渉雑音成分を計算し、
求められた干渉雑音成分と、各局からの搬送波信号の位相情報から求められたタップ係数とに基づき、合成成分を求め、
希望信号についての相関値から求められた合成成分を減算し、希望受信信号を得る
ようにした干渉除去方法を提供する。
【００１６】
【発明の実施の形態】
図１に、本発明に係る干渉除去装置を備えた無線端末装置の第１の実施の形態の構成図を示す。ただし、本発明は、次の条件を前提にしている。
▲１▼すべての拡散符号のチップ同期がとれていること
▲２▼各局が使用する搬送波位相の相対的な関係は保たれ、受信側で知ることができること
【００１７】
この無線端末装置（受信機）は、アンテナ１、同期回路２、乗算回路３、各成分の同期検波回路４、相関値計算回路５、タップ係数制御回路６、干渉発生部７、減算回路８、判定回路９を備える。
【００１８】
同期回路２は、アンテナ１から受信されたスペクトル拡散信号に基づき、希望信号の拡散符号と各局からの搬送波信号を検出する。乗算回路３は、受信されたスペクトル拡散信号と、同期回路２により出力された希望信号の拡散符号とを乗算する。同期検波回路４は、乗算回路３からの出力と、同期回路２から出力された各局からの搬送波信号とをそれぞれ乗算する。相関値計算回路５は、同期検波回路４からの各乗算結果と希望信号の拡散符号との相関値に基づき、各非希望信号の干渉雑音成分を計算する。タップ係数制御回路６は、各局からの搬送波信号の位相情報からタップ係数を求める。干渉発生部７は、相関値計算回路５により求められた干渉雑音成分と、タップ係数制御回路６により求められたタップ係数とに基づき、合成成分を求める。減算回路８は、相関値計算回路５により求められた希望信号についての相関値から、干渉発生部７により求められた合成成分を減算し、希望受信信号を得る。
【００１９】
つぎに、動作を詳細に説明する。
まず、アンテナ１から入力された受信信号r(t)を次のように記述する。
【００２０】
【数３】

【００２１】
ここで、ｋ = 1を希望局の信号（希望信号）と定める。その他のｋ＝2,3,〜,Kは非希望局の信号（非希望信号）とする。乗算回路３は、同期回路２で同期の確立した希望信号の拡散符号c₁(t)を受信信号r(t)と乗算する。各成分の同期検波回路４は、その乗算結果を、同期回路２から出力した信号（各局からの搬送波信号）2cos(2πf_ct +θ_i), i = 1,2,〜,Kと乗算する。各成分の同期検波回路４により乗算された結果は、相関値計算回路５に供給される。相関値計算回路５において、相関値γ_iを求める操作は次の様に行われる。
【００２２】
【数４】

【００２３】
なお、正弦波の和成分は積分操作で除去されるので、記述していない。また、Ｔｂは１ビット時間である。
相関値γ_１ 〜 γ_Kを整理すると、次のようになる。
【００２４】
【数５】

【００２５】
この計算では、希望信号に対してはフレーム同期がとれているとして、データd₁が出力すると仮定している。ベクトル表示にすると、次のように整理できる。
【００２６】
【数６】

【００２７】
したがって、求める干渉成分R₂₁, R₃₁, 〜, R_K1は次の演算で求めることができる。
【００２８】
【数７】

【００２９】
このようにして、干渉雑音成分、R₂₁, R₃₁, 〜, R_K1が求まれば、この値を干渉発生部７に供給する。タップ係数w₂, w₃, 〜 w_Kの値は、タップ係数制御回路６で同時通信している干渉信号の情報（例，希望信号との位相差）から、次のように決定され、干渉発生部７に供給される。
w₂ = cos(θ₂₁)
w₃ = cos(θ₃₁)
−−
w_k = cos(θ_k1)
希望信号の相関値γ_１は
γ₁ = d₁ + R₂₁ cos(θ₂₁) + R₃₁ cos(θ₃₁) +・ ・ ・+R_K1 cos(θ_K1)
である。
【００３０】
干渉発生部７から出力される、計算により求めた干渉成分の合成信号をv(t)と表わすと、
v(t) = R₂₁ cos(θ₂₁) + R₃₁ cos(θ₃₁) +・ ・ ・+R_{Ｋ 1} cos(θ_K1)
となる。減算回路８では、この信号をγ₁より引き算し、x(t)を求める。判定回路９では、受信されたデータを決定して出力する。雑音が無い場合、x(t)はデータd₁になる。
【００３１】
つぎに、図２に、本発明に係る干渉除去装置を備えた無線端末装置の第２の実施の形態の構成図を示す。ここでは、雑音による不確実性を吸収するのに、誤差信号e(t)の命令でチップ係数制御を行うものである。
【００３２】
この受信機は、アンテナ１、同期回路２、乗算回路３、各成分の同期検波回路４、相関値計算回路５、干渉発生部７、減算回路８、判定回路９、タップ係数制御回路１０、リミタ１１、比較器１２を備える。
このような構成において、雑音がある場合は、相関値γ_１ 〜 γ_Kが不正確になるので、減算回路８から出力されたデータx(t)をリミタ１１で制限後、減算回路１２によりリミタ入力x(t)出力とd₁ ^〜(t)とを比較し誤差信号e(t)を得る。タップ係数制御回路１０では、この誤差信号e(t)をできるだけ小さくするように干渉発生部７におけるタップ係数w_２ 〜 w_Kを制御する。減算回路８からの出力は、このようなループを経て、リミタ１１の出力としてデータの予測結果d₁ ^〜(t)を得る。判定回路９では、d₁ ^〜(t)から受信されたデータを決定してd₁＾(t)を出力する。他の構成部及びその動作は、第１の実施の形態と同様である。
【００３３】
つぎに、本発明に係る干渉除去のシュミレーションについて説明する。
図３に、シミュレーションについての説明図を示す。横軸は同時通信局数で、縦軸は BER ( Bit Error Rate, ビット誤り率）を示す。図の中のEb／Noは、１ビットあたりの信号対雑音比である。ここでは、一例として、拡散符号には符号長31チップのGold符号を用いた。図中、点線が干渉除去を行わない時の理論値で、実線が本発明を用いた時のシミュレーションの特性である。
【００３４】
このシミュレーションで、タップ係数は、雑音があっても相関値を計算した結果だけを用い、タップ係数制御は行っていない。すなわち、この結果は、第１の実施の形態の構成についてシミュレーションを行ったものである。図から実線の結果の誤り率が低く、干渉信号が除去されていることが分る。第２の実施の形態の構成ように係数制御を最適な値に制御すれば、更に誤り率の改善を行うことができる。
本発明はPSK、BPSKの他、適宜の変調方式に適用することができる。例えば、QPSKへ適用する場合、同相成分と直交成分に本発明の回路を設けるようにすれば良い。
【００３５】
【発明の効果】
本発明によると、以上のように、移動端末に組み込むことができ、容易に他局信号からの干渉信号を除去することができる。また、本発明によると、スペクトル拡散通信方式において、雑音として作用する他局の信号成分を除去し、耐雑音特性を向上させ、同時通信局数を増やすことができる。
【図面の簡単な説明】
【図１】本発明に係る干渉除去装置を備えた無線端末装置の第１の実施の形態の構成図。
【図２】本発明に係る干渉除去装置を備えた無線端末装置第２の実施の形態の構成図。
【図３】シミュレーションについての説明図。
【図４】従来のスペクトル拡散通システムの構成図。
【符号の説明】
アンテナ１
同期回路２
乗算回路３
各成分の同期検波回路４
相関値計算回路５
タップ係数制御回路６
干渉発生部７
減算回路８
判定回路９
タップ係数制御回路１０
リミタ１１
比較器１２[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an interference cancellation apparatus, a radio terminal apparatus, and an interference cancellation method, and more particularly to an interference cancellation apparatus, a radio terminal apparatus, and an interference cancellation method that use phase information in a direct spread spectrum communication system.
[0002]
[Prior art]
FIG. 4 shows a configuration diagram of a conventional spread spectrum communication system.
This system includes a transmitter 100 and a receiver 200. The transmitter 100 includes a data transmission circuit 101, a primary modulation circuit 102, a secondary modulation circuit 103, a spread code generation circuit 104, and an antenna 105. The receiver 200 includes a data reception circuit 201, a primary demodulation circuit 202, a secondary demodulation circuit 203, a synchronization circuit 204, and an antenna 205.
[0003]
Where d ₁ (t) is the data transmitted by the local station, a ₁ (t) is the first-order modulated signal, s ₁ (t) is the second-order modulated signal, the spread spectrum signal, and c ₁ ( t) represents a code for spreading the spectrum. Spread spectrum signals from other stations are represented as s _i (t), i = 2, 3,.
[0004]
In a spread spectrum communication system, communication is performed in a state where a plurality of signals coexist in the same frequency band. Since each signal is modulated with a spreading code having orthogonal characteristics, a signal including a code that does not match the desired spreading code is excluded during demodulation. However, since they are not completely orthogonal, there are a small number of cross-correlation values, and the sum thereof increases as the number of other station signals increases, limiting the number of simultaneous communication stations.
[0005]
Next, the operation of the spread spectrum communication system will be described with reference to the drawings. In the transmitter 100, data d ₁ (t) transmitted from the data transmission circuit 101 is data that randomly takes +1 and −1, and the primary modulation by the primary modulation circuit 102 is, for example, PSK (phase shift keying). ). The output a ₁ (t) of the primary modulation circuit 102 is described as follows.
a ₁ (t) = d ₁ (t) cos (2πf _c t + θ ₁ )
Where f _c is the carrier frequency and θ ₁ represents the phase of the carrier wave.
[0006]
Here, c ₁ (t) is a spreading code that takes +1 and −1. Secondary modulation circuit 103, the multiplication of this spread code c ₁ (t) and the primary modulation signal a ₁ (t) subjected to secondary modulation, to generate a spread spectrum signal s ₁ (t). The spread spectrum signal s ₁ (t) is described as follows.
s ₁ (t) = c ₁ (t) d ₁ (t) cos (2πf _c t + θ ₁ )
[0007]
The spread spectrum signal from the other station is expressed as follows.
s _k (t) = c _k (t) d _k (t) cos (2πf _c t + θ _k ), k = 2, 3, 4, ~, K
On the other hand, the receiver 200 demodulates the spread spectrum signal s ₁ (t) as a desired signal. The received signal r (t) is described as follows.
[0008]
[Expression 1]

[0009]
Here, n (t) is receiver noise.
In the following description, noise will be omitted for convenience.
The synchronization circuit 204 establishes synchronization of the spread code c ₁ (t) included in the received signal r (t), and supplies the code from the synchronization circuit 204 to the secondary demodulation circuit 203. The secondary demodulation circuit 203 multiplies the received signal r (t) and the code c ₁ (t), and obtains a ₁ (t) by the following calculation.
[0010]
[Expression 2]

[0011]
Where γ _k (t) = c ₁ (t) × c _k (t), a _k (t) = d _k (t) cos (2πf _c t + θ _k ), k = 2, 3, ~, K Therefore, the relationship c ₁ (t) × c ₁ (t) = 1 is used.
The first term is a modulation signal of the desired signal, and the second term is a term that contributes as a noise component due to the other station signal. γ _k (t) is the product of the code c ₁ (t) that spreads the desired signal and the code c _k (t) that spreads the other station signal, and is not orthogonal, so it is zero even if it integrates for one period It must remain a broadband signal.
In primary demodulator 202, and outputs the data d ₁ (t) demodulates a ₁ a (t).
[0012]
[Problems to be solved by the invention]
Thus, as a method for increasing the number of communication stations such as mobile phones, a code modulation method using spread spectrum is becoming mainstream. However, in the spread spectrum method, it is necessary to remove interference from a plurality of other station signals, and this interference wave limits the number of communication stations. Conventionally, since the base station supports interference wave removal, the system configuration is large.
[0013]
The present invention has been made in view of the above points, and is intended to be easily incorporated into a wireless terminal and easily remove interference signals from other station signals. Another object of the present invention is to remove signal components of other stations acting as noise in a spread spectrum communication system, improve noise resistance characteristics, and increase the number of simultaneous communication stations.
[0014]
[Means for Solving the Problems]
According to the first solution of the present invention,
A synchronization circuit for detecting a spread code of a desired signal and a carrier signal from each station based on the received spread spectrum signal;
A multiplication circuit that multiplies the received spread spectrum signal by the spreading code of the desired signal output by the synchronization circuit;
A synchronous detection circuit that multiplies the output from the multiplication circuit and the carrier signal from each station output from the synchronization circuit;
A correlation value calculation circuit for calculating an interference noise component of each undesired signal based on a correlation value between each multiplication result from the synchronous detection circuit and a spreading code of the desired signal;
A tap coefficient control circuit for obtaining a tap coefficient from phase information of a carrier wave signal from each station;
Based on the interference noise component obtained by the correlation value calculation circuit and the tap coefficient obtained by the tap coefficient control circuit, an interference generator that obtains a combined component;
There is provided an interference cancellation device comprising a subtraction circuit for subtracting a combined component obtained by the interference generation unit from a correlation value for a desired signal obtained by the correlation value calculation circuit to obtain a desired received signal.
[0015]
According to the second solution of the present invention,
An antenna for receiving a spread spectrum signal;
The interference cancellation apparatus according to any one of claims 1 to 3, wherein a signal received by the antenna is input;
Provided is a wireless terminal device including a demodulation circuit that demodulates an output from the interference canceling device.
According to the third solution of the present invention,
Multiplying the output obtained by multiplying the received spread spectrum signal by the spreading code of the desired signal and the carrier signal from each station,
Based on the correlation value between each multiplication result and the spreading code of the desired signal, the interference noise component of each undesired signal is calculated,
Based on the obtained interference noise component and the tap coefficient obtained from the phase information of the carrier wave signal from each station, a composite component is obtained,
Provided is an interference cancellation method for obtaining a desired received signal by subtracting a composite component obtained from a correlation value for a desired signal.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows a configuration diagram of a first embodiment of a wireless terminal apparatus including an interference canceling apparatus according to the present invention. However, the present invention is based on the following conditions.
(1) Chip synchronization of all spreading codes is taken. (2) The relative relationship of the carrier phase used by each station is maintained and can be known on the receiving side.
The wireless terminal device (receiver) includes an antenna 1, a synchronization circuit 2, a multiplication circuit 3, a synchronous detection circuit 4 for each component, a correlation value calculation circuit 5, a tap coefficient control circuit 6, an interference generation unit 7, a subtraction circuit 8, A determination circuit 9 is provided.
[0018]
The synchronization circuit 2 detects the spread code of the desired signal and the carrier signal from each station based on the spread spectrum signal received from the antenna 1. The multiplier circuit 3 multiplies the received spread spectrum signal by the spread code of the desired signal output from the synchronization circuit 2. The synchronous detection circuit 4 multiplies the output from the multiplication circuit 3 and the carrier signal from each station output from the synchronization circuit 2. The correlation value calculation circuit 5 calculates the interference noise component of each undesired signal based on the correlation value between each multiplication result from the synchronous detection circuit 4 and the spread code of the desired signal. The tap coefficient control circuit 6 obtains a tap coefficient from the phase information of the carrier wave signal from each station. The interference generator 7 obtains a composite component based on the interference noise component obtained by the correlation value calculation circuit 5 and the tap coefficient obtained by the tap coefficient control circuit 6. The subtracting circuit 8 subtracts the combined component obtained by the interference generating unit 7 from the correlation value for the desired signal obtained by the correlation value calculating circuit 5 to obtain a desired received signal.
[0019]
Next, the operation will be described in detail.
First, the received signal r (t) input from the antenna 1 is described as follows.
[0020]
[Equation 3]

[0021]
Here, k = 1 is defined as a desired station signal (desired signal). The other k = 2, 3,..., K are undesired station signals (unwanted signals). The multiplier circuit 3 multiplies the received signal r (t) by the spread code c ₁ (t) of the desired signal that has been synchronized by the synchronization circuit 2. The synchronous detection circuit 4 for each component multiplies the multiplication result by a signal (carrier signal from each station) 2cos (2πf _c t + θ _i ), i = 1, 2,. . The result of multiplication by the synchronous detection circuit 4 for each component is supplied to the correlation value calculation circuit 5. In the correlation value calculation circuit 5, the operation for obtaining the correlation value γ _i is performed as follows.
[0022]
[Expression 4]

[0023]
Since the sum component of the sine wave is removed by the integration operation, it is not described. Tb is one bit time.
Correlation value γ ₁ ~ Γ _K is organized as follows.
[0024]
[Equation 5]

[0025]
In this calculation, it is assumed that the data d ₁ is output assuming that the desired signal is frame-synchronized. In vector display, it can be organized as follows.
[0026]
[Formula 6]

[0027]
Therefore, the interference components R ₂₁ , R ₃₁ ,..., R _K1 to be obtained can be obtained by the following calculation.
[0028]
[Expression 7]

[0029]
When the interference noise components R ₂₁ , R ₃₁ ,..., R _K1 are found in this way, these values are supplied to the interference generator 7. The values of tap coefficients w ₂ , w ₃ ,..., W _K are determined as follows from information on interference signals (for example, phase difference from the desired signal) simultaneously communicated by the tap coefficient control circuit 6, and interference It is supplied to the generator 7.
w ₂ = cos (θ ₂₁ )
w ₃ = cos (θ ₃₁ )
−−
w _k = cos (θ _k1 )
The correlation value γ ₁ of the desired signal is γ ₁ = d ₁ + R ₂₁ cos (θ ₂₁ ) + R ₃₁ cos (θ ₃₁ ) + ・ ・ + R _K1 cos (θ _K1 )
It is.
[0030]
A combined signal of interference components obtained by calculation and output from the interference generator 7 is expressed as v (t).
v (t) = R ₂₁ cos (θ ₂₁ ) + R ₃₁ cos (θ ₃₁ ) + ・ ・ ・ + R _{K 1} cos (θ _K1 )
It becomes. The subtracting circuit 8 subtracts this signal from γ ₁ to obtain x (t). The determination circuit 9 determines the received data and outputs it. When there is no noise, x (t) becomes data d ₁ .
[0031]
Next, FIG. 2 shows a configuration diagram of a second embodiment of a wireless terminal apparatus including the interference cancellation device according to the present invention. Here, in order to absorb the uncertainty due to noise, chip coefficient control is performed by an instruction of the error signal e (t).
[0032]
The receiver includes an antenna 1, a synchronization circuit 2, a multiplication circuit 3, a synchronous detection circuit 4 for each component, a correlation value calculation circuit 5, an interference generation unit 7, a subtraction circuit 8, a determination circuit 9, a tap coefficient control circuit 10, a limiter 11 and a comparator 12 are provided.
In such a configuration, when there is noise, the correlation value γ ₁ Comparison Since ~ gamma _K becomes inaccurate, after limited output from the subtracting circuit 8 the data x (t), in limiter 11, by the subtraction circuit 12 Limiter input x (t) output and d ₁ ^~ a ^(t) An error signal e (t) is obtained. In the tap coefficient control circuit 10, the tap coefficient w ₂ in the interference generator 7 is set so as to make this error signal e (t) as small as possible. To control the ~ w _K. The output from the subtraction circuit 8 passes through such a loop, and obtains the data prediction results d ₁ ^to (t) as the output of the limiter 11. The decision circuit 9 determines the data received from d ₁ ^to (t) and outputs d ₁ ^ (t). Other components and their operations are the same as those in the first embodiment.
[0033]
Next, the simulation of interference removal according to the present invention will be described.
FIG. 3 is an explanatory diagram for the simulation. The horizontal axis represents the number of simultaneous communication stations, and the vertical axis represents BER (Bit Error Rate). Eb / No in the figure is the signal-to-noise ratio per bit. Here, as an example, a Gold code having a code length of 31 chips is used as the spreading code. In the figure, the dotted line is a theoretical value when interference removal is not performed, and the solid line is a simulation characteristic when the present invention is used.
[0034]
In this simulation, even if there is noise, the tap coefficient is only used as a result of calculating the correlation value, and tap coefficient control is not performed. That is, this result is a simulation of the configuration of the first embodiment. From the figure, it can be seen that the error rate of the result of the solid line is low and the interference signal is removed. If the coefficient control is controlled to an optimum value as in the configuration of the second embodiment, the error rate can be further improved.
The present invention can be applied to an appropriate modulation method in addition to PSK and BPSK. For example, when applied to QPSK, the circuit of the present invention may be provided for the in-phase component and the quadrature component.
[0035]
【The invention's effect】
According to the present invention, as described above, it can be incorporated into a mobile terminal, and an interference signal from another station signal can be easily removed. Further, according to the present invention, in the spread spectrum communication system, signal components of other stations that act as noise can be removed, noise resistance characteristics can be improved, and the number of simultaneous communication stations can be increased.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a first embodiment of a wireless terminal device including an interference canceller according to the present invention.
FIG. 2 is a configuration diagram of a second embodiment of a wireless terminal device including the interference canceller according to the present invention.
FIG. 3 is an explanatory diagram about simulation.
FIG. 4 is a configuration diagram of a conventional spread spectrum communication system.
[Explanation of symbols]
Antenna 1
Synchronous circuit 2
Multiplication circuit 3
Synchronous detection circuit 4 for each component
Correlation value calculation circuit 5
Tap coefficient control circuit 6
Interference generator 7
Subtraction circuit 8
Determination circuit 9
Tap coefficient control circuit 10
Limiter 11
Comparator 12

Claims (6)

A synchronization circuit for detecting a spread code of a desired signal and a carrier signal from each station based on the received spread spectrum signal;
A multiplication circuit that multiplies the received spread spectrum signal by the spreading code of the desired signal output by the synchronization circuit;
A synchronous detection circuit that multiplies the output from the multiplication circuit and the carrier signal from each station output from the synchronization circuit;
A correlation value calculation circuit for calculating an interference noise component of each undesired signal based on a correlation value between each multiplication result from the synchronous detection circuit and a spreading code of the desired signal;
A tap coefficient control circuit for obtaining a tap coefficient from phase information of a carrier wave signal from each station;
Based on the interference noise component obtained by the correlation value calculation circuit and the tap coefficient obtained by the tap coefficient control circuit, an interference generating unit for obtaining a combined component;
An interference removal apparatus comprising: a subtraction circuit that subtracts a composite component obtained by the interference generation unit from a correlation value for a desired signal obtained by the correlation value calculation circuit to obtain a desired reception signal. A limiter for limiting the received signal obtained by the subtracting circuit;
The interference removal apparatus according to claim 1, wherein the tap coefficient control circuit controls the tap coefficient based on an error signal between the input and output of the limiter. The correlation value calculation circuit calculates the correlation value obtained by integrating the product of the spread code of the received signal, the desired signal and each carrier signal over a predetermined bit time, and the phase difference between the desired signal and each undesired signal. The interference cancellation apparatus according to claim 1, wherein an interference noise component is obtained based on the interference noise component. An antenna for receiving a spread spectrum signal;
The interference cancellation apparatus according to any one of claims 1 to 3, wherein a signal received by the antenna is input;
A determination circuit for determining data from the output of the interference cancellation device;
A wireless terminal device. Multiplying the output obtained by multiplying the received spread spectrum signal by the spreading code of the desired signal and the carrier signal from each station,
Based on the correlation value between each multiplication result and the spreading code of the desired signal, the interference noise component of each undesired signal is calculated,
Based on the obtained interference noise component and the tap coefficient obtained from the phase information of the carrier wave signal from each station, a composite component is obtained,
An interference cancellation method in which a desired component is obtained by subtracting a synthesized component obtained from a correlation value for a desired signal. Obtain an error signal from the desired received signal
The interference cancellation method according to claim 5, wherein the tap coefficient is controlled so as to reduce the error signal.

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