Wireless system with transmitter having multiple transmit antennas and combining open loop and closed loop transmit diversities

Abstract

A wireless communication system (40). The system comprises transmitter circuitry (42) comprising encoder circuitry (44) for receiving a plurality of symbols (S_i). The system further comprises a plurality of antennas (AT1-AT4) coupled to the transmitter circuitry and for transmitting signals from the transmitter circuitry to a receiver (UST), wherein the signals are responsive to the plurality of symbols. Further, the encoder circuitry is for applying open loop diversity and closed loop diversity to the plurality of symbols to form the signals.

Description

CROSS-REFERENCES TO RELATED APPLICATIONS

H₂=[h₂h₄]  Equation 3

For each of Equations 2 and 3, if there are a total of N resolvable multipaths from base station BST to user station UST, then h_i is further defined as a vector relating to each of those multipaths as shown in the following Equation 4:

$\begin{array}{cc}{h}_i=\left[\begin{array}{c}{\alpha }_i^1\\ {\alpha }_i^2\\ \\ {\alpha }_i^N\end{array}\right]& \mathrm{Equation}4\end{array}$

Next, a term r₁ is defined in Equation 5 and is the signal received by user station UST after despreading the signal transmitted over time [0, T) and taking into account a noisefactor, n₁:
r₁=h₁W₁S₁−h₂W₁S*₂+h₃W₂S₁−h₄W₂S*₂+n₁   Equation 5

Similarly, a term r₂ is defined in Equation 6 and is the signal received by user station UST after despreading the signal transmitted over time [T, 2T), and taking into account a noise factor, n₂:
r₂=h₁W₁S₂+h₂W₁S*₁+h₃W₂S₂+h₄W₂S*₁+n₂   Equation 6

Rearranging the preceding yields Equation 7 for the value r₁:
r₁=(h₁W₁+h₃W₂)S₁−(h₂W₁+h₄W₂)S*₂+n₁=H₁ WS₁−H₂WS₂+n₁   Equation 7

Rearranging the preceding yields Equation 8 for the value r₂:
r₂=(h₂W₁+h₄W₂)S*₁+(h₁W₁+h₃W₂)S₂+n₂=H₂ WS*₁+H₁WS*₂+n₂   Equation 8

When signals r₁ and r₂ reach decoder 52, they are decoded as known in the STFD art. This decoding therefore may be represented as in the following Equation 9, and using the conventions that the symbol (.)^H denotes conjugate transpose of a vector, the symbol (.)^T denotes a transpose of a vector, and the symbol (.)* denotes its conjugate:

$\begin{array}{cc}{\stackrel{\_}{W}}^H{H}_1^H{r}_1+{\stackrel{\_}{W}}^T{H}_2^T{r}_2^{*}=\left({\stackrel{\_}{W}}^H{H}_1^H{H}_1\stackrel{\_}{W}\right)S_1+\left({\stackrel{\_}{W}}^T{H}_2^T{H}_2^{*}{\stackrel{\_}{W}}^{*}\right)S_1+W^H{H}_1^H{n}_1+{\stackrel{\_}{W}}^T{H}_2^T{n}_2^{*}& \mathrm{Equation}9\end{array}$

Since W^TH₂^TH*₂ W* is a real number, the the following Equation 10 properties hold:
W^TH₂^TH*₂ W*=( W^TH₂^TH*₂ W*)*= W^HH₂^HH₂ W  Equation 10

Equation 10 then implies the following Equation 11:
W^HH₁^Hr₁+^TH₂^Tr*₂=( W^H(H₁^HH₁+H₂^HH₂) W)S₁+^HH₁^Hn₁+^TH₂^Tn*₂   Equation 11

Similarly, therefore:
−^TH₂^Tr*₁+^HH₁^Hr₂=( W^H(H₁^HH₁+H₂^HH₂) W)S₂−^TH₂^Tn*₁+^HH₁^Hn_s   Equation 12

The signal to noise ratio for symbol S₁ is now given by Equation 13:

$\begin{array}{cc}\begin{array}{c}\mathrm{SNR}\left(S_1\right)=\frac{{\left({\stackrel{\_}{W}}^H\left(H_1^H{H}_1+H_2^H{H}_2\right)\stackrel{\_}{W}\right)}^2}{E\left[\left({\stackrel{\_}{W}}^H{H}_1^H{n}_1+{\stackrel{\_}{W}}^T{H}_2^T{n}_2^{*}\right){\left({\stackrel{\_}{W}}^H{H}_1^H{n}_1+{\stackrel{\_}{W}}^T{H}_2^T{n}_2^{*}\right)}^{*}\right]}\\ =\frac{\left({\stackrel{\_}{W}}^H\left(H_1^H{H}_1+H_2^H{H}_2\right)\stackrel{\_}{W}\right)}{{\sigma }^2}\end{array}& \mathrm{Equation}13\end{array}$
where σ²=E[n₁^Hn₁]=E[n₂^Hn₂] is the variance of the noise.

Similarly the SNR for symbol S₂ is given by Equation 14:

$\begin{array}{cc}\mathrm{SNR}\left(S_2\right)=\frac{\left({\stackrel{\_}{W}}^H\left(H_1^H{H}_1+H_2^H{H}_2\right)\stackrel{\_}{W}\right)}{{\sigma }^2}& \mathrm{Equation}14\end{array}$

Maximization of Equations 13 and 14 with respect to the weight vector implies the calculation of the eigen vectors for the matrix (H₁^HH₁+H₂^HH²). Let V₁, V₂ indicate the two eigen vectors and μ₁, μ₂ be the two corresponding eigen values. User station UST picks the eigen vector with the maximum eigen value implying that:
μ₁>μ₂=V₁
μ₂>μ₁=V₂   Equation 15

User station UST then sends back the weight values W₁ and W₂ back to base station BST. Normalizing the weight W₁=1, user station UST can optionally send back only the ratio (W₂/W₁) to base station BST and base station BST then sets the weights on the antennas accordingly.

To further illustrate Equations 1 through 15 for simplicity, assume that there is only one multipath from base station BST to user station UST implying that N=1. Given this assumption, then user station UST receives the following two symbols shown in Equations 16 and 17 after despreading:

$\begin{array}{cc}{r}^1=W_1\left({\alpha }_1^1{S}_1-{\alpha }_2^1{S}_2^{*}\right)+W_2\left({\alpha }_3^1{S}_1-{\alpha }_4^1{S}_2^{*}\right)+N_2& \mathrm{Equaion}16\end{array}$

$\begin{array}{cc}{r}^2=W_1\left({\alpha }_1^1{S}_2+{\alpha }_2^1{S}_1^{*}\right)+W_2\left({\alpha }_3^1{S}_2+{\alpha }_4^1{S}_1^{*}\right)+N_1& \mathrm{Equaion}17\end{array}$
where N₁ and N₂ are additive white Guassian noise.

Rearranging Equations 16 and 17 yields the following Equations 18 and 19, respectively:

$\begin{array}{cc}{r}^1=S_1\left(W_1{\alpha }_1^1+W_2{\alpha }_3^1\right)-S_2^{*}\left(W_1{\alpha }_2^1+W_2{\alpha }_4^1\right)+N_2& \mathrm{Equaion}18\\ r^2=S_2\left(W_1{\alpha }_1^1+W_2{\alpha }_3^1\right)+S_1^{*}\left(W_1{\alpha }_2^1+W_2{\alpha }_4^1\right)+N_1& \mathrm{Equaion}19\end{array}$

For subsituting into Equations 18 and 19, and letting

$\tilde{\alpha }=\left(W_1{\alpha }_1^1+W_2{\alpha }_3^1\right),\tilde{\beta }=\left(W_1{\alpha }_2^1+W_2{\alpha }_4^1\right),$
then one skilled in the art will appreciate that Equations 18 and 19 are in the form of standard STTD implying that the total SNR for each symbol S₁ and S₂ after STTD decoding will be as shown in the following Equation 20:

$\begin{array}{cc}\frac{{\left(W_1{\alpha }_1^1+W_2{\alpha }_3^1\right)}^2+{\left(W_1{\alpha }_2^1+W_2{\alpha }_4^1\right)}^2}{{\sigma }^2}& \mathrm{Equation}20\end{array}$

Having detailed system 40, various of its advantages now may be observed. For example, system 40 achieves a 2N path diversity where N is the number of paths from base station BST to user station UST. As another example, versus an open loop approach alone, there is an increase of a 3 dB gain in average SNR due to the use of closed loop transmit diversity across the two antenna groups (i.e., AT1 and AT2 versus AT3 and AT4). As still another example, the required reverse link bandwidth for providing the W₁ and W₂ feedback information is that corresponding to only two antennas while system 40 is supporting four transmit antennas. As a final example, the processing operations for receiving data by user station UST may be implemented using standard STTD decoding for each of the symbols S₁, S₂. From each of the preceding advantages, one skilled in the art should appreciate that the preferred embodiment achieves better performance with a lesser amount of complexity than is required in a prior art approach that increases the number of transmit antennas for a given (i.e., either closed or open) diversity scheme. As yet another advantage of the preferred embodiments, while such embodiments have been described in detail, various substitutions, modifications or alterations could be made to the descriptions set forth above without departing from the inventive scope. To further appreciate this inventive flexibility, various examples of additional changes contemplated within the preferred embodiments are explored below.

While the example of system 40 has demonstrated the use of four transmit antennas, the inventive implementation of system 40 also may be applied to wireless systems with other numbers of antennas, again using a combination of open loop transmit diversity and closed loop transmit diversity as between subsets of the entire number of transmit antennas. For example, one alternative embodiment contemplated includes six transmit antennas, which for the sake of discussion let such antennas be referred to as AT10 through AT15. With this system, open loop transmit diversity may applied to pairs of those antennas, as with a first antenna pair AT10 and AT11, a second antenna pair AT12 and AT13, and a third antenna pair AT14 and AT15. Further, closed loop transmit diversity may then be applied between each of those pairs of antennas, whereby a first weight is applied to signals transmitted by the first antenna pair, a second weight is applied to signals transmitted by the second antenna pair, and a third weight is applied to signals transmitted by the third antenna pair. As another example, a combination of open loop transmit diversity and closed loop transmit diversity may be applied to a transmitter with eight antennas. In this case, however, various additional alternatives exist. For example, the eight antennas may be split into four pairs of antennas, where open loop transmit diversity is applied within each pair of antennas, and closed loop transmit diversity is applied as between each antenna pair (i.e., four different weights, one for each antenna pair). Alternatively, the eight antennas may be split into two sets of four antennas each, where open loop transmit diversity is applied within each set of four antennas, and closed loop transmit diversity is applied as between the sets (i.e., two different weights, one for each set of four antennas).

Also while the previous examples have demonstrated more than two transmit antennas, it is recognized in connection with the present inventive aspects that a combination of open loop transmit diversity and closed loop transmit diversity may prove worthwhile for a transmitter with only two transmit antennas. Specifically, instances may arise where a transmitter in a closed loop diversity system receives feedback from a receiver to develop weights for future transmissions, but due to some factor (e.g., high Doppler) the transmitter is informed of some reduced amount of confidence in the weights; for such an application, therefore, an alternative of the preferred embodiment may be created by adding an open loop diversity technique to the closed-loop transmissions, thereby creating a combined diversity system. FIG. 5 illustrates an example of such an application, and is now explored in greater detail.

FIG. 5 illustrates an open and closed loop encoder 60, and which may be included within a transmitter such as transmitter 42 described above in connection with FIG. 4. Encoder 60 has an input 62, which by way of example is shown to receive a first symbol S₁ at a time T followed by a second symbol S₂ at a time 2T, and again assume by way of example that symbols S₁ and S₂ are QPSK symbols. STTD encoder 32 has two outputs 64₁ and 64₂, each connected to a respective antenna A60₁ and A60₂.

The operation of encoder 60 may be understood in view of the principles discussed above, and further in view of the signals shown as output to antennas A60₁ and A60₂. For example, at time T′, antenna A60₁ outputs a combined signal formed by two addends, W₃W₁S₁+W₄S₁, while at the same time T′ antenna A60₂ outputs a combined signal formed by two addends, W₃W₂S₁−W₄S₂*. The notion of combining an open and closed loop diversity may be appreciated from these combined signals by looking at the addends in each signal; specifically, as shown below, encoder 60 operates so that for each signal transmitted it includes two addends, where the second-listed addend has a closed loop diversity and the first-listed addend has an open loop diversity. Each of the diversity types is separately discussed below.

To appreciate the open loop addends communicated by encoder 60, assume that W₃=0 in which case the signals communicated by antennas A60₁ and A60₂ at time T′ reduce to the second-listed addends of the combined signals shown above. Specifically, for W₃=0, the signals output at time T′ by encoder 60 reduce to an output of W₄S₁ by antenna A60₁ and an output of −W₄S₂* by antenna A60₂. By removing the common factor of W₄ from these two addends, one skilled in the art will appreciate that the remaining factors (i.e., S₁ for antenna A60₁ and −S₂* for antenna A60₂) have an open loop diversity with respect to one another. This same observation with respect to open loop diversity may be found at time 2T′. Specifically, if W₃=0, then the signals output at time 2T′ by encoder 60 reduce to an output of W₄S₂ by antenna A60₁ and an output of W₄S₁* by antenna A60₂. By removing the common factor of W₄ from these two addends, one skilled in the art will appreciate that the remaining factors (i.e., S₂ for antenna A60₁ and S₁* for antenna A60₂) have an open loop diversity with respect to one another.

To appreciate the closed loop addends communicated by encoder 60, assume that W₄=0 in which case the signals communicated by antennas A60₁ and A60₂ at time T′ reduce to the first-listed addends of the combined signals shown above. Thus, for W₄=0, the signals output at time T′ by encoder 60 reduce to an output of W₃W₁S₁ by antenna A60₁ and an output of W₃W₂S₁ by antenna A60₂. By removing the common factor of W₃ from these two addends, one skilled in the art will appreciate that the remaining factors (i.e., W₁S₁ for antenna A60₁ and W₂S₁ for antenna A60₂) have a closed loop diversity with respect to one another inasmuch as they represent a product involving the same symbol but with a different weight multiplied times each symbol. This same observation with respect to closed loop diversity may be found at time 2T. Specifically, if W₄=0, then the signals output at time 2T′ by encoder 60 reduce to W₃W₁S₂ by antenna A60₁ and an output of W₃W₂S₂ by antenna A60₂. Once more, by removing the common factor of W₃ from these two addends, one skilled in the art will appreciate that the remaining factors (i.e., W₁S₂ for antenna A60₁ and W₂S₂ for antenna A60₂) have an open loop diversity with respect to one another.

Concluding the discussion of FIG. 5, it may be observed that encoder 60 again supports a transmitter with two sets of transmit antennas, where in this case each set consists of a single antenna rather than multiple antennas as in the previously-described embodiments. Nonetheless, the transmitter receives feedback from its receiver in order to implement closed loop diversity by applying different weights to some of the symbols to form signals for communication by the transmitter (via its encoder) while other of the signals communicated by the transmitter result from symbols selectively modified according to an open loop diversity technique.

As still another example of the present inventive scope, the types of open loop and closed loop transmit diversity also may be changed as applied to the preferred embodiments. Thus, while TxAA has been shown above as a closed loop technique, and STTD has been shown as an open loop technique, one or both of these may be replaced by corresponding alternative techniques and applied to a multiple transmit antenna system, thereby again providing a combined closed loop and open loop transmit antenna system. Indeed, recall above an example is set forth for an inventive system having eight antennas split into sets of four antennas, where open loop transit diversity is applied within each set of four antennas. In this case, the application of open loop transmit diversity as applied within a set of four antennas will require a type of open loop diversity other than solely the transmission of conjugates; in other words, a use only of conjugates provides two different signals, whereas for four different antennas a corresponding four different signals are required to achieved the open loop diversity. Accordingly, for this as well as other embodiments, a different open loop diversity approach may be implemented. For example, another open loop diversity technique that may be implemented according to the preferred embodiment includes orthogonal transmit diversity (“OTD”), and which is shown for a single OTD encoder 70 in FIG. 6 and for BPSK symbols. In FIG. 6, OTD encoder 70 is coupled to transmit symbols to four antennas A70₁ through A70₄. Further, in operation, OTD encoder 70 buffers a number of symbols equal to its number of antennas (i.e., four in the example of FIG. 6), and then each antenna transmits only one corresponding symbol and that is in a form that is orthogonal to all other symbols transmitted along the other antennas. These forms are shown by way of the output symbols in FIG. 6 along antas A70₁ through A70₄ from time T′ through time 4T. Further, for simplicity FIG. 6 only illustrates the OTD operation and, thus, does not further show the use of weighting to achieve the combined closed loop diversity. Nonetheless, the addition of a closed loop weighting operation should be readily implemented by one skilled in the art given the preceding teachings with respect to other embodiments. As another example of an alternative open loop diversity that may be used according to the preferred embodiments, FIG. 7 illustrates an STTD encoder 80 for four antennas A80₁ through A80₄. The conventions of FIG. 7 should be readily appreciated from the preceding examples, where the signals transmitted along antennas A80₁ through A80₄ therefore represent open loop diverse signals, and for the example where the symbols are BPSK symbols. Also as in the case of FIG. 6, for simplicity FIG. 7 only illustrates the open loop diversity operation (i.e., STTD) and, thus, FIG. 7 does not furhter show the use of weighting to achieve the combined closed loop diversity, where such additional weighting may be implemented by one skilled in the art according to the teachings of this document. As still another example of an alternative open loop diversity that may be used according to the preferred embodiments, FIG. 8 illustrates time switched time diversity (“TSTD”) for four antennas. Lastly, other closed loop diversity techniques that may be used to create still further alternative embodiments include switched diversity.

As still another example of the inventive scope, note that various of such teachings may be applied to other wireless systems. For example, the preceding may be applied to systems complying with the 3^rd Generation partnership Project (“3GPPP”) for wireless communications, and to 3GPPP 2 systems, as well as still other standardized or non-standardized systems. Further, while the preceding example has been shown in a CDMA system (or a WCDMA system), the preferred embodiment may be implemented by including transmitter antenna diversity combining both open loop and closed loop diversity in a time division multiple access (“TDMA”) system, which has a spreading gain of one.

As a final example of the inventive scope, while the preceding embodiments have been shown in connection with a receiver having only a single antenna, note that systems using multiple receive antennas also are contemplated. In other words, therefore, the preceding also may be combined with various techniques of receive antenna diversity.

From the preceding, one skilled in the art should appreciate various aspects of the inventive scope, as is defined by the following claims.

Claims

1. A wireless communication system, comprising:

transmitter circuitry comprising encoder circuitry for receiving a plurality of symbols;

a plurality of antennas coupled to the transmitter circuitry and for transmitting signals from the transmitter circuitry to a receiver, wherein the signals are responsive to the plurality of symbols; and

wherein the encoder circuitry is for applying space time block coded transmit antenna open loop diversity and closed loop diversity to the plurality of symbols to form the signals;

wherein the plurality of antennas comprises a pluraltty plurality of sets of antennas;

wherein for each of the sets of antennas the encoder circuitry is for applying space tile time block coded transmit antenna diversity to selected ones of the plurality of symbols such that signals transmitted by any one antenna in the set of antennas represent open loop diversity with respect to signals transmitted by any other antenna in the set of antennas; and

wherein for each of the sets of antennas the encoder circuitry is for applying a weight to the plurality of symbols such that signals fitted in response to the weight represent a closed loop diversity with respect to signals transmitted by any other antenna in any other of the sets of antennas.

2. The system of claim 1:

wherein the plurality of sets of antennas consists of two sets of antennas; and

wherein each of the sets of antennas consists of two antennas.

3. The system of claim 1:

wherein the plurality of sets of antennas consists of three sets of antennas; and

wherein each of the sets of antennas consists of two antennas.

4. The system of claim 1:

wherein the plurality of sets of antennas consists of two sets of antenas; and

wherein each of the sets of antennas consists of four antennas.

5. The system of claim 1:

wherein the plurality of sets of antennas consists of four sets of antennas; and

wherein each of the sets of antennas consists of two antennas.

6. The system of claim 1 wherein the closed loop diversity comprises transmit adaptive array diversity.

7. The system of claim 1 and further comprising the receiver.

8. The system of claim 7 wherein the receiver comprises one antenna for receiving the signals transmitted from the plurality of antennas.

9. The system of claim 7 wherein the receiver comprises a plurality of antennas, wherein each of the plurality of antennas is for receiving the signals transmitted from the plurality of antennas.

10. The system of claim 7 wherein the receiver comprises decoder circuitry for decoding open loop diversity and closed loop diversity with respect to the plurality of symbols.

11. The system of claim 10 wherein the receiver further comprises:

a despreader having an output and for producing a despread symbol stream at the output in response to the signals, wherein the output is coupled to the decoder circuitry;

a channel estimator coupled to the output of the despreader and for determining estimated channel impulse responses based on the despread symbol stream; and

wherein the decoder circuitry is for decoding open loop diversity and closed loop diversity with respect to the despread symbol stream and in response to the estimated channel impulse responses.

12. The system of claim 11 wherein the receiver further comprises a deinterleaver coupled to an output of the decoder circuitry and for providing an inverse interleaving function with respect to information received from the decoder circuitry.

13. The system of claim 12 wherein the receiver further comprises a channel decoder coupled to an output of the deinterleaver and for improving a data error rate of information received from the deinterleaver.

14. The system of claim 1 wherein the signals comprise CDMA communications.

15. The system of claim 1 wherein the signals comprise WCDMA communications.

16. The system of claim 1 wherein the signals comprise TDMA communications.

17. The system of claim 1:

wherein the transmitter circuitry is located in a base station; and

wherein the receiver comprises a mobile receiver.

18. The system of claim 1 wherein the plurality of symbols comprise quadrature phase shift keying symbols.

19. The system of claim 1 wherein the plurality of symbols comprise binary phase keying symbols.

20. The system of claim 1 wherein the plurality of symbols comprise quadrature amplitude modulation symbols.

21. The system of claim 1 wherein the transmitter circuitry further comprises:

a channel encoder for receiving a plurality of bits;

an interleaver coupled to an output of the channel encoder and for shuffling a block of encoded bits; and

a symbol mapper coupled to an output of the interleaver for converting shuffled bits into the plurity of symbols.

22. A wireless communication receiver for receiving signal from transmitter circuitry transmitting along a plurality of sets of transmit antennas, wherein the signals are formed by the transmitter circuitry by applying space time block coded transmit antenna diversity to selected ones of the plurality of symbols such that signals transmitted by any one antenna in the set of antenas represent space time block coded open loop diversity with respect to signals transmitted by any other antenna in the set of antennas and wherein for each of the sets of antennas the encoder circuitry is for applying a weight to the plurality of symbols such that signals transmitted in response to the weight represent a closed loop diversity with respect to signals transmitted by any other antenna in any other of the uses of antennas, the receiver comprising

a despreader having an output and for producing a despread symbol stream at the output in response to the signals; and

decoder circuitry coupled to the output of the despreader and for decoding space time block coded open loop diversity and closed loop diversity with respect to the despread symbol stream.

23. The receiver of claim 22 and further comprising one antenna for receiving the signals transmitted from the plurality of transmit antennas.

24. The receiver of claim 22 and further comprising a plurality of antennas for receiving the signals transmitted from the plurality of transmit antennas.

25. The receiver of claim 22 and further comprising:

a channel estimator coupled to the output of the despreader and for determining estimated channel impulse responses based on the despread symbol stream; and

wherein the decoder circuitry is for decoding space time block coded open loop diversity and closed loop diversity with respect to the despread symbol strum and in response to the estimated channel impulse responses.

26. The receiver of claim 25 and further comprising a deinterleaver coupled to an output of the decoder circuitry and for providing an inverse interleaving function with respect to information received from the decoder circuitry.

27. The system of claim 26 and further comprising a channel decoder coupled to an output of the deinterleaver and for improving a data error rate of information received from the deinterleaver.

28. A method of operating a wireless communication system, comprising the steps of

receiving a plurality of symbols into encoder circuitry;

applying space time block coded open loop diversity and closed loop diversity to the plurality of symbols to form a plurality of signals; and

transmitting the plurality of signals along a plurality of antenna to a receiver;

wherein the plurality of antennas comprises a plurality of sets of antennas; and

wherein the step of applying space time block coded open loop diversity and closed loop diversity applies space time block coded open loop diversity to selected ones of the plurality of symbols such that signals transmitted by any one antenna in the set of antennas represent open loop diversity with respect to signals transmitted by any other antenna in the set of antennas.

29. The method of claim 28 wherein for each of the sets of antennas the step of applying open loop diversity and closed loop diversity applies a weight to the plurality of symbols such that signals transmitted in response to the weight represent a closed loop diversity with respect to signals transmitted by any other antenna in any other of the sets of antennas.

30. A diversity encoder circuit for a wireless communication system, comprising:

an input terminal coupled to receive a first symbol and a second symbol, each symbol having plural data bits;

a first output terminal coupled to a first antenna and arranged to produce a product of a first scalar weight and one of the first symbol and a conjugate of the first symbol at a first time and a product of a second scalar weight and one of the second symbol and negative conjugate of the second symbol at a second time; and

a second output terminal coupled to a second antenna and arranged to produce a product of a third scalar weight and one of the second symbol and negative conjugate of the second symbol at the first time and a product of a fourth scalar weight and one of the first symbol and the conjugate of the first symbol at the second time.

31. A diversity encoder circuit as in claim 30, comprising:

a third output terminal coupled to a third antenna and arranged to produce a product of the third scalar weight and the first symbol at a first time and a product of the fourth scalar weight and the second symbol at a second time; and

a fourth output terminal coupled to a fourth antenna and arranged to produce a product of the first scalar weight and the negative conjugate of the second symbol at the first time and a product of the second scalar weight and the conjugate of the first symbol at the second time.

32. A diversity encoder circuit as in claim 31, wherein the first scalar weight is equal to the second scalar weight, and wherein the third scalar weight is equal to the fourth scalar weight.

33. A diversity encoder circuit as in claim 30, wherein the symbols comprise one of CDMA symbols, WCDMA symbols, and TDMA symbols.

34. A diversity encoder circuit as in claim 30, comprising a transmitter circuit located at a base station.

35. A diversity encoder circuit as in claim 30, wherein the first and second symbols comprise quadrature phase shift keying symbols.

36. A diversity encoder circuit as in claim 30, wherein the first and second symbols comprise quadrature amplitude modulation symbols.

37. A diversity encoder circuit as in claim 30, wherein the first and second symbols comprise binary phase shift keying symbols.

38. A diversity encoder circuit as in claim 30, wherein the first scalar weight is equal to the second scalar weight, and wherein the third scalar weight is equal to the fourth scalar weight.

39. A diversity decoder circuit for a wireless communication system, comprising:

an input terminal coupled to receive a product of a first scalar weight and one of a first symbol and a conjugate of the first symbol from a first antenna of a remote transmitter and a product of a third scalar weight and one of a second symbol and negative conjugate of the second symbol at a first time from a second antenna of the remote transmitter, wherein the input terminal is coupled to receive a product of a second scalar weight and one of the second symbol and negative conjugate of the second symbol and a product of a fourth scalar weight and one of the first symbol and the conjugate of the first symbol at a second time from the remote transmitter; and

a decoder coupled to the input terminal and producing the first symbol and the second symbol.

40. A diversity decoder circuit as in claim 39, wherein the first scalar weight is equal to the second scalar weight, and wherein the third scalar weight is equal to the fourth scalar weight.

41. A diversity decoder circuit as in claim 39, wherein the input terminal is coupled to receive the product of the first scalar weight and the first symbol and the product of the third scalar weight and the negative conjugate of the second symbol at the first time and the product of the second scalar weight and the second symbol and the product of the fourth scalar weight and the conjugate of the first symbol at the second time.

42. A diversity decoder circuit as in claim 41, wherein the input terminal is coupled to receive the product of the first scalar weight and the first symbol from the first antenna, the product of the third scalar weight and the negative conjugate of the second symbol from the second antenna, a product of the first scalar weight and the negative conjugate of the second symbol from a third antenna, and a product of the third scalar weight and the first symbol from a fourth antenna, and wherein the first, second, third, and fourth antennas are coupled to a remote transmitter.

43. A diversity decoder circuit as in claim 39, wherein the symbols comprise one of CDMA symbols, WCDMA symbols, and TDMA symbols.

44. A diversity decoder circuit as in claim 39, wherein the wireless communication system comprises a wireless user station.

45. A diversity decoder circuit as in claim 39, wherein the first and second symbols comprise quadrature phase shift keying symbols.

46. A diversity decoder circuit as in claim 39, wherein the first and second symbols comprise quadrature amplitude modulation symbols.

47. A diversity decoder circuit as in claim 39, wherein the first and second symbols comprise binary phase shift keying symbols.

48. A method of diversity encoding a signal for transmission to a remote wireless communication circuit, comprising the steps of:

producing a first product of a first weight and a first symbol at a first time;

producing a second product of a second weight and a second symbol at a second time;

producing a third product of a third weight and a negative conjugate of the second symbol at the first time;

producing a fourth product of a fourth weight and a conjugate of the first symbol at the second time;

applying the first and second products to a first antenna; and

applying the third and fourth products to a second antenna, wherein each of the first and second weights is determined in response to a channel effect between the first antenna and the remote wireless communication circuit, and wherein each of the third and fourth weights is determined in response to a channel effect between the second antenna and the remote wireless communication circuit.

49. A method as in claim 48, wherein the first weight is equal to the second weight, and wherein the third weight is equal to the fourth weight.

50. A method as in claim 48, comprising the steps of:

applying a product of the first weight and a negative conjugate of the second symbol to a third antenna at the first time;

applying a product of the second weight and the conjugate of the first symbol to the third antenna at the second time;

applying a product of the third weight and the first symbol to a fourth antenna at the first time; and

applying a product of the fourth weight and the second symbol to the fourth antenna at the second time.

51. A method as in claim 48, wherein the symbols comprise one of CDMA symbols, WCDMA symbols, and TDMA symbols.

52. A method as in claim 48, wherein the first and second symbols comprise quadrature phase shift keying symbols.

53. A method as in claim 48, wherein the first and second symbols comprise quadrature amplitude modulation symbols.

54. A method as in claim 48, wherein the first and second symbols comprise binary phase shift keying symbols.

55. A method as in claim 50, wherein the first weight is equal to the second weight, and wherein the third weight is equal to the fourth weight.

56. A method of diversity decoding a signal from a remote wireless communication circuit, comprising the steps of:

receiving a first product of a first weight and a first symbol at a first time from a first antenna of the wireless communication circuit;

receiving a third product of a third weight and a negative conjugate of a second symbol at the first time from a second antenna of the wireless communication circuit, wherein the first weight is determined in response to a channel effect from the first antenna of the remote wireless communication circuit, and wherein the third weight is determined in response to a channel effect from the second antenna of the remote wireless communication circuit;

decoding the first and third products; and

producing the first symbol and the second symbol.

57. A method as in claim 56, comprising the steps of:

receiving a second product of a second weight and the second symbol at a second time from the first antenna of the wireless communication circuit; and

receiving a fourth product of a fourth weight and a conjugate of the first symbol at the second time from the second antenna of the wireless communication circuit, wherein the second weight is determined in response to a channel effect from the first antenna of the remote wireless communication circuit, and wherein the fourth weight is determined in response to a channel effect from the second antenna of the remote wireless communication circuit.

58. A method as in claim 57, comprising the steps of:

receiving a product of the first weight and the negative conjugate of the second symbol from a third antenna at the first time;

receiving a product of the third weight and the first second symbol from a fourth antenna at the first time;

receiving a product of the second weight and the conjugate of the first symbol from the third antenna at the second time; and

receiving a product of the fourth weight and the second symbol from the fourth antenna at the second time.

59. A method as in claim 58, wherein the first weight is equal to the second weight, and wherein the third weight is equal to the fourth weight.

60. A method as in claim 56, comprising a wireless user station.

61. A method as in claim 56, wherein the first and second symbols comprise quadrature phase shift keying symbols.

62. A method as in claim 56, wherein the first and second symbols comprise quadrature amplitude modulation symbols.

63. A method as in claim 56, wherein the first and second symbols comprise binary phase shift keying symbols.

64. A method as in claim 57, wherein the first weight is equal to the second weight, and wherein the third weight is equal to the fourth weight.

65. A method of diversity encoding a signal for transmission to a remote wireless communication circuit, comprising the steps of:

receiving a plurality of data symbols including a first symbol and a second symbol, each symbol having plural data bits;

receiving a plurality of weights from the remote wireless communication circuit;

producing a first product of a first weight and the first symbol at a first time;

producing a second product of a second weight and a second symbol at a second time;

producing a third product of a third weight and a negative conjugate of the second symbol at the first time;

producing a fourth product of a fourth weight and a conjugate of the first symbol at the second time;

applying the first and second products to a first antenna; and

applying the third and fourth products to a second antenna.

66. A method as in claim 65, wherein the first and fourth weights are different.

67. A method as in claim 65, wherein the first weight is equal to the second weight, and wherein the third weight is equal to the fourth weight.

68. A method as in claim 65, wherein the first symbol comprises one of a CDMA symbol, a WCDMA symbol, and a TDMA symbol.

69. A method as in claim 65, wherein the first symbol comprises a quadrature phase shift keying symbol.

70. A method as in claim 65, wherein the first symbol comprises a quadrature amplitude modulation symbol.

71. A method as in claim 65, wherein the first symbol comprises a binary phase shift keying symbol.

72. A method of diversity decoding a signal from a remote wireless communication circuit, comprising the steps of:

receiving a first product of a first weight and a first symbol at a first time from a first antenna of the remote wireless communication circuit;

receiving a second product of a second weight and the second symbol at a second time from the first antenna of the remote wireless communication circuit;

receiving a third product of a third weight and a negative conjugate of a second symbol at the first time from the second antenna of the remote wireless communication circuit;

receiving a fourth product of a fourth weight and a conjugate of the first symbol at the second time from a second antenna of the remote wireless communication circuit; and

decoding the first and fourth products and producing the first symbol.

73. A method as in claim 72, wherein the first and fourth weights are different.

74. A method as in claim 72, wherein the first weight is equal to the second weight, and wherein the third weight is equal to the fourth weight.

75. A method as in claim 72, comprising receiving the first and fourth products at a wireless user station.

76. A method as in claim 72, wherein the first symbol comprises a quadrature phase shift keying symbol.

77. A method as in claim 72, wherein the first and second symbols comprise quadrature amplitude modulation symbols.

78. A method as in claim 72, wherein the first and second symbols comprise binary phase shift keying symbols.