Apparatus and method for mode transition of a transmit diversity scheme in a mobile communication system for using transmit diversity

• US 20050084029A1
• Filed: 05/17/2004
• Published: 04/21/2005
• Est. Priority Date: 05/16/2003
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Lim, Young-Seok
• Granted Patent: US 7,391,831 B2
• Time in Patent Office: Days
• US Class Current: 375/267
• CPC Class Codes: H04B 7/0604 with predefined switching scheme
• CPC Class Codes: H04B 7/0634 Antenna weights or vector/matrix coefficients
• CPC Class Codes: H04B 7/0669 using different channel coding between antennas space-time coding H04L1/0618
• CPC Class Codes: H04B 7/0689 using different transmission schemes, at least one of them being a diversity transmission scheme

Abstract

An apparatus and method for Transmit Diversity mode transition in a mobile communication system for use with transmit diversity is disclosed. In a mobile communication system including a Node B comprising one or more antennas and a Mobile Station (MS) for transmitting Transmit Diversity information to the Node B to enable the plurality of antennas to implement the maximum Transmit Diversity. The apparatus and method for assigning weights to transmission data of the antennas to enable the Node B to implement the maximum Transmit Diversity when the mode transition occurs in the Transmit Diversity modes comprise determining whether the mode transition occurs using the Transmit Diversity information; and assigning a weight generated considering the relationship between a current weight and a previous weight used before the mode transition time to the data transmitted over the antennas if it is determined that the mode transition occurs.

Claims

1. A method for controlling a Node B to change a Transmit Diversity scheme to another scheme in a mobile communication system including the Node B for transmitting data using the Transmit Diversity scheme and a Mobile Station (ms) for transmitting weights of antennas to the Node B to provide the Node B with maximum Transmit Diversity performance, such that it can implement a maximum Transmit Diversity, the method comprising the steps of:

determining whether there is a mode transition in the Transmit Diversity scheme upon receiving Transmit Diversity information;

generating weights associated with individual antennas using a predetermined relationship between weights for use in different Transmit Diversity schemes if it is determined that the mode transition occurs in the Transmit Diversity scheme; and

transmitting data using the generated weights.

2. The method according to claim 1, further comprising the step of:

associating a weight of a Transmit Diversity scheme used before the mode transition with a weight of a Transmit Diversity scheme to be used after the mode transition, such that the weights are positioned in the same quadrant included in a constellation indicative of weight information.

3. The method according to claim 2, further comprising the step of:

generating weights using a predetermined relationship between the weights of the different Transmit Diversity schemes if an open loop transmit diversity scheme is changed to the closed loop transmit diversity scheme.

4. The method according to claim 3, wherein the step of generating the weights includes the step of:

updating either phase information or phase/magnitude information in the weights generated by the predetermined relationship according to the Transmit Diversity information, thereby generating weights for use in individual antennas each having a maximum Transmit Diversity.

5. The method according to claim 2, wherein the closed loop transmit diversity schemes each comprise a Mode1 scheme including only phase information, and a Mode2 scheme including phase and magnitude information.

6. The method according to claim 5, wherein the weights for use in individual antennas of the Mode1 scheme are denoted by the following equation:

$w_1=\frac{1}{\sqrt{2}},w_2=\left[\frac{1+j}{2},\frac{1-j}{2},\frac{-1+j}{2},\frac{-1-j}{2}\right]$

where w₁ is indicative of a weight for use in a reference antenna, and w₂ is indicative of weights for use in antennas other than the reference antenna.

7. The method according to claim 5, wherein the weights for use in individual antennas of the Mode2 scheme are denoted by the following equation:

$\begin{array}{c}{w}_1=<br><br>\left\{\sqrt{0.8},\sqrt{0.2}\right\},\\ w_2=<br><br>\left\{\begin{array}{c}\sqrt{0.2}<br><br>{\mathrm{e<br><br>}}^{\mathrm{j0\pi <br><br>}},\sqrt{0.2}<br><br>{\mathrm{e<br><br>}}^{j<br><br>\frac{\mathrm{\pi <br><br>}}{4}},\sqrt{0.2}<br><br>{\mathrm{e<br><br>}}^{j<br><br>\frac{\mathrm{\pi <br><br>}}{2}},\sqrt{0.2}<br><br>{\mathrm{e<br><br>}}^{j<br><br>\frac{3<br><br>\mathrm{\pi <br><br>}}{4}},\sqrt{0.2}<br><br>{\mathrm{e<br><br>}}^{\mathrm{j\pi <br><br>}},\sqrt{0.2}<br><br>{\mathrm{e<br><br>}}^{-j<br><br>\frac{\mathrm{\pi <br><br>}}{4},}<br><br>\sqrt{0.2}<br><br>{\mathrm{e<br><br>}}^{-j<br><br>\frac{\mathrm{\pi <br><br>}}{2}},\sqrt{0.2}<br><br>{\mathrm{e<br><br>}}^{-j<br><br>\frac{3<br><br>\mathrm{\pi <br><br>}}{4}},\\ \sqrt{0.8}<br><br>{\mathrm{e<br><br>}}^{\mathrm{j0\pi <br><br>}},\sqrt{0.8}<br><br>{\mathrm{e<br><br>}}^{j<br><br>\frac{\mathrm{\pi <br><br>}}{4}},\sqrt{0.8}<br><br>{\mathrm{e<br><br>}}^{j<br><br>\frac{\mathrm{\pi <br><br>}}{2}},\sqrt{0.8}<br><br>{\mathrm{e<br><br>}}^{j<br><br>\frac{3<br><br>\mathrm{\pi <br><br>}}{4}},\sqrt{0.8}<br><br>{\mathrm{e<br><br>}}^{\mathrm{j\pi <br><br>}},\sqrt{0.8}<br><br>{\mathrm{e<br><br>}}^{-j<br><br>\frac{\mathrm{\pi <br><br>}}{4}},\sqrt{0.8}<br><br>{\mathrm{e<br><br>}}^{-j<br><br>\frac{\mathrm{\pi <br><br>}}{2}},\sqrt{0.8}<br><br>{\mathrm{e<br><br>}}^{-j<br><br>\frac{3<br><br>\mathrm{\pi <br><br>}}{4}},\end{array}\right\}\end{array}$

where w₁ is indicative of a weight for use in the reference antenna, and w₂ is indicative of weights for use in antennas other than the reference antenna.

8. The method according to claim 5, wherein:

individual antennas of the changed mode use the same magnitude information if the Mode1 scheme is changed to Mode2 scheme.

9. A data transmission apparatus for implementing a maximum Transmit Diversity when changing a current Transmit Diversity scheme to another scheme in a mobile communication system including a Node B for transmitting data using a Transmit Diversity scheme and a Mobile Station (MS) for transmitting weights of a plurality of antennas to the Node B to provide the Node B with maximum Transmit Diversity performance, the apparatus comprising:

a mode transition determination unit for determining whether there is a mode transition in the Transmit Diversity scheme upon receiving Transmit Diversity information;

a weight generator for generating weights associated with individual antennas using a predetermined relationship between weights of different Transmit Diversity schemes according to the determination result of the mode transmission determination unit, and transmitting the generated weights to a signal processor; and

the signal processor for transmitting data using the generated weights.

10. The apparatus according to claim 9, wherein the weight generator determines whether the mode transition occurs in the Transmit Diversity scheme, selectively generates a weight in response to the mode transition from among a constellation including a weight of a Transmit Diversity scheme used before the mode transition and a weight of a Transmit Diversity scheme to be used after the mode transition in the same quadrant if it is determined that the mode transition occurs in the Transmit Diversity scheme, and generates a new weight using received weight information if it is determined that no mode transition occurs in the Transmit Diversity scheme.

11. The apparatus according to claim 10, wherein the weight generator selects weights from the constellation if an open loop transmit diversity scheme is changed to the closed loop transmit diversity scheme, and generates the selected weights.

12. The apparatus according to claim 10, wherein the weight generator does not generate weights in the constellation if the closed loop transmit diversity scheme is changed to the open loop transmit diversity scheme.

13. The apparatus according to claim 9, wherein the weight generator stores the closed loop transmit diversity modes each comprise a Mode1 scheme including only phase information and a Mode2 scheme including phase and magnitude information.

14. The apparatus according to claim 13, wherein the weights for use in individual antennas of the Mode1 scheme are denoted by the following equation:

$w_1=\frac{1}{\sqrt{2}},w_2=\left[\frac{1+j}{2},\frac{1-j}{2},\frac{-1+j}{2},\frac{-1-j}{2}\right]$

where w₁ is indicative of a weight for use in a reference antenna, and w₂ is indicative of weights for use in antennas other than the reference antenna.

15. The apparatus according to claim 13, wherein the weights for use in individual antennas of the Mode2 scheme are denoted by the following equation:

$\begin{array}{c}{w}_1=<br><br>\left\{\sqrt{0.8},\sqrt{0.2}\right\},\\ w_2=<br><br>\left\{\begin{array}{c}\sqrt{0.2}<br><br>{\mathrm{e<br><br>}}^{\mathrm{j0\pi <br><br>}},\sqrt{0.2}<br><br>{\mathrm{e<br><br>}}^{j<br><br>\frac{\mathrm{\pi <br><br>}}{4}},\sqrt{0.2}<br><br>{\mathrm{e<br><br>}}^{j<br><br>\frac{\mathrm{\pi <br><br>}}{2}},\sqrt{0.2}<br><br>{\mathrm{e<br><br>}}^{j<br><br>\frac{3<br><br>\mathrm{\pi <br><br>}}{4}},\sqrt{0.2}<br><br>{\mathrm{e<br><br>}}^{\mathrm{j\pi <br><br>}},\sqrt{0.2}<br><br>{\mathrm{e<br><br>}}^{-j<br><br>\frac{\mathrm{\pi <br><br>}}{4},}<br><br>\sqrt{0.2}<br><br>{\mathrm{e<br><br>}}^{-j<br><br>\frac{\mathrm{\pi <br><br>}}{2}},\sqrt{0.2}<br><br>{\mathrm{e<br><br>}}^{-j<br><br>\frac{3<br><br>\mathrm{\pi <br><br>}}{4}},\\ \sqrt{0.8}<br><br>{\mathrm{e<br><br>}}^{\mathrm{j0\pi <br><br>}},\sqrt{0.8}<br><br>{\mathrm{e<br><br>}}^{j<br><br>\frac{\mathrm{\pi <br><br>}}{4}},\sqrt{0.8}<br><br>{\mathrm{e<br><br>}}^{j<br><br>\frac{\mathrm{\pi <br><br>}}{2}},\sqrt{0.8}<br><br>{\mathrm{e<br><br>}}^{j<br><br>\frac{3<br><br>\mathrm{\pi <br><br>}}{4}},\sqrt{0.8}<br><br>{\mathrm{e<br><br>}}^{\mathrm{j\pi <br><br>}},\sqrt{0.8}<br><br>{\mathrm{e<br><br>}}^{-j<br><br>\frac{\mathrm{\pi <br><br>}}{4}},\sqrt{0.8}<br><br>{\mathrm{e<br><br>}}^{-j<br><br>\frac{\mathrm{\pi <br><br>}}{2}},\sqrt{0.8}<br><br>{\mathrm{e<br><br>}}^{-j<br><br>\frac{3<br><br>\mathrm{\pi <br><br>}}{4}},\end{array}\right\}\end{array}$

where w₁ is indicative of a weight for use in the reference antenna, and w₂ is indicative of weights for use in antennas other than the reference antenna.

16. The apparatus according to claim 13, wherein:

individual antennas of the changed mode use the same magnitude information if the Mode1 scheme is changed to Mode2 scheme.

17. A method for changing a Transmit Diversity scheme to another scheme in a mobile communication system including a Node B for transmitting data using the Transmit Diversity scheme and a Mobile Station (MS) for transmitting weights of a plurality of antennas to the Node B so as to provide the Node B with maximum Transmit Diversity performance, the method comprising the steps of:

receiving, by the MS, transmission signals from the plurality of antennas, and estimating channel state of the Node B;

determining weights of the antennas having the maximum Transmit Diversity using the estimated channel state, including the determined weights in Transmit Diversity information, and transmitting the Transmit Diversity information containing the determined result; and

determining, by the Node B, whether a mode transition occurs in the Transmit Diversity scheme on the basis of the Transmit Diversity information, and generating weights associated with individual antennas by considering a predetermined relationship between predetermined Transmit Diversity schemes if it is determined that the mode transition occurs in the Transmit Diversity scheme; and

transmitting data over the plurality of antennas using the generated weights.

18. The method according to claim 17, wherein the MS assigns the Transmit Diversity information to a Feedback information (FBI) field, such that the Transmit Diversity information is transmitted to the Node B over an uplink Dedicated Physical Control CHannel (DPCCH).

19. The method according to claim 17, wherein the relationship between predetermined Transmit Diversity schemes associates a weight of a Transmit Diversity scheme used before the mode transition with a weight of a Transmit Diversity scheme to be used after the mode transition, such that the weights are positioned in the same quadrant included in a constellation indicative of weight information.