Automatic power control in a data transmission system

• US 6,724,829 B1
• Filed: 03/18/1999
• Issued: 04/20/2004
• Est. Priority Date: 03/18/1999
• Status: Expired due to Term

• Current Assignee: MaxLinear Communications, LLC (f/k/a Entropic Communications, LLC) (Maxlinear Incorporated)
• Original Assignee: Conexant Systems Incorporated (Synaptics Incorporated)
• Inventors: Kalit, Gadi, Tzukerman, Shimon, Wardani, Ladd S. El
• Primary Examiner(s): Fan, Chieh M.
• Application Number:
  US09/272,632
• Time in Patent Office: 1,860 Days
• Field of Search: 375/219, 375/222, 375/257, 375/295, 375/298, 375/308, 375/345, 375/279, 375/261, 485/23.1, 485/234.1, 330/51, 330/129, 330/254, 704/258, 102/512
• US Class Current: 375/295
• CPC Class Codes: H04L 25/03866 using scrambling
• CPC Class Codes: H04L 27/0008 arrangements for allowing a transmitter or receiver to use more than one type of modulation negotiating modulation type for two-way transmission paths H04L5/1453
• CPC Class Codes: H04L 27/36 Modulator circuits; Transmitter circuits
• CPC Class Codes: H04W 52/343 taking into account loading or congestion level
• CPC Class Codes: H04W 52/52 using AGC [Automatic Gain Control] circuits or amplifiers

Abstract

A system for use in transmitting digital data includes a modulation element that receives block of digital data and modulates each block using one of at least two modulation types, such as QPSK and k-QAM, where k is a power of 2. The system also includes an automatic power control element that applies a selected gain value to each of the blocks of data before transmission. The automatic power control element selects each of the gain values from a group of at least two predetermined gain values, each of which corresponds to one of the modulation types. In general, the modulation types have different associated average power levels, and the power control element selects the gain values to maintain substantially constant average transmission power level among all of the blocks of data.

Claims

1. A system for use in transmitting digital data, the system comprising:

(a) a modulation element configured to receive blocks of digital data and to modulate each block using one of at least two digital modulation types, each having different associated power levels;

(b) an automatic power control element configured to;

(1) apply a selected gain value to each of the blocks of modulated data before transmission;

(2) select the gain value to be applied to each of the blocks of modulated data from a group of at least two predetermined gain values, each corresponding to one of the modulation types, where the selected gain values maintain substantially constant average transmission power level among all of the blocks of modulated data; and

(c) a register in which the predetermined gain values are stored.

2. The system of claim 1, wherein the automatic power control element includes a gain element that applies the selected gain values to the blocks of modulated data and a control element that selects the gain values from the group of predetermined gain values.

3. The system of claim 2, wherein the control element includes a switch that selectively applies the gain to the gain element in response to a signal indicating the modulation type to be used in transmitting each of the blocks of modulated data.

4. The system of claim 1, further comprising a transmission element configured to transmit each block of modulated data over a transmission channel during a predetermined time slot assigned to the block of modulated data.

5. The system of claim 4, wherein the transmission channel comprises a cable TV network.

6. The system of claim 1, further comprising a data blocking element configured to receive a stream of digital data and to divide the stream into the blocks of digital data.

7. The system of claim 1 wherein the digital modulation types have different associated average power levels.

8. The system of claim 1, wherein the digital modulation types include QPSK and k-QAM, where k is a power of two.

9. A system for use in transmitting digital data, the system comprising:

(a) a modulation element configured to receive blocks of digital data and to modulate each block using one of at least two digital modulation types, each having different associated power levels;

(b) an automatic power control element configured to;

(1) apply a selected gain value to each of the blocks of modulated data before transmission;

(2) select the gain value to be applied to each of the blocks of modulated data from a group of at least two predetermined gain values, each corresponding to one of the digital modulation types, where the selected gain values maintain substantially constant average transmission power level among all of the blocks of modulated data; and

a modulation controller configured to provide a signal to the modulation element and to the automatic power control element indicating which of the digital modulation types is to be used in transmitting each block of modulated data.

10. A system for use in transmitting digital data, the system comprising:

(a) a modulation element configured to receive blocks of digital data and to modulate each block using one of at least two digital modulation types;

(b) an automatic power control element configured to;

(1) apply a selected gain value to each of the modulated blocks of data before transmission;

(2) select the gain value to be applied to each of the blocks of modulated data from a group of at least two predetermined gain values, each corresponding to one of the digital modulation types; and

wherein the digital modulation types have different associated average power levels, and the automatic power control element is configured to select the gain values to maintain substantially constant average transmission power level among all of the blocks of modulated data.

11. An automatic power control system for use in transmitting digital data, the system comprising:

(a) a gain element configured to;

(1) receive blocks of digital data, each of which is to be transmitted using one of at least two different digital modulation types, each having different associated power levels; and

(2) apply a selected gain value to each of the blocks of modulated data before transmission; and

(b) a control element configured to select the gain value to be applied to each of the blocks of modulated data from a group of at least two predetermined gain values, each corresponding to one of the digital modulation types, where the selected gain values maintain substantially constant average transmission power level among all of the blocks of modulated data; and

(c) at least one data storage device that stores each of the predetermined gain values in a dedicated storage location.

12. The system of claim 11, wherein the digital modulation types have different associated average power levels.

13. The system of claim 11, wherein the data storage device comprises a computer memory and each of the dedicated storage locations begins at an individually addressable location in the memory device.

14. The system of claim 11, wherein the data storage device includes multiple registers, each dedicated to storing one of the predetermined gain values.

15. The system of claim 11, wherein the control element includes a switch configured to selectively deliver the gain values from the dedicated storage locations to the gain element.

16. The system of claim 15, wherein the switch is configured to select the gain values in response to a signal indicating, for each of the blocks of modulated data, which of the digital modulation types is to be used in transmitting the block of modulated data.

17. The system of claim 11, wherein the digital modulation types include QPSK and k-QAM, where k is a power of two.

18. An automatic power control system for use in transmitting digital data, the system comprising:

(a) a gain element configured to;

(1) receive blocks of digital data, each of which is to be transmitted using one of at least two different digital modulation types; and

(2) apply a selected gain value to each of the blocks of modulated data before transmission; and

(b) a control element configured to select the gain value to be applied to each of the blocks of modulated data from a group of at least two predetermined gain values, each corresponding to one of the digital modulation types; and

wherein the digital modulation types have different associated average power levels, and the control element is configured to select the gain values to maintain substantially constant average transmission power level among all of the blocks of modulated data.

19. A method for use in transmitting digital data comprising:

storing a group of at least two predetermined gain values;

receiving blocks of digital data;

modulating each block using one of at least two digital modulation types;

selecting a gain value to be applied to each of the blocks of modulated data from the group of at least two predetermined gain values, each corresponding to one of the digital modulation types, each digital modulation type having a different associated power level; and

applying the selected gain value to each of the blocks of modulated data before transmission, where the selected gain values maintain substantially constant average transmission power level among all of the blocks of modulated data.

20. The method of claim 19, further comprising transmitting each block of modulated data over a transmission channel during a predetermined time slot assigned to the block of modulated data.

21. The method of claim 20, wherein the transmission channel comprises a cable TV network.

22. The method of claim 19, further comprising receiving a stream of digital data and deriving the blocks of digital data from the stream.

23. The method of claim 19, further comprising receiving a signal indicating which of the digital modulation types is to be used in transmitting each block of modulated data.

24. The method of claim 19, wherein the digital modulation types have different associated average power levels.

25. The method of claim 19, wherein the digital modulation types include QPSK and k-QAM, where k is a power of two.

26. A method for use in transmitting digital data comprising:

receiving blocks of digital data;

modulating each block using one of at least two digital modulation types;

selecting a gain value to be applied to each of the blocks of modulated data from a group of at least two predetermined gain values, each corresponding to one of the digital modulation types;

applying the selected gain value to each of the blocks of modulated data before transmission; and

wherein the digital modulation types have different associated average power levels and selecting a gain value includes selecting the values to maintain substantially constant average transmission power level among all of the blocks of modulated data.

27. A system for use in transmitting digital data, the system comprising:

a data blocking element configured to receive a stream of digital data and to divide the stream into blocks of digital data;

a modulation element configured to receive the blocks of digital data and to modulate each block using one of at least two digital modulation types, including QPSK and k-QAM, where k is a power of two, where the digital modulation types have different associated average power levels;

an automatic power control element including;

a gain element that applies a selected gain value to each of the blocks of modulated data before transmission; and

a control element that selects the gain value to be applied to each of the blocks of modulated data from a group of at least two predetermined gain values, each corresponding to one of the digital modulation types, the control element including a switch that selectively provides the gain values to the gain element in response to a signal indicating the digital modulation type to be used in transmitting each of the blocks of data, such that the selected gain values maintain substantially constant average transmission power level among all of the blocks of modulated data; and

a transmission element configured to transmit each block of modulated data over a cable TV network during a predetermined time slot assigned to the block of modulated data.