Methods and apparatus for multi-carrier communications with variable channel bandwidth

• US 7,787,431 B2
• Filed: 04/29/2005
• Issued: 08/31/2010
• Est. Priority Date: 05/01/2004
• Status: Active Grant

• Current Assignee: Intellectual Ventures II LLC (Intellectual Ventures LLC)
• Original Assignee: Ditromossi Remote Bv, LLC (Intellectual Ventures LLC)
• Inventors: Lo, Titus, Huang, Haiming, Li, Xiaodong, Li, Kemin
• Primary Examiner(s): Vu; Huy D
• Assistant Examiner(s): SEKUL, MARIA LYNN
• Application Number:
  US10/583,534
• Publication Number:
  US 20070242600A1
• Time in Patent Office: 1,950 Days
• Field of Search: 370/343, 370/408, 370/485, 370/536
• US Class Current: 370/343
• CPC Class Codes: H04L 27/2613 Structure of the reference signals
• CPC Class Codes: H04L 5/0007 the frequencies being orthogonal, e.g. OFDM(A), DMT
• CPC Class Codes: H04L 5/0021 in which codes are applied as a frequency-domain sequences, e.g. MC-CDMA
• CPC Class Codes: H04L 5/0028 Variable division signaling therefor H04L5/0092
• CPC Class Codes: H04L 5/0041 Frequency-non-contiguous
• CPC Class Codes: H04L 5/0042 intra-user or intra-terminal allocation
• CPC Class Codes: H04L 5/0044 allocation of payload
• CPC Class Codes: H04L 5/0048 Allocation of pilot signals, i.e. of signals known to the receiver
• CPC Class Codes: H04L 5/0064 Rate requirement of the data, e.g. scalable bandwidth, data priority
• CPC Class Codes: H04L 5/0094 Indication of how sub-channels of the path are allocated
• CPC Class Codes: H04L 5/1469 using time-sharing
• CPC Class Codes: H04W 48/16 Discovering, processing access restriction or access information
• CPC Class Codes: H04W 72/00 Local resource management
• CPC Class Codes: H04W 72/23 in the downlink direction of a wireless link, i.e. towards a terminal
• CPC Class Codes: H04W 72/30 Resource management for broadcast services
• CPC Class Codes: H04W 76/10 Connection setup

Abstract

Methods and apparatus for multi-carrier communication with variable channel bandwidth are disclosed, where the time frame structure and the OFDM symbol structure are invariant and the frequency-domain signal structure is flexible. In one embodiment, a mobile station, upon entering a geographic area, uses a core-band to initiate communication and obtain essential information and subsequently switches to full operating bandwidth of the area for the remainder of the communication. If the mobile station operates in a wide range of bandwidths, the mobile station divides the full range into sub-ranges and adjusts its sampling frequency and its FFT size in each sub-range.

Claims

1. In a variable bandwidth wireless communication system communicating under multiple different communication schemes that each have a different bandwidth, a process performed by a base station of generating an information bearing signal for wireless transmission, the process comprising:

utilizing by the base station a number of subcarriers to construct a variable bandwidth wireless channel;

utilizing by the base station groups of subcarriers, wherein each group includes a plurality of subcarriers;

maintaining a fixed spacing between adjacent subcarriers;

adding or subtracting, by the base station, groups of subcarriers to scale the variable bandwidth wireless channel and achieve an operating channel bandwidth; and

wherein a core-band, including a plurality of subcarrier groups, substantially centered at an operating center frequency of the different communication schemes, is utilized by the base station as a broadcast channel carrying radio control and operation signalling, where the core-band is substantially not wider than a smallest possible operating channel bandwidth of the system; and

wherein the information bearing signal has a primary preamble sufficient for basic radio operation and wherein;

the primary preamble is a direct sequence in the time domain with a frequency content confined within the core-band, or is an orthogonal frequency-divisional multiplexing (OFDM) symbol corresponding to a particular frequency pattern within the core-band; and

wherein properties of the primary preamble comprise;

an autocorrelation having a large correlation peak with respect to sidelobes;

a cross-correlation with other primary preambles having a small cross-correlation coefficient with respect to power of other primary preambles; and

a small peak-to-average ratio; and

wherein a large number of primary preamble sequences exhibit the properties.

2. The process of claim 1, wherein the information bearing signal is:

an orthogonal frequency division multiple access (OFDMA) signal; and

is

utilized in a downlink with a duplexing technique that is either Time Division Duplexing (TDD) or Frequency Division Duplexing (FDD).

3. The process of claim 1, wherein an auxiliary preamble, occupying the side-band, is combined with the primary preamble to form a full-bandwidth preamble in either the time domain or the frequency domain, wherein the side-band is the difference between the core-band and an operating bandwidth, and wherein:

the auxiliary preamble is either a direct sequence in the time domain with a frequency response confined within the side-band, or is an OFDM symbol corresponding to a particular frequency pattern within the side-band;

the full-bandwidth preamble allows a base station to broadcast the full-bandwidth preamble and a mobile station to use the primary preamble of the full-bandwidth preamble to access the base station; and

properties of the full-bandwidth preamble sequence comprise;

a large correlation peak with respect to sidelobes, in case of an autocorrelation;

a large ratio between the correlation peak and sidelobes, in case of a correlation with the primary preamble of the full-bandwidth preamble;

a small cross-correlation coefficient with respect to power of other full-bandwidth preamble sequences, in case of cross-correlation with other full-bandwidth preambles

a small cross-correlation coefficient with respect to the power of the full-bandwidth preamble, in case of cross-correlation with a primary preamble different from the primary preamble of the full-bandwidth preamble;

a small peak-to-average ratio; and

wherein a large number of full-bandwidth preamble sequences exhibit such properties.

4. In a variable bandwidth communication network of base stations and mobile stations, wherein a signal comprises groups of subcarriers and each group includes a plurality of subcarriers, a method performed by a mobile station comprising:

maintaining a fixed spacing between adjacent subcarriers;

adjusting a number of groups of subcarriers to scale a channel and attain an operational bandwidth;

utilizing a core-band, substantially centered at an operating center frequency to carry synchronization information, wherein the core-band is narrower than or equal to a smallest possible operating channel bandwidth of the network and the signal includes a primary preamble sufficient to enable radio operations, the primary preamble including a direct sequence in the time domain with a frequency content confined within the core-band or including an OFDM symbol corresponding to a particular frequency pattern within the core-band;

wherein properties of the primary preamble comprise;

an autocorrelation having a large correlation peak with respect to sidelobes;

a cross-correlation with other primary preambles having a small cross-correlation coefficient with respect to power of other primary preambles; and

a small peak-to-average ratio; and

wherein a large number of primary preamble sequences exhibit the properties; and

scanning spectral bands of different center frequencies and detecting the synchronization information in the core-band of the operating center frequency and decoding a broadcast channel carrying radio control and operation signalling provided by a base station to the mobile station via the core-band.

5. The method of claim 4, wherein the signal is an orthogonal frequency division multiple access (OFDMA) signal, and the signal is utilized in a downlink with a duplexing technique that is either Time Division Duplexing (TDD) or Frequency Division Duplexing (FDD).

6. In a variable bandwidth communication network wherein a communication signal utilizes groups of subcarriers, wherein each group comprises a plurality of subcarriers, and a mobile station has an adaptable bandwidth, the mobile station comprising:

an analog-to-digital converter for signal sampling;

a Fast Fourier Transform and Inverse Fast Fourier Transform processor (FFT/IFFT), wherein a fixed spacing between adjacent subcarriers is maintained;

a scanner for scanning spectral bands of specified center frequencies;

a facility for decoding a broadcast channel including radio control and operation signalling associated with a core-band including a plurality of groups, wherein the core-band is not wider than a smallest possible operating channel bandwidth of the network; and

a facility for adding groups to widen the channel bandwidth for remainder of the communication, wherein the communication signal further utilizes the core-band for communicating a primary preamble sufficient to enable radio operations, the primary preamble being a direct sequence in the time domain with a frequency content confined within the core-band or being an OFDM symbol corresponding to a particular frequency pattern within the core-band,

wherein properties of the primary preamble comprise;

an autocorrelation haying a large correlation peak with respect to sidelobes;

a cross-correlation with other primary preambles having a small cross-correlation coefficient with respect to power of other primary preambles; and

a small peak-to-average ratio; and

wherein a large number of primary preamble sequences exhibit the properties.

7. The mobile station of claim 6, wherein the communication signal is an orthogonal frequency division multiple access (OFDMA) signal, and the communication signal is utilized in a downlink with a duplexing technique that is either Time Division Duplexing (TDD) or Frequency Division Duplexing (FDD).

8. A cellular base station comprising:

circuitry configured to transmit a broadcast channel in an orthogonal frequency division multiple access (OFDMA) core-band, wherein the core-band is substantially centered at an operating center frequency and the core-band includes a first plurality of subcarrier groups, wherein each subcarrier group includes a plurality of subcarriers, wherein the core-band is utilized to communicate a primary preamble sufficient to enable radio operations, the primary preamble being a direct sequence in the time domain with a frequency content confined within the core-band or being an OFDM symbol corresponding to a particular frequency pattern within the core-band,

wherein properties of the primary preamble comprise;

an autocorrelation having a large correlation creak with respect to sidelobes;

a cross-correlation with other primary preambles having a small cross-correlation coefficient with respect to power of other primary preambles; and

a small peak-to-average ratio; and

wherein a large number of primary preamble sequences exhibit the properties; and

circuitry configured to transmit control and data channels using a variable band including a second plurality of subcarrier groups, wherein the variable band includes at least the core-band.

9. The cellular base station of claim 8 wherein the circuitry configured to transmit the broadcast channel is further configured to transmit radio network information in the broadcast channel.

10. The cellular base station of claim 8 further comprising circuitry configured to transmit synchronization information in the core-band.

11. The cellular base station of claim 8 wherein the circuitry configured to transmit the broadcast channel is further configured to transmit in a time slot format.

12. The cellular base station of claim 8 wherein the base station operates in an OFDMA frequency division duplex (FDD) or time division duplex (TDD) mode.

13. A cellular mobile station comprising:

circuitry configured to receive synchronization information from a base station in an orthogonal frequency division multiple access (OFDMA) core-band, wherein the core-band is substantially centered at an operating center frequency and the core-band includes a first plurality of subcarrier groups where each subcarrier group includes a plurality of subcarriers, wherein the core-band is utilized to communicate a primary preamble sufficient to enable radio operations, the primary preamble being a direct sequence in the time domain with a frequency content confined within the core-band or being an OFDM symbol corresponding to a particular frequency pattern within the core-band,

wherein properties of the primary preamble comprise;

an autocorrelation having a large correlation peak with respect to sidelobes;

a cross-correlation with other primary preambles having a small cross-correlation coefficient with respect to power of other primary preambles; and

a small peak-to-average ratio; and

wherein a large number of primary preamble sequences exhibit the properties;

circuitry configured to synchronize with the base station using the received synchronization information; and

circuitry configured to receive control and data channels using a variable band including a second plurality of subcarrier groups, wherein the variable band includes at least the core-band.

14. The cellular mobile station of claim 13 wherein the circuitry configured to receive the synchronization information from the base station in the core-band is further configured to receive cell identification information from the base station in the core-band.

15. The cellular mobile station of claim 13 further comprising circuitry configured to receive a broadcast channel in the core-band.

16. The cellular mobile station of claim 15 wherein the broadcast channel carries radio network information.

17. The cellular mobile station of claim 13 further comprising circuitry configured to transmit a preamble after synchronizing with the base station.

18. A variable bandwidth communication method comprising:

transmitting a broadcast channel by a cellular base station in an orthogonal frequency division multiple access (OFDMA) core-band, wherein the core-band is substantially centered at an operating center frequency and the core-band includes a first plurality of subcarrier groups, wherein each subcarrier group includes a plurality of subcarriers, wherein the core-band is utilized to communicate a primary preamble sufficient to enable radio operations, the primary preamble being a direct sequence in the time domain with a frequency content confined within the core-band or being an OFDM symbol corresponding to a particular frequency pattern within the core-band

wherein properties of the primary preamble comprise;

an autocorrelation having a large correlation peak with respect to sidelobes;

a cross-correlation with other primary preambles having a small cross-correlation coefficient with respect to power of other primary preambles; and

a small peak-to-average ratio; and

wherein a large number of primary preamble sequences exhibit the properties; and

transmitting control and data channels by the cellular base station using a variable band including a second plurality of subcarrier groups, wherein the variable band includes at least the core-band.

19. The method of claim 18 wherein the broadcast channel carries radio network information.

20. The method of claim 18 further comprising transmitting by the base station synchronization information in the core-band.

21. The method of claim 18 wherein the transmissions are in a time slot format.

22. The method of claim 18 wherein the cellular base station operates in an OFDMA frequency division duplex (FDD) or time division duplex (TDD) mode.

23. A variable bandwidth communication method comprising:

receiving synchronization information by a cellular mobile station from a base station in an orthogonal frequency division multiple access (OFDMA) core-band, wherein the core-band is substantially centered at an operating center frequency and the core-band includes a first plurality of subcarrier groups where each subcarrier group includes a plurality of subcarriers, wherein the core-band is utilized to communicate a primary preamble sufficient to enable radio operations, the primary preamble being a direct sequence in the time domain with a frequency content confined within the core-band or being an OFDM symbol corresponding to a particular frequency pattern within the core-band

wherein properties of the primary preamble comprise;

an autocorrelation having a large correlation peak with respect to sidelobes;

a cross-correlation with other primary preambles having a small cross-correlation coefficient with respect to power of other primary preambles; and

a small peak-to-average ratio; and

wherein a large number of primary preamble sequences exhibit the properties;

synchronizing the cellular mobile station with the base station using the received synchronization information; and

receiving control and data channels by the cellular mobile station using a variable band including a second plurality of subcarrier groups, wherein the variable band includes at least the core-band.

24. The method of claim 23 wherein the receiving of the synchronization information by the cellular mobile station from the base station in the core-band includes receiving cell identification information from the base station in the core-band.

25. The method of claim 23 further comprising receiving by the cellular mobile station a broadcast channel in the core-band.

26. The method of claim 25 wherein the broadcast channel carries radio network information.

27. The method of claim 23 further comprising transmitting by the cellular mobile station a preamble after synchronizing with the base station.