Method and apparatus using cell-specific and common pilot subcarriers in multi-carrier, multi-cell wireless communication networks

• US 8,934,473 B2
• Filed: 04/30/2013
• Issued: 01/13/2015
• Est. Priority Date: 01/29/2004
• Status: Active Grant

• Current Assignee: Neo Wireless LLC (f/k/a CFIP NCF LLC) (SoftBank Group Corp.)
• Original Assignee: Neocific Incorporated
• Inventors: Li, Xiaodong, Lo, Titus, Li, Kemin, Huang, Haiming
• Primary Examiner(s): Sarwar, Babar
• Application Number:
  US13/874,278
• Publication Number:
  US 20130242937A1
• Time in Patent Office: 623 Days
• Field of Search: 370/350, 370/324, 370331-332, 370/319, 370/344, 370/329, 370/338, 370/328, 370/203, 370/280, 370/342, 370/335, 455 6711- 6713, 455/423, 455/503, 455/115.1, 455436-444, 455/502, 455/552.1, 455/562.1, 455/422.1, 455/434, 455/525
• US Class Current: 370/350
• CPC Class Codes: H04B 1/707 using direct sequence modulation
• CPC Class Codes: H04B 7/0413 MIMO systems
• CPC Class Codes: H04J 11/005 of intercell interference
• CPC Class Codes: H04L 25/0228 with direct estimation from sounding signals
• CPC Class Codes: H04L 25/03834 using pulse shaping
• 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 27/0012 arrangements for identifying the type of modulation
• CPC Class Codes: H04L 27/2602 Signal structure
• CPC Class Codes: H04L 27/2607 Cyclic extensions
• CPC Class Codes: H04L 27/2613 Structure of the reference signals
• CPC Class Codes: H04L 27/26134 Pilot insertion in the transmitter chain, e.g. pilot overlapping with data, insertion in time or frequency domain
• CPC Class Codes: H04L 27/2637 with direct modulation of individual subcarriers
• CPC Class Codes: H04L 27/2646 using feedback from receiver for adjusting OFDM transmission parameters, e.g. transmission timing or guard interval length
• CPC Class Codes: H04L 27/2655 Synchronisation arrangements
• CPC Class Codes: H04L 27/2657 Carrier synchronisation
• CPC Class Codes: H04L 5/0007 the frequencies being orthogonal, e.g. OFDM(A), DMT
• CPC Class Codes: H04L 5/0016 Time-frequency-code
• CPC Class Codes: H04L 5/0028 Variable division signaling therefor H04L5/0092
• CPC Class Codes: H04L 5/0048 Allocation of pilot signals, i.e. of signals known to the receiver
• CPC Class Codes: H04W 16/02 Resource partitioning among network components, e.g. reuse partitioning
• CPC Class Codes: H04W 72/044 : based on the type of the allocated resource
• CPC Class Codes: H04W 72/0446 : Resources in time domain, e.g. slots or frames

Abstract

A multi-carrier cellular wireless network (400) employs base stations (404) that transmit two different groups of pilot subcarriers: (1) cell-specific pilot subcarriers, which are used by a receiver to extract information unique to each individual cell (402), and (2) common pilots subcarriers, which are designed to possess a set of characteristics common to all the base stations (404) of the system. The design criteria and transmission formats of the cell-specific and common pilot subcarriers are specified to enable a receiver to perform different system functions. The methods and processes can be extended to other systems, such as those with multiple antennas in an individual sector and those where some subcarriers bear common network/system information.

Claims

1. A transmitting method for a base station in a cell within a group of cells in an orthogonal frequency division multiplexing system, the base station having multiple transmission branches, the method comprising:

transmitting cell-specific pilot subcarriers, in accordance with a transmission diversity scheme or a multiple-input multiple-output scheme, wherein

the cell-specific pilot subcarriers possess amplitudes, phases, and frequency subcarrier indices specific to the cell; and

some of the cell-specific pilot subcarriers are not aligned in frequency subcarrier index with cell-specific pilot subcarriers transmitted by another base station in the group of cells;

transmitting common pilot subcarriers in accordance with a common pilot transmission scheme, wherein;

the common pilot subcarriers are aligned in frequency subcarrier index with common pilot subcarriers transmitted by other base stations in the group of cells;

a ratio of an amplitude (a_i,m and a_n,m) of two common pilot subcarriers having a same time index (t_k) that are transmitted via a common transmission branch is a constant for the group of cells; and

a difference of a phase (φ

_i,m and φ

_n,m) of two common pilot subcarriers having a same time index (t_k) that are transmitted via a common transmission branch is a constant for the group of cells; and

controlling independently a transmission power of the cell-specific pilot subcarriers and a transmission power of the common pilot subcarriers.

2. The method of claim 1, wherein the transmission power of the cell-specific pilot subcarriers is higher than the transmission power of the common pilot subcarriers.

3. The method of claim 1, wherein the transmission power of the cell-specific pilot subcarriers is lower than the transmission power of the common pilot subcarriers.

4. The method of claim 1, wherein the cell-specific pilot subcarriers enable a mobile station in the cell to determine channel coefficients for a channel from the base station to the mobile station.

5. The method of claim 1, wherein the specific amplitudes, phases, and frequency subcarrier indices of the cell-specific pilot subcarriers enable a mobile station in the cell to differentiate the cell-specific pilot subcarriers from pilot subcarriers transmitted by base stations in other cells.

6. The method of claim 1, wherein the common pilot subcarriers enable a mobile station in the cell to determine composite channel coefficients for a composite channel, the composite channel corresponding to an aggregate of different channels from base stations in the group of cells to the mobile station.

7. In a cell within a group of cells in an orthogonal frequency division multiplexing system, a base station having multiple transmission branches, the base station comprising:

a first transmitter component that is configured to transmit cell-specific pilot subcarriers, in accordance with a transmission diversity scheme or a multiple-input multiple-output scheme, wherein the cell-specific pilot subcarriers possess amplitudes, phases, and frequency subcarrier indices specific to the cell, and wherein some of the cell-specific pilot subcarriers are not aligned in frequency subcarrier index with cell-specific pilot subcarriers transmitted by another base station in the group of cells;

a second transmitter component that is configured to transmit common pilot subcarriers in accordance with a common pilot transmission scheme, wherein;

the common pilot subcarriers are aligned in frequency subcarrier index with common pilot subcarriers transmitted by other base stations in the group of cells; and

a ratio of an amplitude (a_i,m and a_n,m) of two common pilot subcarriers having a same time index (t_k) that are transmitted via a common transmission branch is a constant for the group of cells; and

a difference of a phase (φ

_i,m and φ

_n,m) of two common pilot subcarriers having a same time index (t_k) that are transmitted via a common transmission branch is a constant for the group of cells; and

a controller component that is configured to control independently a transmission power of the cell-specific pilot subcarriers and a transmission power of the common pilot subcarriers.

8. The base station of claim 7, wherein the transmission power of the cell-specific pilot subcarriers is higher than the transmission power of the common pilot subcarriers.

9. The base station of claim 7, wherein the transmission power of the cell-specific pilot subcarriers is lower than the transmission power of the common pilot subcarriers.

10. The base station of claim 7, wherein the cell-specific pilot subcarriers enable a mobile station in the cell to determine channel coefficients for a channel from the base station to the mobile station.

11. The base station of claim 7, wherein the specific amplitudes, phases, and frequency subcarrier indices of the cell-specific pilot subcarriers enable a mobile station in the cell to differentiate the cell-specific pilot subcarriers from pilot subcarriers transmitted by base stations in other cells.

12. The base station of claim 7, wherein the common pilot subcarriers enable a mobile station in the cell to determine composite channel coefficients for a composite channel, the composite channel corresponding to an aggregate of different channels from base stations in the group of cells to the mobile station.