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

• US 9,749,168 B2
• Filed: 06/22/2015
• Issued: 08/29/2017
• Est. Priority Date: 01/29/2004
• Status: Active Grant

• Current Assignee: Neo Wireless LLC (f/k/a CFIP NCF LLC) (FIG LLC (d/b/a Fortress Investment Group LLC))
• Original Assignee: Neocific Incorporated
• Inventors: Li, Xiaodong, Lo, Titus, Li, Kemin, Huang, Haiming
• Primary Examiner(s): Sarwar, Babar
• Application Number:
  US14/746,676
• Publication Number:
  US 20150312076A1
• Time in Patent Office: 799 Days
• Field of Search: 4554042, 4554121-4142, 455418-4221, 455 6711- 6713, 4551151, 455423, 455436-444, 455502, 4555521, 4555621, 455434, 455525, 370324, 370332, 370319, 370344, 370350, 370329, 370338, 370328, 370203, 370280, 370342, 370335
• 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 method for a mobile device served by a base station in a group of adjacent cells in a multi-cell, Orthogonal Frequency Division Multiple Access (OFDMA) wireless communication system, wherein base stations in the group of adjacent cells are synchronized in time and frequency to a common reference source, the method comprising:

receiving, by the mobile device, a plurality of signals in a time slot transmitted by the base stations in the group of adjacent cells using the same frequency subcarrier indices and the same time indices, the plurality of signals comprising a set of common pilot signals that has been randomized in the frequency-domain, wherein the frequency-domain signal randomization is specific to the group of adjacent cells and different from frequency-domain signal randomization applied on pilot signals outside of the group of adjacent cells; and

determining a composite channel coefficient for a composite channel based on the frequency-domain randomized set of common pilot signals, the composite channel corresponding to an aggregate of different channels from the base stations in the group of adjacent cells to the mobile device.

2. The method of claim 1, wherein the plurality of signals further comprise a set of common data signals that carry data information common to the group of adjacent cells.

3. The method of claim 2, further comprising applying the determined composite channel coefficient to the set of common data signals to recover data information.

4. The method of claim 1, further comprising performing frame synchronization, frequency offset estimation, or timing estimation based on the frequency-domain randomized set of common pilot signals.

5. The method of claim 4, wherein the frequency offset estimation is calculated in the time domain.

6. A mobile device served by a base station in a group of adjacent cells in a multi-cell, Orthogonal Frequency Division Multiple Access (OFDMA) wireless communication system, wherein base stations in the group of adjacent cells are synchronized in time and frequency to a common reference source, the mobile device comprising:

a receiver to receive a plurality of signals in a time slot transmitted by the base stations in the group of adjacent cells using the same frequency subcarrier indices and the same time indices, the plurality of signals comprising a set of common pilot signals that has been randomized in the frequency-domain, wherein the frequency-domain signal randomization is specific to the group of adjacent cells and different from frequency-domain signal randomization applied on pilot signals outside of the group of adjacent cells; and

a processor to determine a composite channel coefficient for a composite channel based on the frequency-domain randomized set of common pilot signals, the composite channel corresponding to an aggregate of different channels from the base stations in the group of adjacent cells to the mobile device.

7. The mobile device of claim 6, wherein the plurality of signals further comprise a set of common data signals that carry data information common to the group of adjacent cells.

8. The mobile device of claim 7, wherein the processor further applies the determined composite channel coefficients to the set of common data signals to recover data information.

9. The mobile device of claim 6, wherein the processor further performs frame synchronization, frequency offset estimation, or timing estimation based on the set of common pilot signals.

10. The mobile device of claim 6, wherein the frequency offset estimation is calculated in the time domain.