Special Subframe Allocation in Heterogeneous Network

• US 20130107705A1
• Filed: 10/28/2012
• Published: 05/02/2013
• Est. Priority Date: 10/29/2011
• Status: Active Grant

• Current Assignee: Comcast Cable Communications LLC (Comcast Corporation)
• Original Assignee: Ofinno Technologies, LLC
• Inventors: Dinan, Esmael Hejazi
• Granted Patent: US 8,929,215 B2
• Time in Patent Office: Days
• US Class Current: 370/230
• CPC Class Codes: H04H 20/33 by plural channels
• CPC Class Codes: H04W 16/06 Hybrid resource partitioning, e.g. channel borrowing
• CPC Class Codes: H04W 16/32 Hierarchical cell structures
• CPC Class Codes: H04W 52/60 using different transmission rates for TPC commands
• CPC Class Codes: H04W 56/001 Synchronization between nodes
• CPC Class Codes: H04W 72/0446 Resources in time domain, e.g. slots or frames
• CPC Class Codes: H04W 72/21 in the uplink direction of a wireless link, i.e. towards the network
• CPC Class Codes: H04W 72/23 in the downlink direction of a wireless link, i.e. towards a terminal
• CPC Class Codes: H04W 72/52 based on load
• CPC Class Codes: H04W 88/02 Terminal devices
• CPC Class Codes: H04W 88/08 Access point devices

Abstract

A first base station provides overlapping coverage area with second base stations and third base stations. Second base stations allow regular access to wireless devices and configure a second plurality of special subframes. Second base stations configure the same set of subframes as the second plurality of special subframes. Third base stations allow regular access to a restricted subset of wireless devices and configure a third plurality of special subframes. At least two base stations in the third base stations configure different set of subframes as the second plurality of special subframes.

Claims

1. A method comprising:

a) providing, by a first base station, an overlapping coverage area with each of a plurality of second base stations and each of a plurality of third base stations, said first base station having a different base station type than said plurality of second base stations and said plurality of third base stations;

b) transmitting, by said first base station, a first message to a first plurality of wireless devices in connected mode, said first message comprising a first subframe allocation bitmap indicating a first plurality of subframes, said first plurality of subframes comprising a first plurality of special subframes;

c) each of said plurality of second base stations;

i) allowing regular access to a plurality of wireless devices; and

ii) transmitting a second message to a second plurality of wireless devices in connected mode, said second message comprising a second subframe allocation bitmap indicating a second plurality of subframes, said second plurality of subframes comprising a second plurality of special subframes, all base stations in said plurality of second base stations identifying the same set of subframes as said second plurality of special subframes, said first plurality of special subframes and said second plurality of special subframes not having a substantial overlap in time; and

d) each of said plurality of third base stations;

i) allowing regular access only to a restricted subset of said plurality of wireless devices; and

ii) transmitting a third message to a third plurality of wireless devices in connected mode, said third message comprising a third subframe allocation bitmap indicating a third plurality of subframes, said third plurality of subframes comprising a third plurality of special subframes, wherein at least two base stations in said plurality of third base stations identify different sets of subframes as said second plurality of special subframes; and

 

wherein during a majority of symbols of a special subframe of said base station;

no signal is transmitted by said base station;

or signals are transmitted at a special subframe power level that is substantially lower than a transmit power during a non-special subframe.

2. The method of claim 1, wherein said first message further comprises said second special subframe allocation period and said second special subframe allocation offset.

3. The method of claim 1, further comprising, transmitting in said special subframe, a common reference signal only in a control region.

4. The method of claim 1, wherein said first message, said second message, and said third message are broadcast employing a physical downlink shared channel.

5. The method of claim 1, further comprising transmitting a plurality of unicast messages to a subset of said first plurality of wireless devices, said plurality of unicast messages configuring:

a) measurement subframes of a primary carrier for said subset of said first plurality of wireless devices; and

b) measurement subframes of a plurality of neighboring carriers for said subset of said first plurality of wireless devices.

6. The method of claim 1, wherein frame and subframe transmission of said first base station and each of said second plurality of base stations and each of said plurality of third base stations are substantially synchronized.

7. The method of claim 1, further comprising, each of said plurality of third base stations broadcasting a closed subscriber group indicator and a closed subscriber group identity.

8. The method of claim 1, wherein said at least two base stations in said third plurality of base stations provide an overlapping coverage area in at least a region in the service area of said network.

9. A method comprising:

a) providing, by a first base station, an overlapping coverage area with each of a plurality of second base stations and each of a plurality of third base stations, said first base station having a different base station type than said plurality of second base stations and said plurality of third base stations;

b) each of said plurality of second base stations;

i) allowing regular access to a plurality of wireless devices; and

ii) transmitting a second message to a second plurality of wireless devices in connected mode, said second message comprising a second subframe allocation bitmap indicating a second plurality of subframes, said second plurality of subframes comprising a second plurality of special subframes, base stations in said plurality of second base stations identifying the same set of subframes as said second plurality of special subframes; and

c) each of said plurality of third base stations;

i) allowing regular access only to a restricted subset of said plurality of wireless devices; and

ii) transmitting a third message to a third plurality of wireless devices in connected mode, said third message comprising a third subframe allocation bitmap indicating a third plurality of subframes, said third plurality of subframes comprising a third plurality of special subframes, at least two base stations in said plurality of third base stations identifying different sets of subframes as said second plurality of special subframes; and

wherein during a majority of symbols of a special subframe of said base station;

no signal is transmitted by said base station;

or signals are transmitted at a special subframe power level that is substantially lower than a transmit power during a non-special subframe.

10. The method of claim 9, wherein said first base station decreases the number of special subframes in said first plurality of special subframes in response to an increase in the traffic load of said first base station by an amount greater than a load value.

11. The method of claim 9, wherein said first base station increases the number of special subframes in said first plurality of special subframes in response to a decrease in the traffic load of said first base station by an amount greater than a load value.

12. The method of claim 9, further comprising said first base station transmitting a message to each of said at least one second base station, said message comprising a first pattern bitmap indicating said first special subframe allocation.

13. The method of claim 12, wherein said message further comprises a second pattern bitmap indicating a subset of said special subframes indicated by said first pattern bitmap used to configure measurement parameters for a subset of said second plurality of wireless devices.

14. A method comprising:

a) providing, by a first base station, an overlapping coverage area with each of a plurality of second base stations and each of a plurality of third base stations, said first base station having a different base station type than said plurality of second base stations and said plurality of third base stations;

b) each of said plurality of second base stations;

i) allowing regular access to a plurality of wireless devices; and

ii) configuring a second plurality of special subframes, base stations in said plurality of second base stations configuring the same set of subframes as said second plurality of special subframes; and

c) each of said plurality of third base stations;

i) allowing regular access only to a restricted subset of said plurality of wireless devices; and

ii) configuring a third plurality of special subframes, at least two base stations in said plurality of third base stations not configuring the same set of subframes as said second plurality of special subframes; and

 

wherein during a majority of symbols of a special subframe of said base station;

no signal is transmitted by said base station;

or signals are transmitted at a special subframe power level that is substantially lower than a transmit power during a non-special subframe.

15. The method of claim 14, further comprising broadcasting, by each base station in said first plurality of base stations and said second plurality of base stations:

a) the n most significant bits of said system frame number employing a plurality of subcarriers in the in the middle of the frequency band of a carrier, said system frame number being represented by m bits, m>

n; and

b) the (m-n) least significant bits of said system frame number by encoding control blocks in said physical broadcast channel over 2^(m-n) frames, sequential position of said encoded control blocks determining the (m-n) least significant bits.

16. The method of claim 14, wherein each base station in said plurality of base stations broadcasts the same system frame number if said frames are transmitted substantially at the same time.

17. The method of claim 14, wherein each of said third plurality of wireless devices is configured with a closed subscriber group white-list including the closed subscriber group identity of a base station in said plurality of third base stations.

18. The method of claim 14, wherein said at least two base stations in said third plurality of base stations broadcast different closed subscriber group identities.

19. The method of claim 14, further comprising, transmitting in said special subframe, a common reference signal only in a control region.

20. The method of claim 14, further comprising, each of said plurality of third base stations broadcasting a closed subscriber group indicator and a closed subscriber group identity.