Methods and apparatus for secondary bandwidth detection and allocation

1. A method, comprising

receiving a current bandwidth allocation of a primary device via receiving at least one broadcast message sent from an associated base station;

determining whether a secondary bandwidth is available by comparing a maximum bandwidth configuration with the received current bandwidth allocation of the primary device, wherein the secondary bandwidth is available if the received current bandwidth allocation is less than the maximum bandwidth configuration, and the secondary bandwidth corresponds to a portion of the maximum bandwidth configuration that is unused by the received current bandwidth allocation;

allocating the secondary bandwidth to a secondary application on a secondary device if the secondary bandwidth becomes available;

keeping track of changes in the bandwidth allocation of the primary device; and

returning the secondary bandwidth to the primary device when the changes in the bandwidth allocation of the primary device indicates a need for the secondary bandwidth by the primary device.

2. The method of claim 1 wherein receiving the at least one broadcast message comprises receiving at least one of a main information block (MIB) and a system information block (SIB) included in the broadcast message sent from an associated long-term evolution node B (eNB).

3. The method of claim 2 wherein determining whether the secondary bandwidth is available is based on an indicator in the received broadcast message.

4. The method of claim 3 wherein the indicator is included in the at least one of the SIB and the MIB and the indicator comprises a single bit to indicate whether a 20 megahertz bandwidth is available in a current cell.

5. The method of claim 4 wherein determining whether the secondary bandwidth is available comprises comparing an uplink bandwidth allocation with a downlink bandwidth allocation and determining that the secondary bandwidth is available if the uplink bandwidth allocation is sufficiently smaller than the downlink bandwidth allocation for the primary device.

6. The method of claim 1 wherein receiving the bandwidth allocation of the primary device comprises keeping track of a current cell identifier and a current bandwidth configuration combination and keeping a maximum bandwidth configuration per detected cell in a register.

7. The method of claim 6 wherein determining whether the secondary bandwidth is available comprises detecting that edges of the bandwidth allocation of the primary device are unused by the primary device upon detecting that the current bandwidth configuration is less than a previous bandwidth configuration stored in the register for a current cell.

8. The method of claim 1 wherein keeping track of the changes in bandwidth allocation of the primary device comprises receiving and decoding broadcast messages sent by the associated base station and detecting a bandwidth allocation change for the primary device.

9. The method of claim 8 wherein returning the secondary bandwidth to the primary device further comprises reallocating the secondary bandwidth to the primary device when an interference from use of the secondary bandwidth by the secondary device reaches such a level that use of the primary bandwidth by the primary device is affected.

10. An apparatus, comprising:

at least one processor; and

at least one memory including computer program code,

the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus to perform at least the following:

receiving a current bandwidth allocation of a primary device via receiving at least one broadcast message sent from an associated base station;

determining whether a secondary bandwidth is available by comparing a maximum bandwidth configuration with the received current bandwidth allocation of the primary device, wherein the secondary bandwidth is available if the received current bandwidth allocation is less than the maximum bandwidth configuration, and the secondary bandwidth corresponds to a portion of the maximum bandwidth configuration that is unused by the received current bandwidth allocation;

allocating the secondary bandwidth to a secondary application on a secondary device if the secondary bandwidth becomes available;

keeping track of changes in the bandwidth allocation of the primary device; and

returning the secondary bandwidth to the primary device when the changes in the bandwidth allocation of the primary device indicates a need for the secondary bandwidth by the primary device.

11. The apparatus of claim 10 wherein receiving the bandwidth allocation of the primary device further comprises receiving and decoding system information contained in the at least one broadcast message on a broadcast channel.

12. The apparatus of claim 11 wherein receiving the at least one broadcast message comprises receiving at least one of a system information block (SIB) and a main information block (MIB) included in the at least one broadcast message sent by a long-term evolution node B (eNB).

13. The apparatus of claim 10 wherein the secondary bandwidth is at edge of an uplink bandwidth allocated to the primary device and wherein the secondary application is one of a device-to-device application, a sensory network application, and an ad-hoc network application without a signaling message going to the associated base station.

14. The apparatus of claim 10 wherein the secondary bandwidth comprises at least one orthogonal frequency-division multiplexing (OFDM) subcarrier.

15. The apparatus of claim 10 wherein the apparatus is authenticated by an associated network and the apparatus is also the primary device.

16. The apparatus of claim 10 wherein the at least one memory and the computer program code is further configured to cause the apparatus to receive and decode broadcast messages from more than one cell.

17. An apparatus comprising:

a secondary bandwidth module configured to

determine whether a secondary bandwidth is available by comparing a maximum bandwidth configuration with a current bandwidth allocation to a primary device, wherein the secondary bandwidth is available if the current bandwidth allocation is less than the maximum bandwidth configuration, and the secondary bandwidth corresponds to a portion of the maximum bandwidth configuration that is unused by the current bandwidth allocation; and

construct a field in a broadcast message indicating whether the secondary bandwidth is available; and

an interface module configured to send the broadcast message including the indicator indicating whether the secondary bandwidth is available, wherein the broadcast message is sent from a base station.

18. The apparatus of claim 17 wherein the secondary bandwidth module is further configured to instruct the primary device to shrink an allocated bandwidth around a center frequency or shift the center frequency to save power.

19. The apparatus of claim 18 wherein the secondary bandwidth module is configured to determine whether the secondary bandwidth is available via at least one of:

comparing a downlink bandwidth allocation with an uplink allocation for the primary device; and

determining that the secondary bandwidth is available if the uplink allocation is sufficiently less than the downlink allocation.

20. The apparatus of claim 17 wherein

the secondary bandwidth module is further configured to

reallocate the secondary bandwidth to the primary device when the primary device increases its bandwidth allocation;

construct a field in a second broadcast message indicating that the secondary bandwidth is re-allocated to the primary device; and

the interface module is further configured to broadcast the second broadcast message.