Channel bandwidth

1. A communication device for communicating via a wireless network that is permitted to operate only in communication channels that are not designated for use by another network, the communication device being configured to:

determine that it is permitted to use a communication channel; and

use only a part of the bandwidth of that communication channel by adjusting a bandwidth And center frequency of a transmission based on an activity associated with a device operating outside of the wireless network, wherein the adjusted center frequency is different from a center frequency of the communication channel, wherein

the communication device is configured to select a spreading factor to use when communicating via the part of the bandwidth of the communication channel in dependence on the bandwidth of the communication channel, and

the communication device is configured to select the spreading factor that is, compared with a spreading factor the communication device is configured to use to transmit over the channel as a whole, reduced by a same divisor as the part of the bandwidth of the communication channel is reduced compared to the bandwidth of the channel as a whole.

2. A method for communicating via a wireless network that is permitted to operate only in communication channels that are not designated for use by another wireless network, the method comprising:

determining that a communication device is permitted to use a communication channel; and

the communication device using only a part of the bandwidth of the communication channel by adjusting a bandwidth and a center frequency of its transmission in dependence on an activity associated with another device, wherein the adjusted frequency is different from the center frequency of the communication channel;

the communication device selecting a spreading factor to use when communicating via the part of the bandwidth of the communication channel in dependence on bandwidth of the communication channel;

the communication device selecting a spreading factor that is, compared with the spreading factor a communication device is configured to use to transmit over the channel as a whole, reduced by a same divisor as the part of the bandwidth of the communication channel is reduced compared to the bandwidth of the channel as a whole.

3. A communication device for communicating via a wireless network that is permitted to operate only in communication channels that are not designated for use by another network, the communication device being configured to:

determine that it is permitted to use a communication channel; and

use only a part of the bandwidth of the communication channel by adapting a bandwidth and center frequency of a transmission based on an activity associated with a device operating outside of the wireless network, wherein

the communication device is configured to select a spreading factor to use when communicating via the part of the bandwidth of the communication channel in dependence on the bandwidth of the communication channel, and

the communication device is configured to select the spreading factor that is, compared with a spreading factor the communication device is configured to use to transmit over the channel as a whole, reduced by a same divisor as the part of the bandwidth of the communication channel is reduced compared to the bandwidth of the channel as a whole.

4. A communication device as claimed in claim 3 , wherein the communication device is configured to:

detect interference associated with the activity of the other device; and

select the part of the bandwidth in dependence on the detected interference.

5. The communication device as claimed in claim 3 , wherein the communication device is configured to:

predict an interference that will be associated with the activity of the other device; and

select the part of the bandwidth in dependence on the predicted interference.

6. The communication device as claimed in claim 3 , wherein the communication device is configured to select the part of the bandwidth in dependence on information received from another communication device.

7. A communication device as claimed in claim 3 , wherein the communication device is configured to select the part of the bandwidth in dependence on a part of the bandwidth of a channel over which it received a communication from another communication device.

8. The communication device as claimed claim 3 , wherein the communication device is configured to select the bandwidth of the communication channel to be a guard band associated with a television signal.

9. The communication device as claimed in claim 3 , wherein the communication device is configured to use a lager part of the bandwidth of the communication channel for a downlink communication than for an uplink communication.

10. The communication device as claimed in claim 3 , wherein the communication device is configured to communicate via a wireless network that operates in white space.

11. A communication device as claimed in claim 3 , wherein the communication device is configured to communicate via a wireless network that is configured for machine-to-machine communication.

12. The communication device as claimed in claim 3 , wherein the communication device is configured to use only part of the bandwidth of the communication channel by using less bandwidth than that which is available to it in accordance with a protocol governing use of that channel.

13. The communication device as claimed in claim 3 , wherein the communication device is configured to use only part of the bandwidth of the communication channel by using a part of the channel that is unavailable for conventional use in accordance with a protocol governing use of that channel.