Method and arrangement for signaling of parameters in a wireless network

1. A method in a user equipment, the method comprising:

configuring the user equipment to receive transmissions over a second cell configured on a carrier frequency based on a physical layer characteristic for the second cell, wherein the physical layer characteristic is derived from one or more parameters received over a first cell configured on a carrier frequency;

receiving the transmissions over the second cell;

receiving, over the first cell, an indication that no cell-specific reference signals are detectable in the second cell; and

in response to the indication that no cell-specific reference signals are detectable, the user equipment does not attempt to perform any measurement on cell-specific reference signals in the second cell.

2. The method of claim 1 wherein the one or more parameters comprise information indicating a cell identity of the second cell, and a number of transmit antenna ports at the second cell.

3. The method of claim 1 further comprising receiving, over the first cell, an indication that the user equipment should use the one or more parameters received over a first cell to derive the at least one physical layer characteristic for the second cell.

4. The method of claim 1 wherein the at least one physical layer characteristic comprises one or more of: a scrambling code, a reference signal configuration, a control signaling configuration.

5. The method of claim 4 wherein the at least one physical layer characteristic comprises one or more of: a PUSCH scrambling code, a PDSCH scrambling code, a L1/L2 control signaling scrambling code.

6. The method of claim 4 wherein the at least one physical layer characteristic comprises one or more of: a cell-specific reference signal configuration, a sounding reference signal configuration, an MBSFN reference signal configuration, an uplink demodulation reference signal configuration, a reference signal hopping pattern, a PUSCH hopping pattern, a downlink control channel configuration, an uplink control channel configuration.

7. The method of claim 1 wherein the one or more parameters further comprise one or more of: the carrier frequency, a number of transmit antenna ports, a bandwidth, and a cyclic prefix length indication.

8. The method of claim 1 wherein the at least one physical layer characteristic comprises a reference signal configuration, the method further comprising:

performing a measurement of a signal received over the second cell based on the reference signal configuration; and

transmitting a measurement report.

9. The method of claim 2 wherein the cell identity is included in a request to add a secondary cell.

10. The method of claim 9 further comprising adding the second cell corresponding to the received cell identity.

11. The method of claim 1 wherein the first cell is configured on the same carrier frequency as the second cell.

12. The method of claim 1 wherein if the one or more parameters received at the user equipment does not include the carrier frequency, a number of transmit antenna ports, a bandwidth, or a cyclic prefix length indication, the user equipment assumes that the parameters not received have a same value in the second cell as in the first cell.

13. A method in a network node, the network node serving a first cell configured on a carrier frequency, the method comprising:

configuring user equipment to receive transmissions over a second cell configured on a carrier frequency, wherein configuring the user equipment comprises:

transmitting one or more parameters associated with the second cell to the user equipment over the first cell, wherein for each of the one or more parameters, the network node transmits the parameter only if the parameter has a different value in the second cell than in the first cell; and

indicating to the user equipment to derive at least one physical layer characteristic for the second cell based on the one or more parameters.

14. The method of claim 13 wherein the one or more parameters comprise a cell identity of the second cell and a number of transmit antenna ports.

15. The method of claim 13 wherein the network node serves the second cell, the method further comprising transmitting synchronization signals, reference signals or parts of system information over the second cell with reduced or zero power.

16. The method of claim 13 further comprising transmitting, over the first cell, an indication that no cell-specific reference signals are detectable in the second cell.

17. A mobile terminal comprising:

processing circuitry configured to:

configure the mobile terminal to receive transmissions over a second cell configured on a carrier frequency based on a physical layer characteristic for the second cell, wherein the physical layer characteristic is derived from one or more parameters received over a first cell configured on a carrier frequency;

receive, over the first cell, an indication that no cell-specific reference signals are detectable in the second cell; and

in response to the indication that no cell-specific reference signals are detectable, not attempt to perform any measurement on cell-specific reference signals in the second cell; and

a transceiver configured to receive the transmissions over the second cell.

18. A network node comprising:

processing circuitry operative to:

configure a mobile terminal to receive transmissions over a second cell configured on a carrier frequency based on a physical layer characteristic for the second cell, wherein the physical layer characteristic is derived from one or more parameters sent to the user equipment over a first cell configured on a carrier frequency; and

a transceiver configured to transmit:

the one or more parameters to mobile terminal over the first cell, wherein for each of the one or more parameters, the transceiver transmits the parameter only if the parameter has a different value in the second cell than in the first cell; and

an indication to the mobile terminal to derive the physical layer characteristic for the second cell based on the one or more parameters.