1. A method for identifying a User Equipment(s) (UE(s)) interfering with a pico Base Station (BS) located within the coverage of a macro BS in a wireless communication system, the method comprising:
receiving, by the macro BS, an UpLink (UL) interference control request message from the pico BS and signaling a random access preamble for UL interference control to each of a plurality of candidate interfering UEs served by the macro BS; and
receiving from the pico BS information about received signal strength of the random access preambles transmitted by the plurality of candidate interfering UEs and determining a UE(s) causing UL interference to the pico BS based on the information about received signal strength,
wherein transmission power of each of the random access preambles is set specifically to the random access preamble.
2. The method according to claim 1, wherein a maximum transmission number for each of the random access preambles is set specifically to the random access preamble.
3. The method according to claim 1, wherein the transmission power of each of the random access preambles is fixed.
4. The method according to claim 1, wherein a power ramping step (powerRampingStep) for each of the random access preambles is set specifically to the random access preamble.
5. The method according to claim 1, wherein the random access preambles are shared between the macro BS and the pico BS in advance.
6. The method according to claim 1, further comprising, after transmitting random access responses in response to the random access preambles, receiving information about transmission power of a random access preamble used last by each of the plurality of candidate interfering UEs from the plurality of candidate interfering UEs.
7. The method according to claim 6, further comprising: transmitting the information about transmission power of the random access preamble used last by each of the plurality of the candidate interfering UEs to the pico BS.
8. The method according to claim 7, further comprising: receiving from the pico BS information about received signal strength of the random access preamble, which corresponds to the transmission power of the random access preamble used last by each of the plurality the candidate interfering UEs.
9. A method for identifying a User Equipment(s) (UE(s)) interfering with a pico Base Station (BS) located within the coverage of a macro BS in a wireless communication system, the method comprising:
transmitting, by the pico BS, an UpLink (UL) interference control request message to the macro BS, detecting random access preambles transmitted by a plurality of candidate interfering UEs according to a random access procedure for UL interference control triggered by the UL interference control request message and received signal strength of the random access preambles, and transmitting information about the detected received signal strength of the random access preambles to the macro BS,
wherein transmission power of each of the random access preambles is set specifically to the random access preamble.
10. The method according to claim 9, wherein a maximum transmission number of each of the random access preambles is set specifically to the random access preamble.
11. The method according to claim 9, wherein the transmission power of each of the random access preambles is fixed.
12. The method according to claim 9, wherein a power ramping step (powerRampingStep) for each of the random access preambles is set specifically to the random access preamble.
13. The method according to claim 9, wherein the random access preambles are shared between the macro BS and the pico BS in advance.
14. The method according to claim 9, further comprising receiving from the macro BS information about transmission power of a random access preamble used last by each of the plurality of candidate interfering UEs.
15. The method according to claim 14, further comprising transmitting to the macro BS information about received signal strength of the random access preamble, which corresponds to transmission power of the random access preamble used last by each of the plurality of candidate interfering UEs.
16. A macro Base Station (BS) for identifying a User Equipment(s) (UE(s)) interfering with a pico BS located within the coverage of the macro BS in a wireless communication system, the macro BS comprising:
a Radio Frequency (RF) unit; and
a processor configured to control the RF unit,
wherein the processor is configured to receive an UpLink (UL) interference control request message from the pico BS and signaling a random access preamble for UL interference control to each of a plurality of candidate interfering UEs served by the macro BS, to receive from the pico BS information about received signal strengths of the random access preambles transmitted by the plurality of candidate interfering UEs, and to determine a UE(s) causing UL interference to the pico BS based on the information about received signal strength, and
wherein transmission power of each of the random access preambles is set specifically to the random access preamble.
17. A pico Base Station (BS) located within the coverage of a macro BS, for identifying a User Equipment(s) (UE(s)) interfering with the pico BS in a wireless communication system, the pico BS comprising:
a Radio Frequency (RF) unit; and
a processor configured to control the RF unit,
wherein the processor is configured to transmit an UpLink (UL) interference control request message to the macro BS, to detect random access preambles transmitted by a plurality of candidate interfering UEs according to a random access procedure for UL interference control triggered by the UL interference control request message and received signal strength of the random access preambles, and to transmit information about the detected received signal strength of the random access preambles to the macro BS, and
wherein transmission power of each of the random access preambles is set specifically to the random access preamble.
The claims below are in addition to those above.
All refrences to claims which appear below refer to the numbering after this setence.
1. A method for evaluating reliability of a semiconductor chip, comprising the steps of:
determining strain at a location in structure including determining strain at the bottom of a via in contact with a liner in the via;
evaluating failures in a plurality of the structures after stress cycling to determine a strain threshold with respect to a feature characteristic; and
evaluating structures on a chip based on the feature characteristic to predict reliability based on the strain threshold and the feature characteristic.
2. The method as recited in claim 1, wherein the feature characteristic includes a liner thickness formed in via holes and the step of evaluating structures on a chip based on the feature characteristic to predict reliability includes measuring a thickness of a liner to predict electrical failures.
3. The method as recited in claim 1, wherein the step of evaluating failures in a plurality of the structures includes the step of thermal cycling the plurality of structures.
4. The method as recited in claim 1, wherein the step of evaluating failures in a plurality of the structures includes the step of determining the strain threshold such that below the threshold no failures occur in the structures.
5. The method as recited in claim 1, wherein the strain is generated by thermal mismatch and the method further comprises the step of altering geometry of the feature characteristic to reduce strain.
6. The method as recited in claim 5, wherein the step of altering includes altering a thickness of a via liner.
7. The method as recited in claim 1, wherein the strain is generated by thermal mismatch and the method further comprises the step of altering material selection of the feature characteristic to reduce strain.
8. The method as recited in claim 7, wherein the thermal mismatch is greater than 30 ppm\xb0 C. between the feature characteristic and its surroundings.
9. A method for evaluating reliability of a semiconductor chip, comprising the steps of:
providing a semiconductor chip design having a metal structure therein, the metal structure being in contact with dielectric material;
determining strain at a location at or adjacent to the metal structure due to thermal stress;
evaluating failures in a plurality of the metal structures to determine a strain threshold for failures;
correlating the strain threshold to characteristics of the metal structure, wherein the characteristics of the metal structure include a liner thickness formed in via holes; and
predicting reliability of semiconductor chips based upon measured characteristics of the metal structure including measuring a thickness of a liner to predict electrical failures.
10. The method as recited in claim 9, wherein the step of evaluating failures includes the step of thermal cycling the plurality of metal structures.
11. The method as recited in claim 9, wherein the step of evaluating failures includes the step of determining the strain threshold such that below the threshold no failures occur in the structures.
12. The method as recited in claim 9, wherein the strain is generated by thermal mismatch and the method further comprises the step of altering geometry or material selection of the metal structures to reduce strain.
13. The method as recited in claim 12, wherein the mismatch between the metal structure and the dielectric is greater than 30 ppm\xb0 C.