Method of scaling soft symbols of an uplink enhanced dedicated transport channel (E-DCH) and method for enabling use of a log-map turbo decoding algorithm for processing the E-DCH
View Patent ↗A method of scaling soft symbols of an uplink E-DCH is provided, where the E-DCH is received from a user in a network for processing in a base station receiver in the network employing a log-MAP turbo decoding algorithm to process the E-DCH. The E-DCH includes an E-DPDCH from which the soft symbols are generated at the base station receiver, and an E-DPCCH used to transmit control information associated with the E-DPDCH, which along with configuration information from a radio network controller (RNC) of the network enables the base station receiver to determine a reference amplitude ratio linked to the actual power offset of the E-DPDCH from the legacy DPCCH. In the method, an estimated E-DPDCH to DPCCH amplitude ratio that represents a scaling factor for the soft symbols is determined, and the soft symbols are scaled by the scaling factor to enable the soft symbols to be processed by the log-MAP turbo decoding algorithm in the base station receiver.
1. A method of scaling soft symbols of an uplink Enhanced Dedicated transport Channel (E-DCH) received from a user in a network for processing in a base station receiver in the network employing a log-MAP turbo decoding algorithm to process the E-DCH, the E-DCH having an Enhanced Dedicated Physical Data Channel (E-DPDCH) from which the soft symbols are generated at the base station receiver, and an Enhanced Dedicated Physical Control Channel (E-DPCCH) used to transmit control information associated with the E-DPDCH, which along with configuration information from a radio network controller (RNC) enables the base station receiver to determine a reference amplitude ratio linked to the actual power offset of the E-DPDCH from a legacy DPCCH, the method comprising:
determining an estimated E-DPDCH to DPCCH amplitude ratio that represents a scaling factor for the soft symbols, and
scaling the soft symbols by the scaling factor to enable the soft symbols to be processed by the log-MAP turbo decoding algorithm in the base station receiver.
2. The method of claim 1 , wherein determining the estimated amplitude ratio further includes
determining an initial estimated E-DPDCH to DPCCH amplitude ratio, and
evaluating the initial estimated E-DPDCH to DPCCH amplitude ratio against a reference E-DPDCH to DPCCH amplitude ratio to determine a final estimated E-DPDCH to DPCCH amplitude ratio to be used as the scaling factor for the soft symbols.
3. The method of claim 2 , wherein determining the initial estimated amplitude ratio further includes:
calculating a first energy value of the E-DPDCH,
calculating a second energy value of the DPCCH,
dividing the first energy value by the second energy value to obtain an amplitude ratio, and
determining the square root of the amplitude ratio for output as the initial estimated amplitude ratio.
4. The method of claim 2 , wherein
the initial and reference amplitude ratios are in dB, and
evaluating the initial estimated ratio against the reference amplitude ratio further includes
setting the final estimated amplitude ratio to be used as the scaling factor to the value of the reference amplitude ratio, if the initial estimated amplitude ratio is less than the reference amplitude ratio.
5. The method of claim 2 , wherein the initial and reference amplitude ratios are in dB, and
evaluating the initial estimated ratio against the reference amplitude ratio further includes
determining if the initial estimated amplitude ratio is greater than the reference amplitude ratio plus a specified maximum offset, and if so
setting the final estimated amplitude ratio to the value of the reference amplitude ratio plus the offset, else
setting the final estimated amplitude ratio to a value equal to a difference between the initial estimated and reference amplitude ratios, rounded up to the next highest integer value, plus the value of the reference amplitude ratio.
6. The method of claim 2 , wherein the reference E-DPDCH to DPCCH amplitude ratio is carried by the E-DPCCH.
7. A method for enabling use of a log-MAP turbo decoding algorithm in a base station receiver within a network for processing an Enhanced Dedicated transport Channel (E-DCH) received from a user in the network, the E-DCH having an Enhanced Dedicated Physical Data Channel (E-DPDCH) which carries the E-DCH and from which soft symbols are generated at the base station receiver, and having an Enhanced Dedicated Physical Control Channel (E-DPCCH) used to transmit control information associated with the E-DPDCH, which along with configuration information from a radio network controller (RNC) of the network enables the base station receiver to determine a reference amplitude ratio linked to the actual power offset of the E-DPDCH from a legacy DPCCH, the method comprising:
determining an estimated E-DPDCH to DPCCH amplitude ratio, and
multiplying the soft symbols by the estimated amplitude ratio,
to enable the soft symbols of the E-DPDCH to be processed by the log-MAP turbo decoding algorithm in the base station receiver.
8. The method of claim 7 , wherein determining the estimated amplitude ratio further includes
determining an initial estimated E-DPDCH to DPCCH amplitude ratio, and
evaluating the initial estimated E-DPDCH to DPCCH amplitude ratio against a reference E-DPDCH to DPCCH amplitude ratio to determine a final estimated E-DPDCH to DPCCH amplitude ratio to be used in said multiplying step.
9. The method of claim 8 , wherein determining the initial estimated amplitude ratio further includes:
calculating a first energy value of the E-DPDCH,
calculating a second energy value of the DPCCH,
dividing the first energy value by the second energy value to obtain an amplitude ratio, and
determining the square root of the amplitude ratio for output as the initial estimated amplitude ratio.
10. The method of claim 8 , wherein
the initial and reference amplitude ratios are in dB, and
evaluating the initial estimated ratio against the reference amplitude ratio further includes
setting the final estimated amplitude ratio to be used as the scaling factor to the value of the reference amplitude ratio, if the initial estimated amplitude ratio is less than the reference amplitude ratio.
11. The method of claim 8 , wherein the initial and reference amplitude ratios are in dB, and
evaluating the initial estimated ratio against the reference amplitude ratio further includes
determining if the initial estimated amplitude ratio is greater than the reference amplitude ratio plus a specified maximum offset, and if so
setting the final estimated amplitude ratio to the value of the reference amplitude ratio plus the offset, else
setting the final estimated amplitude ratio to a value equal to a difference between the initial estimated and reference amplitude ratios, rounded up to the next highest integer value, plus the value of the reference amplitude ratio.
12. The method of claim 8 , wherein the reference E-DPDCH to DPCCH amplitude ratio can be inferred by the base station receiver from the E-DPCCH along with configuration information from the RNC.