Alternative signal processing functions in a software modem
Systems are described that reduce or obviate the impact of limited processing resources and/or limit the power consumption in a receiver having signal processing functions at least partially implemented in software. A wireless receiver includes reception means for receiving a signal over a wireless channel in a wireless external environment. The receiver includes storage means, and a processor configured to perform a plurality of signal processing functions for extracting processed data from said signal, each of said signal processing functions having a plurality of alternative software implementations requiring different levels of usage of a processing resource. The processor estimates at least one parameter relating to the external environment and selects and executes one of the software alternatives for each of the respective signal processing functions to apply a set of implementations adapted to a required quality of said processed data. Related methods and computer program products are described.
1. A wireless receiver comprising:
reception means for receiving a signal over a channel in a wireless external environment;
a processor configured to perform a plurality of signal processing functions for extracting processed data from said signal, each of said signal processing functions having a plurality of alternative software implementations that are substitutable for performing said each of said signal processing functions and that require different levels of usage of a processing resource; and
a memory storing for each of the plurality of signal processing functions its plurality of alternative software implementations in the form of code portions, each alternative software implementation requiring different levels of usage of a processing resource for extracting said processed data from said signal when executed by the processor to implement the signal processing function;
wherein the processor is configured to estimate at least one parameter relating to the external environment and, in dependence on said at least one parameter and on an availability of said processing resource, to select and execute one of the software alternatives for each of the respective signal processing functions so as to apply a set of implementations adapted to a required quality of said processed data.
2. The receiver of claim 1 , wherein said processing resource comprises at least one of:
a number of processor cycles; and
an amount of memory, the memory comprising at least one of a RAM, a cache and a set of registers.
3. The receiver of claim 1 , comprising means for determining said availability based on one of: a maximum availability of said processing resource, and an upper limit target constrained by power consumption.
4. The receiver of claim 1 , wherein said required quality is based on at least one of: error rate performance in recovering the transmitted data from the received signal, signal-to-distortion ratio required to achieve a specified error rate performance; time delay required to achieve a specified error rate performance; a measurable distortion in the recovered data; and a likelihood of the receiver being dropped from a cell of a cellular network.
5. The receiver of claim 4 , wherein the error rate performance comprises at least one of bit error rate and block error rate.
6. The receiver of claim 1 , wherein one of said signal processing functions comprises a signal detection function.
7. The receiver of claim 6 , wherein the signal detection function comprises a receive diversity function, alternative implementations of which correspond to processing of different numbers of signals received on separate transmission propagation channels.
8. The receiver of claim 6 , wherein the alternative implementations of the signal detection function comprise a rake receiver and an equaliser.
9. The receiver of claim 6 , wherein the alternative implementations of the signal detection function comprise a plurality of different equaliser algorithms.
10. The receiver of any of claims 6 to 9 , wherein the alternative implementations of the signal detection function comprise a plurality of different equaliser parameters.
11. The receiver of claim 1 , comprising a selection criterion table accessible by said at least one parameter and said availability of processing resource.
12. The receiver of claim 1 , wherein the at least one parameter is indicative of channel conditions, network operating conditions or system conditions.
13. A method of processing a wireless signal in a wireless external environment;
estimating at least one parameter relating to the external environment;
determining an availability of at least one processing resource; and
in dependence on said at least one parameter and on an availability of said processing resource, selecting and executing on a processor one of a plurality of software alternatives for each of a plurality of signal processing functions for extracting processed data from said signal, each of said signal processing functions having a plurality of alternative and substitutable software implementations in the form of code portions, each alternative and substitutable software implementation requiring different levels of usage of a processing resource for extracting processed data from said signal when executed by the processor to implement the signal processing function so as to apply a set of implementations adapted to a required quality of said processed data.
14. The method of claim 13 , wherein said processing resource comprises at least one of:
a number of processor cycles; and
an amount of memory, the memory comprising at least one of a RAM, a cache and a set of registers.
15. The method of claim 13 , wherein said availability comprises determining based on one of: a maximum availability of said processing resource, and an upper limit target constrained by power consumption.
16. The method of claim 13 , wherein said required quality is based on at least one of: error rate performance in recovering the transmitted data from the received signal; signal-to-distortion ratio required to achieve a specified error rate performance; time delay required to achieve a specified error rate performance, which includes a number of transmission of the information data as specified by a retransmission scheme; a measurable distortion in the recovered data; and a likelihood of the receiver being dropped from a cell of a cellular network.
17. The method of claim 13 , wherein the error rate performance comprises at least one of bit error rate and block error rate.
18. The method of claim 13 , comprising supplying the at least one parameter and said availability to a selection criterion table thereby to select the software alternative.
19. The method of claim 13 , wherein the at least one parameter is indicative of channel conditions, network operating conditions or system conditions.
20. A computer program product comprising:
a plurality of code blocks, each code block comprising a substitutable software implementation of a signal processing function, each software implementation requiring different levels of usage of a processing resource for extracting processed data when executed by a processor to implement the signal processing function;
estimation code means configured to estimate at least one parameter relating to an external wireless environment; and
selection code means adapted to select, in dependence on said one or more parameters and on an availability of said processing resource, one of the substitutable software alternatives for each of a plurality of signal processing functions so as to apply a set of implementations adapted to a required quality of said processed data.