The efficiency of ubiquitous SIMD (Single Instruction Multiple Data) media processors is seriously limited by the bottleneck effect of the scalar kernels in media applications. To solve this problem, a dual-core framework, composed of a micro control unit and an instruction buffer, is proposed. This framework can dynamically decouple the scalar and vector pipelines of the original single-core SIMD architecture into two free-running cores. Thus, the bottleneck effect can be eliminated by effectively exploiting the parallelism between scalar and vector kernels. The dual-core framework achieves the best attributes of both single-core and dual-core SIMD architectures. Experimental results exhibit an average performance improvement of 33%, at an area overhead of 4.26%. What's more, with the increase of the SIMD width, higher performance gain and lower cost can be expected.

Repetitive synchronization sequences in the time domain can be used to estimate Carrier Frequency Offset (CFO). The Un-Guarded Maximum Likelihood (UGML) estimator and Guarded ML (GML) estimator of CFO in the frequency selective channel are proposed in this paper. The results of theoretical analysis show that the UGML estimator is hard to implement if the channel response is not known while the GML estimator can be easily implemented due to inserted guard sequences. The guard sequences can be easily implemented as Cyclic Prefix (CP) in OFDM system. Therefore, the UGML estimator is only suitable for the systems where the channel response can be predetermined. This paper also gives a comparison with the existing CFO estimator. Theoretical and simulation results show that both the proposed estimators outperform the existing estimator.