In this paper, a block-constrained trellis coded vector quantization (BC-TCVQ) algorithm is combined with an algebraic codebook to produce an algebraic trellis vector code (ATVC) to be used in ACELP coding. ATVC expands the set of allowed algebraic codebook pulse position, and the trellis branches are labeled with these subsets. The Viterbi algorithm is used to select the excitation codevector. A fast codebook search method using an efficient non-exhaustive search technique is also proposed to reduce the complexity of the ATVC search procedure while maintaining the quality of the reconstructed speech. The ATVC block code is used as the fixed codebook of AMR-NB (12.2 kbps), which reduces the computational complexity compared to the conventional algebraic codebook.

In this letter, we propose an efficient user selection algorithm aiming to select users with less spatially correlation and meet the user number limit of zero-forcing beamforming in downlink multiuser MIMO systems. This algorithm yields a considerable complexity reduction with only a small loss in performance and it only needs partial users' CSI feedback. Coupled with the algorithm, a null space updating method in O(K2) time and a modified proportional fair scheduling algorithm are also proposed.

In this work, a V-band low noise amplifier (LNA) is developed in a commercial 0.13 µm RFCMOS technology. Common-source (CS) topology, known to show a better noise performance than the cascode topology, was adopted and 4-stage was employed to achieve a sufficient gain at the target frequency near the cutoff frequency fT. The measured gain was 18.6 dB with VDD = 1.2 V and increased up to 20.2 dB with VDD = 1.8 V at 66 GHz. The measured NF showed a minimum value of 7.0 dB at 62 GHz. DC power consumption was 24 mW with VDD = 1.2 V. The size of the fabricated circuit is as compact as 0.45 mm 0.69 mm. This work was further extended to investigate the effect of dummy fills on LNA performance. An identical LNA, except for the dummy fills formed very close to (and under) the metal lines of spiral inductors and interconnects, was also fabricated and compared with the standard LNA. A peak gain degradation of 3.6 dB and average NF degradation of 1.3 dB were observed, which can be ascribed to the increased mismatch and line loss due to the dummy fills.