This paper presents a hardware-efficient architecture of tree-depth scan (TDS) and multiple quantization (MQ) scheme for zerotree coding in MPEG-4 still texture coder. The proposed TDS architecture can achieve its maximal throughput to area ratio and minimize the external memory access with only one wavelet-tree size on-chip buffer. The MQ scheme adopts the power-of-two (POT) quantization to realize a cost-effective hardware implementation. The prototyping chip has been implemented in TSMC 0.35 µm CMOS 1P4M technology. This architecture can handle 30 4-CIF (704576) frames per second with five spatial scalability and five SNR scalability layers at 100 MHz working frequency.

The auto-correlation function (ACF) of Binary Offset Carrier (BOC) modulated signals has multiple peaks which raise the problem of ambiguity in acquisition and tracking. In this paper, the ACF is split into several sub-correlation functions (SCFs) through dividing the integration period of ACF into several partials. Then a pseudo correlation function (PCF) is constructed from the SCFs through a combination function to eliminate all side-peaks. The unambiguous tracking method based on the PCF achieves better code phase tracking accuracy than the conventional methods in AWGN environment. It only requires half computation cost of Bump-Jumping (BJ) and nearly quarter of Double-Estimator, although offers slightly less accurate tracking than BJ and Double-Estimator in multi-path environment. Moreover, this method suits all kinds of BOC signals without any auxiliary correlators.

In this letter, we consider an Orthogonal Frequency Division Multiplexing (OFDM) system without cyclic prefix (CP), i.e. with full spectral efficiency and present an optimum frequency-domain filtering scheme for mitigating inter-symbol interference (ISI) and inter-carrier interference (ICI). Simulation results show the signal to interference and noise ratio (SINR) improvement.

In OFDM systems, employing a cyclic prefix (CP) as the guard interval is a simple way to combat the inter-symbol interference (ISI) and the inter-carrier interference (ICI), however it reduces the transmission efficiency of the system, especially for some channels with a very long delay spread. In this paper, we consider the OFDM system with insufficient CP, much more efficient than conventional OFDM systems. First, we present the system mathematical model and give the ISI and ICI analysis. Then the signal-to-interference power ratio (SIR) performance is presented. To reduce the ISI and ICI due to the insufficient CP, we develop a minimum-mean-square-error decision feedback equalizer (MMSE_DFE). Based on the MMSE criterion, the optimum feedforward and feedback filter coefficients are derived. For time-varying channel, to avoid brute force matrix inversion in conventional schemes, we propose an adaptive LMS based solution to update the filtering coefficients by tracing the channel variation. Since the high complexity of MMSE_DFE, a reduced complexity scheme, ordered successive partial interference cancellation DFE (OSPIC_DFE), is developed. From the performance comparison between the MMSE_DFE and the OSPIC_DFE, we see that the latter is very near to the former. Finally the simulation shows these proposed methods are highly effective in combating ISI and ICI with low complexity.

In a typical OFDM system, a time domain equalizer (TEQ) can be used in order to reduce the channel length, allowing for shortening of the Cyclic Prefix (CP). In this paper, a novel TEQ method is proposed for OFDM systems, which can reduce implementation complexity without sacrificing performance. Furthermore, the length of the proposed TEQ may be arbitrary. For time-varying channels, an adaptive method is also developed to track the variation of the optimum TEQ coefficients rather than recomputing inversion of the channel matrix.