This paper presents a 4 th order continuous-time bandpass delta-sigma modulator (CT-BPDSM) with a programmable center frequency ranging from 1.55 GHz to 2.45 GHz. The modulator is suited to be applied in multistandar...
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ISBN:
(纸本)9781424433773
This paper presents a 4 th order continuous-time bandpass delta-sigma modulator (CT-BPDSM) with a programmable center frequency ranging from 1.55 GHz to 2.45 GHz. The modulator is suited to be applied in multistandard class-S power amplifiers. The circuit features a multifeedback architecture with return-to-zero (RZ) and half-return-to-zero (HRZ) pulses. The loop filters consist of LC-resonators with emitter degenerated input transconductors and Q-enhancement circuits. A configuration register allows to program the resonator input transconductors, the Q-enhancement circuits and the resonator capacitances with 5 bit resolution. Fine tuning of the resonator center frequency is achieved with varactors. The circuit is implemented in a 200 GHz-f T SiGe-bipolar technology. The measured SNR at 2.2 GHz center frequency is 45.5 dB in a bandwidth of 20 MHz. At 1.55 GHz the SNR decreases to 40.7 dB. The measured uplink UMTS-FDD ACLR (adjacent channel leakage power ratio) of the modulator output is 48.4 dB in the first adjacent channel.
Bit-interleaved coded modulation (BICM) is a sub- optimal scheme from the average mutual information (AMI) point of view due to independent demapping. However, this AMI loss can be neglected for signal constellations ...
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Bit-interleaved coded modulation (BICM) is a sub- optimal scheme from the average mutual information (AMI) point of view due to independent demapping. However, this AMI loss can be neglected for signal constellations with Gray mapping at high coding rates. AMI of amplitude-phase shift keying (APSK) constrained additive white Gaussian noise (AWGN) channel is provided in this paper, which shows that the BICM scheme has considerable loss with APSK constellations since no Gray mapping exists. Bit-interleaved low-density parity-check (LDPC) coded modulation (BILCM) is an excellent scheme and has been employed in many broadcasting and communication systems, however, such scheme also suffers from the independent demapping loss. Therefore, BILCM with iterative demapping and decoding (BILCM-ID) is proposed in this paper to overcome such loss. Simulation results show that the BILCM-ID scheme outweighs BILCM scheme by about 0.5 and 0.3 dB over AWGN channel for 32-APSK constellation at coding rates 2/3 and 4/5, respectively.
Hybrid implementation of DACs using a combination of thermometer coded DACs together with binary weighted DACs to achieve high conversion performance have been reported. This work compares and analyzes between 12-bit ...
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ISBN:
(纸本)9781424451869;9781424451876
Hybrid implementation of DACs using a combination of thermometer coded DACs together with binary weighted DACs to achieve high conversion performance have been reported. This work compares and analyzes between 12-bit and 14-bit DACs. It is found that the speed depends on the segmentation configuration where simpler segmentation results in higher conversion speeds. The power dissipation is also dependent on the simplicity of segmentation where simpler segmentation also results in lower power consumption.
We propose a novel communication scheme that combines rateless transmission and multilevel coding (MLC). The scheme is able to attain a throughput that is equal to the constellation-constrained channel capacity. It is...
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We propose a novel communication scheme that combines rateless transmission and multilevel coding (MLC). The scheme is able to attain a throughput that is equal to the constellation-constrained channel capacity. It is particularly useful in cases where the celebrated bit-interleaved coded modulation (BICM) would leave significant gaps to the channel capacity and therefore, MLC is necessary for efficient transmission. We illustrate the application of this scheme to pulse-position modulation (PPM) in free-space optical and multiple-input multiple-output (MIMO) transmission in radio-frequency communication systems. Our numerical results show that, employing an off-the-shelf Raptor code, the proposed scheme achieves a throughput that exceeds the BICM capacity limit in a wide range of signal power.
Wireless mesh networks (WMNs) support a variety of modulation and coding schemes (MCSs) and hence enable adaptive modulation and coding. On the one hand, adaptive modulation and coding significantly increases the over...
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Wireless mesh networks (WMNs) support a variety of modulation and coding schemes (MCSs) and hence enable adaptive modulation and coding. On the one hand, adaptive modulation and coding significantly increases the overall system capacity, as it allows to maximize the throughput on each link in dependence of the channel conditions. On the other hand, there is a trade-off between link data rate and spatial reuse, as high data rate links are less robust against interference. For maximizing the wireless mesh network performance, an intelligent link rate assignment strategy is thus required. By evaluating the max-min fair WMN throughput under different link rate assignment strategies, we are able to show that using more robust MCSs improve the overall WMN throughput and point out directions towards an optimized MCS choice.
As shown in the literature, the performance of bit-interleaved coded modulation systems (BICM-ID) depends on the binary sequences mapping to constellation symbols. In this paper, we present a new multidimensional mapp...
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As shown in the literature, the performance of bit-interleaved coded modulation systems (BICM-ID) depends on the binary sequences mapping to constellation symbols. In this paper, we present a new multidimensional mapping for multi-input multi-output communication systems employing BICM-ID over fast fading channel. To introduce the optimized mapping, cost function is derived based on upper bound on the pairwise error probability over fast fading. Analytical and simulation results show that the optimized mapping outperforms the conventional mapping, and other proposed mappings.
In August 2006, the Chinese digital terrestrial television broadcasting (DTTB) standard named "Frame structure, channel coding and modulation for digital television terrestrial broadcasting system" (referred...
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In August 2006, the Chinese digital terrestrial television broadcasting (DTTB) standard named "Frame structure, channel coding and modulation for digital television terrestrial broadcasting system" (referred to as DTMB) was published. This work presents a design of modulator for DTMB standard. In this modulator, all patterns of the DTMB standard are implemented and the Single Frequency Network (SFN) can also be supported. The design of the modulator also meets the Chinese exciter standard and SFN standard. Through the laboratory test, it is shown that the modulator's signal output is in conformance with the DTMB standard and synchronization of multiple modulators is achieved in SFN working mode. The design of modulator bases on function blocks are made by existing mature chips and modules. So the feasibility is increased and meanwhile the costs are reduced. The structure of the modulator is scalable and can be developed into a variety of digital TV standards signal sources.
As the demand for high wireless data rates in indoor environments grows, we must find new ways to increase the performance of wireless links in multi-path fading. One common way to do this is to add diversity in the f...
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As the demand for high wireless data rates in indoor environments grows, we must find new ways to increase the performance of wireless links in multi-path fading. One common way to do this is to add diversity in the form of spatial or temporal diversity through the application of space-time block codes (STBCs). Recently, a method for combining STBCs with polarization diversity has been presented that allows for modeling the changes in polarization with quaternion numbers, introducing space-time-polarization block codes (STPBCs). This presentation shows some results from an initial investigation into the quality of cross polarized channels as compared to spatially separated channels to determine the feasibility of using STPBCs to enhance wireless data rates. It also presents a comparison of ergodic capacity of cross polarized channels and spatially separated transmits with polarized receive channels to compare the usefulness of hybrid spatial/polarization diversity schemes.
In this paper, a space-time trellis code (STTC) concatenated with space-time block code (STBC) for multi- carrier code-division multiple-access (MC-CDMA) system in the multi-path fading channel is considered, and the ...
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In this paper, a space-time trellis code (STTC) concatenated with space-time block code (STBC) for multi- carrier code-division multiple-access (MC-CDMA) system in the multi-path fading channel is considered, and the performance of the system is evaluated through simulations. The corresponding bit error rate (BER) of the concatenated STTC-STBC-MC-CDMA system is compared with STTC-MC-CDMA system. The results show that the improved performance can be achieved by concatenated STTC-STBC-MC-CDMA system having 16 states STTC.
In this paper, we consider frequency-selective adaptation from a link and a MAC layer perspective. In particular, we focus on the question of how to combine forward error correction with adaptive modulation and hybrid...
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In this paper, we consider frequency-selective adaptation from a link and a MAC layer perspective. In particular, we focus on the question of how to combine forward error correction with adaptive modulation and hybrid ARQ. The link adaptation scheme is then fitted into a packet-oriented multi-user OFDM system with a dynamic scheduler.
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