This paper investigates the system-level performance of downlink non-orthogonal multiple access (NOMA) combined with single user MIMO (SU-MIMO) for future LTE (Long-Term Evolution) enhancements. The goal is to clarify...
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ISBN:
(纸本)9781479974702
This paper investigates the system-level performance of downlink non-orthogonal multiple access (NOMA) combined with single user MIMO (SU-MIMO) for future LTE (Long-Term Evolution) enhancements. The goal is to clarify the performance gains of NOMA combined with SU-MIMO transmission, taking into account the LTE radio interface such as frequency-domain scheduling, adaptive modulation and coding (AMC), and NOMA specific functionalities such as multi-user pairing/ordering and transmit power allocation. In particular, we propose practical schemes to efficiently combine NOMA with open-loop SU-MIMO (Transmission Mode 3: TM3) and closed-loop SU-MIMO (Transmission Mode 4: TM4) specified in LTE. Based on computer simulations, we compare NOMA performance gains for different granularities of scheduling and MCS (modulation and coding scheme) selection, for both genie-aided channel quality information (CQI) estimation and approximated CQI estimation, and using different number of power sets. Evaluation results show that NOMA can still provide a hefty portion of its expected gains even with approximated CQI estimation and limited number of power sets, and also when LTE compliant subband scheduling and wideband MCS are applied.
In recent years, it is required to realize higher speed and higher quality mobile communication due to the increase in Internet use. adaptive modulation and coding (AMC) scheme is now commonly implemented to maximize ...
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ISBN:
(纸本)9781538667705;9789532900873
In recent years, it is required to realize higher speed and higher quality mobile communication due to the increase in Internet use. adaptive modulation and coding (AMC) scheme is now commonly implemented to maximize the throughput performance under the given link qualities. Forward error correction (FEC) based link adaptation is effective to improve throughput in a lower SNR regime, however, it immolates maximal throughput in good channel condition. Frequency symbol spreading (FSS) has been proposed that can improve BER even without FEC. It fully exploits the frequency diversity gain by spreading symbol per subcarrier to all frequency components. This paper proposes a new adaptation control scheme for FSS-based OFDM incorporating AMC. Simulation result verifies its maximized throughput performance harvesting both of coding gain and frequency diversity gain.
We propose adaptive turbo coded modulation orthogonal frequency division multiplexing (OFDM) schemes with power variable over subcarriers, variable over subbands, and constant over subcarriers. Our object is to improv...
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ISBN:
(纸本)0780379748
We propose adaptive turbo coded modulation orthogonal frequency division multiplexing (OFDM) schemes with power variable over subcarriers, variable over subbands, and constant over subcarriers. Our object is to improve the overall throughput under target bit-error-rate (BER) for OFDM transmissions. Simulation results indicate that our fixed power adaptation scheme exhibits a more than 7dB signal-noise-ratio (SNR) gain relative to non-adaptive turbo coded modulation, and about 2dB additional gain can be achieved with our variable power adaptation. We also discuss the effect of the amount of subbands on throughput performance in our adaptive scheme.
Unmanned Aerial Vehicles (UAVs) constitute a key technology for next generation wireless communications. Compared to terrestrial communications, wireless systems with low-altitude UAVs are in general faster to deploy,...
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ISBN:
(纸本)9789897584459
Unmanned Aerial Vehicles (UAVs) constitute a key technology for next generation wireless communications. Compared to terrestrial communications, wireless systems with low-altitude UAVs are in general faster to deploy, more flexible and are likely to have better communication channels due to the presence of short-range Line of Sight (LoS) links. In this contribution, a Latent Dirichlet Allocation (LDA) based machine learning algorithm was utilized to optimize the content caching of UAVs, while the K-means clustering algorithm was invoked for optimizing the assignment of mobile users to the UAVs. We further investigated a practical adaptive Low Density Parity Check (LDPC) coded modulation (ALDPC-CM) scheme for the communication links between the UAVs and the users. We found that the caching efficiency of each UAV can be boosted from 50% with random caching to above 90% with the employment of LDA. We also found that the proposed ALDPC-CM scheme is capable of performing closely to the ideal perfect coding based scheme, where the mean delay of the former is only about 0.05 ms higher than that of the latter, when the UAV system aims to minimize both the transmission and request delays.
The impact of varying wireless channel on the performance of handover scheme in Low Earth Orbit (LEO) satellite systems operating in different propagation environments, is analytically presented in this work. Generall...
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ISBN:
(纸本)9781479974986
The impact of varying wireless channel on the performance of handover scheme in Low Earth Orbit (LEO) satellite systems operating in different propagation environments, is analytically presented in this work. Generally LEO mobile satellite systems are adversely affected by diverse impairing factors like shadowing and multipath fading which increases the rate of handover failure and blocking of new connections. In essence, this work proposes to adopt the concept of adaptive modulation and coding (AMC) operating at two different transmission rates that suit the channel states of the network Futhermore, a study of the performance of LEO satellite network in three different propagation environment is presented. In addition, the effect of channel variation on the overall transmission time for these environments is shown by analytical performance measures. The performance metrics considerd for this analysis are the blocking probability of new call attempts (P-b1), handover failure probability due to lack of available resources in the destination cell of the mobile (P-b2), call dropping probability due to an unsuccessful handoff (P-drop) and unsuccessful call probability (P-drop)
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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ISBN:
(纸本)9781424447442
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.
Group layered multi-antenna architectures (GLAs) employing orthogonal space-time block codes and spatial multiplexing techniques may simultaneously exploit diversity and multiplexing gains with simple decoding algorit...
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ISBN:
(纸本)9781424425167
Group layered multi-antenna architectures (GLAs) employing orthogonal space-time block codes and spatial multiplexing techniques may simultaneously exploit diversity and multiplexing gains with simple decoding algorithms based on successive interference cancellation (SIC). In this paper we first describe a decoding method of a SIC receiver based on QR decomposition in a GLA using LDPC codes, and then find a combination of code rate and modulation order which optimizes the asymptotic performance of the GLA. Simulation results show that the performance of the GLA using code rates and modulation orders found by our method is better by 2 dB than that of a GLA using the same code rate and modulation order in all layers. Our optimization method can be applied to adaptive modulation and coding schemes for GLAs.
The paper derives a more accurate upper bound for BER for M-QAM than is currently used in the literature. This allows a more thorough analysis of the power adaptation to fading conditions for optimization of spectral ...
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ISBN:
(纸本)9781424445462
The paper derives a more accurate upper bound for BER for M-QAM than is currently used in the literature. This allows a more thorough analysis of the power adaptation to fading conditions for optimization of spectral efficiency. By taking into account the effect of error coding gain on power adaptation, a 7-state FSMC model for the implementation of the adaptive modulation and coding scheme in WiMAX is proposed.
As UMTS enhancement function, High Speed Downlink Packet Access (HSDPA) was specified in 3GPP in year 2002. This enhanced system supplies higher packet data rate on the downlink. One of the key techniques supporting H...
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ISBN:
(纸本)7505350668
As UMTS enhancement function, High Speed Downlink Packet Access (HSDPA) was specified in 3GPP in year 2002. This enhanced system supplies higher packet data rate on the downlink. One of the key techniques supporting HSDPA is adaptive modulation and coding (AMC) that the modulation scheme and the coding rate for error correction are adaptively changed according to the radio channel condition. Therefore, the channel quality information dominates the accuracy of AMC and affects the system performance. In current 3GPP specification release 5, periodic channel quality feedback by the UE is defined. However, the coexistence of high throughput and low uplink interference isn't easy. This paper proposes the additional feedback scheme in addition to current scheme to aim at the coexistence of such system performance. After the description of this proposal, the throughput performance on the downlink, the interference situation on the uplink and the error probability of the retransmission are shown. This proposal scheme has been proposed as further enhancement technique of HSDPA for specification release 6.
We consider an Underwater Acoustic Network (UAN) where each node is equipped with a suite of signals and so there is the flexibility to aim for different bit rates at each transmission slot. A Cross-Entropy (CE) centr...
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ISBN:
(纸本)9780578576183
We consider an Underwater Acoustic Network (UAN) where each node is equipped with a suite of signals and so there is the flexibility to aim for different bit rates at each transmission slot. A Cross-Entropy (CE) centralized algorithm is explored to optimize the combination of modulation scheme and transmission power level in the presence of unreliable channels. Optimization metrics such as throughput, energy per bit, latency and their combination are considered. The motivation for this research stems from the fact that surveillance networks using battery-powered Autonomous Underwater Vehicles (AUVs) need to be able to promptly deliver critical data while prolonging their lifetime and reducing the footprint of their transmissions. The proposed strategy has been validated by post-processing thousands of acoustic signals recorded during the Littoral Acoustic Communications Experiment 2017 (LACE17) sea trial in the Gulf of La Spezia, Italy. Our analysis shows the trade-off between the bit rate and the transmission power given the selected optimization metrics. The solution computed when combining all the considered metrics makes possible to improve up to three times the throughput performance and up to one order of magnitude the energy consumption with respect to considering single other optimization metrics.
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