H.264 Encoder Parameter Optimization for Encoded Wireless Multimedia Transmissions

In this paper, we propose a novel model of dualmode quantizer that combines the restricted and unrestricted forward adaptive piecewise linear scalar quantizers based on the first degree-spline functions, one of them being forward adaptive G.711 quantizer used as the unrestricted one. The analysis presented in the paper can be considered as our further research in the field of dualmode quantization. In particular, in our novel model we utilize G.711 codec due to the compatibility reasons and we develop one completely novel model of restricted quantizer based on the first-degree spline approximation, which is optimized for the assumed Laplacian source so that to provide a minimal mean-squared error distortion. Moreover, unlike previous dual-model quantizer models that processed signals in frame-by-frame manner, our novel model utilizes frame/subframe processing of the signal in order to decrease the total bit rate. The theoretical analysis in a wide dynamic range of input signal variances reveals that the proposed model of quantizer is superior versus the unrestricted G.711 quantizer as well as other similar baselines having the same number of quantization levels. In addition, the results of the experimental analysis performed on the real speech signal show a good agreement with the theoretical ones.

Section: Resultsmentioning

confidence: 99%

Forward Adaptive Dual-Mode Quantizer Based on the First-Degree Spline Approximation and Embedded G.711 Codec

Perić¹,

Nikolic²,

Denic³

et al. 2019

“…The maximum value of retransmission T 1 The duration of active period T 2 The duration of inactive period T…”

Section: Notationmentioning

confidence: 99%

“…The fifth generation (5G) wireless networks are expected to support various services such as Voice over Internet Protocol (VoIP), real-time video streams [1], interactive online games and so on. Different applications have different quality of service (QoS) requirements.…”

Section: Introductionmentioning

confidence: 99%

Analysis of Access Delay and Delay Jitter for the CSMA/CA Mechanism with Inactive Period

F.¹,

Zhang²,

Zhao³

et al. 2019

Owing to the distributed features and flexibility, carrier sense multiple access with collision avoidance (CSMA/CA) mechanisms have been widely adopted in wireless networks. Considering energy consumption, we devote to exploring an energy efficient carrier sense multiple access with collision avoidance (EE-CSMA/CA) mechanism. The access delay and delay jitter are two of most important quality of service (QoS) metrics. EE-CSMA/CA inevitably experiences the tortures bred from its delay and delay jitter performance, because its frame structure with inactive period brings delay. In this paper, we aim to analyze the access delay and delay jitter of packets for the CSMA/CA with inactive period under the unsaturated conditions. Based on the Markov theory, we model the mechanism of EE-CSMA/CA as a four-dimensional Markov chain, and the fourth variable of Markov chain differentiates the active period and the inactive period of EE-CSMA/CA. Then, deriving in probability generation domain, we get the probability distribution of service time and obtain the access delay. Finally, the queue in a node is decoupled, and two queues with different states of empty and non-empty are configured logically, which helps to enable the complex analysis of delay jitter. Based on the whole probability analysis, the probability distribution of delay jitter is obtained. We show that the active ratio (active time over whole frame time) affects the access delay and delay jitter. When the active ratio is constant, the duration of active period has less effect on the access delay while it deteriorates delay jitter performance.

“…Substituting (15) into (7) and with some simple calculations, we can get the lower bound of achievable rate for the k-th user pair R L k (α) with RMMSE CE which has the same form as (11). However, the values of A, B, C and D are different from (12) and can be computed as…”

Section: Derivation Of Lower Bound Of Rate With Rmmse Cementioning

confidence: 99%

“…The above studies on IA with imperfect CSI are mostly based on the fixed duration training. In the information processing or communication system design, the system performance can be improved by optimizing some parameters [11][12][13]. In this paper, we introduce the time splitting factor (TSF) as the optimization variable.…”

Section: Introductionmentioning

confidence: 99%

Optimized Time Splitting to Maximize the Lower Bound of Rate with Channel Estimation in An Interference Alignment Based Network

Yao¹,

Yao²,

Xu³

et al. 2019

In this paper, for an interference alignment (IA) based network, a time splitting scheme for transmitting training and data symbols is optimized. The time allocated for transmitting training symbol will affect the precision of channel estimation (CE) and thus the achievable rate as well as the duration for data symbol transmission. With the least square (LS) and relaxed minimum mean square error (RMMSE) CE algorithm, the lower bounds of achievable rate are carefully derived, respectively. Then we formulate an optimization problem to maximize the lower bounds of achievable rate by optimizing the time splitting factor (TSF). The existence of optimum is first proved. Then, regarding the complexity of solution, Taylor expansion is adopted to find the approximated optimal TSF. Numerical results are presented to show the optimal TSF can achieve larger lower bound of achievable rate over other fixed TSFs due to its adaptivity to the channel characteristics and its statistics of CE errors. Numerical results also validate that the approximation just brings out some small and acceptable errors on the system rate. In addition, RMMSE CE algorithm shows better performance than LS CE because RMMSE considers noise statistics as modification.