Optimized Unequal Error Protection Using Multiplexed Hierarchical Modulation

Chang, Shengjiang; Cosman, Pamela C.; Milstein, L.B.

doi:10.1109/tit.2011.2173613

Cited by 45 publications

(42 citation statements)

References 29 publications

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“…Considering the real-time traffic situation, the proposed method is first theoretically optimized and the achievable performance gain is analyzed. To apply the proposed method into practice, hierarchical quadrature amplitude modulation (HQAM) [18] is employed to implement our SCM-based broadcast scheme. Although HQAM has been used in digital video broadcasting [19], its usage in VANET context is different from the former because of the relatively small single-hop-transmission coverage and time-varying QoS requirements.…”

Section: Improving the Channel Utilization Of Basic Safety Message Inmentioning

confidence: 99%

Improving the Channel Utilization of Basic Safety Message in VANETs with Superposition Coded Modulation

Wang

Liu

et al. 2016

TELKOMNIKA

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In this paper, we propose a broadcast scheme to effectively utilize the scarce and shared wireless medium for vehicular ad-hoc networks (VANETs). By using superposition coded modulation (SCM) Keywords: Vehicular ad hoc networks, Superimposed coded modulation, Hierarchical quadrature amplitude modulationCopyright © 2016 Universitas Ahmad Dahlan. All rights reserved. IntroductionAs a promising wireless communication technology for future intelligent transportation systems, vehicular ad-hoc networks (VANETs) [1] have attracted significant attention. By providing high speed and low-latency data links among vehicles, VANETs enable a broad range of applications to enhance driving safety and transportation efficiency [2]. VANETs have been standardized by IEEE 802.11p [3]. However, given the high mobility of vehicles and the timevarying requirements of quality-of-service (QoS), 802.11p-based vehicular communications still suffer from a few open challenges. One of the most important problems is medium access congestion [4]. To enable versatile applications, moving vehicles in VANETs need to periodically broadcast their own status information, i.e., the so-called basic safety message (BSM), which is composed of several data elements (DEs), e.g., position, acceleration, heading, and velocity. The BSM packet has a typical length of 300-400 bytes, is disseminated at a data rate of 6 Mbps, has single-hop coverage of 300-500 m, and has a message rate of 1-10 Hz [5]. The bandwidth of the shared wireless medium is limited, and guaranteeing the required delivery rate and transmission delay of the BSM dissemination of all vehicles is difficult, particularly in dense traffic scenarios. This problem significantly reduces the validity of VANETs in aiding driving. In the current paper, we aim to reduce the bandwidth requirement of BSM broadcast by improving channel utilization.Several studies have addressed this problem in the context of VANETs and have used media-access-control (MAC) methods and information compression methods in the application layer. On one hand, given that the random access scheme employed by the MAC layer of the IEEE 802.11p standard is the main inducement of packet collisions and medium access congestion [6,7], numerous studies have focused on improving channel utilization by novel access schemes [4]. In [8], instead of the random media access, a time-slotted-based MAC scheme was proposed to reduce packet collisions. By dividing the entire service period into the collision detection and collision avoidance phases, a content-based MAC scheme was proposed in [9] to improve the reliability of BSM delivery. On the other hand, considering that the BSM is

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Section: Improving the Channel Utilization Of Basic Safety Message Inmentioning

confidence: 99%

Improving the Channel Utilization of Basic Safety Message in VANETs with Superposition Coded Modulation

Wang

Liu

et al. 2016

TELKOMNIKA

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“…In [5], it was demonstrated that prioritized QAM constellation mapping has a positive impact on the error performance of Turbo Codes by using the UEP characteristics of the QAM constellation where the systematic information bits are given a higher protection. A robust transmission of H.264/AVC coded video using hierarchical QAM (HQAM) was presented in [6]. The non-uniformly distributed importance of frames as well as the sensitivity of the coded bitstream against transmission error were taken into consideration.…”

Section: Introductionmentioning

confidence: 99%

Performance of a Two Level Unequal Error Protection Scheme for MP3 Transmission over LTE

Ragpot¹,

Pawan²,

Sunjiv³

2017

CAE

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Long-Term Evolution (LTE) is a wireless broadband communication technology which is highly used for the transmission of data and voice over the internet. However, due to noise and other channel deteriorations, the transfer of data and voice over LTE is very challenging. With the phenomenal increase of data and voice traffic, the management of Quality of Service (QoS) is a challenging problem. This paper presents an enhanced audio transmission scheme with two levels of Unequal Error Protection (UEP) for audio over LTE. The unequal importance of the bits generated by an MP3 codec as well as the varying importance of the bitstreams generated by a Turbo encoder is exploited and different level of protection are offered to them during LTE transmission. This is achieved by positioning the different bits in such a way so that the least important ones are given less protection than the more important bits. With 16-Quadrature Amplitude Modulation (QAM), the proposed two level UEP scheme provides an average gain of 22.36 dB in Segmented Signal to Noise Ratio (SSNR) over a conventional Equal Error Protection (EEP) one at a Turbo code rate of 1/2.

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“…Hence unequal error protection (UEP) is proposed to make the best use of the bandwidth. A practical approach to achieving UEP is based on modulation, for example, Seok-Ho Chang proposed a multilevel UEP system using multiplexed hierarchical quadrature amplitude modulation (QAM) [1]. Another way to achieve UEP is through channel coding with different coding rates.…”

Section: Introductionmentioning

confidence: 99%