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Multimedia Transmission Mechanism for Streaming Over Wireless Communication Channel

With the evolution of wireless communication technologies (i.e., 4G/5G), the explosion of multimedia transmission of content sharing has become an integral part of users' daily lives. It expects further growth in Quality of Service (QoS) and Quality-of-Experience (QoE) performance. Therefore, multimedia service providers are developing new technologies to offer higher video streaming quality content along with video compression standards, which is highly demanded by the receivers. Thus, inventing precise and efficient quality-based media transmission protocol will significantly help to improve the multimedia QoS over wireless networks. This comprehensive research study discusses standard research work progress in multimedia transmission protocol for wireless communication networks. It also investigates the limitations of such literature found some challenging factors that play a significant role in managing the superior signal quality for digital or video content transmission over heavy traffic conditions. The final section provides a briefing on crucial open research issues to develop a multimedia transmission model that can seamlessly communicate multimedia content irrespective of adverse traffic conditions. Keywords—Multimedia transmission; video encoding; multimedia streaming; quality of service; quality of experience; video compression standards


I. INTRODUCTION
The evolution of media communication systems (i.e., 4G and 5G) has led to increased digital services and applications, such as IPTV, social networking, video conferencing, multimedia games, educational digital presentation, etc. These multimedia applications are becoming an integral part of our daily lives and are provisioned to grow exponentially. Various multimedia service providers, e.g., subway system [1], chroma-keying [2], 2D and 3D animation industries, etc., are discovering differing technologies to offer a higher quality of experience, which end users are progressively insisting. In the current scenario, almost all users having/utilizing smart devices for multi-purpose like generating data, communicating, or sharing information from person to person or device to device anywhere and anytime. Most of the users spending time viewing and sharing multimedia content from the internet. At present, viewing video content over the internet is almost free for public users. It is also studied that there will be a phenomenon increase in user base for using multimedia streamed contents over the internet [3]. Apart from this, it is also figured out that it reaches up to 80% by 2020. In the future, most of the multimedia access traffic will be transmitted wirelessly. Nowadays, video transmission has become common for all internet users.
Despite the increasing growth of advanced technologies, the audio-video transmission process suffers from impairments by lossy transmission and source encoding over the network channels, thereby degrading the quality of multimedia content [4]. For example, the user may receive a sample video file that may group different quality ranges due to rendering errors or another transmission. However, other technologies and network standards have been developed that facilitate a high communication range among digital devices. Such standard networks are; IEEE 802.15 WPAN [5], IEEE 802.11 WLAN [6], IEEE 802.16 WMAN [7], and 4G telecommunication networks [8]. The high-speed network availability and video transmission with high speed and minimum cost provide a new era for video communication that has not been implemented over the past decades. Video communication technology dominates the high traffic over the wireless networks and is envisioned for multiple applications. The deployment of high-standard networks like 3G and 4G and advancements in intelligent device development had led to the massive demand for digital media transmission over wireless channels. The increasing requirement for multimedia content creates challenges for all digital media streaming systems, such as wireless network service providers [9], content providers, and mobile device makers.
The mobile network service providers and content providers strive to enhance their services while adopting advanced technologies-for example, improving processing power and high-quality displays. Ultimately, the common goal of all service providers is to improve the quality of experience (i.e., QoE) for end-users. The objective of QoE is t evaluate the video streaming quality by end-users. It can be assessed in-display smoothness, streaming bit-rate, video quality range like PSNR, etc. Therefore, in [10], the authors provided a comprehensive survey study on existing video transmission methods and offered a research direction towards defining high QoE and new transmission methods for 3D video streaming. Video streaming or video transmission over wireless channels remains challenging, for example, signal interference between nodes, unreliable quality due to multiwww.ijacsa.thesai.org path fading, and dynamicity in connectivity. Routing problems always influence the end-to-end QoS of video applications; an example is finding an optimal route that could help for video transmission with high quality. The conventional routing protocols rely on packet delay and packet loss metrics to achieve the high perceived video quality. The case study shows that multiple techniques exist to address the routing issues for real-time video transmission over wireless networks to enhance the quality of video at the end user. The practical use of these theoretical results of existing studies offers better guidelines toward formulating new studies for better QoS and QoE performance in routing strategies.
Therefore, most research was carried out on developing optimal routing for video transmission in wireless networks, mainly focused on network-oriented QoS (i.e., delay, throughput, and packet loss) and less concentrated on application-oriented QoS perceived video quality. Thus, the present survey study overviews different challenges in designing a multimedia transmission protocol to improve the signal quality in heavy traffic over wireless networks. From the prior research study, it can be observed that very little research has been done towards multimedia compression, which does not have an explicit module of wireless networks and its associated problems. The transmission protocols designed to date seriously lack multi-level optimization, showing that the existing algorithms can provide a one-way solution and cannot go beyond that. Since multimedia transmission protocols play a significant role in delivering the requirements of WSN applications, there is less work done that needs to extend the conventional real-time communication systems. Multimedia transmission protocols must be upgraded to be suitable for wireless environments. The significant challenge in implementing multimedia transmission protocol involves real-time data streaming over wireless networks with high QoS. Another challenging task is the compression technique, where a slight increment in the compression level causes data quality to decrease. Hence, the present study's contribution presents the relevant prior research study towards multimedia transmission protocol over wireless channels that have been recently introduced. Also, investigate such literature's limitations and find some challenging factors that play a significant role in managing the superior signal quality for digital or video content transmission over heavy traffic conditions. With the increasing usage of streaming-based services over various commercial applications for different causes, a smoother streaming experience is needed. This streaming is eventually carried out using different variants of the wireless network. Adoption of wireless network offers cost-effective utilization towards the user, but it also introduces various challenges. There are multiple archives of research-based solutions for dealing with the difficulties in data transmission over a wireless network. However, the challenges still exist, and there is yet evolving research work.
Hence, the biggest problem is a snapshot of the existing transmission methods for multimedia contents over a wireless network. Therefore, this manuscript contributes towards more detailed insight into the strength and weaknesses of existing multimedia transmission in a wireless network. The overall organization of the current manuscript is as follows; Section II briefs about multimedia transmission standards. Section III discusses different researchers who have introduced various theoretical and implementation research studies. Section IV presents the other multimedia transmission protocols that help improve QoS in the streaming process concerning compression standards. Section V reviews current research challenges found from existing studies. Finally, in the last Section VI, the summary of the study is presented in the form of a conclusion.

II. MULTIMEDIA TRANSMISSION PROTOCOLS
The multimedia transmission means forwarding data packets that usually consist of audio, video, or audio-visual streaming. Multimedia transmission is the fundamental process for sending media content to mobile users. The scalable transmission process will need efficient and robust routing protocols which provide high-quality output video content. Therefore, effective and scalable video streaming protocols intend to transmit multimedia content through the internet while enabling users to access it without completing the transmission process. Generally, all video transmission protocols preferred a transport layer where transmission occurs via live video streaming. The functionality of the transmission protocol is to offer real-time, sequential, less packet loss, low delay, minimum energy consumption for video/digital data streaming. This section discusses the most common and frequently adopted multimedia transmission protocol.
 Real-Time Messaging Protocol (RTMP): RTMP is best and significantly utilized for media streaming technology in all listed transmission protocols. Macromedia developed RTMP to stream digital data over the internet. It is a TCP-based protocol that provides low latency communication with a persistent connection. It contains multiple features such as; it is very flexible and enables audio, video, audio-visual streaming, even text content in several formats to various devices. Another significant feature is the multiplatform transmission protocol; users can access the media content using any platform (i.e., Android, Mac, Windows, etc.).
 Nevertheless, one of the drawbacks of this protocol is that users need to consider it before selecting it for video streaming activities. RTMP is an old protocol and well-proof multimedia streaming technology that has been adopted for years now. The Flash-Player helps in viewing media streams via RTMP, which is very famous and utilized over the globe [11].
 Real-time Transport / Control Protocol (RTP/RTCP): A transport layer protocol built on UDP enables real-time multimedia content transport. It may be exploited for single-way transport services like video on demand and internet telecalls. One of the features of RTP is closely associated with RTCP, which performs at the session layer of the ISO model. It offers feedback for the quality of content distribution. RTP is mainly designed  Real-time Streaming Protocol (RTSP): Primarily, RTSP is utilized to control real-time media streaming applications such as HD-video streaming. It is a network control protocol that establishes communication sessions among the endpoints. This protocol uses TCP protocol to balance the end-to-end session, and RTP is utilized to deliver the media content over the UDP. Additionally, RTSP protocol may interact with HTTP server such that hand over devices is specified among the media and web server. This makes, as, the delivered file content to be requested via HTTP or RTSP. "VOCAL" optimized software is utilized for media transmission, which supports RTSP protocol [12].  Shout-Cast: It is one of the popular technologies which delivers broadcast streaming. Shoutcast utilizes its protocols, and it was developed by Nullsoft and named ICY; at present, Ultravox is using for ShoutCast-2. This protocol can operate over either UDP or TCP. The major drawback of this protocol is only applicable for broadcasting, not for on-demand video delivery.
 Moving Picture Expert Group-DASH: (MPEG-DASH): Generally, MPEG was developed for multimedia streaming with multiple standards, i.e., MPEG-2, MPEG-4, and MPEG-7. The dynamic adaptive streaming standard over HTTP is the MPEG-DASH, which can solve media delivery problems to several devices with a unified standard [16].
Above discussed, all multimedia protocols have different methods and formats as well as unique features. Therefore, a dynamic supportable protocol must be needed to deliver or receive media content from servers to users. However, all these standard protocols can provide multimedia content over wireless channels. Apart from this, there are some recent studies carried out in this direction. The study presented by Li et al. [17] has implemented a parallel coding scheme to improve multimedia transmission considering turbo coding. Reinforcement learning is another scheme that offers better video transmission performance considering a case study of the internet of things, as seen in the analysis of Xiao et al. [18]. Ta et al. [19] have developed a cooperation scheme of image transmission considering sensor networks as a wireless medium. Huang et al. [20] have presented a Q-Learning scheme over the cognitive network for improving multimedia transmission. Liu et al. [21] have used the beamforming approach for enhancing multimedia transmission in 5G, harnessing the potential of the relay network. The following section discusses existing strategies for multimedia transmission over different variants of the wireless network.

III. EXISTING APPROACHES
Different theoretical and implementation research studies have been introduced by other researchers that achieved multimedia transmission over other network technologies. Therefore, this section discusses relevant research studies on multimedia transmission protocols in wireless networks. At present, various wireless protocols are claimed to offer the quality of service for multimedia transmission. Table I highlights this comparative analysis of these standards. At present, most online users are widely utilizing multimedia content for various reasons to ensure public and personal services. The multimedia content is transferred or distributed over different networks, i.e., ranging from classical wireless networks to IoT (Internet of Things). However, the deployment of the network has multiple reasons: ensuring high QoS and QoE with minimum latency reduction specific to traffic concerns. To tackle this challenging task, Bennis et al. [27] introduced a cross-layer protocol that handles the video transmission procession over WSN's. The proposed approach also cooperated with the application layer to frame an aware strategy for queuing policy that solves the various functions (i.e., enqueuing, dequeuing) to optimum latency reduction and enhances the video streaming quality. Asha and Mahadevan [28] adopted the exact cross-layer mechanism, which addressed QoS challenges in mobile networks for multimedia applications. To enhance the QoS for the mobile web, the authors proposed a combined approach that improves the network lifetime. This represents three objectives; network modeling, threshold-based packet transmission, and queuing model on physical-layer, which support the QoS.
Current cloud computing environment, multimedia transmission via IoT technology presents lots of challenges to nodes' diversity. Said et al. [29] explored adaptive real-time transport and control protocols over IoT environments. The experimental study considered the heterogeneous network for transmission, threshold value, and various multimedia sources. The primary intention was to split the scalable multimedia sessions into multiple sessions with network status awareness. The proposed technique can decrease network overload under critical traffic conditions. Also advantageous for an end-to-end delay, minimum packet loss, and energy consumption. Another research study by Huang et al. [30] focused on the concept of improving QoE over multimedia IoTs for network users. First, the author introduced a Quality-of-Experience (QoE) optimization mechanism for multimedia IoTs that leverages the data fusion technique. Initially, the proposed method involves two core phases; the data fusion model builds a QoE mapping among the un-controllable streaming data with controllable network system data. Then, another automatic QoE optimization model was designed to automatically adjust the network systems and achieve higher optimization results.
Multiple approaches have been proposed which ensures the energy trade-off for network performance [31] [32]. However, the routing challenge has been considered a significant problem and needs to resolve to support future communication technologies. Therefore, in the context of work carried out by Khernane et al. [31], who have addressed the different routing problems based on a routing matrix. As a solution, a single selective routing protocol has been introduced. The solution strategy allows the end-to-end routing for each video sensor without any path discovery. Therefore, it is named as a change of dynamic network topology.
Another challengeable issue in the transmission process is the security because voluminous data content is quite impossible by conventional methods to encrypt the video content fully. Almasalha et al. [32] presented a scalable model for securing multimedia content on low energized mobile devices. The proposed technique is mainly applicable to the compressed video stream and will not require any decoding. The system encrypts 3% of packet load and offers equivalent security by doing bit-stream encryption. This phenomenon has experimented on laptops, desktops, notebooks, and mobile phones. Canovas et al. [33] have proposed a multimedia distribution system that delivers the video streams over the IP network. The proposed mechanism adopted a heuristic decision method and a probabilistic distribution system that provides the media streams among the service providers. Clients can upload and download the media files. The proposed approach takes into account energy conservation as well as enhances the QoE of end-users. However, the wireless multimedia transmission process contains multiple constraints and faces several problems: bit rate, storage problem, power consumption, bandwidth, and processing rate. Hassan et al. [34] explored an advanced multimedia compression technique that lacks such challenges, i.e., H.264 has been developed jointly with MPEG. The proposed compression standard offers multiple tunable parameters which tailor the video encoding operation as per the provisions. Additionally, the proposed framework to resolve the multi-objective problems achieved relevant results in bit-rate improvement, power consumption, and quality enhancement in multimedia content.
Due to wireless sensor technology's advanced improvement, sensor nodes can perform multimedia data processing, but the significant challenge is the real-time routing system over wireless multimedia networks [35]. Therefore, Ahmed et al. [35] introduced a real-time routing protocol for video streaming over next-generation wireless multimedia sensor networks. This study elaborates an algorithm to accomplish adaptive traffic shaping for video streaming. It exploits a multi-route forwarding approach with dynamic cost computation for a section of the next node. The author mainly focused on video streaming and real-time routing. Majeed et al. [36] have provided a comprehensive survey study on several problems in the art of informationcentric networking systems and discussed respective architectures and literature concerning multimedia streaming.
Additionally, a roadmap is provided on the research community studying in a similar domain. Huang et al. [30] introduced analytical modeling for multimedia data flow scheduling systems over SDNs (software-defined networks). This study author presented a hybrid data flow scheduling system by integrating priority-based queuing packets and offering QoS for multimedia applications in SDN. Several researchers provided different multimedia transmission methods. Some of them addressed multimedia transmission over VANETs. For example, Xu et al. [37] have explored an information-centric networking model that delivers multimedia content over mobile vehicular networks. The proposed mechanism implements two significant factors, data mobility, and provider supply-demand balance. They also formulated an optimized mixed-integer programming module that is cost-effective concerning QoS multimedia. In another research study, author Moussaoui et al. [38] have adopted VANETs technology to implement cost-free and efficient multimedia content sharing among the two vehicles and their www.ijacsa.thesai.org passengers. In this study, the authors proposed an improved cross-layer protocol that deals with routing challenges over VANETs. Yang et al. [39] have presented a movie recommendation model based on user scores. From the viewpoint of the movie formulation system, the level of access control & media security are analyzed, along with cloud storage security architecture was implemented. The primary objective is to ensure the safety of multimedia content during the data transmission process. Dien et al. [40] have presented cross-layer architecture to implement a security-based routing protocol for multimedia transmission on the wireless sensor network. The primary focus was on energy consumption during packet transmission and path scheduling. The authors concluded that the proposed framework is suitable for enhancing real-time video quality and prolonging the network performance from the implementation results.
Rapid advancement in wireless technology infrastructure and smart devices, video streaming like cloud gaming, live sports watching, YouTube video uploading and downloading, etc., has dominated the harmful applications over the web. With the increasing rate in emerging multimedia applications, providing a better quality of video services (e.g., YouTube and many more) provides multimedia streaming up to sixty frames in a second. Therefore, Wu et al. [41] mainly focused on realtime video transmission problems on mobile devices like the example video conferencing or calls, video games, etc. hence, nowadays, it is becoming a highly challenging issue for the service providers to provide and ensures about high-quality content delivery as well as high-quality video streaming. For that purpose, the authors proposed a frame scheduling and error resilience model for mobile devices over heterogeneous wireless networks. Hameed et al. [42] have introduced an energy-efficient video quality prediction model for wireless communications. The entire work mainly consists of two components: real-time video quality with low complexity. Another is the content and energy-aware model to balance the video quality during packet transmission over the network. The authors showed that the proposed prediction model achieves ~ 90% accuracy, and as compared to conventional techniques, the proposed communication model reduces the network overhead by 41%. With the growth of new generation networks and communication technologies, video services are becoming pervasive for large-scale heterogeneous wireless networks. More and more uploading, downloading, and accessing video information with the help of various devices (PCs, tablets, smart TVs, smartphones, etc.) is becoming very common for all users. Offering heterogeneity with QoE, which supports a wide range of multiple multimedia devices, is crucial and challenging to broadcast the video over new generation wireless networks. Chen et al. [43] have reviewed different existing video broadcasting technologies and founds present requirements ranging from homogeneous to heterogeneous transmission network technologies. Also presented is a typical modeling approach for video broadcasting with large-scale heterogeneous network support that enables QoE, joint coding, cross-layer transmission, optimal and dynamic adaptation to enhances the receiving quality of heterogeneous devices.
One of the challenging factors for digital media transmission over multimedia WSN is the spectrum scarcity with high radio interference in the current digital world. In that context, Bradai et al. [44] proposed a solution mechanism for multimedia transmission over multimedia WSNs which exploit radio interferences for spectrum scarcity and clustering method for energy efficiency. Also highlighted significant issues and challenges of multimedia WSNs, i.e., high bandwidth requirements, energy efficiency, QoS, data processing cross-layer routing issues, and compressing techniques. On the other hand, Gur [45] has mainly focused on QoE and QoS requirements over multimedia applications or services deployed over mobile networks. Also defined the network performance parameters utilized to balance the service performance like; throughput, latency, packet loss, reliability, and availability. Han et al. [46] have investigated the new concept of a fast directional hand-off mechanism that helps to enhance or improves the quality of multimedia over WSN. Also introduced is a lightweight retransmission protocol that reduces the packet loss on WiFi without generating any acknowledgment. The proposed mechanisms can be applied on android based smart devices, and their performance has been evaluated in the indoor wireless LAN environment. The experiment results demonstrated that the proposed mechanism balances the seamless quality for video streaming under hand-off operation. Some studies have analyzed the challenges facing multimedia transmission in the IoT environment. Alvie et al. [47] have introduced a novel of the internet of multimedia things where smart multimedia devices can cooperate and interact with each other and connect with the internet to provide multimedia-based services to global users. Jiang and Meng [48] have designed an IoTbased multimedia platform that improves real-time multimedia transmission protocol quality. The following Table II highlights a summary of the existing multimedia transmission techniques that different authors have proposed. Multimedia compression is a technique that transmits the media content over a wired or wireless channel by encoding digital video content. The compression for media content transmission offers multiple benefits like fewer storage requirements and minimum bandwidth requirements. The compression technique typically involves deletion of information not considered critical to viewing the video content and a good video codec technique that provides multiple benefits mentioned above: without significant degradation in the visual content experience, postcompression, and without requiring significant hardware overhead achieve the compression. Even within a particular video compression technique, different levels of compression standards can be applied. Hence, the more aggressive compression, high storage space and transmission bandwidth efficiency, and the higher computing power required. However, ISO/IEC and ITU-T are the influential international organizations that classified the multimedia compression standards into two major categories; i.e., ISO/IEC includes MPEG standards like MPEG-1, 2, 3, 4, MPEG-4(AVC), and Motion-JPEG [49]. At the same time, ITU-T has H.26x series standards, viz. H.261, H.263, H.264, and H.265 (HEVC) [50].
Most video retailers utilize few standard compression techniques (i.e., M-JPEG, MPEG-4, and H.264). However, such standards techniques are mainly relevant to video compression since video can be used for several purposes, such as video surveillance. Therefore, this section has briefly discussed work in state of the art in standard video compression techniques. Additionally, Fig. 1 illustrates the media transmission process at a different layer of the IOS model. Motion-JPEG: M-JPEG is a digital video sequence that contains a series of JPEG images. An image in the video file has equal quality determined from the compression level selected for the video encoder. The high compression level lowers the video file size as well as quality. Some image files require more bandwidth and memory during the compression process since the file size is more significant. Thus, to prevent more storage and bandwidth requirements, video retailers allow the users to set up the file size range for the image frame. The higher quality video content requires additional bandwidth and more storage for file transmission. The mezzanine image compression technique reduces the file transmission capacity and provides higher resolution with high-quality video content [51].
Additionally, the authors introduced a term called JPEG-XS which addressed the requirement for interoperable video over IP. In another research study, Willeme et al. [52] adopted a similar approach to JPEG-XS for image buffer compression. The proposed research aims to reduce the frame buffers' bandwidth and make HEVC more reliable for energy-aware applications.
Moving Pictures Experts Group (i.e., MPEG) is the traditional video compression technique that can compress the media contents like images and audio and combine both files. Several MPEG compression standards are currently available, i.e., MPEG-1, 2, 3, and MPEG-4. All MPEG versions have their features concerning the data rates variation. For example MPEG-1 intended for intermediate data-rates (i.e. 1.5 Mbit/sec), whereas MPEG-4 intended for very less data rates (i.e. <64 KB/sec). The study of Hameed et al. [53] has introduced a decision-tree-based media quality prediction model using the MPEG-4 compression standard. This technique extracts frames from the compressed bit-streams and predicts the video quality based on resultant features. The proposed model provides high video quality content with low complexity.
Meanwhile, Seethram et al. [54] investigated a scheduling algorithm to deliver a multimedia stream from the server to mobile users. Also introduced is an epoch-by  [59] to reduce and delete the redundant media content such that compressed video files can be successfully transmitted over the wireless network. However, the significant challenge of any technique is to reduce the content size and provide high visual quality without any packet loss. Therefore, Chang et al. [56] presented a multi-pooling control access scheme that ensures low latency during the transmission of video frames and reduces transmission overhead. At the same time, Wu et al. [57] presented a video frame scheduling mechanism that reduces the total distortion. The result performance can be evaluated in terms of analyzing video PSNR values.   Inadequacies of transport layer protocols performance: The existing transport layer protocol analyzes the primary reason behind the packet loss: congestion and unusual delay in the network. These two factors, i.e., packet loss and delay rate, affect the transmission process and media quality. However, in the wireless communication system, packet loss may occur due to network errors. Therefore, a QoS and transmission viewpoint should focus on designing a reliable transport protocol because the transmission process mainly occurs at the transport layer.
 Heterogeneity between the receivers and networks: The end-user is in the multimedia transmission process is quite different in QoS requirements, latency reduction, power consumption, processing capabilities, bandwidth demand, etc. Additionally, multimedia may deliver to varying networks with non-similar characteristics (i.e., delay, jitter, reliability, many more) and MAC (medium access control) mechanism.
 Lack of performance in the video compression standard: Existing multimedia transmission standards do not emphasize the signal quality, and the techniques lack a decision mechanism to perform compression. Moreover, existing methods do not ensure the perceptual quality of the multimedia framework to support higher pixel resolution. Although used more frequently in current times, HEVC is a new protocol; currently, no standard and potential studies exist in literature archival to further improve it. Very few works were found to adopt HEVC on a wireless mobile networking platform to check the efficiency of the HEVC algorithm and its potential to mitigate the loading impact of a dynamic traffic system (especially in a wireless environment).
Discussion: Apart from the points mentioned above, Table III highlights the contribution of the proposed survey work with some of the existing survey work. It is seen that existing review papers do not possess discussion of the www.ijacsa.thesai.org research gap. At the same time, their emphasis is particular, while the proposed study intends to offer a clear discussion about research challenges and contributes towards a simplified debate on the strength/weaknesses of related work. The review findings show that multiple aspects can be classified into two parts, viz. i) standard protocol for wireless transmission and ii) research-based protocol for wireless transmission. There is a significant trade-off between this two. The first standard methods are meant for the theoretical formulation of transmission, while the second research part is particular and narrowed in its applicability process. Hence, not much higher scope is witnessed in the existing system. The existing literature is found with highly scattered technique implementation where multiple methods have been used to improve the performance. However, apart from this, a potential research gap exists, which requires immediate attention for future research work.

VI. CONCLUSION
The extreme growth in the various wireless communication technologies, the convergences of standard protocols, availability of small-sized hardware devices, software tools, and collaborative frameworks have paved a solid basis to visualizing real-time multimedia content, including; audio, video, and audio-visual applications in future endeavors. Furthermore, the advancement in the emerging wireless network technologies (i.e., 4G/5G) leads to having many multimedia-based new applications in the direction of augmented reality. However, order to perform transmission of multimedia content over the wireless channel is always a challenging factor. Various studies have focused on multimedia contents transmission over wireless sensor networks, mobile ad-hoc networks, using IEEE standard, etc. However, the mechanism adopted mainly applies conventional encoding techniques evolved from conventional discrete cosine transform, which does not hold much validity in upcoming encoders, e.g., HEVC (High-Efficiency Video Coding) standards. Therefore, from the comprehensive research study, there is a provision to investigate the better and reliable multimedia transmission proclaiming for wireless channels. The contribution of the present research study is to provide a dept investigational research study on understanding different existing techniques, challenges over multimedia transmission, and its significant impact on perceptual quality and traffic rate in wireless communication. The novelty of the study is in terms of its findings as research gap, i.e., i) The trade-off between improvements in the physical layer and network technologies, ii) Less Efficient network coding for successful transmission, iii) High Media Content Loss Rate and Bit Error Rate, iv) Energy Consumption Rate, v) Inadequacies of transport layer protocols performance, vi) Heterogeneity between the receivers and networks, vii) Lack of performance in the video compression standard.
Therefore, for the future, there is an aim to develop a multimedia transmission model that can perform seamless transmission of multimedia content irrespective of any adverse traffic conditions. Additionally, there is a need to design a novel and efficient compression mechanism using H.265 for next-generation wireless networks.