Evaluating Performance of Beacon Enabled 802.15.4 Network with Different Bit Error Rate and Power Models

This research finds the most suited Bit Error Rate (BER) and Power Model for IEEE 802.15.4 network. A total of three BER models and three Power Models were used for testing purposes. Their respective algorithms have been developed as well. alt_ber was found to be most suited as BER model and dra_power was found to be most suited for power model for 802.15.4 based networks. The relationship between BER and throughput has been established and the same has been confirmed by simulating the network. The most suited BER and power model settings were confirmed from the graphs obtained from network performance. This research paper can further be used for future references by all the researchers who aim to study this particular aspect of 802.15.4 based networks

A Direct Sequence Code-Division Multiple-Access Local Area Network Model

The United States Air Force relies heavily on computer networks for every-day operations. The medium access control (MAC) protocol currently used by most local area (LAN) permits a single station to access the network at a time (e.g. CSMA/CD or Ethernet). This limits network throughput to, at most, the maximum transmission rate of a single node with overhead neglected. Significant delays are observed when a LAN is overloaded by multiple users attempting to access the common medium. In CSMA/CD, collisions are detected and the data sent by the nodes involved are delayed and transmitted at a later time. The retransmission time is determined with a binary exponential back-off-algorithm. Code Division Multiple Access (CDMA) is a technique that increases channel capacity by allowing multiple signals to occupy the same bandwidth simultaneously. Each signal is spread through multiplication with a unique pseudo-random code that distinguishes it from all other signals. Upon reception, the signal of interest is despread and separated from other incoming signals by multiplying it with the same exact code. With this technique, it is possible for multiple stations to transmit simultaneously with minimal ill effects. A simulation model is developed for a direct sequence spread spectrum CDMA (DS/CDMA) channel that incorporates the effects of multiple access interferers (MAI) having spreading codes from the same or different code families. The model introduces cross-correlation coefficients to calculate the signal-to-interference ratio and determine channel bit error performance. Transmission media attenuation and the near-far effects are accounted for in the model design. The model utility is demonstrated by determining the loss characteristics of a coaxial spread spectrum network. Due to the modular design, other transmission media characteristic can be easily incorporated. A bus network topology is simulated using 10Base2 coaxial cable. The model is compared and validated against a spread spectrum local area network hardware test bed

3D multiple description coding for error resilience over wireless networks

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.Mobile communications has gained a growing interest from both customers and service providers alike in the last 1-2 decades. Visual information is used in many application domains such as remote health care, video –on demand, broadcasting, video surveillance etc. In order to enhance the visual effects of digital video content, the depth perception needs to be provided with the actual visual content. 3D video has earned a significant interest from the research community in recent years, due to the tremendous impact it leaves on viewers and its enhancement of the user’s quality of experience (QoE). In the near future, 3D video is likely to be used in most video applications, as it offers a greater sense of immersion and perceptual experience. When 3D video is compressed and transmitted over error prone channels, the associated packet loss leads to visual quality degradation. When a picture is lost or corrupted so severely that the concealment result is not acceptable, the receiver typically pauses video playback and waits for the next INTRA picture to resume decoding. Error propagation caused by employing predictive coding may degrade the video quality severely. There are several ways used to mitigate the effects of such transmission errors. One widely used technique in International Video Coding Standards is error resilience. The motivation behind this research work is that, existing schemes for 2D colour video compression such as MPEG, JPEG and H.263 cannot be applied to 3D video content. 3D video signals contain depth as well as colour information and are bandwidth demanding, as they require the transmission of multiple high-bandwidth 3D video streams. On the other hand, the capacity of wireless channels is limited and wireless links are prone to various types of errors caused by noise, interference, fading, handoff, error burst and network congestion. Given the maximum bit rate budget to represent the 3D scene, optimal bit-rate allocation between texture and depth information rendering distortion/losses should be minimised. To mitigate the effect of these errors on the perceptual 3D video quality, error resilience video coding needs to be investigated further to offer better quality of experience (QoE) to end users. This research work aims at enhancing the error resilience capability of compressed 3D video, when transmitted over mobile channels, using Multiple Description Coding (MDC) in order to improve better user’s quality of experience (QoE). Furthermore, this thesis examines the sensitivity of the human visual system (HVS) when employed to view 3D video scenes. The approach used in this study is to use subjective testing in order to rate people’s perception of 3D video under error free and error prone conditions through the use of a carefully designed bespoke questionnaire.Petroleum Technology Development Fund (PTDF

Analytical and simulation performance modelling of indoor infrared wireless data communications protocols

The Infrared (IR) optical medium provides an alternative to radio frequencies (RF) for low cost, low power and short-range indoor wireless data communications. Low-cost optoelectronic components with an unregulated IR spectrum provide the potential for very high-speed wireless communication with good security. However IR links have a limited range and are susceptible to high noise levels from ambient light sources. The Infrared Data Association (IrDA) has produced a set of communication protocol standards (IrDA I. x) for directed point-to-point IR wireless links using a HDLC (High-level Data Link Control) based data link layer which have been widely adopted. To address the requirement for multi-point ad-hoc wireless connectivity, IrDA have produced a new standard (Advanced Infrared -AIr) to support multiple-device non-directed IR Wireless Local Area Networks (WLANs). AIr employs an enhanced physical layer and a CSMA/CA (Carrier Sense Multiple Access with Collision Avoidance) based MAC (Media Access Control) layer employing RTS/CTS (Request To Send / Clear To Send) media reservation. This thesis is concerned with the design of IrDA based IR wireless links at the datalink layer, media access sub-layer, and physical layer and presents protocol performance models with the aim of highlighting the critical factors affecting performance and providing recommendations to system designers for parameter settings and protocol enhancements to optimise performance. An analytical model of the IrDA 1.x data link layer (IrLAP Infrared Link Access -Protocol) using Markov analysis of the transmission window width providing saturation condition throughput in relation to the link bit-error-rate (BER), datarate andprotocol parameter settings is presented. Results are presented for simultaneous optimisation of the data packetsize and transmission window size. A simulation model of the IrDA l. x protocol, developed with OPNETTM Modeler, is used for validation of analytical results and to produce non-saturation throughput and delay performance results. An analytical model of the AIr MAC protocol providing saturation condition utilisation and delay results in relation to the number of contending devices and MAC protocol parametersis presented.Results indicate contention window size values for optimum utilisation. The effectiveness of the AIr contention window linear back-off process is examined through Markov analysis. An OPNET simulation model of the Alf protocol is used for validation of the analytical model results and provides non-reservation throughput and delay results. An analytical model of the IR link physical layer is presented and derives expressions for signal-to-noise ratio (SNR) and BER in relation to link transmitter and receiver characteristics, link geometry, noise levels and line encoding schemes. The effect of third user interference on BER and resulting link asymmetry is also examined, indicating the minimum separation distance for adjacent links. Expressions for BER are linked to the data link layer analysis to provide optimum throughput results in relation to physical layer propertiesandlink distance

3D multiple description coding for error resilience over wireless networks

Mobile communications has gained a growing interest from both customers and service providers alike in the last 1-2 decades. Visual information is used in many application domains such as remote health care, video –on demand, broadcasting, video surveillance etc. In order to enhance the visual effects of digital video content, the depth perception needs to be provided with the actual visual content. 3D video has earned a significant interest from the research community in recent years, due to the tremendous impact it leaves on viewers and its enhancement of the user’s quality of experience (QoE). In the near future, 3D video is likely to be used in most video applications, as it offers a greater sense of immersion and perceptual experience. When 3D video is compressed and transmitted over error prone channels, the associated packet loss leads to visual quality degradation. When a picture is lost or corrupted so severely that the concealment result is not acceptable, the receiver typically pauses video playback and waits for the next INTRA picture to resume decoding. Error propagation caused by employing predictive coding may degrade the video quality severely. There are several ways used to mitigate the effects of such transmission errors. One widely used technique in International Video Coding Standards is error resilience. The motivation behind this research work is that, existing schemes for 2D colour video compression such as MPEG, JPEG and H.263 cannot be applied to 3D video content. 3D video signals contain depth as well as colour information and are bandwidth demanding, as they require the transmission of multiple high-bandwidth 3D video streams. On the other hand, the capacity of wireless channels is limited and wireless links are prone to various types of errors caused by noise, interference, fading, handoff, error burst and network congestion. Given the maximum bit rate budget to represent the 3D scene, optimal bit-rate allocation between texture and depth information rendering distortion/losses should be minimised. To mitigate the effect of these errors on the perceptual 3D video quality, error resilience video coding needs to be investigated further to offer better quality of experience (QoE) to end users. This research work aims at enhancing the error resilience capability of compressed 3D video, when transmitted over mobile channels, using Multiple Description Coding (MDC) in order to improve better user’s quality of experience (QoE). Furthermore, this thesis examines the sensitivity of the human visual system (HVS) when employed to view 3D video scenes. The approach used in this study is to use subjective testing in order to rate people’s perception of 3D video under error free and error prone conditions through the use of a carefully designed bespoke questionnaire.EThOS - Electronic Theses Online ServicePetroleum Technology Development Fund (PTDF)GBUnited Kingdo

Use of V-band geostationary satellites to deliver multimedia services

EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Analytical and simulation performance modelling of indoor infrared wireless data communications protocols

The Infrared (IR) optical medium provides an alternative to radio frequencies (RF) for low cost, low power and short-range indoor wireless data communications. Low-cost optoelectronic components with an unregulated IR spectrum provide the potential for very high-speed wireless communication with good security. However IR links have a limited range and are susceptible to high noise levels from ambient light sources. The Infrared Data Association (IrDA) has produced a set of communication protocol standards (IrDA I. x) for directed point-to-point IR wireless links using a HDLC (High-level Data Link Control) based data link layer which have been widely adopted. To address the requirement for multi-point ad-hoc wireless connectivity, IrDA have produced a new standard (Advanced Infrared -AIr) to support multiple-device non-directed IR Wireless Local Area Networks (WLANs). AIr employs an enhanced physical layer and a CSMA/CA (Carrier Sense Multiple Access with Collision Avoidance) based MAC (Media Access Control) layer employing RTS/CTS (Request To Send / Clear To Send) media reservation. This thesis is concerned with the design of IrDA based IR wireless links at the datalink layer, media access sub-layer, and physical layer and presents protocol performance models with the aim of highlighting the critical factors affecting performance and providing recommendations to system designers for parameter settings and protocol enhancements to optimise performance. An analytical model of the IrDA 1.x data link layer (IrLAP Infrared Link Access -Protocol) using Markov analysis of the transmission window width providing saturation condition throughput in relation to the link bit-error-rate (BER), datarate andprotocol parameter settings is presented. Results are presented for simultaneous optimisation of the data packetsize and transmission window size. A simulation model of the IrDA l. x protocol, developed with OPNETTM Modeler, is used for validation of analytical results and to produce non-saturation throughput and delay performance results. An analytical model of the AIr MAC protocol providing saturation condition utilisation and delay results in relation to the number of contending devices and MAC protocol parametersis presented.Results indicate contention window size values for optimum utilisation. The effectiveness of the AIr contention window linear back-off process is examined through Markov analysis. An OPNET simulation model of the Alf protocol is used for validation of the analytical model results and provides non-reservation throughput and delay results. An analytical model of the IR link physical layer is presented and derives expressions for signal-to-noise ratio (SNR) and BER in relation to link transmitter and receiver characteristics, link geometry, noise levels and line encoding schemes. The effect of third user interference on BER and resulting link asymmetry is also examined, indicating the minimum separation distance for adjacent links. Expressions for BER are linked to the data link layer analysis to provide optimum throughput results in relation to physical layer propertiesandlink distance.EThOS - Electronic Theses Online ServiceGBUnited Kingdo