This paper considers the use of infrared wireless communications for uplink transmission in extra wireless body-area networks. We focus on a multiuser medical application, where the collected medical data of several patients inside a hospital room is transmitted to one or several access points (APs). For this uplink transmission, we investigate the performance of optical code-division multiple access in asynchronous mode, while taking into account the effect of random transmitter orientation. For this purpose and to consider realistic scenarios, we implement an orientation-based random waypoint mobility model to consider the mobility of patients inside a hospital ward. Performance evaluation is done in terms of the link average bit-error-rate and outage probability. We further investigate the performance improvement by using several APs, compared with the case of a single AP. INDEX TERMS Wireless body area networks; Medical WBAN; Telemedicine; Wireless optical communications; Infrared data transmission; Optical code-division multiple access; Random waypoint model; Binary pulse-position modulation.
This paper considers the use of infrared-based optical wireless communications for multi-user uplink wireless body-area networks. We propose the use of optical-orthogonal frequency division multiple access (O-OFDMA) signaling to manage the multiple access (MA) requirement for relatively high-rate medical applications. In particular, we consider asymmetrically clipped O-OFDMA and analyze its performance in terms of bit-errorrate and outage probability in the presence of multi-user time synchronization errors. These latter may occur due to mobility and random transmitter orientations, and will impact the link performance by inducing MA interference (MAI). We show that the effect of MAI increases with increasing the data rate. For instance, for 1 and 2 Mbps data rates, to achieve a target biterror-rate of 10 −3 , the link distance is limited to 1.9 and 1 m, respectively, compared to 2.2 and 1.8 m in the absence of MAI.
The transfer of health monitoring data from multiple patients using wireless body-area networks requires the use of robust, and energy and bandwidth efficient multipleaccess schemes. This paper considers the frequency-division multiple access for the wireless uplink to a fixed access point when using infrared signals to collect medical data from several patients inside an emergency waiting room. The conventional optical orthogonal scheme applies Hermitian symmetry to obtain real-valued signals, which implies increased computational complexity. We consider a new approach transmitting only the real part of a complex-valued signal, where no such constraint is imposed. Based on the proposed scheme, and taking into account the limited dynamic range of an infrared light-emitting diode, we study the performance of direct current biased and asymmetrically clipped schemes, and show their advantage in terms of energy efficiency and computational complexity, as compared with the conventional schemes. For instance, we show that by using asymmetric clipping, around 35 mW less transmit power is needed to achieve a bit error rate of 10 -3 in the considered scenario. We also demonstrate the robustness of the proposed scheme against multiple access interference.
Ethernet network, standardized by IEEE 802.3, is vastly installed in Local Area Network (LAN) for cheaper cost and reliability. With the emergence of cost effective and enhanced user experience needs, the Quality of Service (QoS) of the underlying Ethernet network has become a major issue. A network must provide predictable, reliable and guaranteed services. The required QoS on the network is achieved through managing the end-to-end delay, throughput, jitter, transmission rate and many other network performance parameters. The paper investigates QoS parameters based on packet size to analyze the network performance. Segmentation in packet size larger than 1500 bytes, Maximum Transmission Unit (MTU) of Ethernet, is used to divide the large data into small packets. A simulation process under Riverbed modeler 17.5 initiates several scenarios of the Ethernet network to depict the QoS metrics in the Ethernet topology. For analyzing the result from the simulation process, varying sized packets are considered. Hence, the network performance results in distinct throughput, end-to-end delay, packet loss ratio, bit error rate etc. for varying packet sizes.Ethernet network is covered under IEEE 803.2 working group referring to the LAN family of network protocols. Since it is published as an official standard in 1985, several supplements have been defined to support additional network media and higher data rate compatibilities with the advancement of network technologies [1] [2]. Nowadays, Ethernet supports longer transmission distance up to 150 km which indicates the mass installation in an optical fiber network in most LAN environments. Ethernet network uses both packet and frame for the transmission using the physical and data link layer at the same time [3]. Ethernet stations communicate sending the data as packets where the Ether-Type field uses frames at the receiving station to select an appropriate protocol module by the operating system [4].Performance is the key issue for the installation of Ethernet in any LAN environment. In the field of telecommunication QoS is defined through some network parameters such as delivery rate, throughput, delay, collision probability, bandwidth efficiency, packet loss ratio, bit error rate, queuing delay, and jitter [5]. Ethernet has MTU of 1500 bytes which is much higher and potential to degrade the performance of the network [6]. However, if the packet sizes increase in the transmission, congestion occurs and probability of packet drop increases. Segmenting the larger packets to divide into smaller ones avoids congestion and impacts on QoS on the overall Ethernet network. Packet size impacts on the queuing in the switch and router's buffer during the transmission process among the Ethernet stations. This varies the packet arrival and departure rate consequently the packet processing rate [7]. When the packet size exceeds the MTU, the end-to-end packet arrival/departure delay increases [7]. Segmentation requires time and impacts on the data rate and degrades the QoS of the network....
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The uninterrupted development of memory market has experienced a new face since the beginning of the 21 st century due to the emergence of pc markets such as Laptop, Server PC, Tablet and Smart phones. This paper demonstrates the implementation of intelligent high performance memory access technique of DDR3 SDRAM. This paper discusses the full architecture of DDR3 SDRAM controller with minimum accessible time. It is designed to achieve high performance memory access with faster read and write.
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