摘要：
Nowadays multiple wireless communication systems operate in industrial environments side by side.In such an environment performance of one wireless network can be degraded by the collocated hostile wireless network having higher transmission power or higher carrier sensing threshold.Unlike the previous research works which considered IEEE 802.15.4 for the Industrial Wireless communication systems(iWCS)this paper examines the coexistence of IEEE 802.11 based iWCS used for delay-stringent communication in process automation and gWLAN(general-purpose WLAN)used for non-real time communication.In this paper,we present a Markov chain-based performance model that described the transmission failure of iWCS due to geographical collision with gWLAN.The presented analytic model accurately determines throughput,packet transaction delay,and packet loss probability of iWCS when it is collocated with gWLAN.The results of the Markov model match more than 90%with our simulation results.Furthermore,we proposed an adaptive transmission power control technique for iWCS to overcome the potential interferences caused by the gWLAN transmissions.The simulation results show that the proposed technique significantly improves iWCS performance in terms of throughput,packet transaction,and cycle period reduction.Moreover,it enables the industrial network for the use of delay critical applications in the presence of gWLAN without affecting its performance.
摘要：
Brain computer interface(BCI)systems permit individuals with motor disorders to utilize their thoughts as a mean to control external devices.BCI is a promising interdisciplinary field that gained the attention of many researchers.Yet,the development of BCI systems is facing several challenges,such as network lifetime.The Medium Access Control(MAC)Protocol is the bottle-neck of network reliability.There are many MAC protocols that can be utilized for dependable transmission in BCI applications by altering their control parameters.However,modifying these parameters is another source of concern due to the scarcity in knowledge about the effect of modification.Also,there is still no instrument that can receive and actualize these parameters on transmitters embedded inside the cerebrum.In this paper,we propose two novel MAC protocols using passive UHF-RFID,the proposed protocols provide efficient and reliable communication between the transmitters and the receiver.The UHF-RFID transmitters were used because they are energy efficient which makes them compatible with BCI application.The first protocol is designed for the EEG signals.While the second protocol was designed for the ECoG signals.The evaluation results showed the validity of the proposed protocols in terms of network performance.The results also proved that the protocols are suitable and reliable for designing efficient BCI applications.
摘要：
無(wú)線局域網(wǎng)絡(luò)(Wireless Local Area Networks,WLAN)是指采用無(wú)線媒體或介質(zhì),利用射頻技術(shù),在一定的區(qū)域內(nèi)所形成的無(wú)線網(wǎng)絡(luò).無(wú)線局域網(wǎng)絡(luò)使得用戶(hù)得以擺脫網(wǎng)線等物理傳輸媒介的束縛,在無(wú)線局域網(wǎng)絡(luò)覆蓋的范圍之內(nèi),能夠低成本、高速、便捷地訪問(wèn)互聯(lián)網(wǎng)或局域網(wǎng).如今無(wú)線局域網(wǎng)已經(jīng)進(jìn)入尋常百姓家,為人們的生活帶來(lái)極大便利.本文將從無(wú)線局域網(wǎng)的產(chǎn)生、發(fā)展、關(guān)鍵技術(shù)、應(yīng)用和發(fā)展趨勢(shì)五個(gè)方面對(duì)無(wú)線局域網(wǎng)進(jìn)行分析和介紹.
摘要：
針對(duì)電力線通信信號(hào)強(qiáng)度和時(shí)延指標(biāo)無(wú)法準(zhǔn)確測(cè)量,且網(wǎng)絡(luò)建立過(guò)程中缺少路徑權(quán)值和方向的問(wèn)題,文章提出了基于AMI測(cè)量參數(shù)的路徑指標(biāo)間接測(cè)量方法.從AMI系統(tǒng)的智能電能表和集中器獲取線路電壓、電流、相位等測(cè)量參數(shù),并以臺(tái)區(qū)負(fù)荷中心的測(cè)量值為參考,利用基爾霍夫定律計(jì)算出不同相線測(cè)量點(diǎn)的電壓損失大小和方向,也可結(jié)合線路材質(zhì)參數(shù)計(jì)算出線路距離,從而實(shí)現(xiàn)了通信網(wǎng)絡(luò)路徑權(quán)值和方向的間接測(cè)量.為了驗(yàn)證方法的有效性,提出了一種采用AMI測(cè)量參數(shù)的p-persistent CSMA洪泛路由算法,實(shí)驗(yàn)證明該方法可有效縮短電力線通信網(wǎng)絡(luò)路徑深度和網(wǎng)絡(luò)時(shí)延.%In current power line communication(PLC)networks,there still exists great difficulty to measure the sig-nal power and the time delay,and the lack of effective path weights and direction is also a problem in the process of network establishment.Aimed to solve these problems,this paper proposes an indirect measuring method based on the AMI measuring parameters.By obtaining the circuit voltage,current,and phase parameters from the smart meters and concentrator of AMI system,the value of circuit voltage loss and the voltage direction can be calculated according to Kirchhoff's law,which belongs to the different phase line based on the load center of the low voltage distribution net -work.Moreover,the power line distance can also be achieved based on the material parameters, and the indirect measurement of the communication network path value and direction can be realized.In order to verify the effective-ness of the method,this paper proposes a p-persistent CSMA flooding network scheme based on AMI parameters.Ex-perimental results show that the application of AMI parameters plays an important role on reducing the depth of the re -lay and improving the networking delay.
摘要：
We consider a carrier sense multiple access (CSMA) in an unslotted cognitive radio network with random residence time. In this system, if an arriving secondary user (SU) does not find any idle channels, then the SU either enters the back-off group or gives up its service and leaves the system. SUs in the back-off group have random mobility, so may re-access the channel after random time or go to the other network after random residence time. We model the system by 3-demensional Continuous Time Markov Chain (CTMC) and obtain the steady state probability of the system by matrix analytic method. In numerical results, we compare the performance of two systems with and without residence time of SUs. It is shown that the random mobility of SUs has an impact on the performance of SUs in cognitive radio networks.
AI期刊論文
查重降重
文獻(xiàn)查詢(xún)
文獻(xiàn)下載
文獻(xiàn)閱讀
文獻(xiàn)發(fā)表
