通信工程畢業(yè)設(shè)計(jì)外文翻譯-一個(gè)新的協(xié)作頻譜感知算法認(rèn)知無(wú)線電網(wǎng)絡(luò)(編輯修改稿)
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【文章內(nèi)容簡(jiǎn)介】 obtain navgK as follows： 11001 ????? PPK a v g （ 8） From (8), It can be seen that, the normalized average number of sensing bits navgK is always smaller than 1. the munication traffic of our method is are deduced as opposed to the conventional energy detection method. III. THE PERFORMANCE ANALYSIS OF SPECTRUM SENSING In this section, the spectrum sensing performance of the proposed method will be analyzed. Assume the control channel between the unlicensed users and the mon receiver is perfect, the local decisions are reported without any error. Let )(?F and )(?G denote the cumulative distribution function (CDF) of the local test statistic ? under the hypothesis 0H and 1H , respectively. Then, we have [10]: ??????? ????0 0 )()2/,(1)|()( mmdHFF (9) ?? ? ??? 0 1 )|()( dHfG (10) Obviously, )()( 210 ?? FF ??? ， )()( 121 ?? GG ??? . If no any local decision is reported to the mon receiver, ., K=0 , we call that fail sensing. For this case, the mon receiver will request the user which has the highest reputation to send its local decision based on conventional energy detection method. Let 0? and 1? denote the probability of fail sensing under hypothesis 0H and 1H , respectively. Here we have: NNFFHKP 01200 ))()((}|0{ ??????? ??? (11) NNGGHKP 11211 ))()((}|0{ ??????? ??? (12) Apparently, N00 ??? and N11 ??? .In our scheme, the false alarm probability fQ ,the detection probability dQ ,and the missing probability mQ : )1)(1(}1,|1{}|1{}|0,1{0000AfPKHuPHKPHKuPQ??????????? (13) mQ = dQHKuP ???? 1}|0,0{ 1 (14) )1)(1(}1,|1{}|1{}|0,1{1111?PaKHuPHKPHKuPQ d?????????? (15) For simplicity, we assume the channel between the unlicensed users and the base station are ideal, the local decision will be reported without any error. So AP stand for the probability of the event that under hypothesis 0H , all the K users claim 0H and other NK users make no local decisions. dA QHKuPP ????? 1}|0,0{ 1 =????????????NKKNk FFFKN1 121 ))()(()( ??? = 02)( ?? ?NF （ 16） 12)( ?? ??GPB （ 17） ))(_1)(1( 020 ??? ??? Nf FQ （ 18） ))(_1)(1( 121 ??? ??? Nf GQ （ 19） IV. SIMULATION RESULTS In this section, some simulation results are presented to illustrate the system performance of our cooperative spectrum sensing algorithm based on reputation. The results of the conventional one threshold energy detection method are also shown for a parison. In our simulation, the mon simulation parameters are given as follows: Table 1. Simulation parameters 10?N db10_ ?? 5?m ?op ?p depicts the performance of cooperative spectrum sensing dQ and fQ . ?? .It can be observed that, pared it with the conventional method, the detection performance has improved significantly. For example, while fQ = , our method achieves extra detection probability. shows the decrease of the normalized transmission bits for different values of fail sensing, . 0? = 0, , , . Compared with conventional method, ., when 0? = 0, the normalized average number of sensing bits is dramatically decreased and bandwidth limited problem of the reporting channel is relieved. For example, when fQ = , almost 44% and 38% reduction of the normalized average number of sensing bits can be obtained for 0? = and 0? = , respectively. In our algorithm, fQ is upper bounded and lower bounded because of the probability of fail sensing 0? and the false alarm probability are based on (7), (13). Fig 2. dQ vs. fQ , ?? Fig 3. navgK vs. fQ , 0? =00, V. CONCLUSION In this paper, a new scheme in cooperative spectrum sensing for cognitive radio works under bandwidth constraints was proposed. In our method, only the secondary users with reliable information are allowed to report their sen
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