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GSM/GPRS分裂信道高效重分配策略
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作者 蒋体钢 范平志 +1 位作者 Kam-Yiu Lam Yi Pan 《电路与系统学报》 CSCD 北大核心 2008年第4期1-6,共6页
现有GSM/GPRS系统各种信道分裂策略都仅限于话音呼叫,即仅允许分裂信道分配给话音呼叫而不允许分配给包呼叫。因而,当系统没有空信道时,即使可以提供分裂信道,一个新到达的包呼叫也将被阻塞。本文提出的分裂信道重分配策略允许话音呼叫... 现有GSM/GPRS系统各种信道分裂策略都仅限于话音呼叫,即仅允许分裂信道分配给话音呼叫而不允许分配给包呼叫。因而,当系统没有空信道时,即使可以提供分裂信道,一个新到达的包呼叫也将被阻塞。本文提出的分裂信道重分配策略允许话音呼叫和包呼叫均可获得分裂信道,论文还研究了包呼叫得到分裂信道的条件。研究结果表明,允许将分裂信道分配给新到达包呼叫可以获得更优越的性能;在本文的参数设置下,在门限参数θ=2/3时,新策略的话音阻塞率和平均包传输时间没有明显恶化,而包阻塞率和平均信道利用率却得以显著改善。 展开更多
关键词 GSM/GPRS 信道分裂 信道分配
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Formation, structure and properties of GeC_(n)^(±) and Ge_(2)C_(n)^(±) binary clusters
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作者 CAOYali LIGuoliang TANGZichao 《Chinese Science Bulletin》 SCIE EI CAS 2005年第9期845-852,共8页
The binary cluster ions Ge2Cn+/Ge2Cn? and GeCn+ have been produced by laser ablation. The parity ef- fect is present in the negative ions Ge2Cn?, though it is not very prominent. While the experiments tell that the pa... The binary cluster ions Ge2Cn+/Ge2Cn? and GeCn+ have been produced by laser ablation. The parity ef- fect is present in the negative ions Ge2Cn?, though it is not very prominent. While the experiments tell that the parity effect is totally not shown in the positive ions Ge2Cn+. An extensive theoretical investigation on GeCn/GeCn+/GeCn?(n = 1?10) and Ge2Cn/Ge2Cn+/Ge2Cn?(n = 1?9) has been carried out by density functional theory at B3LPY level. The calcula- tion shows that the low-lying states of GeCn/GeCn+/GeCn?(n = 1?10) and Ge2Cn/Ge2Cn+/Ge2Cn? (n = 1?9) are linear structure with germanium atoms locating at terminals respectively. The electronic distributions, ionization potential (IPad), elec- tron affinity (EA) and increasing bonding energy reveal that the parity effect of neutral species is much stronger than that of ions, which is attributed to the valence π-electrons. It is explained that the differences between experiments and cal- culations are due to the kinetic factor in the formation of Ge2Cn±. 展开更多
关键词 锗离子 密度函数 分裂信道 奇偶效应
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