This paper presented a scheme of two-hop cellular network with fixed relay nodes (FRN). Based on this scheme, co-channel interference and signal interference ratio(SIR) received by base station(BS) and FRN were analyz...This paper presented a scheme of two-hop cellular network with fixed relay nodes (FRN). Based on this scheme, co-channel interference and signal interference ratio(SIR) received by base station(BS) and FRN were analyzed. Both the theoretical analysis and simulation results show that the SIR can be improved significantly when relays are employed in the network. The higher spectral efficiency can be obtained due to the improved two-hop link quality through the use of adaptive modulation and coding (AMC). The antenna height of FRN and the cell radius of BS and that of FRN influence SIR received by BS and FRN and the system spectral efficiency greatly. The proper antenna height of FRN and cell radius of BS and that of FRN were also given to get the highest spectral efficiency.展开更多
The growing demand for wireless services coupled with the limited availability of suitable electromagnetic spectrum is increasing the need for more efficient RF spectrum utilization. Spectrum allocated to TV operators...The growing demand for wireless services coupled with the limited availability of suitable electromagnetic spectrum is increasing the need for more efficient RF spectrum utilization. Spectrum allocated to TV operators can potentially be shared by wireless data services, either when the primary service is switched off or by exploiting spatial reuse opportunities. This paper describes a dynamic spectrum access scheme for use in the TV bands which uses cognitive radio techniques to determine the spectrum availability. The approach allows secondary users (SU) to operate in the presence of the primary users (PU) and the OPNET simulation and modelling software has been used to model the performance of the scheme. An analysis of the results shows that the proposed scheme protects the primary users from harmful interference from the secondary users. In comparison with the 802.11 MAC protocol, the scheme improves spectrum utilization by about 27% while limiting the interference imposed on the primary receiver.展开更多
采用三阶信噪比(signal to interference ratio,SIR)干扰谐振器作为基本谐振单元,通过调整阻抗比控制主频和第一杂散频率的位置,设计了一种新型高阻带抑制双通带滤波器.滤波器第一通带由主谐振频率产生,第二通带由第一杂散频率产生.运...采用三阶信噪比(signal to interference ratio,SIR)干扰谐振器作为基本谐振单元,通过调整阻抗比控制主频和第一杂散频率的位置,设计了一种新型高阻带抑制双通带滤波器.滤波器第一通带由主谐振频率产生,第二通带由第一杂散频率产生.运用三角耦合结构作为该滤波器的拓扑结构,使得整体滤波器呈现出带外传输零点和阻带的高抑制度.使用交指型耦合结构实现输入/输出端的强耦合,得到较高的外部品质因数.该滤波器的两个通带中心频率分别为1.57 GHz(GPS)和2.5 GHz(4G),3 d B带宽分别为4.0%和2.4%.结果表明,测量结果和仿真结果基本吻合.展开更多
Interference cancellation is made available by using smart antenna at cellular base stations. Well distributed cumulative probability of signal to interference plus noise power ratio appears to be vital for cellular m...Interference cancellation is made available by using smart antenna at cellular base stations. Well distributed cumulative probability of signal to interference plus noise power ratio appears to be vital for cellular mobile multimedia communications. A scenario of dual links dynamic power control combined to a solution of smart antenna is proposed to adjust the instant transmission power in terms of the disparity from the favorite range. Simulation results show that this method is quite effective to improve the cumulative distribution probability performance. Meanwhile, accompanying low power consumption is also obtained at both base stations and mobile stations.展开更多
Power control is of paramount importance in combating the near-far problem and co-channel interference in a CDMA cellular system. Due to fast fading and ambient interference in a wireless channel, conventional fixed-s...Power control is of paramount importance in combating the near-far problem and co-channel interference in a CDMA cellular system. Due to fast fading and ambient interference in a wireless channel, conventional fixed-step power control schemes have difficulty in compensating for the fast fading channel dynamically and in a timely manner. To acquire flexible power regulation in order to maintain required transmission capacity under the given transmission quality requirement, we propose a hybrid power control scheme which makes full use of the simple fuzzy inference rule refined by an operator in the fuzzy control and prediction property from related previous results in Generalized Prediction Control (GPC). In implementation of this strategy, we classify the fading zone into three levels according to the signal-to-noise-rate (SNR) requirement. In each level the power compensation amount varies with fading gradient and the compensation scheme varies as well. The digital results show that adoption of the fuzzy-GPC power regulation scheme has acquired a reasonable performance improvement when compared with fixed-step and fuzzy schemes. According to theoretic analysis and simulation results, we can conclude that under a variational transmission environment, a flexible power regulation scheme such as fuzzy-GPC is easy to adapt to the environment and thus overcomes the near-far effect and multi-access interference effectively.展开更多
We consider the Signal-to-Interference plus Noise Ratio(SINR) balancing problem in-volving joint beamfoming and power allocation in the Cognitive Radio(CR) network,wherein the Single-Input Multi-Output Multiple Access...We consider the Signal-to-Interference plus Noise Ratio(SINR) balancing problem in-volving joint beamfoming and power allocation in the Cognitive Radio(CR) network,wherein the Single-Input Multi-Output Multiple Access Channels(SIMO-MAC) are assumed.Subject to two sets of constraints:the interference temperature constraints of Primary Users(PUs) and the peak power constraints of Cognitive Users(CUs),a low-complexity joint beamforming and power allocation algo-rithm called Semi-Decoupled Multi-Constraint Power Allocation with Constraints Preselection(SDMCPA-CP) for SINR balancing is proposed.Compared with the existing algorithm,the proposed SDMCPA-CP can reduce the number of matrix inversions and matrix eigen decompositions signifi-cantly,especially when large numbers of PUs and CUs are active,while still providing the optimal balanced SINR level for all the CUs.展开更多
基金National Science Fund for Creative ResearchGroups (No. 60521002) Chinese NationalKey Technology R&D Program(No. 2005-BA908B02)Science Foundation of ShanghaiMunicipal Commission of Science and Tech-nology(No.05dz05802)
文摘This paper presented a scheme of two-hop cellular network with fixed relay nodes (FRN). Based on this scheme, co-channel interference and signal interference ratio(SIR) received by base station(BS) and FRN were analyzed. Both the theoretical analysis and simulation results show that the SIR can be improved significantly when relays are employed in the network. The higher spectral efficiency can be obtained due to the improved two-hop link quality through the use of adaptive modulation and coding (AMC). The antenna height of FRN and the cell radius of BS and that of FRN influence SIR received by BS and FRN and the system spectral efficiency greatly. The proper antenna height of FRN and cell radius of BS and that of FRN were also given to get the highest spectral efficiency.
文摘The growing demand for wireless services coupled with the limited availability of suitable electromagnetic spectrum is increasing the need for more efficient RF spectrum utilization. Spectrum allocated to TV operators can potentially be shared by wireless data services, either when the primary service is switched off or by exploiting spatial reuse opportunities. This paper describes a dynamic spectrum access scheme for use in the TV bands which uses cognitive radio techniques to determine the spectrum availability. The approach allows secondary users (SU) to operate in the presence of the primary users (PU) and the OPNET simulation and modelling software has been used to model the performance of the scheme. An analysis of the results shows that the proposed scheme protects the primary users from harmful interference from the secondary users. In comparison with the 802.11 MAC protocol, the scheme improves spectrum utilization by about 27% while limiting the interference imposed on the primary receiver.
文摘采用三阶信噪比(signal to interference ratio,SIR)干扰谐振器作为基本谐振单元,通过调整阻抗比控制主频和第一杂散频率的位置,设计了一种新型高阻带抑制双通带滤波器.滤波器第一通带由主谐振频率产生,第二通带由第一杂散频率产生.运用三角耦合结构作为该滤波器的拓扑结构,使得整体滤波器呈现出带外传输零点和阻带的高抑制度.使用交指型耦合结构实现输入/输出端的强耦合,得到较高的外部品质因数.该滤波器的两个通带中心频率分别为1.57 GHz(GPS)和2.5 GHz(4G),3 d B带宽分别为4.0%和2.4%.结果表明,测量结果和仿真结果基本吻合.
文摘Interference cancellation is made available by using smart antenna at cellular base stations. Well distributed cumulative probability of signal to interference plus noise power ratio appears to be vital for cellular mobile multimedia communications. A scenario of dual links dynamic power control combined to a solution of smart antenna is proposed to adjust the instant transmission power in terms of the disparity from the favorite range. Simulation results show that this method is quite effective to improve the cumulative distribution probability performance. Meanwhile, accompanying low power consumption is also obtained at both base stations and mobile stations.
文摘Power control is of paramount importance in combating the near-far problem and co-channel interference in a CDMA cellular system. Due to fast fading and ambient interference in a wireless channel, conventional fixed-step power control schemes have difficulty in compensating for the fast fading channel dynamically and in a timely manner. To acquire flexible power regulation in order to maintain required transmission capacity under the given transmission quality requirement, we propose a hybrid power control scheme which makes full use of the simple fuzzy inference rule refined by an operator in the fuzzy control and prediction property from related previous results in Generalized Prediction Control (GPC). In implementation of this strategy, we classify the fading zone into three levels according to the signal-to-noise-rate (SNR) requirement. In each level the power compensation amount varies with fading gradient and the compensation scheme varies as well. The digital results show that adoption of the fuzzy-GPC power regulation scheme has acquired a reasonable performance improvement when compared with fixed-step and fuzzy schemes. According to theoretic analysis and simulation results, we can conclude that under a variational transmission environment, a flexible power regulation scheme such as fuzzy-GPC is easy to adapt to the environment and thus overcomes the near-far effect and multi-access interference effectively.
基金Supported by the National Basic Research Program (973) of China (No. 2009CB320400)the National High-Tech Research and Development Program (863) of China (No. 2009AA01Z243)+1 种基金the National Science Fundation of China (No. 61072044)the Natural Science Fundation of Jiangsu Province (BK2009056)
文摘We consider the Signal-to-Interference plus Noise Ratio(SINR) balancing problem in-volving joint beamfoming and power allocation in the Cognitive Radio(CR) network,wherein the Single-Input Multi-Output Multiple Access Channels(SIMO-MAC) are assumed.Subject to two sets of constraints:the interference temperature constraints of Primary Users(PUs) and the peak power constraints of Cognitive Users(CUs),a low-complexity joint beamforming and power allocation algo-rithm called Semi-Decoupled Multi-Constraint Power Allocation with Constraints Preselection(SDMCPA-CP) for SINR balancing is proposed.Compared with the existing algorithm,the proposed SDMCPA-CP can reduce the number of matrix inversions and matrix eigen decompositions signifi-cantly,especially when large numbers of PUs and CUs are active,while still providing the optimal balanced SINR level for all the CUs.
