A resource allocation protocol is presented in an orthogonal frequency division multiple access （OFDMA） cognitive radio （CR） network with a hybrid model which combines overlay and underlay models. Without disrupti...A resource allocation protocol is presented in an orthogonal frequency division multiple access （OFDMA） cognitive radio （CR） network with a hybrid model which combines overlay and underlay models. Without disrupting the primary user （PU） transmissions, the overlay model allows the secondary user （SU） to utilize opportunistically the idle sub-channels; the underlay model allows the SU to occupy the same sub-channels with PU. The proposed protocols are designed for maximizing the quality of experience （QoE） of CR users and switching dynamically between the overlay and underlay models. QoE is measured by the mean opinion score （MOS） rather than simply fulfilling the physical and medium access control （MAC） layer requirements. The simulations considering the file transfer and video stream services show that the proposed resource allocation strategy is spectrum efficient.展开更多
Industrial wireless sensor networks adopt a hierarchical structure with large numbers of sensors and routers. Time Division Multiple Access (TDMA) is regarded as an efficient method to reduce the probability of confli...Industrial wireless sensor networks adopt a hierarchical structure with large numbers of sensors and routers. Time Division Multiple Access (TDMA) is regarded as an efficient method to reduce the probability of confliction. In the intra-cluster part, the random color selection method is effective in reducing the retry times in an application. In the inter-cluster part, a quick assign algorithm and a dynamic maximum link algorithm are proposed to meet the quick networking or minimum frame size requirements. In the simulation, the dynamic maximum link algorithm produces higher reductions in the frame length than the quick assign algorithm. When the number of routers is 140, the total number of time slots is reduced by 25%. However, the first algorithm needs more control messages, and the average difference in the number of control messages is 3 410. Consequently, the dynamic maximum link algorithm is utilized for adjusting the link schedule to the minimum delay with a relatively high throughput rate, and the quick assign algorithm is utilized for speeding up the networking process.展开更多
In this paper,we demonstrate a novel multi-service wired/wireless integrated access architecture of cloud radio access network(C-RAN) based on radio-over-fiber passive optical network(RoF-PON) system,which utilizes sc...In this paper,we demonstrate a novel multi-service wired/wireless integrated access architecture of cloud radio access network(C-RAN) based on radio-over-fiber passive optical network(RoF-PON) system,which utilizes scalable multiple-frequency millimeter-wave(MF-MMW) generation based on tunable optical frequency comb(TOFC).In the baseband unit(BBU) pool,the generated optical comb lines are modulated into wired,RoF and WiFi/WiMAX signals,respectively.The multi-frequency RoF signals are generated by beating the optical comb line pairs in the small cell.The WiFi/WiMAX signals are demodulated after passing through the band pass filter(BPF) and band stop filter(BSF),respectively,whereas the wired signal can be received directly.The feasibility and scalability of the proposed multi-service wired/wireless integrated C-RAN are confirmed by the simulations.展开更多
基金The National Natural Science Foundation of China(No.61271207,61372104)the Natural Science Foundation of Jiangsu Province(No.BK20130530)+1 种基金the Natural Science Foundation of the Jiangsu Higher Education Institutions of China(No.12KJB510002)the Programs of Senior Talent Foundation of Jiangsu University(No.11JDG130)
文摘A resource allocation protocol is presented in an orthogonal frequency division multiple access （OFDMA） cognitive radio （CR） network with a hybrid model which combines overlay and underlay models. Without disrupting the primary user （PU） transmissions, the overlay model allows the secondary user （SU） to utilize opportunistically the idle sub-channels; the underlay model allows the SU to occupy the same sub-channels with PU. The proposed protocols are designed for maximizing the quality of experience （QoE） of CR users and switching dynamically between the overlay and underlay models. QoE is measured by the mean opinion score （MOS） rather than simply fulfilling the physical and medium access control （MAC） layer requirements. The simulations considering the file transfer and video stream services show that the proposed resource allocation strategy is spectrum efficient.
基金supported by Beijing Education and Scientific Research Programthe National High Technical Research and Development Program of China (863 Program) under Grant No. 2011AA040101+2 种基金the National Natural Science Foundation of China under Grants No. 61173150, No. 61003251Beijing Science and Technology Program under Grant No. Z111100054011078the State Scholarship Fund
文摘Industrial wireless sensor networks adopt a hierarchical structure with large numbers of sensors and routers. Time Division Multiple Access (TDMA) is regarded as an efficient method to reduce the probability of confliction. In the intra-cluster part, the random color selection method is effective in reducing the retry times in an application. In the inter-cluster part, a quick assign algorithm and a dynamic maximum link algorithm are proposed to meet the quick networking or minimum frame size requirements. In the simulation, the dynamic maximum link algorithm produces higher reductions in the frame length than the quick assign algorithm. When the number of routers is 140, the total number of time slots is reduced by 25%. However, the first algorithm needs more control messages, and the average difference in the number of control messages is 3 410. Consequently, the dynamic maximum link algorithm is utilized for adjusting the link schedule to the minimum delay with a relatively high throughput rate, and the quick assign algorithm is utilized for speeding up the networking process.
基金supported by the National Natural Science Foundation of China(No.61301156)
文摘In this paper,we demonstrate a novel multi-service wired/wireless integrated access architecture of cloud radio access network(C-RAN) based on radio-over-fiber passive optical network(RoF-PON) system,which utilizes scalable multiple-frequency millimeter-wave(MF-MMW) generation based on tunable optical frequency comb(TOFC).In the baseband unit(BBU) pool,the generated optical comb lines are modulated into wired,RoF and WiFi/WiMAX signals,respectively.The multi-frequency RoF signals are generated by beating the optical comb line pairs in the small cell.The WiFi/WiMAX signals are demodulated after passing through the band pass filter(BPF) and band stop filter(BSF),respectively,whereas the wired signal can be received directly.The feasibility and scalability of the proposed multi-service wired/wireless integrated C-RAN are confirmed by the simulations.
