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ABSTRACT: Multiple input multiple output (MIMO) transceivers can potentially increase overall network throughput via spatial reuse of spectrum by allowing multiple simultaneous communications. Efficient use of MIMO technique in wireless ad hoc networks still meets challenges especially for upper layer protocols. In this paper we propose a cross-layer strategy of allowing the data stream and routing control stream transmitting concurrently with different antennas of the MIMO system. Implementing on the ad hoc on-demand distance vector (AODV) protocol, simulation results show that the strategy of queuing different type of packets obviously decreases the duration of route establishment, especially when the network is suffering heavy traffic load.
Personal, Indoor and Mobile Radio Communications, 2009 IEEE 20th International Symposium on; 10/2009
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Wireless Communications and Mobile Computing. 01/2006; 6:467-474.
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ABSTRACT: One of the principal disadvantages of Orthogonal Frequency Division Multiplexing (OFDM) is very sensitive to carrier frequency
offset. The integer frequency offset has no effect on the orthogonality among the subcarriers, but it causes a circular shift
and phase rotation of the received data symbols sequence, resulting in a Bit Error Rate(BER) of 0.5. In this paper, a novel
integer frequency offset estimator for OFDM is derived based on maximum likelihood estimation technique and exploration of
the differential relation between two consecutive OFDM data symbol sequences in frequency domain. Its performance is compared
with the conventional method by computer simulations for the additive white Gaussian noise channel and a multipath fading
channel. Simulation results show that the performance of the proposed estimator is better than the conventional estimator.
Journal of Electronics (China) 10/2005; 22(6):569-574.
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ABSTRACT: An exact approach to analyze the access delay of the media access schemes that employ beamforming to locate users out of the broadcast range of the access point (AP) in a WLAN is put forward. Results show that the scheme which distinguishes the users residing in or out of broadcast range of the AP can provide rapider media access. And then the simulation verifies the proposed approach.
Parallel and Distributed Systems, 2005. Proceedings. 11th International Conference on; 08/2005
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ABSTRACT: The use of smart antennas in extending coverage range and capacity of wireless LANs dictates the employment of novel media access control (MAC) schemes, with which the access point (AP) provides access to users by learning their spatial signatures. This paper puts forward an exact approach to analyze the performance of the schemes in terms of required time so that the AP becomes aware of user locations and grants access to the system. The numerical results show that the scheme which distinguishes the users residing in or out of broadcasting coverage range of the AP can provide rapider media access. In addition, the simulation results verify the theoretical approach.
Communications, 2005. ICC 2005. 2005 IEEE International Conference on; 06/2005
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ABSTRACT: This paper studies the performance of the IEEE 802.11 standard MAC protocol for integrated data and voice transmission with the DCF (distributed coordination function) and the PCF (point coordination function). By simulation, we evaluate the network performance for various protocol parameters, especially, the delay jitter for voice traffic. The main factor to influence delay jitter is given. Numerical results show that it is important to choose appropriate parameters and compromise the number of voice stations and the data traffic throughput to get the enhanced performance of IEEE 802.11. The performance of protocol in theory is derived and is verified by the simulation results.
Advanced Information Networking and Applications, 2004. AINA 2004. 18th International Conference on; 04/2004
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ABSTRACT: The IEEE 802.11 standard MAC is a hybrid protocol of random access and polling when both DCF (distributed coordination function) and PCF (point coordination function) are used. This paper evaluates the performance of the MAC protocol for integrated data and voice transmission with the two access mechanisms. By simulation, we evaluate the network performance for various values of the protocol parameters. Especially, voice traffic is sensitive to delay jitter and here we point out the main factors to influence it. Numerical results show that it is important to choose appropriate parameters and we should compromise the number of the voice stations and the data traffic throughput to get the enhanced performance of IEEE 802.11. Finally, the performance of protocol in theory is derived and is verified by the simulation results.
Wireless Communications and Networking Conference, 2004. WCNC. 2004 IEEE; 04/2004
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18th International Conference on Advanced Information Networking and Applications (AINA 2004), 29-31 March 2004, Fukuoka, Japan; 01/2004
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ABSTRACT: The IEEE 802.11 standard MAC is a hybrid protocol of random access and polling when both DCF (distributed coordination function) and PCF (point coordination function) are used. On the base of the performance analysis of the MAC protocol for integrated data and voice transmission by simulation, this paper puts forward a self-adaptive transmission scheme to support multi-service over the IEEE 802.11 WLAN. The simulation results show that, on the premise of satisfying the maximum allowable delay of packet voice, the self-adaptive transmission scheme can improve the data traffic performance and increase the WLAN capacity through dynamic and appropriate adjustment of the protocol parameters. Especially, the scheme is easy to be realized for no change in the MAC protocol is needed.
Wireless Ad-Hoc Networks, 2004 International Workshop on;
