This paper proposes a Service Differentiated-Dynamic Slotted Multiple Access （SD-DSMA） protocol with QoS guarantee. The Media Access Control （MAC） frame format is variable according to the traffic of uplink and do...This paper proposes a Service Differentiated-Dynamic Slotted Multiple Access （SD-DSMA） protocol with QoS guarantee. The Media Access Control （MAC） frame format is variable according to the traffic of uplink and downlink and the traffic of control and data. In addition, the services are divided into two categories, Guaranteed Bandwidth （GB） and Best Effort （BE）. Uplink control message slots are designed for the GB users to reduce contention. Taking into consideration the techniques in physical layer, a two-Dimensional Radio Resource Allocation （2-D RRA） method is proposed. The 2-D RRA is an efficient way to allocate radio resources for multi-cell, multi-user OFDM/TDMA system as it takes into consideration both the channel condition and the co-channel interference. The piggyback mechanism and fair scheduling algorithm are adopted for GB services, and the max C/I scheduling algorithm is used for BE services. The simulation results show that the proposed MAC protocol has better performance in terms of delay, probability of successful access request.展开更多
An outdoor propagation measurement campaign for beyond 3G （B3G） as well as a wide-band indoor measurement campaign have been performed recently in Beijing, China, in which the sounding signals are transmitted by an ...An outdoor propagation measurement campaign for beyond 3G （B3G） as well as a wide-band indoor measurement campaign have been performed recently in Beijing, China, in which the sounding signals are transmitted by an one-antenna base station and received by a two-antenna mobile receiver operated at 3.49～3.51 GHz bandwidth. Different scenarios： stationary line-of-sight （LoS）, stationary non-LoS （NLoS） scenarios, and dynamic NLoS are deliberately chosen in a classic urban environment and office environment. The initial results are presented in this article. Parameters including vector channel impulse response, path loss, rays number, excess delay spread etc. are extracted, analyzed, and briefly reported here.展开更多
The Wide-Sense Stationary Uncorrelated Scattering （WSSUS） model has long been viewed as a basic channel model to describe the fading dispersive channel. But non- WSSUS models have more universal applicability when t...The Wide-Sense Stationary Uncorrelated Scattering （WSSUS） model has long been viewed as a basic channel model to describe the fading dispersive channel. But non- WSSUS models have more universal applicability when the wireless mobile channel with broadband is studied with finer and more detailed knowledge of propagation environments. So the four-Dimension （4-D） characteristics of channel, namely time, lag, frequency, and Doppler, should be studied together. In this paper, Wigner-Ville distribution of Time-Frequency （TF） domain is introduced to analyze channel in which the incidence rays are non-stationary and correlated with each other. Several channel models, according to different move modes of incidence rays, with time-varying Doppler shift are designed and 4-D Local Scattering Function （LSF） are computed and simulated respectively. Our simulation results show the LSF present asymmetric and non-periodic TF distri- bution for some symmetric and periodic move modes of incidence rays.展开更多
基金This workis supported by National Nature Science Foundation of China (60302024 ,60496312 ,60132010) .
文摘This paper proposes a Service Differentiated-Dynamic Slotted Multiple Access （SD-DSMA） protocol with QoS guarantee. The Media Access Control （MAC） frame format is variable according to the traffic of uplink and downlink and the traffic of control and data. In addition, the services are divided into two categories, Guaranteed Bandwidth （GB） and Best Effort （BE）. Uplink control message slots are designed for the GB users to reduce contention. Taking into consideration the techniques in physical layer, a two-Dimensional Radio Resource Allocation （2-D RRA） method is proposed. The 2-D RRA is an efficient way to allocate radio resources for multi-cell, multi-user OFDM/TDMA system as it takes into consideration both the channel condition and the co-channel interference. The piggyback mechanism and fair scheduling algorithm are adopted for GB services, and the max C/I scheduling algorithm is used for BE services. The simulation results show that the proposed MAC protocol has better performance in terms of delay, probability of successful access request.
文摘An outdoor propagation measurement campaign for beyond 3G （B3G） as well as a wide-band indoor measurement campaign have been performed recently in Beijing, China, in which the sounding signals are transmitted by an one-antenna base station and received by a two-antenna mobile receiver operated at 3.49～3.51 GHz bandwidth. Different scenarios： stationary line-of-sight （LoS）, stationary non-LoS （NLoS） scenarios, and dynamic NLoS are deliberately chosen in a classic urban environment and office environment. The initial results are presented in this article. Parameters including vector channel impulse response, path loss, rays number, excess delay spread etc. are extracted, analyzed, and briefly reported here.
文摘The Wide-Sense Stationary Uncorrelated Scattering （WSSUS） model has long been viewed as a basic channel model to describe the fading dispersive channel. But non- WSSUS models have more universal applicability when the wireless mobile channel with broadband is studied with finer and more detailed knowledge of propagation environments. So the four-Dimension （4-D） characteristics of channel, namely time, lag, frequency, and Doppler, should be studied together. In this paper, Wigner-Ville distribution of Time-Frequency （TF） domain is introduced to analyze channel in which the incidence rays are non-stationary and correlated with each other. Several channel models, according to different move modes of incidence rays, with time-varying Doppler shift are designed and 4-D Local Scattering Function （LSF） are computed and simulated respectively. Our simulation results show the LSF present asymmetric and non-periodic TF distri- bution for some symmetric and periodic move modes of incidence rays.
