4,134 research outputs found
Layered Steered SpaceāTime-Spreading-Aided Generalized MC DS-CDMA
AbstractāWe present a novel trifunctional multiple-inputā multiple-output (MIMO) scheme that intrinsically amalgamates spaceātime spreading (STS) to achieve a diversity gain and a Vertical Bell Labs layered spaceātime (V-BLAST) scheme to attain a multiplexing gain in the context of generalized multicarrier direct-sequence code-division multiple access (MC DS-CDMA), as well as beamforming. Furthermore, the proposed system employs both time- and frequency-domain spreading to increase the number of users, which is also combined with a user-grouping technique to reduce the effects of multiuser interference
UTHM water quality classification based on sub index
River or stream at their source is unpolluted, but as water flow downstream, the river or lake is receiving point and non-point pollutant source. Ammoniacal nitrogen (NH3- N) and suspended solids (SS) strongly influences the dynamics of the dissolved oxygen in the water. Studies on monitoring this parameter were conducted for a river or lake but limited to the small man-made lake. This study is initiate to determine the changes in water quality of UTHM watershed as the water flows from upstream to downstream. The monitoring of NH3-N and TSS were monitored at two sampling schemes, 1) at the two-week interval and, 2) at a daily basis followed by the determination of the water quality sub-index particularly SIAN and SISS. The results showed that the two lakes in UTHM watershed were classified as polluted. In conclusion, the remedial action should be implemented to improve the water quality to meet the requirements at least to meet the recreational purpose
Low-complexity Location-aware Multi-user Massive MIMO Beamforming for High Speed Train Communications
Massive Multiple-input Multiple-output (MIMO) adaption is one of the primary
evolving objectives for the next generation high speed train (HST)
communication system. In this paper, we consider how to design an efficient
low-complexity location-aware beamforming for the multi-user (MU) massive MIMO
system in HST scenario. We first put forward a low-complexity beamforming based
on location information, where multiple users are considered. Then, without
considering inter-beam interference, a closed-form solution to maximize the
total service competence of base station (BS) is proposed in this MU HST
scenario. Finally, we present a location-aid searching-based suboptimal
solution to eliminate the inter-beam interference and maximize the BS service
competence. Various simulations are given to exhibit the advantages of our
proposed massive MIMO beamforming method.Comment: This paper has been accepted for future publication by VTC2017-Sprin
Peak to average power ratio based spatial spectrum sensing for cognitive radio systems
The recent convergence of wireless standards for incorporation of spatial dimension in wireless systems has made spatial spectrum sensing based on Peak to Average Power Ratio (PAPR) of the received signal, a promising approach. This added dimension is principally exploited for stream multiplexing, user multiplexing and spatial diversity. Considering such a wireless environment for primary users, we propose an algorithm for spectrum sensing by secondary users which are also equipped with multiple antennas. The proposed spatial spectrum sensing algorithm is based on the PAPR of the spatially received signals. Simulation results show the improved performance once the information regarding spatial diversity of the primary users is incorporated in the proposed algorithm. Moreover, through simulations a better performance is achieved by using different diversity schemes and different parameters like sensing time and scanning interval
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