• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.10
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• pp.2259-2264
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• 2013

In this paper, a selective multiple-input multiple-output(MIMO) transmission scheme is proposed in dual-hop MIMO relaying systems, in which orthogonal space-time block code(OSTBC) transmission and transmit antenna selection(TxAS) transmission are selectively used. Assuming independent Rayleigh fading channels, the outage probability is analyzed for a decode-and-forward(DF) relaying system using the selective MIMO transmission scheme. Also, through numerical investigation, the outage performance for the DF relaying system using the selective MIMO transmission scheme is compared with that for the conventional DF relaying system using OSTBC or TxAS. Moreover, from the performance comparison, it is shown that the proposed scheme can reduce the system overhead without outage performance degradation.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.8
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• pp.53-60
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• 2013

In this paper, the new multi-beamforming is proposed for Multiple-input multiple-output (MIMO) Multicarrier-Code division multiple access(MC-CDMA) systems to overcome the decrease of performance due to multiuser interference and multiple-antenna interference. Installing the number of multi-beamformer which is equal to the number of multi-transmitter antennas and exploiting the proposed approach at the receiver of MIMO MC-CDMA, the multi-beams are formed toward each multi-antenna of desired user and null beam are formed to other interference. Therefore, the performance of MIMO MC-CDMA system is improved as removing the interference signal. BER performance improvement is investigated through computer simulation by the proposed approach to MIMO MC-CDMA system.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.5
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• pp.21-29
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• 2008

This paper proposes a carrier frequency of set estimation algorithm for IEEE802.11n system. As IEEE802.11n is a multiple input multiple output(MIMO) system, so there are several combining techniques which are used in multiple receive antenna system. In this paper, we propose hybrid carrier frequency offset estimation algorithms using combining techniques in multiple receive antenna systems, and show that the proposed selection combining carrier frequency offset (CFO) estimation algorithm can estimate carrier frequency offset within 1/10 MSE error at SNR 10 dB in channel B and within 1/2 MSE error at SNR 10 dB in channel D rather than the conventional MIMO CFO one.

• ETRI Journal
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• v.26 no.5
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• pp.375-383
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• 2004

This paper proposes a common interleaving method associated with independent channel-encoding among transmitter antenna branches in orthogonal frequency and code division multiplexing based on multiple-input multiple-output (MIMO) multiplexing to achieve an extremely high throughput such as 1 Gbps using a 100 MHz bandwidth. This paper also investigates the average packet error rate performance as a function of the average received signal energy per bit-to-background noise power spectrum density ratio $(E_b/N_0)$. We found that the loss in the required average received $E_b/N_0$ of the proposed method is only within approximately 0.3 dB in up to a 12-path Rayleigh fading channel, using 16QAM and Turbo coding with a coding rate of 5/6. We also clarify that even for a large fading correlation among antenna branches, 1 Gbps is still possible by increasing the transmission power. Therefore, the proposed method reduces the processing rate to 1/4 in the turbo decoder with only a slight loss in the required average received $E_b/N_0$.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.2
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• pp.635-656
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• 2019

In this paper, we investigate the degrees of freedom (DoF) of a multi-cell multi-user multiple-input multiple-output (MIMO) interference broadcast channel (IBC) with non-cooperation distributed base stations (BS), where each BS serves users of its corresponding cell. When all BSs simultaneously transmit their own signals over the same frequency band in the MIMO IBC, the edge users in each cell will suffer the inter-cell interference (ICI) and inter-user interference (IUI) signals. In order to eliminate the ICI and IUI signals, a distributed space time interference alignment (DSTIA) approach is proposed where each BS has only limited access to distributed moderately-delay channel state information at the transmitter (CSIT). It is shown that the DSTIA scheme can obtain the appreciate DoF gains. In addition, the DoF upper bound is asymptotically achievable as the number of antenna at each BS increases. It is shown that the DSTIA method can get DoF gains over other interference alignment schemes with delayed CSIT in literature. Moreover, the DSTIA method can attain higher DoFs than the IA schemes with global CSIT for certain antenna configurations.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.12
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• pp.1132-1138
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• 2011

In this paper, a method for synthesizing the linear antenna array patterns with broad nulls(BN) at the interference directions is newly presented. Opposit to the conventional methods in which the weights of array elements are optimized for BN control, this method simplifies the control process for multiple BN directions and widths by optimally perturbing the zero positions inherent to Schelkunoff polynomial transformed from the array factor. It is also shown that this method can be easily applicable to the phased array antennas. The proposed scheme is numerically verified by substituting the extracted complex weights into the array factor.

• ETRI Journal
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• v.31 no.5
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• pp.481-488
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• 2009

This paper proposes a new multiuser scheduling algorithm that can simultaneously support a variety of different quality-of-service (QoS) user groups while satisfying fairness among users in the same QoS group in MIMO broadcast channels. Toward this goal, the proposed algorithm consists of two parts: a QoS-aware fair (QF) scheduling within a QoS group and an antenna trade-off scheme between different QoS groups. The proposed QF scheduling algorithm finds a user set from a certain QoS group which can satisfy the fairness among users in terms of throughput or delay. The antenna trade-off scheme can minimize the QoS violations of a higher priority user group by trading off the number of transmit antennas allocated to different QoS groups. Numerical results demonstrate that the proposed QF scheduling method satisfies different types of fairness among users and can adjust the degree of fairness among them. The antenna trade-off scheme combined with QF scheduling can improve the probability of QoS-guaranteed transmission when supporting different QoS groups.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.10
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• pp.1338-1343
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• 2018

MIMO(Multiple Input Multiple Output) slot antenna that operates on the dual WiFi band(2.401~2.495GHz, 5.18~5.825GHz), in this paper, was studied. The basic theory for the slot design is based on the coupling between adjacent slot, and slots are fed by the each microstrip lines. Two slot antennas for the MIMO operation are located on the left and the right side of top of the metal notebook, and grounds between a notebook and two microstrip feeding lines are connected. Measurement of return loss showed under -6dB on entire design band, and isolation was below than -30dB. Radiation efficiency, average gain and peak gain for the left and the right slot were measured in the anechoic chamber, and showed good performances as 57.25%, -2.42dBi, 5.64dBi and 55.35%, -2.61dBi, 6.42dBi for the 2.4GHz band and 55.89%, -2.58dBi, 7.3dBi and 53.79%, -2.8dBi, 7.54dBi for the 5GHz band.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.8
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• pp.820-825
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• 2008

A method to improve isolation characteristics of internal MIMO antenna systems for wireless portable devices operating in the $2.3{\sim}2.4$ GHz band is presented. The proposed system incorporates multiple pairs of L-slots between the two antennas in the ground plane, which operate like a band-stop filter, suppressing mutual coupling between the antennas and resulting in improved isolation. A MIMO antenna system with 6 pairs of L-slots shows reflection loss of -26.4 dB and isolation of -37.5 dB.

• Journal of Advanced Navigation Technology
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• v.14 no.5
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• pp.640-647
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• 2010

Many methods have been proposed to detect faults of carrier phase measurements, but there are no distinguished methods for land transportation systems. in this paper, the baseline constraints are used to detect faults in GPS carrier phase measurements with vehicle dynamic information. The faults include the multipath on GPS carrier measurements. Multiple antenna groups are used for this research. In the measurement domain the fault detection has been accomplished so that the implementation is easier than other methods.