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Kenichi Higuchi - One of the best experts on this subject based on the ideXlab platform.
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a simple downlink transmission power control method for worst User Throughput maximization in heterogeneous networks
International Conference on Signal Processing and Communication Systems, 2013Co-Authors: Tomoyuki Aota, Kenichi HiguchiAbstract:This paper proposes a simple downlink transmission power control method in heterogeneous networks aiming at maximization of the worst User Throughput. The proposed method requires inter-base station (BS) cooperation. However, the proposed method can be implemented by sharing only a single metric among BSs, which is different from the conventional BS cooperative transmission power control methods that require exchanging a large amount of channel state information (CSI) of all Users among BSs. In the proposed method, cooperating BSs share the tentative worst User Throughput within the cooperating cells, so the proposed method does not require additional CSI feedback from the User terminals. Using this shared metric information, each BS updates its transmission power so that the target Throughput is achieved for all Users served by that BS. Although the proposed method is computationally efficient and the amount of the shared information via the backhaul is very limited, the worst User Throughput achieved using the proposed method is very close to the upper bound performance. Multi-cell simulation evaluation shows that the proposed method yields advantageous Throughput performance and a transmission power reduction effect compared to conventional approaches.
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ICSPCS - A simple downlink transmission power control method for worst User Throughput maximization in heterogeneous networks
2013 7th International Conference on Signal Processing and Communication Systems (ICSPCS), 2013Co-Authors: Tomoyuki Aota, Kenichi HiguchiAbstract:This paper proposes a simple downlink transmission power control method in heterogeneous networks aiming at maximization of the worst User Throughput. The proposed method requires inter-base station (BS) cooperation. However, the proposed method can be implemented by sharing only a single metric among BSs, which is different from the conventional BS cooperative transmission power control methods that require exchanging a large amount of channel state information (CSI) of all Users among BSs. In the proposed method, cooperating BSs share the tentative worst User Throughput within the cooperating cells, so the proposed method does not require additional CSI feedback from the User terminals. Using this shared metric information, each BS updates its transmission power so that the target Throughput is achieved for all Users served by that BS. Although the proposed method is computationally efficient and the amount of the shared information via the backhaul is very limited, the worst User Throughput achieved using the proposed method is very close to the upper bound performance. Multi-cell simulation evaluation shows that the proposed method yields advantageous Throughput performance and a transmission power reduction effect compared to conventional approaches.
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ISWCS - Uplink non-orthogonal access with MMSE-SIC in the presence of inter-cell interference
2012 International Symposium on Wireless Communication Systems (ISWCS), 2012Co-Authors: Yuki Endo, Yoshihisa Kishiyama, Kenichi HiguchiAbstract:This paper investigates the system-level Throughput performance of non-orthogonal access with minimum mean squared error-based linear filtering followed by a successive interference canceller (MMSE-SIC) in the cellular uplink. Although non-orthogonal access employing the MMSE-SIC achieves the entire region of the multiUser capacity in a multiple access channel (MAC), which should be beneficial in enhancing the total User Throughput and cell-edge User Throughput simultaneously compared to orthogonal access, the multiplexing of multiple Users within the same frequency block increases the inter-cell interference in the context of the cellular uplink. The aim of the transmission power control method investigated in this paper is to mitigate the inter-cell interference increase due to non-orthogonal User multiplexing. We employ a weighted proportional fair (PF)-based multiUser scheduling scheme to achieve a good tradeoff between the total User Throughput and cell-edge User Throughput. Simulation results show that non-orthogonal access employing the MMSE-SIC using the proposed transmission power control significantly enhances the system-level Throughput performance compared to orthogonal access, which is widely used in 3.9 and 4G mobile communication systems.
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VTC Fall - Enhanced User Fairness Using Non-Orthogonal Access with SIC in Cellular Uplink
2011 IEEE Vehicular Technology Conference (VTC Fall), 2011Co-Authors: Tomohiro Takeda, Kenichi HiguchiAbstract:This paper investigates the enhancement of cell-edge User Throughput by using non-orthogonal access with a successive interference canceller (SIC) in the cellular uplink compared to orthogonal access, which is widely used in 3.9 and 4G mobile communication systems. Since both the total User Throughput and cell-edge User Throughput are important in a real system, we compare the cell-edge User Throughput, while subject to the same total User Throughput. The optimum resource allocation such as bandwidth and transmission power for each User is assumed for the respective access schemes based on the instantaneous channel conditions. Based on the evaluation results, we show that non-orthogonal access with a SIC can significantly enhance the cell-edge User Throughput (thus User fairness) compared to the orthogonal access while achieving the same total User Throughput in the context of the cellular uplink, which can yield some insights regarding the direction of the wireless access scheme for the systems beyond IMT-Advanced.
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ISPACS - Non-orthogonal access with SIC in cellular downlink for User fairness enhancement
2011 International Symposium on Intelligent Signal Processing and Communications Systems (ISPACS), 2011Co-Authors: Shun Tomida, Kenichi HiguchiAbstract:This paper investigates the enhancement of cell-edge User Throughput by using non-orthogonal access with a successive interference canceller (SIC) in the cellular downlink compared to orthogonal access, which is widely used in 3.9 and 4G mobile communication systems. Since both the total User Throughput and cell-edge User Throughput are important in a real system, we compare the cell-edge User Throughput while subject to the same total User Throughput. The optimum resource allocation in terms of bandwidth and transmission power for each User is assumed for the respective access schemes based on the instantaneous channel conditions. The evaluation results show that non-orthogonal access with a SIC significantly enhances the cell-edge User Throughput (thus User fairness) compared to orthogonal access while achieving the same total User Throughput in the context of the cellular downlink, which can yield some insights regarding the direction of the wireless access scheme for the systems beyond IMT-Advanced.
Mamoru Sawahashi - One of the best experts on this subject based on the ideXlab platform.
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Investigation of Inter-Cell Transmission Power Control Using Overload Indicator for Selected Users for Evolved UTRA Uplink
IEICE Transactions on Communications, 2009Co-Authors: Daisuke Nishikawa, Kenichi Higuchi, Yoshihisa Kishiyama, Mamoru SawahashiAbstract:This paper proposes the use of inter-cell transmission power control (TPC) with overload indicator (OLI) signaling to User equipment (UE) in addition to intra-cell TPC for the Evolved UTRA uplink. In the proposed inter-cell OLI transmission method, a cell site (Node B) selects UEs offering high-level interferences to the cell site based on the measured path loss difference, and then, the cell site transmits the OLI signal to the selected UEs. The simulation results show that the inter-cell TPC improves both the average User Throughput and cell-edge User Throughput at 5% in the cumulative distribution function (CDF) curve, assuming the same sector Throughput. For instance, when the sector Throughput is 1Mbps using 1.08MHz bandwidth, the inter-cell TPC with the proposed UE-common OLI scheme increases the average User Throughput and the 5%-cell edge User Throughput by approximately 41% and 53%, respectively, compared to the case with intra-cell TPC only. Furthermore, when the inter-cell TPC with the proposed UE-individual OLI is employed, the corresponding average User Throughput and the 5% User Throughput are increased by approximately 87% and 94%, respectively.
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VTC Spring - Investigation on Optimum Radio Link Connection Using Remote Radio Equipment in Heterogeneous Network for LTE-Advanced
VTC Spring 2009 - IEEE 69th Vehicular Technology Conference, 2009Co-Authors: Akihito Morimoto, Kenichi Higuchi, Yoshihisa Kishiyama, Motohiro Tanno, Mamoru SawahashiAbstract:This paper proposes the optimum radio link connection (RLC) using remote radio equipment (RRE) in a heterogeneous network in which various types of cell configurations exist with different cell sizes and downlink transmission power levels for LTE (Long-Term Evolution)-Advanced. The instantaneous received signal-to-interference plus noise power ratio (SINR) and the User Throughput performance employing the proposed RLC methods are investigated using system-level simulations. From the simulation results, we show that the proposed independent RLC method between the downlink and uplink and the proposed multipoint RLC method based on coordinated multipoint transmission/reception achieve a higher User Throughput both in the downlink and uplink compared to the conventional common RLC method. Therefore, the proposed independent and multipoint RLC methods are very promising candidates to improve the User Throughput particularly near the cell edge in a heterogeneous network for LTE-Advanced.
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System-Level Throughput Evaluations in Evolved UTRA
2006 10th IEEE Singapore International Conference on Communication Systems, 2006Co-Authors: Yoshiaki Ofuji, Kenichi Higuchi, Teruo Kawamura, Yoshihisa Kishiyama, Mamoru SawahashiAbstract:This paper presents simulation results on the achievable spectrum efficiency, User Throughput, and peak data rate in the orthogonal frequency division multiplexing (OFDM) based evolved UTRA (E-UTRA) downlink and single-carrier frequency division multiple access (SC-FDMA) based uplink in order to clarify the link-level performance gain of E-UTRA compared to high-speed downlink packet access (HSDPA) and enhanced DCH (E-DCH). The simulation results show that in the OFDM based downlink, the spectrum efficiency is increased to approximately 230% compared to that for HSDPA at the activity factor of approximately 0.6-0.8, and that the User Throughput at the cumulative distribution function (CDF) of 5% and the average User Throughput are increased to greater than 200 and 300%, respectively, compared to those for HSDPA at the spectrum efficiency of less than 0.6 bps/Hz. Moreover, in the SC-FDMA based uplink, the spectrum efficiency of E-UTRA is improved to approximately 190% compared to that for E-DCH, and the User Throughput at the CDF of 5% and average User Throughput are greater than 200% that of E-DCH. In the downlink employing 2-by-2 multiple-input multiple-output (MIMO) multiplexing with a 20-MHz transmission bandwidth, the target peak data rate of 100 Mbps is achieved at the average received signal energy per symbol-to-noise power spectrum density ratio (Es/N0) of approximately 23.5 dB using 64QAM and turbo coding with R=3/4 employing QRM-MLD, i.e., maximum likelihood detection using QR decomposition and the M-algorithm, with adaptive selection of surviving symbol replica candidates (ASESS). Furthermore, in the uplink assuming single-antenna transmission and two-branch antenna diversity reception, the target peak data rate of 50 Mbps is achieved at the average received Es/N0 of approximately 23 dB using 16QAM associated with the coding rate of R=8/9
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VTC Spring - Performance Comparison Between Fast Sector Selection and Simultaneous Transmission with Soft-Combining for Intra-Node B Macro Diversity in Downlink OFDM Radio Access
2006 IEEE 63rd Vehicular Technology Conference, 2006Co-Authors: Akihito Morimoto, Kenichi Higuchi, Mamoru SawahashiAbstract:This paper compares the User Throughput and the sector Throughput performance using fast sector selection (FSS) with muting and simultaneous transmission with soft-combining for the intra-Node B macro diversity in the downlink OFDM based radio access. System-level simulations show that FSS with muting achieves an approximately 10% higher User Throughput for intra-Node B macro diversity User equipment (UE) compared to simultaneous transmission with soft-combining, while maintaining almost the same User Throughput performance for one-link connection UE assuming the equal served traffic model. Therefore, we conclude that FSS with muting is a more promising candidate than simultaneous transmission with soft-combining as the intra-Node B macro diversity scheme in the downlink OFDM based radio access.
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VTC Spring - Performance Comparison Between Fast Sector Selection and Simultaneous Transmission with Soft-Combining for Intra-Node B Macro Diversity in Downlink OFDM Radio Access
2006 IEEE 63rd Vehicular Technology Conference, 2006Co-Authors: Akihito Morimoto, Kenichi Higuchi, Mamoru SawahashiAbstract:This paper compares the User Throughput and the sector Throughput performance using fast sector selection (FSS) with muting and simultaneous transmission with soft-combining for the intra-Node B macro diversity in the downlink OFDM based radio access. System-level simulations show that FSS with muting achieves an approximately 10% higher User Throughput for intra-Node B macro diversity User equipment (UE) compared to simultaneous transmission with soft-combining, while maintaining almost the same User Throughput performance for one-link connection UE assuming the equal served traffic model. Therefore, we conclude that FSS with muting is a more promising candidate than simultaneous transmission with soft-combining as the intra-Node B macro diversity scheme in the downlink OFDM based radio access.
Hiroyuki Otsuka - One of the best experts on this subject based on the ideXlab platform.
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Personal Picocell Scheme Using Adaptive Control CRE in Heterogeneous Mobile Networks
Journal of Sensor and Actuator Networks, 2020Co-Authors: Kento Fujisawa, Fumiya Kemmochi, Hiroyuki OtsukaAbstract:Heterogeneous networks (HetNets), which are combined with a macrocell and picocell in the same coverage, are expected to further increase the system capacity in fifth-generation mobile systems and beyond. In HetNets, the cell range expansion (CRE) technique plays an important role and can allow more User equipment (UE) to access the picocell, i.e., virtually expand the picocell coverage. However, conventional CRE techniques that provide a fixed cell selection offset (CSO) for all UE may worsen User Throughput if UE is forced to connect to the picocell because the received signal-to-interference plus noise ratio of the UE becomes lower. Therefore, we propose a personal picocell scheme using an adaptive control CRE technique to improve User Throughput in which different CSOs are assigned to UE to form each optimal picocell for each UE. In this paper, we first describe the aspects and algorithm of the proposed scheme. Then, we show the User Throughput for adaptive control CRE in comparison with conventional CRE by using system-level computer simulations for the two types of HetNets, i.e., single-band and multi-band HetNets. In the simulations, we first clarify the optimal parameters of the adaptive control CRE. We then show the average and 5-percentile User Throughput of the optimized adaptive control CRE in comparison with that of conventional CRE. From these results, we confirmed that the personal picocell scheme using the adaptive control CRE can improve the 5-percentile User Throughput while maintaining the average User Throughput compared with that of conventional CRE.
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Performance of Adaptive Control CRE against Cluster Size for UE Layout in Multiband HetNets
2020 3rd World Symposium on Communication Engineering (WSCE), 2020Co-Authors: Kento Fujisawa, Fumiya Kemmochi, Ayumi Yoneyama, Hiroyuki OtsukaAbstract:Heterogeneous networks (HetNets) combined with macrocells and picocells in the same coverage are expected to increase system capacity and/or effectively utilize a wide frequency band in fifth-generation (5G) mobile systems and beyond. In HetNets, cell range expansion (CRE) using a positive cell selection offset (CSO) is an important technique that can allow more User equipment (UE) to access picocells. A higher-order modulation scheme such as 1024-quadrature amplitude modulation (QAM) is expected to increase data rates in 5G. This paper describes a personal picocell scheme using adaptive control CRE through the use of two different CSOs to improve User Throughput in a multiband HetNet. In particular, we investigate the User Throughput of the adaptive control CRE against the cluster size for UE layout defined as the radius of circle centered at each pico-evolved Node B (picoeNB), using a new modulation and coding scheme (MCS) incorporating 1024-QAM. From these results, we confirm that the proposed adaptive control CRE can improve the 5percentile User Throughput by 4% compared with conventional CRE while maintaining the average User Throughput for a cluster size of 40 m. We also show that a cluster size of 20 m can improve the average and 5-percentile User Throughputs by 29% and 13% respectively compared with a cluster size of 40 m. This work will provide a remarkably effective solution for designing multiband HetNets with the use of an MCS incorporating 1024-QAM in 5G and beyond.
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VTC-Fall - Personal-Cell Scheme Using Adaptive Control CRE for Multicarrier HetNets
2019 IEEE 90th Vehicular Technology Conference (VTC2019-Fall), 2019Co-Authors: Kento Fujisawa, Fumiya Kemmochi, Hiroyuki OtsukaAbstract:Heterogeneous networks (HetNets) that uses multiple carrier frequencies are expected to further increase the system capacity in fifth-generation mobile systems and beyond. In multicarrier HetNets, the cell range expansion (CRE) technique is important and virtually expands the picocell coverage. This paper proposes a personal-cell scheme using an adaptive control CRE to improve the system User Throughput in multicarrier HetNets. Adaptive control CRE can provide an optimal personal cell for each User equipment by applying different cell-selection offsets (CSOs) in CRE. The concepts and algorithms of the personal cell scheme that uses adaptive control CRE are described in comparison with the conventional CRE method. We first discuss methods of optimizing the combination of two different CSOs for adaptive control CRE in multicarrier HetNets using carrier frequencies of 2.0 and 3.4 GHz. By using the optimized combination of two different CSOs for adaptive control CRE, we then describe the average and 5-percentile User Throughput of adaptive control CRE in comparison with the conventional CRE method. We confirm that the personal-cell scheme that uses adaptive control CRE can improve the 5-percentile User Throughput while maintaining the average User Throughput. This result provides a remarkably effective solution for multicarrier HetNets.
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ICOIN - Throughput Performance of Relay Backhaul Enhancement Using 3D Beamforming
2019 International Conference on Information Networking (ICOIN), 2019Co-Authors: Hiroki Utatsu, Kai Osawa, Satoshi Suyama, Jun Mashino, Hiroyuki OtsukaAbstract:Three-dimensional (3D) beamforming is expected for fifth-generation (5G) mobile systems to improve User Throughput, which operates in both azimuth and elevation antenna domains. Relay transmission is also important technique for 5G particularly to improve cell-edge performance. This paper proposes relay backhaul enhancement using 3D beamforming and provides its Throughput performance using system-level computer simulations. Average and 5-percentile User Throughput of the proposed relay system are investigated for almost blank subframe (ABS) ratio defined in time-division relay scheme, distance between evolved node B (eNB) and relay node (RN), and the transmission power of the RN, as parameters of the number of RNs. It is confirmed that the proposed relay system can improve both average and 5-percentile User Throughput compared to conventional relay system. Further, we clarify the appropriate ABS ratio, the distance between eNB and RN, and the transmission power of the RN to provide the best performance.
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ICOIN - Proposal of CQI table switching control method corresponding to 256-QAM for CRE in HetNet
2018 International Conference on Information Networking (ICOIN), 2018Co-Authors: Norihiro Naganuma, Satoshi Suyama, Kai Osawa, Jun Mashino, Hiroyuki OtsukaAbstract:Higher-order modulation such as 256-QAM is a key technology to increase data rates within a limited bandwidth. This paper proposes a channel quality indicator (CQI) table switching control method corresponding to 256-QAM that improves the 5-percentile User Throughput in Heterogeneous networks (HetNets), in which User equipments (UEs) connected to pico cell can use different CQI table depending on where UE is located within the original pico cell or the related CRE region. The features of the proposed CQI table switching control method are described in comparison with the conventional method. Computer simulation results such as average, 5-percentile and 95-percentile User Throughput are provided as parameters of cell selection offset for two types of HetNets, i.e., co-channel deployment with time-domain enhanced inter-cell interference coordination (eICIC), and different frequency deployment between macro and pico cells. We confirmed that the proposed method can improve 5-percentile User Throughput while maintain or improve the average and the 95-percentile User Throughput for the co-channel HetNet with eICIC.
Ki Won Sung - One of the best experts on this subject based on the ideXlab platform.
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tradeoff between spectrum and densification for achieving target User Throughput
Vehicular Technology Conference, 2015Co-Authors: Yanpeng Yang, Ki Won SungAbstract:Dense deployment which brings small base stations (BS) closer to mobile devices is considered as a promising solution to the booming traffic demand. Meanwhile, the utilization of new frequency bands and spectrum aggregation techniques provide more options for spectrum choice.Whether to increase BS density or to acquire more spectrum is a key strategic question for mobile operators. In this paper, we investigate the relationship between BS density and spectrum with regard to individual User Throughput target. Our work takes into account load-dependent interference model and various traffic demands. Numerical results show that densification is more effective in sparse networks than in already dense networks. In sparse networks, doubling BS density results in almost twofold Throughput increase. However, in dense networks where BSs outnumber Users, more than 10 times of BS density is needed to double User Throughput. Meanwhile, spectrum has a linear relationship with User Throughput for a given BS density. The impact of traffic types is also discussed. Even with the same area Throughput requirement, different combination of User density and individual traffic amount leads to different needs for BS density and spectrum.
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VTC Spring - Tradeoff between Spectrum and Densification for Achieving Target User Throughput
2015 IEEE 81st Vehicular Technology Conference (VTC Spring), 2015Co-Authors: Yanpeng Yang, Ki Won SungAbstract:Dense deployment which brings small base stations (BS) closer to mobile devices is considered as a promising solution to the booming traffic demand. Meanwhile, the utilization of new frequency bands and spectrum aggregation techniques provide more options for spectrum choice.Whether to increase BS density or to acquire more spectrum is a key strategic question for mobile operators. In this paper, we investigate the relationship between BS density and spectrum with regard to individual User Throughput target. Our work takes into account load-dependent interference model and various traffic demands. Numerical results show that densification is more effective in sparse networks than in already dense networks. In sparse networks, doubling BS density results in almost twofold Throughput increase. However, in dense networks where BSs outnumber Users, more than 10 times of BS density is needed to double User Throughput. Meanwhile, spectrum has a linear relationship with User Throughput for a given BS density. The impact of traffic types is also discussed. Even with the same area Throughput requirement, different combination of User density and individual traffic amount leads to different needs for BS density and spectrum.
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attainable User Throughput by dense wi fi deployment at 5 ghz
Personal Indoor and Mobile Radio Communications, 2013Co-Authors: Du Ho Kang, Ki Won Sung, Jens ZanderAbstract:Most of currently deployed Wi-Fi networks use the IEEE 802.11b/g standard and operate in 2.4 GHz ISMband. As mobile traffic demand rapidly increases, significant Wi-Fi deployment in the still very lightly used 5 GHz band is anticipated. In combination with the recent PHY amendments, e.g., 802.11ac, such Wi-Fi in many settings emerges as a strong competitor to small cellular deployment. In this paper, we aim to quantify what total capacity and which data rates per User can be supported by high-density, the state-of-the-art 5 GHz Wi-Fi deployment. Unlike previous studies, we consider the effect of densification by explicitly modeling the different level of interference among access points for office-type scenarios with various internal wall losses. Although abundant spectrum availability at 5 GHz may compensate for system inefficiency caused by carrier sensing and contention, we find that there is a capacity limit. This capacity limit depends on propagation environments and is especially low in “open” environments or environments with low wall losses. To operate at capacities above this limit, cellular systems with their more advanced interference mitigation techniques are required.
Katsunori Yamaoka - One of the best experts on this subject based on the ideXlab platform.
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characteristic analysis of an access point selection for User Throughput and system optimization based on User cooperative moving
Consumer Communications and Networking Conference, 2012Co-Authors: Sumiko Miyata, Tutomu Murase, Katsunori YamaokaAbstract:We propose an optimal access-point (AP) selection algorithm for maximizing system Throughput while preserving newly arrived-User Throughput. In our algorithm, newly arrived Users cooperate with a WLAN system they are trying to use, i.e., they are willing to move toward an appropriate AP. We discuss the effectiveness of our proposed AP selection algorithm by using numerical analysis. We also clarify and analyze the characteristics of system Throughput.
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CCNC - Characteristic analysis of an access-point selection for User Throughput and system optimization based on User cooperative moving
2012 IEEE Consumer Communications and Networking Conference (CCNC), 2012Co-Authors: Sumiko Miyata, Tutomu Murase, Katsunori YamaokaAbstract:We propose an optimal access-point (AP) selection algorithm for maximizing system Throughput while preserving newly arrived-User Throughput. In our algorithm, newly arrived Users cooperate with a WLAN system they are trying to use, i.e., they are willing to move toward an appropriate AP. We discuss the effectiveness of our proposed AP selection algorithm by using numerical analysis. We also clarify and analyze the characteristics of system Throughput.
