The Experts below are selected from a list of 42 Experts worldwide ranked by ideXlab platform
Jeffrey G Andrews - One of the best experts on this subject based on the ideXlab platform.
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the capacity gain from intercell scheduling in multi antenna systems
IEEE Transactions on Wireless Communications, 2008Co-Authors: Wan Choi, Jeffrey G AndrewsAbstract:The capacity and robustness of cellular MIMO systems is very sensitive to other-cell interference which will in practice necessitate network level interference reduction strategies. As an alternative to traditional static frequency reuse patterns, this paper investigates intercell scheduling among neighboring base stations. We show analytically that cooperatively Scheduled Transmission, which is well within the capability of present systems, can achieve an expanded multiuser diversity gain in terms of ergodic capacity as well as almost the same amount of interference reduction as conventional frequency reuse. This capacity gain over conventional frequency reuse is O (M t square-root of log Ns) for dirty paper coding and O (min (Mr, Mt) square-root of log Ns) for time division, where Ns is the number of cooperating base stations employing opportunistic scheduling in an M t x M r MIMO system. From a theoretical standpoint, an interesting aspect of this analysis comes from an altered view of multiuser diversity in the context of a multi-cell system. Previously, multiuser diversity capacity gain has been known to grow as O(log log K), from selecting the maximum of K exponentially-distributed powers. Because multicell considerations such as the positions of the users, lognormal shadowing, and pathless affect the multiuser diversity gain, we find instead that the gain is O(square-root of 2logic K), from selecting the maximum of a compound Iognormal-exponential distribution. Finding the maximum of such a distribution is an additional contribution of the paper.
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base station cooperatively Scheduled Transmission in a cellular mimo tdma system
Conference on Information Sciences and Systems, 2006Co-Authors: Wan Choi, Jeffrey G AndrewsAbstract:The capacity and robustness of cellular MIMO systems is very sensitive to other-cell interference, which will in practice necessitate network level interference reduction strategies. As an alternative to traditional static frequency reuse patterns, this paper investigates cooperatively Scheduled Transmissions among neighboring base stations. We analytically show that cooperatively Scheduled Transmission, which is well within the capability of present systems, can achieve an expanded multiuser diversity gain in terms of ergodic capacity as well as almost the same amount of interference reduction as conventional frequency reuse. From a theoretical standpoint, an interesting aspect of this analysis comes from an altered view of multiuser diversity in the context of a multi-cell system. Previously, multiuser diversity capacity gain has been known to grow as O(log log K), from selecting the maximum of K exponentially-distributed powers. Because the positions of the users are important in a multi-cell system, we find instead that the gain is O(radic(1og K)), from selecting the maximum of a compound lognormal-exponential distribution.
Wan Choi - One of the best experts on this subject based on the ideXlab platform.
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the capacity gain from intercell scheduling in multi antenna systems
IEEE Transactions on Wireless Communications, 2008Co-Authors: Wan Choi, Jeffrey G AndrewsAbstract:The capacity and robustness of cellular MIMO systems is very sensitive to other-cell interference which will in practice necessitate network level interference reduction strategies. As an alternative to traditional static frequency reuse patterns, this paper investigates intercell scheduling among neighboring base stations. We show analytically that cooperatively Scheduled Transmission, which is well within the capability of present systems, can achieve an expanded multiuser diversity gain in terms of ergodic capacity as well as almost the same amount of interference reduction as conventional frequency reuse. This capacity gain over conventional frequency reuse is O (M t square-root of log Ns) for dirty paper coding and O (min (Mr, Mt) square-root of log Ns) for time division, where Ns is the number of cooperating base stations employing opportunistic scheduling in an M t x M r MIMO system. From a theoretical standpoint, an interesting aspect of this analysis comes from an altered view of multiuser diversity in the context of a multi-cell system. Previously, multiuser diversity capacity gain has been known to grow as O(log log K), from selecting the maximum of K exponentially-distributed powers. Because multicell considerations such as the positions of the users, lognormal shadowing, and pathless affect the multiuser diversity gain, we find instead that the gain is O(square-root of 2logic K), from selecting the maximum of a compound Iognormal-exponential distribution. Finding the maximum of such a distribution is an additional contribution of the paper.
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base station cooperatively Scheduled Transmission in a cellular mimo tdma system
Conference on Information Sciences and Systems, 2006Co-Authors: Wan Choi, Jeffrey G AndrewsAbstract:The capacity and robustness of cellular MIMO systems is very sensitive to other-cell interference, which will in practice necessitate network level interference reduction strategies. As an alternative to traditional static frequency reuse patterns, this paper investigates cooperatively Scheduled Transmissions among neighboring base stations. We analytically show that cooperatively Scheduled Transmission, which is well within the capability of present systems, can achieve an expanded multiuser diversity gain in terms of ergodic capacity as well as almost the same amount of interference reduction as conventional frequency reuse. From a theoretical standpoint, an interesting aspect of this analysis comes from an altered view of multiuser diversity in the context of a multi-cell system. Previously, multiuser diversity capacity gain has been known to grow as O(log log K), from selecting the maximum of K exponentially-distributed powers. Because the positions of the users are important in a multi-cell system, we find instead that the gain is O(radic(1og K)), from selecting the maximum of a compound lognormal-exponential distribution.
Mooi Choo Chuah - One of the best experts on this subject based on the ideXlab platform.
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effect of timing adjust algorithms on iub link capacity for voice traffic in w cdma systems
Vehicular Technology Conference, 2002Co-Authors: S Abraham, A Sampath, Cem U Saraydar, Mooi Choo ChuahAbstract:The goal of the timing adjust algorithm in UMTS networks is to adjust the arrival times of downlink frames from the RNC (radio network controller) to the node B so that the frames arrive within a predefined time window before the Scheduled Transmission time of the frame. The algorithm provides feedback from the node B to the RNC, causing a delay or an advance of the next transmitted frame based on the arrival time of the current frame. We present a study of the effect of the timing adjust algorithms in UMTS networks on the Iub link capacity for voice traffic. Through simulation, we present estimates of call carrying capacities and statistical multiplexing gain on Iub links of different capacities. We also present an analytical framework to explain the impact of the timing adjust algorithm on the statistics of Iub delay for voice traffic.
Ekaterina Stepanova - One of the best experts on this subject based on the ideXlab platform.
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clock drift impact on target wake time in ieee 802 11ax ah networks
Canadian Entomologist, 2018Co-Authors: Dmitry Bankov, Evgeny Khorov, Andrey Lyakhov, Ekaterina StepanovaAbstract:In the Internet of Things scenarios, it is crucially important to provide low energy consumption of client devices. To address this challenge, new Wi-Fi standards introduce the Target Wake Time (TWT) mechanism. With TWT, devices transmit their data according to a schedule and move to the doze state afterwards. The main problem of this mechanism is the clock drift phenomenon, because of which the devices cease to strictly comply with the schedule. As a result, they can miss the Scheduled Transmission time, which increases active time and thus power consumption. The paper investigates uplink Transmission with two different TWT operation modes. With the first mode, a sensor transmits a packet to the access point (AP) after waking up, using the random channel access. With the second mode, the AP polls stations and they can transmit a packet only after receiving a trigger frame from the AP. For both modes, the paper studies how the average Transmission time, the packet loss rate and the average energy consumption depend on the different TWT parameters. It is shown that when configured to guarantee the given packet loss rate, the first mode provides lower Transmission time, while the second mode provides lower energy consumption.
Stepanova Ekaterina - One of the best experts on this subject based on the ideXlab platform.
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Clock Drift Impact on Target Wake Time in IEEE 802.11ax/ah Networks
2019Co-Authors: Bankov Dmitry, Khorov Evgeny, Lyakhov Andrey, Stepanova EkaterinaAbstract:In the Internet of Things scenarios, it is crucially important to provide low energy consumption of client devices. To address this challenge, new Wi-Fi standards introduce the Target Wake Time (TWT) mechanism. With TWT, devices transmit their data according to a schedule and move to the doze state afterwards. The main problem of this mechanism is the clock drift phenomenon, because of which the devices cease to strictly comply with the schedule. As a result, they can miss the Scheduled Transmission time, which increases active time and thus power consumption. The paper investigates uplink Transmission with two different TWT operation modes. With the first mode, a sensor transmits a packet to the access point (AP) after waking up, using the random channel access. With the second mode, the AP polls stations and they can transmit a packet only after receiving a trigger frame from the AP. For both modes, the paper studies how the average Transmission time, the packet loss rate and the average energy consumption depend on the different TWT parameters. It is shown that when configured to guarantee the given packet loss rate, the first mode provides lower Transmission time, while the second mode provides lower energy consumption.
