Spatiotemporal Base Station Cooperation in a Cellular Network: The Worst-Case User
01 Dec 2014-pp 1-6
TL;DR: A stochastic geometry model for studying spatiotemporal base station cooperation in a cellular network is presented, and the best performing scheme is shown to be the Alamouti code, when only two BSs cooperate.
Abstract: This paper presents a stochastic geometry model for studying spatiotemporal base station cooperation in a cellular network. Unlike most previous related works in the literature, the paper focuses on the coverage probability at the typical cellcorner user, i.e., a user that is equidistant to its three neighboring base stations (BSs). Three schemes are considered: joint transmission, base station silencing, and the Alamouti space-time code. In addition, BSs are allowed to cooperatively retransmit data across consecutive time slots, such that the cell-corner user can benefit from time diversity. For all these schemes, an expression for the coverage probability at the cell-corner user is derived. The best performing scheme is shown to be the Alamouti code, when only two BSs cooperate. Otherwise, cooperative retransmission performs the best in the high-coverage regime, while joint transmission without retransmission outperforms the remaining schemes in all other regimes. These results extend previous findings on spatiotemporal base station cooperation that only applied to the typical user in a cellular network.
Citations
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TL;DR: The meta distribution provides fine-grained information on the signal-to-interference ratio (SIR) compared with the SIR distribution at the typical user and the worst-case user and insights on the benefits of different cooperation schemes and the impact of the number of cooperating base stations and other network parameters are gained.
Abstract: The meta distribution provides fine-grained information on the signal-to-interference ratio (SIR) compared with the SIR distribution at the typical user. This paper first derives the meta distribution of the SIR in heterogeneous cellular networks with downlink coordinated multipoint transmission/reception, including joint transmission (JT), dynamic point blanking (DPB), and dynamic point selection/dynamic point blanking (DPS/DPB), for the general typical user and the worst-case user (the typical user located at the Voronoi vertex in a single-tier network). A more general scheme called JT-DPB, which is the combination of JT and DPB, is studied. The moments of the conditional success probability are derived for the calculation of the meta distribution and the mean local delay. An exact analytical expression, the beta approximation, and simulation results of the meta distribution are provided. From the theoretical results, we gain insights on the benefits of different cooperation schemes and the impact of the number of cooperating base stations and other network parameters.
81 citations
Cites methods from "Spatiotemporal Base Station Coopera..."
..., wx = 1, and blind demodulation is used at the user [15]–[17], [30], [31]....
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...[16], [17] analyze these performance metrics of both the general and worst-case users in heterogeneous cellular networks with spatiotemporal cooperation techniques including JT, base station silencing, and the Alamouti space-time code, and the decoding techniques including hybrid automatic repeat request (HARQ) and maximum ratio combining (MRC)....
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TL;DR: In this paper, the average rate and outage probability of a typical cell-edge user located at the origin were derived based on the stochastic geometry framework, and a Gamma approximation-based method was proposed to provide approximations with satisfying accuracy.
Abstract: Millimeter wave (mmWave) signals are much more sensitive to blockage, which results in a significant increase of the outage probability, especially for the users at the edge of the cells. In this paper, we exploit the technique of base station (BS) cooperation to improve the performance of the cell-edge users in the downlink transmission of mmWave cellular networks. We design two cooperative schemes, which are referred to as fixed-number BS cooperation (FNC) scheme and fixed-region BS cooperation (FRC) scheme, respectively. In the FNC scheme, the cooperative BSs consist of the $M$ nearest BSs around the served cell-edge users, and in the FRC scheme, the cooperative BSs include all the BSs located within a given region. We derive the expressions for the average rate and the outage probability of a typical cell-edge user located at the origin based on the stochastic geometry framework. To reduce the computational complexity of our analytical results for the outage probability, we further propose a Gamma approximation-based method to provide approximations with satisfying accuracy. Our analytical results incorporate the critical characteristics of mmWave channels, i.e., the blockage effects, the different path loss of LOS and NLOS links, and the highly directional antenna arrays. Simulation results show that the performance of the cell-edge users is greatly improved when mmWave networks are combined with the technique of BS cooperation.
36 citations
19 Mar 2021
TL;DR: In this article, the authors used the multi-slope model to estimate the received signal power at the worst-case user mobile (WMU) in downlink cellular networks.
Abstract: In the cellular networks, the user at the corner of a cell is usually called worst-case user mobile (WMU) experience the lowest performance. This paper studies WMU performance in millimeter wave cellular systems in three aspects such as throughput, Average Packet Delay (APD) and Packet Loss Ratio (PLR). The multi-slope model in which is recommended by 3GPP to simulate wireless communication is utilized to estimate the received signal power at the WMU in downlink. In order to improve the WMU performance, the Carrier Aggregation technique which has been introduced for Long-Term Evolution (LTE) is studied. By utilizing CA scheme, the WMU is allowed to utilize more than one sub-carrier to perform communications. The simulation results in Network Simulation NS3 indicates that the CA technique can significantly improve the WMU performance. For example, maximum achievable throughput of the CA system is 8.25 Mb/s which is nearly double than that of the non-CA system.
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TL;DR: Simulation results show that the performance of the cell-edge users is greatly improved when mmWave networks are combined with the technique of BS cooperation, and a Gamma approximation-based method is proposed to provide approximations with satisfying accuracy.
Abstract: Millimeter wave (mmWave) signals are much more sensitive to blockage, which results in a significant increase of the outage probability, especially for the users at the edge of the cells. In this paper, we exploit the technique of base station (BS) cooperation to improve the performance of the cell-edge users in the downlink transmission of mmWave cellular networks. We design two cooperative schemes, which are referred to as fixed-number BS cooperation (FNC) scheme and fixed-region BS cooperation (FRC) scheme, respectively. In FNC scheme, the cooperative BSs consist of the M nearest BSs around the served cell-edge users, and in FRC scheme, the cooperative BSs include all the BSs located within a given region. We derive the expressions for the average rate and outage probability of a typical cell-edge user located at the origin based on the stochastic geometry framework. To reduce the computational complexity of our analytical results for the outage probability, we further propose a Gamma approximation based method to provide approximations with satisfying accuracy. Our analytical results incorporate the critical characteristics of mmWave channels, i.e., the blockage effects, the different path loss of LOS and NLOS links and the highly directional antenna arrays. Simulation results show that the performance of the cell-edge users is greatly improved when mmWave networks are combined with the technique of BS cooperation.
Cites background from "Spatiotemporal Base Station Coopera..."
...In [25] and [26], the performance of the general and worst-case users in spatiotemporal BS cooperation-aided stochastic networks were investigated, respectively....
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References
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TL;DR: This tutorial article surveys some of these techniques based on stochastic geometry and the theory of random geometric graphs, discusses their application to model wireless networks, and presents some of the main results that have appeared in the literature.
Abstract: Wireless networks are fundamentally limited by the intensity of the received signals and by their interference. Since both of these quantities depend on the spatial location of the nodes, mathematical techniques have been developed in the last decade to provide communication-theoretic results accounting for the networks geometrical configuration. Often, the location of the nodes in the network can be modeled as random, following for example a Poisson point process. In this case, different techniques based on stochastic geometry and the theory of random geometric graphs -including point process theory, percolation theory, and probabilistic combinatorics-have led to results on the connectivity, the capacity, the outage probability, and other fundamental limits of wireless networks. This tutorial article surveys some of these techniques, discusses their application to model wireless networks, and presents some of the main results that have appeared in the literature. It also serves as an introduction to the field for the other papers in this special issue.
1,893 citations
Abstract: Cellular networks are in a major transition from a carefully planned set of large tower-mounted base-stations (BSs) to an irregular deployment of heterogeneous infrastructure elements that often additionally includes micro, pico, and femtocells, as well as distributed antennas. In this paper, we develop a tractable, flexible, and accurate model for a downlink heterogeneous cellular network (HCN) consisting of K tiers of randomly located BSs, where each tier may differ in terms of average transmit power, supported data rate and BS density. Assuming a mobile user connects to the strongest candidate BS, the resulting Signal-to-Interference-plus-Noise-Ratio (SINR) is greater than 1 when in coverage, Rayleigh fading, we derive an expression for the probability of coverage (equivalently outage) over the entire network under both open and closed access, which assumes a strikingly simple closed-form in the high SINR regime and is accurate down to -4 dB even under weaker assumptions. For external validation, we compare against an actual LTE network (for tier 1) with the other K-1 tiers being modeled as independent Poisson Point Processes. In this case as well, our model is accurate to within 1-2 dB. We also derive the average rate achieved by a randomly located mobile and the average load on each tier of BSs. One interesting observation for interference-limited open access networks is that at a given \sinr, adding more tiers and/or BSs neither increases nor decreases the probability of coverage or outage when all the tiers have the same target-SINR.
1,640 citations
TL;DR: The principal feasibility of COMP is shown in two field testbeds with multiple sites and different backhaul solutions between the sites, and significant gains can be shown for both the uplink and downlink.
Abstract: Coordinated multipoint or cooperative MIMO is one of the promising concepts to improve cell edge user data rate and spectral efficiency beyond what is possible with MIMOOFDM in the first versions of LTE or WiMAX. Interference can be exploited or mitigated by cooperation between sectors or different sites. Significant gains can be shown for both the uplink and downlink. A range of technical challenges were identified and partially addressed, such as backhaul traffic, synchronization and feedback design. This article also shows the principal feasibility of COMP in two field testbeds with multiple sites and different backhaul solutions between the sites. These activities have been carried out by a powerful consortium consisting of universities, chip manufacturers, equipment vendors, and network operators.
1,093 citations
"Spatiotemporal Base Station Coopera..." refers methods in this paper
...[6] evaluates the cell-edge spectral efficiency in different scenarios through simulations whereas [7] evaluates cell-edge throughput gain using CoMP through field trials....
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TL;DR: This article presents a comprehensive survey on the literature related to stochastic geometry models for single-tier as well as multi-tier and cognitive cellular wireless networks, and discusses the open research challenges and future research directions.
Abstract: For more than three decades, stochastic geometry has been used to model large-scale ad hoc wireless networks, and it has succeeded to develop tractable models to characterize and better understand the performance of these networks. Recently, stochastic geometry models have been shown to provide tractable yet accurate performance bounds for multi-tier and cognitive cellular wireless networks. Given the need for interference characterization in multi-tier cellular networks, stochastic geometry models provide high potential to simplify their modeling and provide insights into their design. Hence, a new research area dealing with the modeling and analysis of multi-tier and cognitive cellular wireless networks is increasingly attracting the attention of the research community. In this article, we present a comprehensive survey on the literature related to stochastic geometry models for single-tier as well as multi-tier and cognitive cellular wireless networks. A taxonomy based on the target network model, the point process used, and the performance evaluation technique is also presented. To conclude, we discuss the open research challenges and future research directions.
1,065 citations
"Spatiotemporal Base Station Coopera..." refers background in this paper
...Stochastic geometry models for cellular networks have been recently proposed in [8]–[10], where the BSs are assumed to be distributed according to a Poisson point process (PPP)....
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TL;DR: Numerical evaluations illustrate absolute gains in coverage probability for the general user and the worst case user compared with the noncooperative case and it is shown that no diversity gain is achieved using noncoherent joint transmission, whereas full diversity gain can be achieved at the receiver if the transmitting base stations have channel state information.
Abstract: Motivated by the ongoing discussion on coordinated multipoint in wireless cellular standard bodies, this paper considers the problem of base station cooperation in the downlink of heterogeneous cellular networks. The focus of this paper is the joint transmission scenario, where an ideal backhaul network allows a set of randomly located base stations, possibly belonging to different network tiers, to jointly transmit data, to mitigate intercell interference and hence improve coverage and spectral efficiency. Using tools from stochastic geometry, an integral expression for the network coverage probability is derived in the scenario where the typical user located at an arbitrary location, i.e., the general user, receives data from a pool of base stations that are selected based on their average received power levels. An expression for the coverage probability is also derived for the typical user located at the point equidistant from three base stations, which we refer to as the worst case user. In the special case where cooperation is limited to two base stations, numerical evaluations illustrate absolute gains in coverage probability of up to 17% for the general user and 24% for the worst case user compared with the noncooperative case. It is also shown that no diversity gain is achieved using noncoherent joint transmission, whereas full diversity gain can be achieved at the receiver if the transmitting base stations have channel state information.
321 citations