3,108 research outputs found
Statistical Multiplexing and Traffic Shaping Games for Network Slicing
Next generation wireless architectures are expected to enable slices of
shared wireless infrastructure which are customized to specific mobile
operators/services. Given infrastructure costs and the stochastic nature of
mobile services' spatial loads, it is highly desirable to achieve efficient
statistical multiplexing amongst such slices. We study a simple dynamic
resource sharing policy which allocates a 'share' of a pool of (distributed)
resources to each slice-Share Constrained Proportionally Fair (SCPF). We give a
characterization of SCPF's performance gains over static slicing and general
processor sharing. We show that higher gains are obtained when a slice's
spatial load is more 'imbalanced' than, and/or 'orthogonal' to, the aggregate
network load, and that the overall gain across slices is positive. We then
address the associated dimensioning problem. Under SCPF, traditional network
dimensioning translates to a coupled share dimensioning problem, which
characterizes the existence of a feasible share allocation given slices'
expected loads and performance requirements. We provide a solution to robust
share dimensioning for SCPF-based network slicing. Slices may wish to
unilaterally manage their users' performance via admission control which
maximizes their carried loads subject to performance requirements. We show this
can be modeled as a 'traffic shaping' game with an achievable Nash equilibrium.
Under high loads, the equilibrium is explicitly characterized, as are the gains
in the carried load under SCPF vs. static slicing. Detailed simulations of a
wireless infrastructure supporting multiple slices with heterogeneous mobile
loads show the fidelity of our models and range of validity of our high load
equilibrium analysis
Receive Combining vs. Multi-Stream Multiplexing in Downlink Systems with Multi-Antenna Users
In downlink multi-antenna systems with many users, the multiplexing gain is
strictly limited by the number of transmit antennas and the use of these
antennas. Assuming that the total number of receive antennas at the
multi-antenna users is much larger than , the maximal multiplexing gain can
be achieved with many different transmission/reception strategies. For example,
the excess number of receive antennas can be utilized to schedule users with
effective channels that are near-orthogonal, for multi-stream multiplexing to
users with well-conditioned channels, and/or to enable interference-aware
receive combining. In this paper, we try to answer the question if the data
streams should be divided among few users (many streams per user) or many users
(few streams per user, enabling receive combining). Analytic results are
derived to show how user selection, spatial correlation, heterogeneous user
conditions, and imperfect channel acquisition (quantization or estimation
errors) affect the performance when sending the maximal number of streams or
one stream per scheduled user---the two extremes in data stream allocation.
While contradicting observations on this topic have been reported in prior
works, we show that selecting many users and allocating one stream per user
(i.e., exploiting receive combining) is the best candidate under realistic
conditions. This is explained by the provably stronger resilience towards
spatial correlation and the larger benefit from multi-user diversity. This
fundamental result has positive implications for the design of downlink systems
as it reduces the hardware requirements at the user devices and simplifies the
throughput optimization.Comment: Published in IEEE Transactions on Signal Processing, 16 pages, 11
figures. The results can be reproduced using the following Matlab code:
https://github.com/emilbjornson/one-or-multiple-stream
Design, Modeling, and Performance Analysis of Multi-Antenna Heterogeneous Cellular Networks
This paper presents a stochastic geometry-based framework for the design and analysis of downlink multi-user multiple-input multiple-output (MIMO) heterogeneous cellular networks with linear zero-forcing transmit precoding and receive combining, assuming Rayleigh fading channels and perfect channel state information. The generalized tiers of base stations may differ in terms of their Poisson point process spatial density, number of transmit antennas, transmit power, artificial-biasing weight, and number of user equipments served per resource block. The spectral efficiency of a typical user equipped with multiple receive antennas is characterized using a non-direct moment-generating-function-based methodology with closed-form expressions of the useful received signal and aggregate network interference statistics systematically derived. In addition, the area spectral efficiency is formulated under different space-division multiple-access and single-user beamforming transmission schemes. We examine the impact of different cellular network deployments, propagation conditions, antenna configurations, and MIMO setups on the achievable performance through theoretical and simulation studies. Based on the state-of-the-art system parameters, the results highlight the inherent limitations of baseline single-input single-output transmission and conventional sparse macro-cell deployment, as well as the promising potential of multi-antenna communications and small-cell solution in interference-limited cellular environments
Reduction of bandwidth requirement by traffic dispersion in ATM networks
The problem of bandwidth allocation and routing in Virtual Path (VP) based Asynchronous Transfer Mode (ATM) networks was studied. As an efficient way to facilitate the network management, VP concept has been proposed in the literature. Traffic control and resource management are simplified in VP based networks. However, a priori reservation of resources for VP\u27s also reduces the statistical multiplexing gain, resulting in increased Call Blocking Probability (CBP);The focus of this study is on how to reduce CBP (or equivalently, how to improve the bandwidth utilization for a given CBP requirement) by the effective bandwidth allocation and routing algorithms. Equivalent capacity concept was used to calculate the required bandwidth by the call. Each call was represented as a bursty and heterogeneous multimedia traffic;First, the effect of traffic dispersion was explored to achieve more statistical gain. Through this study, it was discovered how the effect of traffic dispersion varies with different traffic characteristics and the number of paths. An efficient routing algorithm, CED, was designed. Since traffic dispersion requires resequencing and extra signaling to set up multiple VC\u27s, it should be used only when it gives significant benefits. This was the basic idea in our design of CED. The algorithm finds an optimal dispersion factor for a call, where the gain balances the dispersion cost. Simulation study showed that the CBP can be significantly reduced by CED;Next, this study provides analysis of the statistical behavior of the traffic seen by individual VP, as a result of traffic dispersion. This analysis is essential in estimating the required capacity of a VP accurately when both multimedia traffic and traffic dispersion are taken into account. Then analytical models have been formulated. The cost effective design and engineering of VP networks requires accurate and tractable mathematical models which capture the important statistical properties of traffic. This study also revealed that the load distribution estimated by equivalent capacity follows Gaussian distribution which is the sum of two jointly Gaussian random variables. For the analysis of load distribution when CED is used, we simplified multiple paths as identical paths using the idea of Approximation by Single Abstract Path (ASAP), and approximated the characteristics of the traffic seen by individual VP. The developed analytical models and approximations were validated in the sense that they agreed with simulation results
Statistical multiplexing and connection admission control in ATM networks
Asynchronous Transfer Mode (ATM) technology is widely employed for the transport of network traffic, and has the potential to be the base technology for the next generation of global communications. Connection Admission Control (CAC) is the effective traffic control mechanism which is necessary in ATM networks in order to avoid possible congestion at each network node and to achieve the Quality-of-Service (QoS) requested by each connection. CAC determines whether or not the network should accept a new connection. A new connection will only be accepted if the network has sufficient resources to meet its QoS requirements without affecting the QoS commitments already made by the network for existing connections. The design of a high-performance CAC is based on an in-depth understanding of the statistical characteristics of the traffic sources
- …