Abstract-The HSPA Evolution will during the next decade be a key radio access technology for a cost-effective provisioning of mobile broadband services. In addition to the continuous improvements of WCDMA/HSPA in terms of spectral efficiency and latency, "multi-carrier operation" (or "carrier aggregation") for individual connections is now introduced. This paper presents the evolution of Multi-Carrier HSPA, discusses implications on network architecture & user equipment, and evaluates the achievable system performance (with focus on downlink). It is concluded that Multi-Carrier HSPA can be implemented at a low incremental cost; both in the radio access network, which already supports multiple carriers, and in terminals (due to synergies with LTE). Numerical results further show that achievable data rates of a Multi-Carrier HSPA system increase proportional to the number of carriers; in terms of peak physical layer data rates as well as (for bursty packet data) average user throughput. Thus, Multi-Carrier HSPA will be an attractive means for operators to provide higher data rates and decrease the production cost of mobile broadband access.
In radio resource management for cellular networks a trade-off has to be made between the congestion level, related to cell coverage and intercell interference, and the Quality of Service (QoS) or data rates of the users. This is implemented by using a fast inner power control loop and an outer rate control algorithm, working on a slower time scale.Due to the distributed nature of the network, both information and control is distributed. Measurements of congestion and QoS are used in the control loops and this introduces a nonlinear feedback. Another complicating factor is that filtering, computations and information exchange in the network introduce time delays.In this paper we propose a general high order model as a cascade system with an outer and inner control loop. The control algorithms use distributed information available in the network. The full system model includes the nonlinear feedback from congestion and QoS measurements, time delays and time scale modelling. We provide sufficient conditions for stability and convergence of the system. Our primary analysis tool is input output theory.
In a cellular network it is necessary to make a trade-off between congestion and Quality of Service (QoS) of the users. To ensure good system performance in uplink of a WCDMA network, control loops are used to adapt to changing radio and interference conditions. A fast inner power control loop updates the transmission powers of the mobiles based on measurements related to QoS, which are compared to a reference value. The reference value is set dynamically by a slower outer rate control loop that uses measurements of congestion. There is a time-scale difference between the loops, but joint dynamics cannot be neglected.In this paper we derive a high order system model with distributed feedback control based on locally measurable information. We model the time-scale difference between the loops and include this in the model. We give sufficient conditions for stability using control theoretic methods and validate the model and results by simulations.
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