Telecommunication Systems

, Volume 71, Issue 4, pp 585–599 | Cite as

Congestion probabilities in the X2 link of LTE networks

  • P. I. Panagoulias
  • I. D. MoscholiosEmail author


In this paper, first we review two multirate loss models, whereby we can assess the call-level QoS of the Long Term Evolution X2 link supporting calls of different service-classes with fixed bandwidth requirements. The X2 interface directly connects two neighboring evolved NodeBs and is mainly responsible for the transfer of user-plane and control-plane data during a handover. In both models, the X2 interface is modelled as a link of fixed capacity. Handover calls are accepted in the X2 link whenever there exists available bandwidth, i.e., no QoS guarantee is achieved for high-speed calls. Secondly, we propose three multirate loss models where calls arrive in the X2 link according to a quasi-random process and compete for the available bandwidth under the Multiple Fractional Channel Reservation (MFCR) policy, the Bandwidth Reservation (BR) policy and the Complete Sharing (CS) policy. The MFCR/BR policies allow the reservation of real/integer number of channels, respectively, in order to benefit high-speed calls. The CS policy allows calls to enter the system when there exists available bandwidth (no reservation is allowed). We propose approximate but recursive formulas for the calculation of time and call congestion probabilities as well as link utilization for all three policies. The accuracy of the proposed formulas is verified through simulation and found to be highly satisfactory.


LTE X2 Time-call congestion Quasi-random Recursive formula Reservation 



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Authors and Affiliations

  1. 1.Department of Informatics and TelecommunicationsUniversity of PeloponneseTripolisGreece

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