A Performance Analysis of Fixed and Dynamic Channel Allocation Schemes in Cellular Networks Author Muhammad Emran Co-authors Syed Asad Hussain, Saqib Hussain Department of Computer Sciences COMSATS Institute of Information Technology, Lahore

The 4th International Workshop on Frontiers of Information Technology 2 Overview of Presentation  Overview of Cellular Network Architecture  Introduction  Channel Allocation Techniques  My Contribution  Dynamic Channel Allocation Scheme (DCA)  Standard Cellular Network Model in OPNET Modeler Modeler  Simulation Statistics  Simulation Results  Results Comparisons  Conclusion

The 4th International Workshop on Frontiers of Information Technology 3 Overview of Cellular Network Architecture

The 4th International Workshop on Frontiers of Information Technology 4 Introduction  Mobile networks, a rapidly growing cellular technology  An efficient method for channel allocation is required to entertain maximum users

The 4th International Workshop on Frontiers of Information Technology 5  What is Channel Allocation?  Channel Allocation Techniques:  Fixed Channel Allocation (FCA) Fixed number of channels are allocated Fixed number of channels are allocated  Dynamic Channel Allocation (DCA) Dynamic Pool of channels is defined  Hybrid Channel Allocation (HCA) Mixture of FCA and DCA Channel Allocation in Cellular Networks

The 4th International Workshop on Frontiers of Information Technology 6 Fixed Channel Allocation  Static allocation of frequency channels  Frequency Reuse  Co-Channel Cells  Co-Channel Reuse Distance  Advantage of Frequency Reuse  To deal with massive number of calls  Huge Coverage Area  Unchangeable allocation

The 4th International Workshop on Frontiers of Information Technology 7 Fixed Channel Allocation (Contd.)  Uniform Channel Allocation  Uniform traffic  Equal number of nominal channels in each cell  Non Uniform Channel Allocation  Non uniform traffic  Allocation on the basis of expected traffic  Reduction of call blocking probability  Disadvantages  Non deterministic traffic at different time slots  Improper use of Bandwidth

The 4th International Workshop on Frontiers of Information Technology 8 Dynamic Channel Allocation  Why do we need it?  To deal with the non uniform traffic  No particular relation among channels and cells  Channels are part of a pool of resources  Frequency Reuse constraint  Co-channel interference consideration  Types  Centralized DCA  Distributed DCA

The 4th International Workshop on Frontiers of Information Technology 9 Dynamic Channel Allocation (contd.)  Centralized DCA  Channel allocation through centralized authority (MTSO/MSC)  Distributed DCA  Channel allocation through base station  Disadvantage  Intensive computation for DCA algorithms

The 4th International Workshop on Frontiers of Information Technology 10 Hybrid Channel Allocation  An amalgam of FCA and DCA Schemes  Channel Borrowing  Statically allocated channels  A pool of reserved channels for borrowing  Disadvantages  Frequency reuse constraints  Call blocking  Complex algorithms to reduce call blocking

The 4th International Workshop on Frontiers of Information Technology 11 Contribution of Research work  To exploit the role of channel allocation schemes (FCA & DCA) to perform load balancing  Implementation of Dynamic Channel Allocation (DCA) in OPNET Modeler  OPNET Simulations and Results Comparisons for FCA and DCA schemes

The 4th International Workshop on Frontiers of Information Technology 12 Standard Cellular Network Model in OPNET Modeler

The 4th International Workshop on Frontiers of Information Technology 13 Dynamic Channel Allocation Scheme (DCA)  Based upon Centralized DCA algorithm  Channel manager of MTSO controls dynamic pool of channels  On request free channel allocation  After termination of a call the assigned channel is returned to the pool

The 4th International Workshop on Frontiers of Information Technology 14 Simulation Statistics Duration of Simulation 1 Hour Values per Statistics 100 Call Generation Distribution Exponential Call Generation Rate 10, 50 & 100 Calls per Hour Call Length 3 Minute per Call Call Length Distribution Exponential Foliage Density No Foliage Setting Type Urban Seed 128

The 4th International Workshop on Frontiers of Information Technology 15 Implementation ► In Header Block, we have made the following amendments. Declare an integer total_channels_free */ Declaration of free channel variable/* Initialize total_channels_free with 56 */Declaration of pool of free channel/* Channel Assignment Code: if (total_channels_free > 0) */Checking availability of even a single free channel/* Get the call request packet Pull all meaningful info off of the request Send response back to call initiator Decrement total_channels_free by 1 */After allocation of a channel decrement “1” from the pool of free channels/* Inc global

The 4th International Workshop on Frontiers of Information Technology 16 Channel Assignment Code else Send blocked response to call initiator Pull all meaningful info off of the request Send response back to call initiator Update necessary statistics Inc global Write out stats Write the global out stats Channel Free Code: Increment total_channels_free by 1 */Upon call termination, the free channel is returned back to the pool of free channels/*

The 4th International Workshop on Frontiers of Information Technology 17 For 10 calls per hour per mobile user Simulation Results Comparison of Serviced and Blocked calls in FCA and DCA based Cellular Systems

The 4th International Workshop on Frontiers of Information Technology 18 For 10 calls per hour per mobile user Results Comparison Calls Requested Calls Serviced Serviced Calls (%) Calls Blocked Blocked Calls (%) FCADCAFCADCAFCADCAFCADCAFCADCA Table 1 Comparison of Global Statistics of FCA and DCA channel allocation schemes

The 4th International Workshop on Frontiers of Information Technology 19 For 50 calls per hour per mobile user Simulation Results (Contd.) Comparison of Serviced and Blocked calls in FCA and DCA based Cellular Systems

The 4th International Workshop on Frontiers of Information Technology 20 For 50 calls per hour per mobile user Calls Requested Calls Serviced Serviced Calls (%) Calls Blocked Blocked Calls (%) FCADCAFCADCAFCADCAFCADCAFCADCA Table 2 Comparison of Global Statistics of FCA and DCA channel allocation schemes Results Comparison (Contd.)

The 4th International Workshop on Frontiers of Information Technology 21 For 100 calls per hour per mobile user Simulation Results (Contd.) Comparison of Serviced and Blocked calls in FCA and DCA based Cellular Systems

The 4th International Workshop on Frontiers of Information Technology 22 For 100 calls per hour per mobile user Calls Requested Calls Serviced Serviced Calls (%) Calls Blocked Blocked Calls (%) FCADCAFCADCAFCADCAFCADCAFCADCA Table 3 Comparison of Global Statistics of FCA and DCA channel allocation schemes Results Comparison (Contd.)

The 4th International Workshop on Frontiers of Information Technology 23 Conclusion  After the careful analysis of Dynamic Channel Allocation (DCA) strategy using OPNET simulation, and comparing these results with the Fixed Channel Allocation (FCA) scheme, it is concluded that DCA performs much better than FCA.  It has been proved that static channel allocation performs badly to handle the congestion in the network.  In a less congested network DCA scheme served 99% of the requested calls whereas FCA handled only 70% calls.  In a more congested network, DCA entertained 48% of requested calls where as FCA served 24% of total requests.

The 4th International Workshop on Frontiers of Information Technology 24 Conclusion (Contd.)  In case of severe congestion in network, DCA catered 29% of requested calls on the other hand FCA could hardly accommodate 14% of the requested calls.  One tradeoff of this research is either to overburden the MTSO by implementing DCA or bear the blockage of 30% by applying FCA in situations of less congestion in the network.  As long as the load gets increased over the network, DCA performs two times better than FCA, in spite of some overhead on MTSO.

The 4th International Workshop on Frontiers of Information Technology 25 Future Work  Handoffs  Frequency Reuse Considerations

The 4th International Workshop on Frontiers of Information Technology 26 Questions?