Instituto Tecnol ogico y de Estudios Superiores de Monterrey - PDF document

Instituto Tecnol´ ogico y de Estudios Superiores de Monterrey Campus Monterrey Divisi´ on de Electr´ onica, Computaci´ on, Informaci´ on, y Comunicaciones Programa de Graduados MULTICARRIER WIRELESS NETWORK EVALUATION WITH LEAST LOADED ROUTING THESIS Presented as a partial fulfillment of the requeriments for the degree of Master of Science in Electronic Engineering Major in Telecommunications Ing. Enrique Stevens Navarro Monterrey, N.L. May 2002

� Enrique Stevens Navarro, 2002 c

Instituto Tecnol´ ogico y de Estudios Superiores de Monterrey Campus Monterrey Divisi´ on de Electr´ onica, Computaci´ on, Informaci´ on, y Comunicaciones Programa de Graduados The members of the thesis committee recommended the acceptance of the thesis of Enrique Stevens Navarro as a partial fulfillment of the requeriments for the degree of Master of Science in: Electronic Engineering Major in Telecommunications THESIS COMMITTEE Cesar Vargas Rosales, Ph.D. Advisor Jos´ e Ram´ on Rodr´ ıguez Cruz, Ph.D. Artemio Aguilar Couti˜ no, M.Sc. Synodal Synodal Approved David Garza Salazar, Ph.D. Director of the Graduate Program May 2002

My work is dedicated with love To God , To Lupita , To Guillermo , To Adri´ an , To Sol.

I am really thankful to the Ph.D. Cesar Vargas Rosales for all this two years of work together and his always professional advice, without his guidance this thesis would not be possible. I also want to thank Ph.D. Jos´ e Ram´ on Rodr´ ıguez Cruz and M.Sc. Artemio Aguilar Couti˜ no, for their feedback comments about this work. Special thanks to my uncle Ing. Hugo Stevens Amaro for all his support during my stay in Monterrey. Thanks to Ulises and Eduardo for their help in the realization of this thesis, figures design and programming advices , respectively. Also thanks to all my friends of the “6th floor” and beyond, specially to Miguel, Isabel, Oscar, Fortino, Yuri, Pepe and his family, Servando, Selene, Evelia, Vladimir, Eric, Martha, Marco, Cuitlahuac, Fernando and German. To all my “La Banda” friends because together with my brother Adri´ an we are a brotherhood, specially to Cesar, Rocio and Ale. Enrique Stevens Navarro Instituto Tecnol´ ogico y de Estudios Superiores de Monterrey May 2002

MULTICARRIER WIRELESS NETWORK EVALUATION WITH LEAST LOADED ROUTING Enrique Stevens Navarro, M.Sc. Instituto Tecnol´ ogico y de Estudios Superiores de Monterrey, 2002 The demand for services provided by wireless networks has been increasing during the last years, particularly cellular telephony networks. Now users expect Quality and Services similar to fixed networks ( QoS ). A very important key factor in the performance perceived by the user of cellular networks is the treatment of handoffs. When an active user is moving from one cell to another, and the new cell does not have a channel available, the handoff call will be blocked, which is considered to be more detrimental than the rejection of new incoming calls. Hence, the handoff blocking probability is an important performance mea- sure of wireless networks. A previous work proposed agreements between different carriers in one coverage area to share idle resources to connect blocked users in overloaded carriers to give better ser- vice to their users. To decide to which carrier to offer the blocked call, now 3 schemes were evaluated and compared. A uniform selection between carriers, a fixed sequence of alternate carriers, both of these schemes already evaluated in previous work. And the new scheme proposed is, with a state-dependent approach, the Least Loaded Routing ( LLR ) Algorithm implemented to select a carrier to offer the blocked call. The LLR scheme se- lects the carrier with more free channels based on the state of the cells. The performance of the multicarrier wireless network is evaluated and the 3 schemes are compared with fixed point models, at cell level, at carrier level and also the network rate of return is presented.

MULTICARRIER WIRELESS NETWORK EVALUATION WITH LEAST LOADED ROUTING Enrique Stevens Navarro, M.Sc. Instituto Tecnol´ ogico y de Estudios Superiores de Monterrey, 2002 La demanda por servicios que prestan las redes inal´ ambricas se ha estado incrementado durante los ´ ultimos a˜ nos, particularmente las redes de telefon´ ıa celular. Ahora los usuarios esperan calidad y servicio similares a los de redes fijas. Un factor muy importante en el desempe˜ no percibido por los usuarios de redes celulares es el tratamiento de los handoffs. Cuando un usuario activo se esta moviendo de una celda a otra, y la nueva celda no cuenta con canales disponibles, la llamada en handoff ser´ a bloqueada, lo cual se considera m´ as da˜ nino que el rechazo de una llamada entrante. Por lo tanto, la probabilidad de bloqueo de un hanfoff es una medida importante del desempe˜ no de las redes inal´ ambricas. Un trabajo previo, propuso acuerdos entre diferentes operadores en una ´ area de cober- tura para compartir recursos no utilizados para conectar usuarios bloqueados en operadores con sobrecarga de trafico mejorando el servicio a sus usuarios. En el presente trabajo 3 esquemas son evaluados y comparados para decidir a cual operador ofrecer la llamada blo- queada. En el trabajo previo fueron presentados y evaluados los esquemas de una selecci´ on uniforme entre operadores y una secuencia fija de operadores alternos; el nuevo esquema propuesto es con un enfoque dependiente del estado de la red, el algoritmo de enrutamiento del menos cargado (LLR) es implementado para seleccionar el operador al cual ofrecer la llamada bloqueada. El esquema de enrutamiento del menos cargado (LLR) selecciona el operador que cuenta con mas canales libres, basado en el estado de las celdas. El desempe˜ no de la red inal´ ambrica de m´ ultiples operadores es evaluado y comparado para los tres esquemas con modelos de punto fijo, a nivel de celda, a nivel de operador y tambi´ en la tasa de retorno de la red es presentada.

Contents List of Figures iii List of Tables v Chapter 1 Introduction 1 1.1 Previous Work . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 1.2 Objective . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.3 Justification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.4 Contributions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.5 Organization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Chapter 2 Background 5 2.1 The Cellular Concept . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 2.1.1 Elements of the Cellular Concept, [18], [12]. . . . . . . . . . . . . . 6 2.1.2 Frequency Reuse and Cell Splitting, [18]. . . . . . . . . . . . . . . . 7 2.1.3 Channel Assignment Strategies . . . . . . . . . . . . . . . . . . . . 9 2.1.4 Handoffs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 2.1.5 Multiple Access Technologies . . . . . . . . . . . . . . . . . . . . . 10 2.2 Quality of Service in Cellular Networks, [17] . . . . . . . . . . . . . . . . . 11 2.2.1 Traffic Performance at Network Level . . . . . . . . . . . . . . . . . 12 2.3 Networking Cellular Concepts . . . . . . . . . . . . . . . . . . . . . . . . . 13 2.3.1 Application of Networks of Queues . . . . . . . . . . . . . . . . . . 13 2.4 Methodology for Performance Analysis . . . . . . . . . . . . . . . . . . . . 15 2.4.1 Erlang Fixed Point Approximation . . . . . . . . . . . . . . . . . . 15 2.4.2 Analysis of a Cellular Network with the Fixed Point Approximation 16 Chapter 3 Model Description 19 3.1 Model for a Multicarrier Cellular Network, [14] . . . . . . . . . . . . . . . . 19 3.2 Strategies for Carrier Assignment . . . . . . . . . . . . . . . . . . . . . . . 22 3.2.1 Routing, [19] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 i

ii CONTENTS 3.2.2 Circuit-Switched Routing . . . . . . . . . . . . . . . . . . . . . . . 23 3.2.3 Alternative Routing Strategies . . . . . . . . . . . . . . . . . . . . . 23 3.2.4 Adaptive Routing Strategies . . . . . . . . . . . . . . . . . . . . . . 25 3.3 Model with State-Dependent Routing . . . . . . . . . . . . . . . . . . . . . 25 3.4 Performance Measures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 Chapter 4 Numerical Results 33 4.1 Mobility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 4.2 Symmetric-Symmetric System Case (SSC) . . . . . . . . . . . . . . . . . . 34 4.2.1 Blocking Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 4.2.2 Revenue Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 4.3 Asymmetric-Symmetric System Case . . . . . . . . . . . . . . . . . . . . . 44 4.3.1 Blocking Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 4.3.2 Revenue Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46 Chapter 5 Conclusions 51 5.1 General Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51 5.2 Future Work . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52 Bibliography 53 Vita 55