This document discusses intermodulation interference between 2G and 3G wireless networks operating in the same geographic areas. It investigates how signals from GSM base stations can cause intermodulation interference that degrades the quality of service of UMTS networks. The document proposes a new frequency planning strategy to optimize the QoS of 3G networks in an environment where 2G and 3G systems coexist and can interfere with each other.
Frequency Assignment in GSM Networks an Intelligent Approach IJSTA
This document proposes an intelligent agent approach using a Belief-Desire-Intention framework for optimal frequency assignment in GSM networks. It begins by discussing the frequency assignment problem in cellular networks and limitations of the electromagnetic spectrum. It then describes the components of a GSM network including transceiver frequency hopping. The paper specifies the design of intelligent agents at the network sector and cell level that would have beliefs about spectrum demand and availability, desires to satisfy demand while minimizing interference, and intentions to execute frequency assignment plans.
Hcs (hierarchical cell structure) system for mbms in umts networksAndrew Ahonobadha
This document proposes a hierarchical cell structure system using distributed antennas for MBMS (Multimedia Broadcast Multicast Service) in UMTS networks. It describes a system where antennas are distributed throughout the coverage area of each cell rather than centered around a base station. This allows for improved routing, resource utilization and integration with future wireless networks. The document outlines the proposed system and topology, simulation aspects considering macrocell and hierarchical cell structure scenarios, and simulation results showing the hierarchical cell structure using distributed antennas and MIMO provides better coverage and throughput than a traditional macrocell approach.
What is the purpose of 5G flexible duplexing?
The purpose of 5G flexible duplexing is to allow the most flexible use of an operator's spectrum for time-frequency resources in a single framework. 5G Flexible duplexing should inherently support both paired and unpaired spectrum and be forward compatible with full-duplex 5G.
Performance Evaluation of QoS parameters in UMTS Network Using Qualnetijdpsjournal
A UMTS network based on the Wide Band-CDMA technology is a 3rd generation telecommunication system which provides various multimedia applications along with the conventional
telephony service. These various multimedia applications fall into four different categories, which are
differentiated from each other on the basis of required bit rate and delay tolerance etc. parameters. In
order to get best Quality of Service (QoS) for a particular application running on the subscriber
equipment the parameters of the respective category to which the application belong need to be in a
required range. In this work the performance of a UMTS network scenario is evaluated by using various values of the precedence bits of the CBR application. The simulation tool used is QUALNET 5.0. The performance of the scenario according to the respective precedence bits is analyzed by four metrics: average jitter, end to end delay, throughput and UMTS signals received and forwarded to MAC. The comparative analysis of all the four metrics according to the precedence bit values will be carried out and it will be concluded in the last section that which precedence bit gives the best performance for the simulated UMTS network scenario.
DISCRETE COSINETRANSFORM-II FOR REDUCTION IN PEAK TO AVERAGE POWER RATIO OF O...ijwmn
Orthogonal frequency Division multiplexing (OFDM) is the most familiar word in telecommunication
and wireless communication systems as it provides enhanced spectral efficiency than Frequency division
multiplexing (FDM).Although it is sustaining an orthogonal relation betweencarriers but high peak to
average power ratio (PAPR) is one of the main disadvantages of OFDM system.Various PAPR reduction
techniques have been used, including techniques based on companding. Incompanding, -Law
companding has potential to reduce the PAPR of OFDMsignals. -Law Companding technique
preserves the dynamic range of samples at low amplitudes.A new method named as precoding which is
having less complexity compared to the other power reduction techniques is proposed to reduce PAPR.
This paper put forward combination of two existing techniques namely -Law Companding Transform
and Discrete Cosine Transform-II precoding technique. The simulation results show that, the proposed
combinedscheme gives better result for PAPR Reduction and results in no distortion.
Cellular networks divide geographic areas into smaller cells to increase capacity and reuse frequencies. Each cell has a base station that transmits and receives from mobile devices within its cell. As mobile devices move between cells during calls, the network performs handovers to transfer the call seamlessly between base stations. Common cellular technologies include GSM, CDMA, and LTE that use techniques like FDMA, TDMA, and CDMA to allow frequency reuse and multiple access across cells.
The document discusses radio technologies for mobile WiMAX networks, including OFDM, OFDMA, S-OFDMA, smart antenna systems, and frequency reuse strategies. It explains how these technologies improve spectral efficiency, coverage, throughput and quality of service. Specifically, it discusses how OFDM/OFDMA divide the frequency band into multiple subcarriers to increase robustness to interference, how smart antennas like beamforming increase signal strength and throughput, and how frequency reuse optimization is important to maximize spectrum usage while minimizing interference.
Comparison between gsm & cdma najmul hoque munshiNajmulHoqueMunshi
This document compares and contrasts GSM and CDMA cellular communication technologies. It begins with an introduction to cellular concepts and architectures. It then describes GSM, including that it uses TDMA and operates at 900/1800 MHz bands. The GSM architecture includes components like the BTS, BSC, HLR, VLR, and AuC. It then describes CDMA, including that it uses spread spectrum technology and references GPS for timing. The CDMA architecture spreads each user's signal over the entire bandwidth using unique codes. Finally, it lists the main differences between GSM and CDMA, such as their use of different multiple access technologies and CDMA providing better security through encryption.
Frequency Assignment in GSM Networks an Intelligent Approach IJSTA
This document proposes an intelligent agent approach using a Belief-Desire-Intention framework for optimal frequency assignment in GSM networks. It begins by discussing the frequency assignment problem in cellular networks and limitations of the electromagnetic spectrum. It then describes the components of a GSM network including transceiver frequency hopping. The paper specifies the design of intelligent agents at the network sector and cell level that would have beliefs about spectrum demand and availability, desires to satisfy demand while minimizing interference, and intentions to execute frequency assignment plans.
Hcs (hierarchical cell structure) system for mbms in umts networksAndrew Ahonobadha
This document proposes a hierarchical cell structure system using distributed antennas for MBMS (Multimedia Broadcast Multicast Service) in UMTS networks. It describes a system where antennas are distributed throughout the coverage area of each cell rather than centered around a base station. This allows for improved routing, resource utilization and integration with future wireless networks. The document outlines the proposed system and topology, simulation aspects considering macrocell and hierarchical cell structure scenarios, and simulation results showing the hierarchical cell structure using distributed antennas and MIMO provides better coverage and throughput than a traditional macrocell approach.
What is the purpose of 5G flexible duplexing?
The purpose of 5G flexible duplexing is to allow the most flexible use of an operator's spectrum for time-frequency resources in a single framework. 5G Flexible duplexing should inherently support both paired and unpaired spectrum and be forward compatible with full-duplex 5G.
Performance Evaluation of QoS parameters in UMTS Network Using Qualnetijdpsjournal
A UMTS network based on the Wide Band-CDMA technology is a 3rd generation telecommunication system which provides various multimedia applications along with the conventional
telephony service. These various multimedia applications fall into four different categories, which are
differentiated from each other on the basis of required bit rate and delay tolerance etc. parameters. In
order to get best Quality of Service (QoS) for a particular application running on the subscriber
equipment the parameters of the respective category to which the application belong need to be in a
required range. In this work the performance of a UMTS network scenario is evaluated by using various values of the precedence bits of the CBR application. The simulation tool used is QUALNET 5.0. The performance of the scenario according to the respective precedence bits is analyzed by four metrics: average jitter, end to end delay, throughput and UMTS signals received and forwarded to MAC. The comparative analysis of all the four metrics according to the precedence bit values will be carried out and it will be concluded in the last section that which precedence bit gives the best performance for the simulated UMTS network scenario.
DISCRETE COSINETRANSFORM-II FOR REDUCTION IN PEAK TO AVERAGE POWER RATIO OF O...ijwmn
Orthogonal frequency Division multiplexing (OFDM) is the most familiar word in telecommunication
and wireless communication systems as it provides enhanced spectral efficiency than Frequency division
multiplexing (FDM).Although it is sustaining an orthogonal relation betweencarriers but high peak to
average power ratio (PAPR) is one of the main disadvantages of OFDM system.Various PAPR reduction
techniques have been used, including techniques based on companding. Incompanding, -Law
companding has potential to reduce the PAPR of OFDMsignals. -Law Companding technique
preserves the dynamic range of samples at low amplitudes.A new method named as precoding which is
having less complexity compared to the other power reduction techniques is proposed to reduce PAPR.
This paper put forward combination of two existing techniques namely -Law Companding Transform
and Discrete Cosine Transform-II precoding technique. The simulation results show that, the proposed
combinedscheme gives better result for PAPR Reduction and results in no distortion.
Cellular networks divide geographic areas into smaller cells to increase capacity and reuse frequencies. Each cell has a base station that transmits and receives from mobile devices within its cell. As mobile devices move between cells during calls, the network performs handovers to transfer the call seamlessly between base stations. Common cellular technologies include GSM, CDMA, and LTE that use techniques like FDMA, TDMA, and CDMA to allow frequency reuse and multiple access across cells.
The document discusses radio technologies for mobile WiMAX networks, including OFDM, OFDMA, S-OFDMA, smart antenna systems, and frequency reuse strategies. It explains how these technologies improve spectral efficiency, coverage, throughput and quality of service. Specifically, it discusses how OFDM/OFDMA divide the frequency band into multiple subcarriers to increase robustness to interference, how smart antennas like beamforming increase signal strength and throughput, and how frequency reuse optimization is important to maximize spectrum usage while minimizing interference.
Comparison between gsm & cdma najmul hoque munshiNajmulHoqueMunshi
This document compares and contrasts GSM and CDMA cellular communication technologies. It begins with an introduction to cellular concepts and architectures. It then describes GSM, including that it uses TDMA and operates at 900/1800 MHz bands. The GSM architecture includes components like the BTS, BSC, HLR, VLR, and AuC. It then describes CDMA, including that it uses spread spectrum technology and references GPS for timing. The CDMA architecture spreads each user's signal over the entire bandwidth using unique codes. Finally, it lists the main differences between GSM and CDMA, such as their use of different multiple access technologies and CDMA providing better security through encryption.
Mobile communication process or cellular networkSudhanshu Jha
This document summarizes a seminar presentation on mobile communication processes. It describes the key components of a cellular communication system including the mobile switching center (MSC), base station subsystem (BSS), base transceiver station (BTS), and base station controller (BSC). It also discusses the types of antennas used, including omni-directional and sectored antennas. Finally, it provides a brief overview of modulation basics and how optical fibers are used for transmission in cellular networks.
Data Communications,Data Networks,computer communications,multiplexing,spread spectrum,protocol architecture,data link protocols,signal encoding techniques,transmission media,asynchronous transfer mode,routing,cellular networks
This document provides an overview of cellular networks and key concepts:
- It defines terminology like base station, mobile station, cells, sectors, and handoff.
- It describes early 1G and 2G cellular systems and technologies like FDMA, TDMA, CDMA.
- It covers fundamental concepts like frequency reuse, cell splitting, and forward/reverse links.
- Finally, it discusses challenges like co-channel interference and techniques for wireless quality of service and handoff management.
This document provides an overview of the architecture and interfaces of the GSM mobile network. It discusses the key components and their functions:
The Base Station Subsystem (BSS) manages radio transmissions between mobile stations and the core network. The Network and Switching Subsystem (NSS) manages communications and connects mobile stations to other networks. The Operational Support System (OSS) provides control and management of the network. [/SUMMARY]
ABSTRACT : Performance enhancement of smart antennas versus their complexity for commercial wireless
applications. The goal of the study presented in this paper is to investigate the performance improvement
attainable using relatively simple smart antenna techniques when applied to the third-generation W-CDMA air
interface. Methods to achieve this goal include fixed multi beam architectures with different beam selection
algorithms (maximum power criterion, combined beams) or adaptive solutions driven by relatively simple direction
finding algorithms. After comparing these methods against each other for several representative scenarios, some
issues related to the sensitivity of these methods are also studied, (e.g., robustness to environment, mismatches
originating from implementation limitations, etc.). Results indicate that overall, conventional beam forming
seems to be the best choice in terms of balancing the performance and complexity requirements, in particular
when the problem with interfering high-bit-rate W-CDMA 3g users is considered.
The document discusses signaling fundamentals in a base station subsystem (BSS). It describes the A, Abis, and Um interfaces between the BSS components. The A interface uses SS7 protocol layers including the physical layer, MTP, SCCP and BSSAP. The BSSAP layer supports BSSMAP messages for connectionless and connection-oriented signaling between the BSS and MSC.
1) The document presents a simulation of an MC-CDMA system using MSK modulation over AWGN and Rayleigh channels.
2) It shows that the BER performance of the MC-CDMA system is affected by both the number of users and the channel type, with higher numbers of users and Rayleigh fading increasing the BER.
3) The results also show that for both channel types, the MC-CDMA system has better BER performance when using MSK modulation compared to BPSK modulation.
Maximising system throughput in wireless powered sub-6 GHz and millimetre-wav...TELKOMNIKA JOURNAL
Millimetre wave (mm-Wave) bands and sub-6 GHz are key technologies in solving the spectrum critical situation in the fifth generation (5G) wireless networks in achieving high throughput with low transmission power. This paper studies the performance of dense small cells that involve a millimetre wave (mm-Wave) band and sub-6 GHz that operate in high frequency to support massive multiple-input-multiple-output systems (MIMO). In this paper, we analyse the propagation path loss and wireless powered transfer for a 5G wireless cellular system from both macro cells and femtocells in the sub-6 GHz (μWave) and mm-Wave tiers. This paper also analyses the tier heterogeneous in downlink for both mm-Wave and sub-6 GHz. It further proposes a novel distributed power to mitigate the inter-beam interference directors and achieve high throughput under game theory-based power constraints across the sub-6 GHz and mm-Wave interfaces. From the simulation results, the proposed distributed powers in femtocell suppresses inter-beam interference by minimising path loss to active users (UEs) and provides substantial power saving by controlling the distributed power algorithm to achieve high throughput.
The Study and Analysis of Effect of MultiAntenna Techniques on LTE network wi...Eswar Publications
Long Term Evolution (LTE) system adapts advanced Multiple Input Multiple Output (MIMO) antenna techniques on both uplink and downlink to achieve high peak data rates and higher system throughput. This enables LTE to support multimedia applications beyond web browsing and voice, which demands higher bandwidth configurations. LTE employs Orthogonal Frequency Division Multiple Access (OFDMA) in downlink
to support spectrum flexibility in order to use upto 20MHz system bandwidth to improve the system throughput and robustness. Therefore the combined study of multi-antenna techniques and spectrum flexibility usage on the performance of LTE system becomes vital. Hence in this paper, an attempt has been made to evaluate the performance of different multi-antenna techniques with various system bandwidth configurations from 1.4MHz to 20MHz using QualNet 5.2 network simulator. The multi-antenna techniques considered for performance evaluation are Single Input Single Output (SISO), Multiple Input Single Output (MISO) and Multiple Input
Multiple Output (MIMO). The performance metrics such as aggregate bytes received, average throughput, average delay and average jitter are considered for simulation study.
IOSR Journal of Electronics and Communication Engineering(IOSR-JECE) is an open access international journal that provides rapid publication (within a month) of articles in all areas of electronics and communication engineering and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications in electronics and communication engineering. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
This document discusses techniques for determining the pinpoint location of mobile devices in Global System for Mobile Communication (GSM) networks. It begins with an introduction to the history and development of GSM standards. It then describes several outdoor propagation models that are commonly used to predict signal strength at different locations, including the Longley-Rice model, Durkin's model, and Okumura's model. These models take into account factors like terrain profile, buildings, foliage and antenna heights to estimate path loss between the base station and mobile.
Mobile cellular-telecommunication-system-revisedJohn Williams
Caller identification allows the called mobile station to display the phone number of the calling party.
2. Short Message Service (SMS) allows users to send and receive text messages to and from other mobile phones or fixed phones.
3. Facsimile (fax) services allow users to send and receive fax messages to and from other fax machines through their mobile phones.
International Journal of Computational Engineering Research(IJCER) is an intentional online Journal in English monthly publishing journal. This Journal publish original research work that contributes significantly to further the scientific knowledge in engineering and Technology.
Analysis of WiMAX Physical Layer Using Spatial Multiplexing Under Different F...CSCJournals
WiMAX is defined as Worldwide Interoperability for Microwave Access by the WiMAX Forum and its industry. WiMAX is basically a wireless digital communication system which is also known as IEEE 802.16 standard intended for wireless \"metropolitan area networks\". WiMAX is based upon OFDM multiplexing technique. It was developed in order to provide high speed data rates to the users located in those areas also where broadband wireless coverage is not available. MIMO systems also play an important role in the field of wireless communication by allowing data to be transmitted and received over different antennas. WiMAX-MIMO systems are developed to improve the performance of WiMAX system. This paper analyzes WiMAX-MIMO system for different modulation schemes with different CC code rates under different fading channels (Rician and Nakagami channel). Spatial Multiplexing technique of MIMO system is used for the simulation purpose. Analysis has been done in the form of Signal-to Noise Ratio (SNR) vs Bit Error Rate (BER) plots.
One of the main challenges faced by the developing (3GPP-LTE-Advanced) standard is providing high throughput at the cell edge.
One solution to improve coverage is the use of fixed relays.
The document provides an overview of cellular network concepts and architecture. It discusses how early cellular networks used a single, high-power base station, which led to capacity issues. The core idea of cellular networks was to use multiple, lower-power base stations divided into cells to increase capacity. Key concepts include cell tessellation, handoffs between cells as users move, frequency reuse between cells to avoid interference, and network architecture components like base stations, switches, and subscriber databases.
Performance of modeling wireless networks in realistic environmentCSCJournals
A wireless network is realized by mobile devices which communicate over radio channels. Since, experiments of real life problem with real devices are very difficult, simulation is used very often. Among many other important properties that have to be defined for simulative experiments, the mobility model and the radio propagation model have to be selected carefully. Both have strong impact on the performance of mobile wireless networks, e.g., the performance of routing protocols varies with these models. There are many mobility and radio propagation models proposed in literature. Each of them was developed with different objectives and is not suited for every physical scenario. The radio propagation models used in common wireless network simulators, in general researcher consider simple radio propagation models and neglect obstacles in the propagation environment. In this paper, we study the performance of wireless networks simulation by consider different Radio propagation models with considering obstacles in the propagation environment. In this paper we analyzed the performance of wireless networks by OPNET Modeler .In this paper we quantify the parameters such as throughput, packet received attenuation.
The document discusses different channel assignment strategies for wireless networks, including fixed channel assignment where each cell is predetermined channels and dynamic channel assignment where channels are allocated on request based on factors like channel occupancy. It also describes a partially overlapping channel (FPOC) assignment strategy that aims to increase capacity while minimizing interference through intelligent channel allocation between neighboring nodes.
Capacity planning(CP) determines operational expenditure, capital expenditure and long-term performance of the system hence it is the most important phase in the life cycle of a cellular system. For the past three decades, capacity planning problems have studied for all generations of the cellular system. So, to increase the capacity of the network in future we focus on small cells of cell structure. Cellular network includes the variety of different cell sizes and types, heterogeneous networks, control, and data plane split architectures, coordinated multipoint, massive multiple inputs multiple outputs.
The objective of this presentation is to focus on traditional deployment reviews and identify future opportunities, challenges, and trends in detail. More specifically we investigate the future capacity planning by reviewing the CP process including its objective input and output parameter to an optimization process and the CP phases.
The document outlines the key concepts and units covered in a course on wireless and cellular communications. Unit 1 discusses cellular system design fundamentals including frequency reuse, interference, and capacity. Unit 2 covers speech coding techniques and radio channel characterization. Unit 3 discusses modulation techniques, diversity techniques, and OFDM. Unit 4 introduces MAC protocols for wireless networks. Unit 5 introduces satellite communication systems. Reference books on wireless communication principles and standards are also listed.
This document provides an overview of Quality of Service (QoS) in computer networks. It discusses several key IP QoS mechanisms including resource reservation using RSVP, admission control with bandwidth brokers, packet classification and marking, queuing disciplines like priority queuing and weighted fair queuing, traffic shaping using leaky bucket and token bucket algorithms, and policing. It also describes QoS frameworks like IntServ and DiffServ that systematically apply these mechanisms. Finally, it covers QoS in wireless networks, focusing on support in 802.11 networks and interactions with mobility protocols.
Mobile communication process or cellular networkSudhanshu Jha
This document summarizes a seminar presentation on mobile communication processes. It describes the key components of a cellular communication system including the mobile switching center (MSC), base station subsystem (BSS), base transceiver station (BTS), and base station controller (BSC). It also discusses the types of antennas used, including omni-directional and sectored antennas. Finally, it provides a brief overview of modulation basics and how optical fibers are used for transmission in cellular networks.
Data Communications,Data Networks,computer communications,multiplexing,spread spectrum,protocol architecture,data link protocols,signal encoding techniques,transmission media,asynchronous transfer mode,routing,cellular networks
This document provides an overview of cellular networks and key concepts:
- It defines terminology like base station, mobile station, cells, sectors, and handoff.
- It describes early 1G and 2G cellular systems and technologies like FDMA, TDMA, CDMA.
- It covers fundamental concepts like frequency reuse, cell splitting, and forward/reverse links.
- Finally, it discusses challenges like co-channel interference and techniques for wireless quality of service and handoff management.
This document provides an overview of the architecture and interfaces of the GSM mobile network. It discusses the key components and their functions:
The Base Station Subsystem (BSS) manages radio transmissions between mobile stations and the core network. The Network and Switching Subsystem (NSS) manages communications and connects mobile stations to other networks. The Operational Support System (OSS) provides control and management of the network. [/SUMMARY]
ABSTRACT : Performance enhancement of smart antennas versus their complexity for commercial wireless
applications. The goal of the study presented in this paper is to investigate the performance improvement
attainable using relatively simple smart antenna techniques when applied to the third-generation W-CDMA air
interface. Methods to achieve this goal include fixed multi beam architectures with different beam selection
algorithms (maximum power criterion, combined beams) or adaptive solutions driven by relatively simple direction
finding algorithms. After comparing these methods against each other for several representative scenarios, some
issues related to the sensitivity of these methods are also studied, (e.g., robustness to environment, mismatches
originating from implementation limitations, etc.). Results indicate that overall, conventional beam forming
seems to be the best choice in terms of balancing the performance and complexity requirements, in particular
when the problem with interfering high-bit-rate W-CDMA 3g users is considered.
The document discusses signaling fundamentals in a base station subsystem (BSS). It describes the A, Abis, and Um interfaces between the BSS components. The A interface uses SS7 protocol layers including the physical layer, MTP, SCCP and BSSAP. The BSSAP layer supports BSSMAP messages for connectionless and connection-oriented signaling between the BSS and MSC.
1) The document presents a simulation of an MC-CDMA system using MSK modulation over AWGN and Rayleigh channels.
2) It shows that the BER performance of the MC-CDMA system is affected by both the number of users and the channel type, with higher numbers of users and Rayleigh fading increasing the BER.
3) The results also show that for both channel types, the MC-CDMA system has better BER performance when using MSK modulation compared to BPSK modulation.
Maximising system throughput in wireless powered sub-6 GHz and millimetre-wav...TELKOMNIKA JOURNAL
Millimetre wave (mm-Wave) bands and sub-6 GHz are key technologies in solving the spectrum critical situation in the fifth generation (5G) wireless networks in achieving high throughput with low transmission power. This paper studies the performance of dense small cells that involve a millimetre wave (mm-Wave) band and sub-6 GHz that operate in high frequency to support massive multiple-input-multiple-output systems (MIMO). In this paper, we analyse the propagation path loss and wireless powered transfer for a 5G wireless cellular system from both macro cells and femtocells in the sub-6 GHz (μWave) and mm-Wave tiers. This paper also analyses the tier heterogeneous in downlink for both mm-Wave and sub-6 GHz. It further proposes a novel distributed power to mitigate the inter-beam interference directors and achieve high throughput under game theory-based power constraints across the sub-6 GHz and mm-Wave interfaces. From the simulation results, the proposed distributed powers in femtocell suppresses inter-beam interference by minimising path loss to active users (UEs) and provides substantial power saving by controlling the distributed power algorithm to achieve high throughput.
The Study and Analysis of Effect of MultiAntenna Techniques on LTE network wi...Eswar Publications
Long Term Evolution (LTE) system adapts advanced Multiple Input Multiple Output (MIMO) antenna techniques on both uplink and downlink to achieve high peak data rates and higher system throughput. This enables LTE to support multimedia applications beyond web browsing and voice, which demands higher bandwidth configurations. LTE employs Orthogonal Frequency Division Multiple Access (OFDMA) in downlink
to support spectrum flexibility in order to use upto 20MHz system bandwidth to improve the system throughput and robustness. Therefore the combined study of multi-antenna techniques and spectrum flexibility usage on the performance of LTE system becomes vital. Hence in this paper, an attempt has been made to evaluate the performance of different multi-antenna techniques with various system bandwidth configurations from 1.4MHz to 20MHz using QualNet 5.2 network simulator. The multi-antenna techniques considered for performance evaluation are Single Input Single Output (SISO), Multiple Input Single Output (MISO) and Multiple Input
Multiple Output (MIMO). The performance metrics such as aggregate bytes received, average throughput, average delay and average jitter are considered for simulation study.
IOSR Journal of Electronics and Communication Engineering(IOSR-JECE) is an open access international journal that provides rapid publication (within a month) of articles in all areas of electronics and communication engineering and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications in electronics and communication engineering. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
This document discusses techniques for determining the pinpoint location of mobile devices in Global System for Mobile Communication (GSM) networks. It begins with an introduction to the history and development of GSM standards. It then describes several outdoor propagation models that are commonly used to predict signal strength at different locations, including the Longley-Rice model, Durkin's model, and Okumura's model. These models take into account factors like terrain profile, buildings, foliage and antenna heights to estimate path loss between the base station and mobile.
Mobile cellular-telecommunication-system-revisedJohn Williams
Caller identification allows the called mobile station to display the phone number of the calling party.
2. Short Message Service (SMS) allows users to send and receive text messages to and from other mobile phones or fixed phones.
3. Facsimile (fax) services allow users to send and receive fax messages to and from other fax machines through their mobile phones.
International Journal of Computational Engineering Research(IJCER) is an intentional online Journal in English monthly publishing journal. This Journal publish original research work that contributes significantly to further the scientific knowledge in engineering and Technology.
Analysis of WiMAX Physical Layer Using Spatial Multiplexing Under Different F...CSCJournals
WiMAX is defined as Worldwide Interoperability for Microwave Access by the WiMAX Forum and its industry. WiMAX is basically a wireless digital communication system which is also known as IEEE 802.16 standard intended for wireless \"metropolitan area networks\". WiMAX is based upon OFDM multiplexing technique. It was developed in order to provide high speed data rates to the users located in those areas also where broadband wireless coverage is not available. MIMO systems also play an important role in the field of wireless communication by allowing data to be transmitted and received over different antennas. WiMAX-MIMO systems are developed to improve the performance of WiMAX system. This paper analyzes WiMAX-MIMO system for different modulation schemes with different CC code rates under different fading channels (Rician and Nakagami channel). Spatial Multiplexing technique of MIMO system is used for the simulation purpose. Analysis has been done in the form of Signal-to Noise Ratio (SNR) vs Bit Error Rate (BER) plots.
One of the main challenges faced by the developing (3GPP-LTE-Advanced) standard is providing high throughput at the cell edge.
One solution to improve coverage is the use of fixed relays.
The document provides an overview of cellular network concepts and architecture. It discusses how early cellular networks used a single, high-power base station, which led to capacity issues. The core idea of cellular networks was to use multiple, lower-power base stations divided into cells to increase capacity. Key concepts include cell tessellation, handoffs between cells as users move, frequency reuse between cells to avoid interference, and network architecture components like base stations, switches, and subscriber databases.
Performance of modeling wireless networks in realistic environmentCSCJournals
A wireless network is realized by mobile devices which communicate over radio channels. Since, experiments of real life problem with real devices are very difficult, simulation is used very often. Among many other important properties that have to be defined for simulative experiments, the mobility model and the radio propagation model have to be selected carefully. Both have strong impact on the performance of mobile wireless networks, e.g., the performance of routing protocols varies with these models. There are many mobility and radio propagation models proposed in literature. Each of them was developed with different objectives and is not suited for every physical scenario. The radio propagation models used in common wireless network simulators, in general researcher consider simple radio propagation models and neglect obstacles in the propagation environment. In this paper, we study the performance of wireless networks simulation by consider different Radio propagation models with considering obstacles in the propagation environment. In this paper we analyzed the performance of wireless networks by OPNET Modeler .In this paper we quantify the parameters such as throughput, packet received attenuation.
The document discusses different channel assignment strategies for wireless networks, including fixed channel assignment where each cell is predetermined channels and dynamic channel assignment where channels are allocated on request based on factors like channel occupancy. It also describes a partially overlapping channel (FPOC) assignment strategy that aims to increase capacity while minimizing interference through intelligent channel allocation between neighboring nodes.
Capacity planning(CP) determines operational expenditure, capital expenditure and long-term performance of the system hence it is the most important phase in the life cycle of a cellular system. For the past three decades, capacity planning problems have studied for all generations of the cellular system. So, to increase the capacity of the network in future we focus on small cells of cell structure. Cellular network includes the variety of different cell sizes and types, heterogeneous networks, control, and data plane split architectures, coordinated multipoint, massive multiple inputs multiple outputs.
The objective of this presentation is to focus on traditional deployment reviews and identify future opportunities, challenges, and trends in detail. More specifically we investigate the future capacity planning by reviewing the CP process including its objective input and output parameter to an optimization process and the CP phases.
The document outlines the key concepts and units covered in a course on wireless and cellular communications. Unit 1 discusses cellular system design fundamentals including frequency reuse, interference, and capacity. Unit 2 covers speech coding techniques and radio channel characterization. Unit 3 discusses modulation techniques, diversity techniques, and OFDM. Unit 4 introduces MAC protocols for wireless networks. Unit 5 introduces satellite communication systems. Reference books on wireless communication principles and standards are also listed.
This document provides an overview of Quality of Service (QoS) in computer networks. It discusses several key IP QoS mechanisms including resource reservation using RSVP, admission control with bandwidth brokers, packet classification and marking, queuing disciplines like priority queuing and weighted fair queuing, traffic shaping using leaky bucket and token bucket algorithms, and policing. It also describes QoS frameworks like IntServ and DiffServ that systematically apply these mechanisms. Finally, it covers QoS in wireless networks, focusing on support in 802.11 networks and interactions with mobility protocols.
The 2G spectrum scam involved the Indian government undervaluing 2G spectrum licenses awarded to telecom companies in 2008, resulting in an estimated loss of ₹1.76 lakh crore to the public exchequer. Key players accused of corruption included DMK politician A. Raja and companies like Swan Telecom and Unitech Wireless. Investigations were conducted by agencies like the CBI, CAG and Enforcement Directorate. The scam significantly weakened the Manmohan Singh-led UPA government and led to demands for reforming the country's telecom policies.
This document compares the 1st through 4th generations of wireless technology. 1G was analog and focused on voice. 2G introduced digital transmission and data services. 3G brought increased speeds and applications like video calling. 4G will provide speeds from 100 Mbps to 1 Gbps for broadband access anywhere. It analyzes the strengths, weaknesses, opportunities, and threats for each generation.
The document discusses the evolution of wireless networks from 1G to 5G. 1G networks were the first generation of cellular networks and used analog signals. 2G introduced digital cellular networks like GSM, which offered benefits over 1G like encrypted calls and greater efficiency. 3G networks brought internet access to mobile phones. 4G aims to provide wireless internet with speeds comparable to fixed broadband. 5G networks will integrate existing cellular and WiFi networks to provide universal wireless connectivity without limitations.
Presentation on 1G/2G/3G/4G/5G/Cellular & Wireless TechnologiesKaushal Kaith
This Presentation is explaining all about the Generations of Mobile or Cellular Technology (1G/2G/2.5/ 3G/4g/5G). This explain the invented details ,features,drawbacks,look of wireless models and comparison and evolution of technology from 1G to 5G and also explaining about wireless application and their services.
Evaluation of Percentage Capacity Loss on LTE Network Caused by Intermodulati...Onyebuchi nosiri
The document evaluates the capacity loss of an LTE network (VISAFONE) due to interference from neighboring networks. It finds that third-order intermodulation distortion (IMD3) between the downlink of an LTE network (INTERCELLULAR) and the uplink of a GSM network (ETISALAT) generates interfering frequencies within the victim receiver's passband. MATLAB simulations were run to evaluate capacity loss at the VISAFONE LTE receiver for distances from 500m to 3000m between the interfering networks. Results showed 80% capacity loss at 500m, decreasing to 5.97% at 3000m, demonstrating that closer distances lead to more severe interference and capacity degradation for the victim LTE network.
Evaluation of Percentage Capacity Loss on LTE Network Caused by Intermodulati...Onyebuchi nosiri
Abstract- The paper evaluates the effects of third order Intermodulation Distortion (IMD3) on the Long Term Evolution (LTE) receiver due to coexistence between LTE and GSM networks. Amongst the various existing IMD orders which include first order, second order, third order, fifth order and seventh order. Third order is known to have the greatest distortion effects on a receiver due to its strength and its proximity to the frequency band of interest. It occurs as a result of the non-linear behavior of components or circuit at both the transmitter and receiver ends of wireless communication networks. IMD has potential negative effects on a victim receiver which majorly leads to increase in noise floor level and system capacity degradation. Deterministic approach was implemented in the work assuming worst case scenario. MATLAB software simulation was deployed to evaluate the capacity loss at the receiver end relative to a range of distances apart. Results obtained showed severe uplink capacity degradation when VISAFONE LTE network was interfered by INTERCELLULAR LTE downlink and ETISALAT GSM uplink. Various distances ranging from 500m to 3000m were varied between the ETISALAT GSM network and the VISAFONE LTE network. The results obtained showed that at 500 meters, the percentage capacity degradation was as high as 80. The least percentage capacity loss was obtained as 5.97 at 3000 meters.
Umts Radio Interface System Planning And OptimizationDavid Rottmayer
The document discusses planning and optimizing UMTS radio networks. It begins with an overview of UMTS network architecture and the differences between UMTS and GSM radio system planning. Key aspects of UMTS planning include coverage and capacity planning occurring simultaneously, as capacity requirements influence coverage. The document then covers WCDMA air interface specifications, propagation environments, and the UMTS radio system planning process. It discusses challenges such as varying traffic levels and distributions. The document provides a typical link budget example and explains transmitter, receiver, and channel parameters considered in UMTS coverage planning.
method for enhancement of coexistence between e gsm and cdma systems in borde...INFOGAIN PUBLICATION
This paper presents a possible method for enhancement of co-existence of an E-GSM system based network with a CDMA sustem based network, in border area between two countries. Since the frequency bands allocated for the deployment of previous mentioned networks can partially overlap and due to the fact that the downlink frequency band of CDMA system is in the same frequrency band as the uplink of E-GSM system, the co-existence of the systems represents a challenge for the spectrum enineering process. In this paper a method for sharing the frequency band between the two countries under discussion is presented, in order to offer an equitable access to limited spectrum resources. Under this approach, there are settled common technical principles of a coordination procedure between country A and country B.
SINR Analysis and Interference Management of Macrocell Cellular Networks in D...umere15
This document analyzes signal-to-interference-plus-noise ratio (SINR) and interference management in 5G macrocell cellular networks operating at 30 GHz in dense urban environments. It first investigates appropriate interference models for predicting outage events. It then creates a network simulation with 19 sites based on real geospatial data from NIT Srinagar, with each site having multiple cells. SINR maps are generated and compared for single antennas versus antenna arrays. The interference ball model is used to simplify interference calculation by only considering nearby interferers. Configuration parameters from ITU-R reports are used to simulate the network according to dense urban specifications.
K Coverage Probability of 5G Wireless Cognitive Radio Network under Shadow Fa...ijeei-iaes
Land mobile communication is burdened with typical propagation constraints due to the channel characteristics in radio systems.Also,the propagation characteristics vary form place to place and also as the mobile unit moves,from time to time.Hence,the tramsmission path between transmitter and receiver varies from simple direct LOS to the one which is severely obstructed by buildings,foliage and terrain.Multipath propagation and shadow fading effects affect the signal strength of an arbitrary Transmitter-Receiver due to the rapid fluctuations in the phase and amplitude of signal which also determines the average power over an area of tens or hundreds of meters.Shadowing introduces additional fluctuations,so the received local mean power varies around the area –mean.The present section deals with the performance analysis of fifth generation wireless cognitive radio network on the basis of signal and interference level based k coverage probability under the shadow fading effects.
Radio field strength propagation data and pathloss calculation methods in umt...Alexander Decker
This document discusses radio signal path loss prediction methods for UMTS networks. It conducted field measurements of signal strength in a UMTS network in Benin City, Nigeria to collect propagation data. It then used this data to calculate path loss and compared the results to several existing path loss prediction models, finding that the Okumura-Hata model provided the closest predictions for the environment studied, showing its suitability for path loss analysis in UMTS networks in urban areas.
Evaluation of the weighted-overlap add model with massive MIMO in a 5G systemTELKOMNIKA JOURNAL
The flaw in 5G orthogonal frequency division multiplexing (OFDM) becomes apparent in high-speed situations. Because the doppler effect causes frequency shifts, the orthogonality of OFDM subcarriers is broken, lowering both their bit error rate (BER) and throughput output. As part of this research, we use a novel design that combines massive multiple input multiple output (MIMO) and weighted overlap and add (WOLA) to improve the performance of 5G systems. To determine which design is superior, throughput and BER are calculated for both the proposed design and OFDM. The results of the improved system show a massive improvement in performance ver the conventional system and significant improvements with massive MIMO, including the best throughput and BER. When compared to conventional systems, the improved system has a throughput that is around 22% higher and the best performance in terms of BER, but it still has around 25% less error than OFDM.
Basic of 3 g technologies (digi lab_project).pptx [repaired]Shahrin Ahammad
The document provides an overview of 3G standards and the radio access network architecture. It discusses the reasons for switching from 2G to 3G technologies, including higher data rates and improved security. It then describes the components of the UMTS network architecture, including user equipment, Node B base stations, radio network controllers, mobile switching centers, and connections to external networks. The document also compares 2G and 3G network structures.
Impact of Next Generation Cognitive Radio Network on the Wireless Green Eco s...ijeei-iaes
Land mobile communication is burdened with typical propagation constraints due to the channel characteristics in radio systems.Also,the propagation characteristics vary form place to place and also as the mobile unit moves,from time to time.Hence,the tramsmission path between transmitter and receiver varies from simple direct LOS to the one which is severely obstructed by buildings, foliage and terrain. Multipath propagation and shadow fading effects affect the signal strength of an arbitrary Transmitter-Receiver due to the rapid fluctuations in the phase and amplitude of signal which also determines the average power over an area of tens or hundreds of meters. Shadowing introduces additional fluctuations, so the received local mean power varies around the area –mean. The present paper deals with the performance analysis of impact of next generation wireless cognitive radio network on wireless green eco system through signal and interference level based k coverage probability under the shadow fading effects.
The document discusses the impact of sectorization on UMTS radio access network coverage planning. It analyzes three different site layout configurations: single omni-directional antenna sites, 3-sector sites, and 6-sector sites. The number of sites required to cover a deployment area is estimated for each configuration. Sectorized sites use high gain directional antennas to cover sectors, replacing omni-directional antennas. Link budget calculations are performed to determine the maximum path loss and cell radius for different clutter types. The results can be used to study the effect of sectorization and antenna gain on the number of sites needed.
This document analyzes the capacity of MIMO wireless channels when accounting for impairments from physical transceiver hardware limitations. It is shown that when including the effects of transceiver impairments like non-linearities, phase noise, and quantization noise, the capacity of MIMO channels reaches a finite limit as SNR increases, rather than increasing without bound. This results in a zero multiplexing gain, unlike the ideal case without impairments. However, the relative capacity increase from MIMO over single-antenna channels remains at least as large when including impairments. Various figures are presented showing the capacity and multiplexing gain for different channel models and transceiver configurations. The document concludes by stating the analysis provides insights into understanding
Handover between WCDMA and GSM allows the GSM network to be used
to give fallback coverage for WCDMA technology. This means that subscribers
can experience seamless services—even with a phased build-out
of WCDMA—which is of importance to the commercial launches in 2003.
As the leading total system provider, Ericsson has developed technologies
that overcome the challenges of interworking between WCDMA and
GSM. For example, Ericsson was first to demonstrate handover from
WCDMA to GSM in a live network.
This document proposes techniques to reduce interference in WCDMA networks through cell resizing. It begins with background on WCDMA and sources of interference. It then proposes classifying cells as normal, saturated or cooperative based on SNR measurements. Saturated cells trigger a cell resizing process where users are transferred to neighboring cooperative cells to balance load and cancel interference. Simulation results showed this approach reduces blocking probability and achieves optimal transmission rates with reduced delay.
LABORATORY ANALYSIS ON THE PERFORMANCE OF 5G NSA COMMUNICATION IN A SUBURBAN ...ijwmn
The propagation of information by electromagnetic waves suffers different types of interference, according
to the characteristics of the environment. The 5G system relies on adaptive modulation and coding
techniques to better suit the channel and maximize effective data exchange between the user equipment and
the network. Practical studies on the behaviour of the system under different environmental conditions,
subject to attenuation processes such as fading, are important to understand and improve the 5G
efficiency. This work has analysed the effect of the MCS (Modulation and Coding Scheme) variation on
throughput for channel degraded by the multipath fading effect in a mobile communication. The analysis
was carried out showing that the decision algorithms in terms of MCS switching to maintain adequate data
rates according to the requirement (QoS) is an important factor. Considering both 64 QAM and 256 QAM,
the throughput degradation effect was more evident in higher-order modulations due to the higher
probability of bit error in the symbol constellation. This study can be a key for understanding and
developing robust MCS switcher for 5G and beyond communications.
LABORATORY ANALYSIS ON THE PERFORMANCE OF 5G NSA COMMUNICATION IN A SUBURBAN ...ijwmn
The propagation of information by electromagnetic waves suffers different types of interference, according
to the characteristics of the environment. The 5G system relies on adaptive modulation and coding
techniques to better suit the channel and maximize effective data exchange between the user equipment and
the network. Practical studies on the behaviour of the system under different environmental conditions,
subject to attenuation processes such as fading, are important to understand and improve the 5G
efficiency. This work has analysed the effect of the MCS (Modulation and Coding Scheme) variation on
throughput for channel degraded by the multipath fading effect in a mobile communication. The analysis
was carried out showing that the decision algorithms in terms of MCS switching to maintain adequate data
rates according to the requirement (QoS) is an important factor. Considering both 64 QAM and 256 QAM,
the throughput degradation effect was more evident in higher-order modulations due to the higher
probability of bit error in the symbol constellation. This study can be a key for understanding and
developing robust MCS switcher for 5G and beyond communications.
Quality of Service in bandwidth adapted hybrid UMTS/WLAN interworking networkTELKOMNIKA JOURNAL
Integration of Universal Mobile Telecommunications System (UMTS) and Wireless Local Area Network (WLAN) result in ubiquitous connection for end users. In the integrated network, ensuring the quality of service to users and enhancing capacity of network are prominent issues. Bandwidth adaptation technique is one of the solutions to overcome these issues. Bandwidth adaptation based on per flow and per class schemes were proposed for loosely coupled interworking network. In this paper, hybrid coupled UMTS and WLAN interworking network is analyzed with bandwidth adaptation based on per flow and per class schemes and the performances have been compared. Simulation result shows that the proposed hybrid coupled interworking network with bandwidth adaptation based on per class scheme performs better with enhanced quality of service and network capacity.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com
This document summarizes research on channel modeling for millimeter wave MIMO communications. It discusses two scenarios: 1) An outdoor deployment using lampposts, where reflections from walls and the ground can cause fading that MIMO techniques can help mitigate. 2) An indoor link where spatial multiplexing is possible even in line-of-sight environments due to the compact sizes of antennas at millimeter wavelengths, though blockages significantly impact performance. The key differences in millimeter wave propagation compared to lower frequencies include higher path losses mitigated by high antenna directivity, sparser multipath environments, and greater sensitivity to blockages.
Similar to The impact of intermodulation interference in superimposed 2 g and 3g (20)
The impact of intermodulation interference in superimposed 2 g and 3g
1. The impact of intermodulation interference in superimposed
2G and 3G wireless networks and optimization issues of the
provided QoS
1
G. Paschos, IEEE member, S. A. Kotsopoulos, D. A. Zogas, Student Member, IEEE, and G.
K. Karagiannidis, IEEE member
Abstract – This paper investigates the critical parameters that affect the overall opera-
tion of the systems that belong to different competing wireless communication consortia.
It is anticipated that the competing consortia will operate separate wireless systems (2G
and 3G) in the same geographical areas where block allocations of channels are made to
facilitate this. Moreover, the generated out-of-band intermodulation interference spec-
trum by each other is examined and finally, a new frequency planning strategy is intro-
duced in order to optimize the QoS of the 3G wireless system.
Index Terms – Intermodulation interference, 2G, 3G, QoS, CDMA capacity.
1
G. Paschos, D. A. Zogas and Dr. S. A. Kotsopoulos are with the Laboratory of Wireless Telecommu-
nications, Electrical & Computer Engineering Dept., University of Patras, Rion, 26442 Patras, Greece,
Tel +32-610-997301, Fax: +32-610-997302, gpaschos@ee.upatras.gr, zogas@space.noa.gr,
kotsop@ee.upatras.gr
Dr. G. K. Karagiannidis is with the Institute for Space Applications & Remote Sensing, National Ob-
servatory of Athens, Metaxa & Vas. Pavlou Str., Palea Penteli, 15236 Athens Greece,
gkarag@space.noa.gr.
2. I. INTRODUCTION
T
HE study of intermodulation interference in the bibliography is rather limited. As a phe-
nomenon, the intermodulation interference is born in coexistence. Naturally, extensive
investigation is stirred only when the advent of a new system invades the set RF envi-
ronment. In [1], an AMPS to CDMA intermodulation interference description can be found.
Intermodulation interference has also engaged another kind of research like the development
of nonlinear RF circuits with a built-in mechanism of intermodulation rejection [2].
In this analysis the overlapping of 2G and 3G is examined. More specifically, the in-
teraction between the already installed GSM system with the new WCDMA technology of
UMTS is showcased. An analysis of interference effects on WCDMA capacity can be found
in [3] where the degradation of QoS is illustrated. Finally, in [4] a frequency planning algo-
rithm for 2G systems is described that takes into account the tradeoff between adjacent chan-
nel and intermodulation interference. In this study we will propose a new frequency planning
logic that optimizes the performance of both GSM and UMTS systems when they coexist in a
geographical area.
In the next section the 2G-3G superposition issues are presented, in section III a theo-
retical background of intermodulation interference is developed. In section IV an estimation
of interference power level is found and in section V the impact on WCDMA capacity is ex-
plored. Section VI, a GSM1800 - UMTS superposition is simulated, while in section VII the
proposed frequency planning is explained and finally in section VIII the paper is concluded.
II. THE SUPERPOSITION OF CELLULAR SYSTEMS
The second generation (2G) systems made their appearance as the first digital sys-
tems for mobile telecommunications. The most popular representative is the worldwide
spread GSM (Global System for Mobile) which is the one that will be the subject of this
analysis. It utilizes hybrid FDMA and TDMA technique with 124 channels of 200KHz
bandwidth and 8 timeslots of 576.92ms each. Using GMSK as the modulation method, it
1
3. manages to serve 9.6kbps throughput. The main applications are speech and short data mes-
sages and the connection type is circuit connection. Another interesting aspect is the realiza-
tion of the infrastructure. As a rule of thumb, GSM cells can have a number of 1 up to 12
base station transceivers (BTS) that are fed to the antenna through a number of adders and
combiners. Bandpass filters are also used as it can be seen in figure 1. The frequency alloca-
tion of GSM900, GSM1800 and UMTS is shown in figure 2.
Figure 1: GSM Base Station diagram - Centre frequencies f1, f2, f3, …, fn are arranged in a frequency
plan so as to minimize the induced level of intra-system interference (the sum of adjacent, co-channel
and intermodulation)
Figure 2: The shape of RF spectrum in a GSM-UMTS coexisting area
2
4. The era of third generation (3G) mobile communications has arrived and research is
still carried on over the smooth installation of the several new systems. The primary objec-
tives of 3G systems are interoperability, high throughput rates (up to 2Mbps), permanent
connection support, transition to packet connection, QoS on demand and full coverage. The
main applications will be streaming applications and the internet. Plans are held for multiple
QoS standards and the potentiality for data load charge instead of time charge. A characteris-
tic representative of 3G systems is the Universal Mobile Telecommunication System
(UMTS).
According to 3GPP standardization, the several possible 3G applications are divided
into categories with different QoS requirements. For example, the conversational class re-
quires minimum delay time while the streaming class requires high throughput rates [5]. In
any case, the QoS of the system depends on several factors with the physical layer parameters
as the most important. High levels of interference and extreme fading can damage the result-
ing QoS and thus restrict the user to applications with low QoS requirements. The available
spectrum for UMTS is shown in figure 2. A UMTS frequency channel may vary from 5MHz
to 20MHz. The total number of channels fitting in the 60MHz spectrum will be distributed to
several service providers or reserved for future use. One channel with FDD support is ade-
quate for the operation of a UMTS network.
A hot aspect of the installation of these new systems is the interoperability with the
existing systems. The efficiency of the whole system and the needs of our society favor the
continuation of GSM operation as a service provider system, thus it is necessary for the
UMTS system to be able to maintain the desired QoS in this crowdy RF environment. One
phenomenon that leads to deterioration of spectrum efficiency is the intermodulation (IM)
interference. CDMA techniques, used by 3G systems, are known to be resilient to narrow-
band interference and multipath fading. However, the degradation can sometimes be notable.
3
5. III. INTERMODULATION INTERFERENCE ISSUES
IM interference is a direct result of nonlinearities. When a signal with centre frequency
f and bandwidth BW is fed into a nonlinear device with a characteristic function of equation
1, it incites an output that bears a rich spectral content, as shown in figure 3.
...)( 4
4
3
3
2
210 +++++= xaxaxaxaaxh (1)
Figure 3: The output of a nonlinear amplifier with x(t)=Acos(2πft) input. 2nd
and 3rd
order are shown
only.
This output signal is in general not desirable in case of transmitters. Sometimes it can
be observed as in-band interference, meaning that spurious signals infect the bandwidth of the
input signal itself. On the other hand, there are occasions when the intermodulation interfer-
ence signals (intermods) take up another place in the RF spectrum and are transmitted
through the air interface, seen as interference to another operating network. When two or
more signals are added in the input of the nonlinear device, the output contains several alge-
braic sums of the input frequencies. The shape of the signal spectrum is altered as well, since
the signal is raised in the nth power. Therefore, a thorough study is needed so as to examine
the several cases that the GSM signal can cause interference to UMTS this way.
In this section the several scenarios where a GSM signal can cause IM interference
that can damage the performance of a UMTS receiver will be discussed. The inverse case is
not of substantial interest because UMTS systems are expected to have very few transmitting
frequencies (absence of FDMA). Similarly, it is assumed that the interference caused by the
4
6. mobile phones is negligible. Since the GSM mobile stations use only one frequency when
communicating, according to figure 2, for an in band intermod at least two different frequen-
cies are required to be combined. In addition to that, mobile stations use much less power and
only one timeslot out of eight in the GSM frame, facts that reduce the imposed interference of
any kind.
Given the aforementioned assumptions, it is clearly understood that our model con-
sists of a GSM base station transmitter and a UMTS receiver that could be a mobile or a base
station. Referring to the real existing network, the interference will be caused due to several
neighboring base stations that comprise the GSM RF interface of a geographical area. To
simplify the problem, we take into account only the 1st
tier interferers as the role of the rest
interferers is rather small. The position of UMTS base can be exactly on one GSM station
(when the provider is the same), or in random position (when belongs to a different service
provider or greater transceiver density is required) for which in practice we can assume the
gravity centre of three GSM transceivers. The mobile, of course could be anywhere. An ex-
ample of these scenarios is given in the figure 4, where a UMTS base station and a UMTS
mobile station suffer from IM interference caused by the adjacent GSM transmitters.
Figure 4: Multiple GSM base station can cause IM interference to UMTS base stations or mobile sta-
tions ( GSMr3=d )
Apart from the topographical characterization of the interference model, multiple
scenarios arise from the number of signal combinations that can result to IM interference. In
5
7. the following table we have several examples of IM products of two, three or four centre fre-
quency signals fed into a nonlinear device that has a characteristic function with ai=0, i>4.
Table 1: IM products of frequency sum
The ideal RF spectrum in an area of superimposed 2G and 3G systems would look
like figure 2. The known uplink and downlink frequencies are also given in the same figure.
It is obvious that only a small fraction of the possible combination of frequencies will give an
IM outcome resulting into the UMTS band. In specific, figures 5 and 6 show the possible
threatening products from GSM-900 and GSM-1800 in case of two simultaneously transmit-
ted frequencies. Also, more than two frequencies can be combined to give similar result (3 in
case of GSM-1800 and 3 or 4 for the GSM-900). However, the results from these scenarios
would be a fraction of the shown ones. That is because the in-band products are created by
long spaced channels (from a combination of a high and a low channel frequency). Channel
frequencies that are not included in the next two diagrams are the intermediate ones. The
sums fi+fj-fk and fi+fj+fl-fk require small fk and great values for the rest. Thus there is no way
to use an intermediate frequency and get closer to UMTS band. This signifies the importance
of frequency spacing. Small distances produce adjacent channel interference and great dis-
tances favor intermodulation interference. A tradeoff between the two brings the best results.
6
8. Figure 5: GSM-900 (4th
order ji ff −3 ) IM products that fall into UMTS band
Figure 6 GSM-1800 (3rd
order ji ff −2 ) channels that can be combined to give UMTS in-band IM
products.
7
9. Concluding the section, when a GSM base station contains several transmitters that
radiate the signal through the same antenna several intermodulation products may be gener-
ated depending on the frequency spacing of the operating transmitters.
IV. ESTIMATION OF THE IM INTERFERENCE LEVEL AT THE INPUT OF THE 3G RE-
CEIVER
This section is dedicated to inspecting the whole path that an IM product follows from
its creation in the nonlinear device to the UMTS receiver end, where it is presented as inter-
ference.
The first thing to look into is the nonlinear device. A typical policy for GSM infrastruc-
ture is to maintain multiple transmission stations (BTS) in one transmitting antenna in order
to increase the cell capacity. An average number is four BTS and the maximum is twelve.
The signal from each transmitter (each transmitter operates in a single frequency with eight
timeslots), is mixed in multiple adders and then fed into a bandpass filter and finally into the
antenna. Some of these adders are active so as to provide some amplification to the input sig-
nals. Active devices tend to be extremely nonlinear. In any case, the adder has a transfer func-
tion like equation 1 even though the ai, i>1, coefficients might be very small in some cases.
Manufacturers of such products provide information about the second and third order inter-
cept points (SOI and TOI) of the device and using this info enables you to calculate the mul-
tiplying coefficients of IM products with respect to the original output signal amplitude. An-
other way to complete the calculation is to measure the path of intermods and extract the
valuable information directly. A way to model the transmission of intermods is to consider
these coefficients as signal losses (LIM) with respect to a GSM signal (as a deviation from its
original power).
)()102103log(10)(,
23 10
)(
10
)(
dBmPdBLor
P
PP
L op
dBPdBP
IM
op
TOIop
IM
TOIop
−×+×=
−
= (2)
, where Pop is the operating power in the input of the nonlinear device and PTOI is the given
third order intercept point.
8
10. The IM product created in the abovementioned adder, is then transmitted through the
filter and the antenna and multiplied by
2
)( ifH and by
2
11 )( ifs−1 , as the filter characteris-
tic function and the SWR of the antenna defines for the certain frequency of the IM product,
and by D(φ) as the directivity pattern designates. This mismatch with the antenna, produces a
loss we name LT.
( ) )()(1)(
2
11
2
ϕDfsfHL iiT −= (3)
, where fi is the frequency of the IM product. In order to calculate such losses, extensive
measurements of the GSM antenna and transmitter are required.
Finally, the signal reaches a UMTS receiver after traveling through the RF interface
and suffering from propagation losses Lp. We choose to apply COST 231 Hata model [9] for
this case, as an easy to use, with adequate approximation model [6]. Alternatively we could
use a simple d-γ
model. If we then add all the possible interfering products we get equation 5,
which represents all the IM interference at the input of the detector of UMTS receiver.
Evaluation of this equation will take place in a following section.
dhhahfL mlip log)log55.69.44()(log82.13log16.2655.69 1−+−−+= (4)
where:fi is the frequency of the IM product (GHz), hl is the effective height of the base sta-
tion antenna (30-200m), hm is the height of the receiver antenna (1-10m), d is the distance
between two points (km), a(hm)=(1.1logfi-0.7)hm-(1.56logfi-0.8).
∑=
if
GSMpTIMactive PLLLP (5)
Pactive in the above is the IM interference that is generated in the transmitter or in gen-
eral in the transmitter end. There exists another mechanism that creates IM products and it is
called passive IM or receiver IM. As the name gives away, it stems from the receiver nonlin-
earities that can be caused even from faded soldering. This IM parameter is difficult to be
measured especially when the token receiver is not available. However, theoretical analysis
may take place. Ppassive is given from equation 6 where Lp is the propagation loss in the path
9
11. from GSM transmitter to UMTS receiver and LIM
’
is a loss factor that indicates the difference
in the level between the GSM signal and the intermods.
GSMp
f
IMpassive PLLP
i
∑ ′= (6)
Finally, the sum of IM interference in the receiver end will be:
passiveactiveIM PPI += (7)
V. 3G CAPACITY ISSUES
Capacity in the modern mobile networks is a major concern. Advanced technology is
used so that the same available resources can serve more users and provide greater channel
bandwidth and bit rate. In this context, capacity is regarded as the number of physical layer
connections that take place in a single cell. UMTS and w-CDMA, are widely known as inter-
ference limited systems. The signal of every subscriber serves as interference to the others
due to the imperfectly orthogonal codes that are used. Capacity and interference compete
with each other in a tradeoff between quality of service and availability of service. Having a
demand for the rate of communications set, means that the engineers press the system to op-
erate with the minimum acceptable SIR. Greater volume of interference will mean that the
receiver will not be able to recover the information sent and less interference will mean less
capacity. Both of these two are unacceptable.
It seems that the effort is concentrated in minimizing every other existing interfer-
ence so as to use the tolerable volume of interference to store more channels into the system.
In this context, it is clear that it is desirable to minimize IM interference even though CDMA
systems tend to reduce the effect of narrowband interference themselves.
In order to calculate the effect of GSM IM interference on UMTS capacity we should
first analyze some UMTS features, like SIR and capacity. We assume that in order to main-
tain the desirable QoS, probability of error should be constant and below the threshold and as
a result, SIR should remain above the desired threshold (usually 5-9dB). Thus the two vari-
ables in this analysis are interference and capacity.
10
12. SIR is known from bibliography and given by equation 8. In this equation we express
the generalized factors. Further analysis of the several factors follows. It is clear that all kinds
of narrowband interference are divided by the PG multiplier. This is the mechanism that pro-
tects CDMA signals from narrowband interference.
IMCDMA
i
IIN
SPG
SIR
++
×
=
0
(8)
, where PG is the processing gain (variable in case of UMTS), Si the power of one UMTS
channel, N0 the background noise and I the several interferences induced. Note that, except
IM interference and the one caused from the existence of the rest of the channels, no other
kind of interference has been taken into account in this study.
IM interference is given from (5) and CDMA interference is usually given from (9)
[8].
SaNSI
N
ij
j
jCDMA )1()1()1(
1
ηηα −−=−= ∑
≠
=
(9)
, where α is the voice activity factor (which is approximately 3/8 in real systems or 1 when
this technique is not used), η is the average orthogonality factor and S the mean value of
channel power. If we assume a perfect power control system we get (10) where S is the
power of any uplink CDMA channel when the signal reaches the base station receiver. This,
of course, is not true for the mobile station receiver.
SSSS ji === (10)
Then, we can extract the formula for capacity in a CDMA system if we solve for N,
(11).
SIRSa
INSIRSPG
N IM
×−
+−×
+=
)1(
)(
1 0
η
(11)
The above equation clearly shows that, as IM interference rises, the capacity of the system
has to be reduced in order to maintain the required SIR and assuming that the other factors of
the equation are already tuned. On the other hand, the power of IM interference products is
multiplied by SIR/PG (in case of the conversational class this expression is 8/256=1/32) and
11
13. then compared to S. Therefore, only an important value of IIM can produce serious damage to
the capacity of the system. In figure 7 we see an evaluation of the equation 11 for several bit
rates.
12
14. Figure 7: CDMA system capacity dependence from IIM/S ratio with η=0.4 and η=0.35 and the cases of
15kbps, 384kbps and 2Mbps
From figure 7 we draw the conclusion that when the IM product power is at least
about -10dB smaller than the original UMTS signal at the receiver it causes reduction in the
system capacity. Moreover, we can confirm that high bit rate connection are more fragile be-
cause of the much smaller processing gain. In the next section we analyze a case study for a
hybrid GSM and UMTS system in order to fully understand the extent of the problem caused
by the intermodulation interference.
VI. EVALUATION OF THE GSM AND UMTS CO-EXISTENCE INTERFERENCE
This section contains a quantitative analysis of IM interference between two real sys-
tems and the conclusions drawn from the results. Passive intermodulation interference is not
considered in the following study because it is impossible to simulate it. Instead, we can
make the assumption that passive intermodulation will do harm in a small percentage of mo-
bile terminals and will result in deteriorating their performance. In the following, the base
station receiver case and the mobile receiver case will be examined separately. Moreover, the
GSM-1800 system will be the target of the analysis as the effects are stronger than the GSM-
900 case.
Firstly, the induced losses from transmission mismatch have to be taken into account.
This issue includes the drop in power level in relation to the original GSM signal. This valu-
able information can be extracted from the specifications of the GSM transceiver, the TOI of
the amplifier, the reject band level of the filter and the SWR of the antenna. Using known
values from the references [7],[8] we get the approximation :
dbdbdbdbLdbL TIM 15011040)()( −=−−=+ (12)
The transmitting power of the GSM and UMTS base stations can be set equal to
30dbm and 20dbm respectively since urban transmission is considered. The mobile station
power is 10dbm. Due to perfect power control, it can be assumed that the receiving signal in
13
15. the UMTS node-b will have minimum power, equal to the receiver’s sensitivity, regardless of
the position of the mobile transmitter. This power level is given by 13.
)(min UMTSpUMTS dLPS ×= (13)
Using the above information and the already described propagation model, a simula-
tion for varying base station positions can be performed. The simulation for several combina-
tions of GSM interferers is showcased in figures 8 and 9. Here, it is assumed that dUMTS=dGSM.
Figure 8: Overview of UMTS signal to GSM IM interference ratio for all the possible locations of
node-b. The positions of GSM BTSs are indicated
14
16. Figure 9: The same SIR chart for 7, 5 and 3 interfering base stations respectively.
A quick mathematical calculation dictates that a UMTS node-b situated d>rGSM/3
away from every GSM interferer will retain its channel capacity untouched. Another conclu-
sion is that the number of actual interfering channels is very important and highly variable. If
more than one interfering combinations exist in one BTS the IM interference power will in-
crease accordingly (e.g. +3dB for two combinations). Another point of interest is the occasion
15
17. when the UMTS node-b and the GSM BTS are co-sited. This situation can not be described
by the diagrams correctly. The relative positions of the two antennae and their coupling are
important parameters. Proper choice of these can lead to minimization of IM interference.
The number of interfering combinations depends on the channel allocation of GSM
and the UMTS channel bandwidth. Channel allocation is usually created adjacent channel
interference sensitive. As the reference [4] indicates, the large spacing between the channels
in a cell, favors IM interference. As shown in figures 5 and 6, only combinations of distant in
frequency channels can cause UMTS in-band interference. The greater the distance, the
higher the intermod frequency. This leads to the conclusion that the lower channels of UMTS
will suffer the most.
The same analysis applies to the case of the mobile receiver. This time, the signal is
the UMTS downlink and its power is increased by +10dB. The frequency is different and so
are the combinations of GSM channels that give IM products in this band. However, the pas-
sive IM phenomena are expected to be amplified here due to the used RF equipment which is
much more compact and of lesser quality. Nonlinearities and rotten soldering are less rare in
this case. This hypothesis rests on the assumption the UMTS system will utilize two-way
power control. Should the uplink fail to support power control, the small-distance communi-
cations will be relieved of interference but the distant ones will suffer dramatically.
VII. ANALYSIS OF THE NEW PROPOSED FREQUENCY PLANNING STRATEGY FOR
GSM
The frequency plan is a major issue of the installation of every cellular system. In this
process, the distribution of the available channels is chosen for every tier following a channel
spacing rule. Then, the rest of the cells use the rest of the channels as the classical cellular
idea demands. The choice of the channel allocation is made frantically so as to achieve mini-
mization of the spurious interference signals. A matter that arises here is that during the in-
stallation of the GSM system, the future superposition of UMTS could not have been fore-
seen. As a matter of fact, in the existing frequency plan, the adjacent cell channels have the
16
18. greatest spacing possible which leads to minimum adjacent channel interference but maxi-
mum IM.
A means of reducing the IM interference is by developing a more insightful fre-
quency plan. In 4, the channel spacing is optimized for better results regarding the tradeoff
between the types of interference mentioned. In 3, RF filtering is used for the same reason.
Although filtering can reduce the intermods power it cannot battle the passive interference
generated in the receiver. In this paper, two different strategies are introduced, the block as-
signment and the frequency banning.
The first solution is based on figures 5, 6. From these diagrams it can be extracted
that there exist block of channels that every combination of them results to out of UMTS
band intermods. An example is shown in figure 10. Using the black blocks in a GSM-1800
cluster guarantees that no IM interference will exist at the UMTS node-b. The drawback of
this solution is that special treatment is required for the identification of these blocks in every
case. Another practical problem is that frequency plans are already made for GSM and it
would be uncomfortable to reorganize the base stations of an entire area.
Figure 10: Frequency planning strategy that utilizes free of IM interference blocks of channels
The second proposed solution utilizes the technique of banning frequencies. The first
step is to identify the channel combinations that give IM products in every GSM cell. Then in
step two, the banning of the most popular channels in the above combinations takes place. By
17
19. banning the channels at the end of the spectrum it is possible to minimize IM products to an
acceptable degree. The third step is the compensation for the loss in the GSM capacity. The
frequency hopping technique can be adopted so as to maintain the same number of channels
with less transceivers. To sum up, in this proposal, the GSM capacity is compromised in or-
der to give way to high capacity UMTS performance. However, the GSM system can benefit
from the spread spectrum techniques which may be used to counter this loss.
The above strategy can be conceived as a tradeoff between GSM and UMTS capacity
depending on the needs of each geographical area (e.g. for a high-speed road the GSM capac-
ity might be more important than UMTS high data rates). Another advantage of this tech-
nique is that it can easily be applied on an already installed system and that it can completely
erase IM products. Moreover, this technique is capable of reducing passive IM interference as
well, since there are no in-band combinations allowed.
VIII. CONCLUSIONS
The special characteristics of the air interface necessitate a careful approach. New
systems are superimposed with old ones and inter-system interference makes its presence. In
this hostile environment a tradeoff between the two systems arises. The high demands of 3G
systems may lead to degradation of 2G systems performance but the opposite may as well be
the case when the 2G services are valuable. This study demonstrated the existence of this
tradeoff and some general rules of the optimization of the systems’ co-existence.
18
20. 19
IX. REFERENCES
[1] Khalied Hamied and Gerald Labedz, “AMPS Cell Transmitter Interference to CDMA Mobile Receiver”,
Vehicular Technology Conference, 1996. Mobile Technology for the Human Race., IEEE 46th , Volume: 3 ,
1996.
[2] Greg Agami, Yi-Chiun Chen and C. C. Lee, “Using RF Filtering to Reduce Competitor-Induced Interfer-
ence”, in IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY, VOL. 51, NO. 2, MARCH 2002.
[3] Kari Heiska, Harri Posti, Peter Muszynski, Pauli Aikio, Jussi Numminen, and Miikka Hamalainen, “Capac-
ity Reduction of WCDMA Downlink in the Presence of Interference From Adjacent Narrow-Band System”,
in IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY, VOL. 51, NO. 1, JANUARY 2002.
[4] Hanwook Jung, Member, IEEE, and Ozan K. Tonguz, Member, IEEE, “Random Spacing Channel Assign-
ment to Reduce the Nonlinear Intermodulation Distortion in Cellular Mobile Communications”, in IEEE
TRANSACTIONS ON VEHICULAR TECHNOLOGY, VOL. 48, NO. 5, SEPTEMBER 1999.
[5] Harri Holma and Antti Toskala, “WCDMA for UMTS”, Second Edition, WILEY.
[6] Ramjee Prasad, “Universal Wireless Personal Communications”, Artech House.
[7] SONY Mobile Communication Data book – Technical specifications.
[8] Savo Glisic and Branka Vucetic, “Spread Spectrum CDMA Systems for Wireless Communications”, Artech
House.
[9] “COST 231, Digital Mobile Radio Towards Future Generation Systems”, European Commission, Brussels,
Belgium, 1999.