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INTRODUCTION
Cellular communications has reached mass-market status over the past decade with the emergence of two very successful standards: CDMA and GSM. Over this same decade, an important enabling technology, “smart antennas,” has also matured. Combined with today’s powerful, low-cost processors, advanced smart antenna technology is destined to become an important part of the cellular landscape over the next decade.
Smart antenna systems utilize multiple antennas at base stations or handsets to better pinpoint or focus radio energy and thereby improve signal quality. Since cellular communications systems employ radio signals that interact with the environment and each other, these improvements in signal quality lead to system-wide benefits with respect to coverage, service quality and, ultimately, the economics of cellular service. To some extent, the phrase “smart antennas” is misleading. There is nothing smart about the antennas themselves. What’s smart is the sophisticated signal processing applied to simultaneous signals from an array or collection of multiple antennas.
For nearly a decade, ArrayComm has been at the forefront of developing smart antenna techniques and intellectual property for commercial cellular systems. IntelliCell® is the name for these techniques and intellectual property. Thru eight years of practical and field implementation, IntelliCell has been perfected to make smart antennas practical and cost effective in actual commercial cellular systems. Today, IntelliCell technology is deployed in more than 90,000 commercial base station deployments worldwide.
1. BASIC CELLULAR ARCHITECTURE
Cellular networks are composed of geographically separated base stations connected to a backbone network, with each base station serving an area called a cell. (See Figure 1.) In some systems, cells are further subdivided into sectors, for reasons that will be described later in this document. The range of each base station may be anywhere from 0.5 km to 15 km, with 1-3 km as the typical range in digital cellular systems. Handsets communicate with a nearby base station via radio signals. The information, voice or data, is digitized prior to transmission in all modern cellular systems. In the United States, most commercial cellular systems operate in licensed radio frequencies in the region of either 850 MHz or 1.9 GHz.
End-to-end connections with public or private data or telephony networks are made possible by a backhaul network that connects all of the base stations to a switching/routing function, which directs users’ voice or data transmissions to and from their correspondents. Note that this same network architecture is used for many types of wireless services, including wireless LANs and point-to-multipoint data services such as LMDS.
In the radio portion of the network, the “uplink” refers to the communication from the handset “up to” the base station: The handset or user terminal suitably digitizes and frames voice or packet data meant for the network. This digitized data then is modulated using digital and radio circuitry and transmitted via the antenna in the handset. The antennas and circuitry at the base station receive the radio signal, demodulate it and send the user’s information on into the wired network.
The “downlink” refers to the reverse direction, where the communication is from the base station “down to” the handset or user terminal. The base station suitably digitizes and frames voice or packet data meant for the subscriber. This digitized data is modulated using digital and radio circuitry and is transmitted via the antennas at the base station. The antenna and circuitry at the handset receive the radio signal, demodulate it and send the information on to the subscriber.
This type of cellular architecture has gained wide acceptance as the most economical and flexible architecture for delivering mass-market personal wireless services. The decline of satellite based systems such as Iridium and Globalstar into niche services has proved this point. Nevertheless, looking forward, cellular systems face a significant challenge as data services and bandwidth become important. The challenge is to improve the quality of the communication channel to handle larger traffic loads while maintaining the same cost
structure, despite the scarcity and exorbitant prices of additional spectrum. This challenge is exacerbated by the expected trend away from today’s low-data-rate digital voice services toward high-data-rate broadband services. Today’s cellular systems will require a 10-fold to 40-fold increase in spectral efficiency and capacity to affordably deliver true Internet content.
IntelliCell®: A Fully Adaptive Approach to Smart Antennas
INTRODUCTION
Cellular communications has reached mass-market status over the past decade with the emergence of two very successful standards: CDMA and GSM. Over this same decade, an important enabling technology, “smart antennas,” has also matured. Combined with today’s powerful, low-cost processors, advanced smart antenna technology is destined to become an important part of the cellular landscape over the next decade.
Smart antenna systems utilize multiple antennas at base stations or handsets to better pinpoint or focus radio energy and thereby improve signal quality. Since cellular communications systems employ radio signals that interact with the environment and each other, these improvements in signal quality lead to system-wide benefits with respect to coverage, service quality and, ultimately, the economics of cellular service. To some extent, the phrase “smart antennas” is misleading. There is nothing smart about the antennas themselves. What’s smart is the sophisticated signal processing applied to simultaneous signals from an array or collection of multiple antennas.
For nearly a decade, ArrayComm has been at the forefront of developing smart antenna techniques and intellectual property for commercial cellular systems. IntelliCell® is the name for these techniques and intellectual property. Thru eight years of practical and field implementation, IntelliCell has been perfected to make smart antennas practical and cost effective in actual commercial cellular systems. Today, IntelliCell technology is deployed in more than 90,000 commercial base station deployments worldwide.
1. BASIC CELLULAR ARCHITECTURE
Cellular networks are composed of geographically separated base stations connected to a backbone network, with each base station serving an area called a cell. (See Figure 1.) In some systems, cells are further subdivided into sectors, for reasons that will be described later in this document. The range of each base station may be anywhere from 0.5 km to 15 km, with 1-3 km as the typical range in digital cellular systems. Handsets communicate with a nearby base station via radio signals. The information, voice or data, is digitized prior to transmission in all modern cellular systems. In the United States, most commercial cellular systems operate in licensed radio frequencies in the region of either 850 MHz or 1.9 GHz.
End-to-end connections with public or private data or telephony networks are made possible by a backhaul network that connects all of the base stations to a switching/routing function, which directs users’ voice or data transmissions to and from their correspondents. Note that this same network architecture is used for many types of wireless services, including wireless LANs and point-to-multipoint data services such as LMDS.
In the radio portion of the network, the “uplink” refers to the communication from the handset “up to” the base station: The handset or user terminal suitably digitizes and frames voice or packet data meant for the network. This digitized data then is modulated using digital and radio circuitry and transmitted via the antenna in the handset. The antennas and circuitry at the base station receive the radio signal, demodulate it and send the user’s information on into the wired network.
The “downlink” refers to the reverse direction, where the communication is from the base station “down to” the handset or user terminal. The base station suitably digitizes and frames voice or packet data meant for the subscriber. This digitized data is modulated using digital and radio circuitry and is transmitted via the antennas at the base station. The antenna and circuitry at the handset receive the radio signal, demodulate it and send the information on to the subscriber.
This type of cellular architecture has gained wide acceptance as the most economical and flexible architecture for delivering mass-market personal wireless services. The decline of satellite based systems such as Iridium and Globalstar into niche services has proved this point. Nevertheless, looking forward, cellular systems face a significant challenge as data services and bandwidth become important. The challenge is to improve the quality of the communication channel to handle larger traffic loads while maintaining the same cost
structure, despite the scarcity and exorbitant prices of additional spectrum. This challenge is exacerbated by the expected trend away from today’s low-data-rate digital voice services toward high-data-rate broadband services. Today’s cellular systems will require a 10-fold to 40-fold increase in spectral efficiency and capacity to affordably deliver true Internet content.
