It is shown that, particularly for terrestrial cellular telephony, the interference-suppression feature of CDMA (code division multiple access) can result in a many-fold increase in capacity over analog and even over competing digital techniques. A single-cell system, such as a hubbed satellite network, is addressed, and the basic expression for capacity is developed. The corresponding expressions for a multiple-cell system are derived. and the distribution on the number of users supportable per cell is determined. It is concluded that properly augmented and power-controlled multiple-cell CDMA promises a quantum increase in current cellular capacity. >

On the capacity of a cellular CDMA system

The demand for wireless mobile communications services is growing at an explosive rate, with the anticipation that communication to a mobile device anywhere on the globe at all times will be available in the near future. An array of antennas mounted on vehicles, ships, aircraft, satellites, and base stations is expected to play an important role in fulfilling the increased demand of channel requirement for these services, as well as for the realization of the dream that a portable communications device the size of a wristwatch be available at an affordable cost for such services. This paper is the first of a two-part study. It provides a comprehensive treatment, at a level appropriate to nonspecialists, of the use of an antenna array to enhance the efficiency of mobile communications systems. It presents an overview of mobile communications as well as details of how an array may be used in various mobile communications systems, including land-mobile, indoor-radio, and satellite-based systems. It discusses advantages of an array of antennas in a mobile communications system, highlights improvements that are possible by using multiple antennas compared to a single antenna in a system, and provides details on the feasibility of antenna arrays for mobile communications applications.

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Applications of antenna arrays to mobile communications. I. Performance improvement, feasibility, and system considerations

Some next-generation personal communication systems propose the use of satellite systems for extending geographical coverage of cellular service. We pursue the idea of using satellite capacity to offload congestion within the area serviced by the terrestrial network. An integrated satellite-cellular network configuration is considered. The performance of this system is evaluated by means of an analytical model for a one-dimensional (highway) cellular system overlaid with satellite footprints and by means of simulation for a planar cellular network with satellite spot beam support. Under certain re-use assumptions, an improvement is found in the blocking performance of the integrated system over the Erlang-B blocking of a purely cellular circuit switched systems. This is achieved by efficient partitioning (static) of the total bandwidth into space and terrestrial segments. Major factors that influence performance, such as different reuse considerations on the satellite and cellular systems, cell size to footprint size ratios, admission control and call management policies, and changes in traffic patterns, are also investigated.

A satellite-augmented cellular network concept

List of Figures. Preface. Acknowledgments. Preliminaries. Basic Data Communication Model. Variations on a Theme. The Communications Channel. Channel Characteristics. Communication Protocols. Connection-Oriented and Connectionless Protocols. The OSI Reference Model. Layer 1 - The Physical Layer-Layer 2 - The Data Link Layer-Layer 3 - The Network Layer-Layer 4 - The Transport Layer-Layer 5 - The Session Layer-Layer 6 - The Presentation Layer-Layer 7 - The Application Layer. Protocols, Primitives, Services. Protocol and Service Data Units. Mobile Data Communications Entities. Summary. 1. Introduction to Mobility. What is Mobility? Basic Approaches to Mobility. Approach 1: Application Awareness-Approach 2: Directory Lookup-Approach 3: Mailbox Service-Approach 4: Administrative Redirection. Aspects of Mobile Communications. Mobile Network Access-Mobility Management. The Essential Challenge of Mobility Management. Knowing Where the Mobile is-Routing Data to the Mobile. Mobility Management is a Network Layer Function. Network Layer Addresses-Network Topology Changes-Routing Table Updates. Mobility Management Schemes. Permanent Address Scheme (PAS)-Temporary Address Scheme (TAS)-Embedded Network Scheme (ENS). Steps in the Mobility Management Process. Registration-Usage-De-registration. A Simple Taxonomy of Mobility. Type 0 Mobility: Stationarity-Type 1 Mobility: Location Independence-Type 2 Mobility: Transience. Range of Mobility. Channel-Cell-Mobility Area-Administrative Domain. Mobility is not Wirelessness. Wireless Considerations. Challenges of Mobility. Geography vs. Network Topology-Part-time Destinations- Moving Targets-Application Transparency-Name-to-Address Mapping-Security-Scale. Summary. 2. Introduction to Cellular Systems. The Ubiquity of Cellular. Radio Channels. The Cellular Concept. Cell Handoff. Cellular Channel Quality. Power Control. Advanced Mobile Phone System (AMPS). AMPS Channels-Roaming-AMPS Cellular Operation-AMPS Mobile Call Origination-AMPS Mobile Call Termination-AMPS Radio Resource Management (RRM)-AMPS Mobility Management. Data Transmission via AMPS. Digital Cellular Technologies. Europe: GSM and DCS 1800. Japan: PDC. North American Digital Standards. TDMA (IS-54/136). CDMA (IS-95,99). PCS: Back to the Future? PCS Licensing-PCS Standards-PCS Challenges. Summary. 3. Overview of CDPD. CDPD Background. CDPD Prototypes-"CDPD Lite" -CDPD Forum-CDPD Service Providers. Relationship of CDPD to other Cellular Data Initiatives. CDPD Services and Characteristics. CDPD Network Services-CDPD Network Support Services-CDPD Network Application Services. CDPD Design Goals and Considerations. Location Independence-Application Transparency- Multiprotocol Support-Interoperability-Minimal Invention- Optimal Usage of RF-Evolutionary Design-Open-Secure- Simple-Transparent to the Existing Cellular Voice Network. The CDPD Architectural Approach. The Three Key CDPD Interfaces. The A-Interface-The E-Interface-The I-Interface. CDPD Network Elements. The Mobile End System (M-ES)-The Mobile Data Base Station (MDBS)-The Mobile Data Intermediate System (MD-IS)-The Intermediate System (IS)-The Fixed End System (F-ES). CDPD Mobility Management. CDPD Radio Resource Management. CDPD Security. CDPD Accounting. Summary. 4. Mobility Management in Wide-Area Networks. The CDPD Mobility Vision. The CDPD Mobility Approach. CDPD Mobility Management Scope. CDPD Mobility Management Functions. CDPD Routing Architecture. CDPD Protocol Architecture. CDPD Support Protocol Architecture. CDPD Mobility Management Operation. Mobile Identification to Network - End System Hello (ESH)- Mobile Redirection Request (RDR)-Confirmation of service -Redirect Confirm (RDC)-Confirmation to M-ES - Intermediate System Confirm (ISC). CDPD Mobile Data Routing. Home MD-IS-Serving MD-IS. Intra-Area Mobility. Inter-area Mobility. Other Administrative Operations. Redirect Flush-Redirect Query and End System Query. Support Data Structures. Home Domain Directory-Registration Directory-Location Directory. Multicast Group Management. CDPD Multicast Service Definition-Multicast Registration- Multicast Authentication-Multicast Data Redirection-Multicast Data Forwarding-Multicast Service Characteristics. Broadcast Addresses. Selection Rationale. CLNP-Triangle routing. Summary. 5. Accessing the Mobile Network. The A-Interface. The Airlink Physical Layer. Shared Channel Environment. Approach 1: Token Passing-Approach 2: Demand Assigned with Reservation-Approach 3: Slotted Aloha-Approach 4: Carrier Sense Multiple Access with Collision Detection (CSMA/CD). The Airlink MAC Sublayer. Reed-Solomon Blocks-Busy/Idle Indicator-Decode Status Flag. M-ES State Machine. Airlink MAC Parameters. Min_Idle_Time-Min_count and Max_count-Max_blocks Parameter. Half Duplex Mobiles. The Airlink Data Link Protocol. Selective Reject-Removal of CRC-Addition of ZAP-Sleep Mode. SNDCF: Protocol Convergence. Segmentation and Reassembly-Multiplexing-Header Compression-V.42bis Data Compression-Data Encryption. How Data Moves Through Layers. Radio Resource Management. Model of Operation. Channel Hopping. Circuit-Switched Cellular Digital Packet Data. Circuit Switch CDPD Control Protocol. Summary. 6. Mobile Data Network Security. Introduction. Security Policy. Security Threats. Security Services and Mechanisms. Encipherment and Data Confidentiality-Digital Signatures- Authentication-Traffic Flow Confidentiality-Data Integrity-Key Management-Access Control-Network Layer Security Considerations. CDPD Security. CDPD Security Design Goals and Tradeoffs-CDPD Authentication-CDPD Confidentiality-CDPD Privacy. CDPD Security Design Rationale. CDPD Security Objectives-One-Way vs. Two-Way Authentication-The TunnelA A*s Data Confidentiality and Authentication-Considerations for Use of PKCS-Consideration of Other Approaches-End-to-End Security Services. 7. Mobile Network Support Services. Support Services Overview. CDPD Support Services. Network Management. Overview of System Management Framework-Systems Management Functional Areas-Relationship of Management Specifications to Functional Areas-CDPD Network Management. Usage Accounting. CDPD Usage Accounting-The CDPD Accounting Model- Accounting Meter-Serving Accounting Distributor (SAD)-Home Accounting Distributor (HAD)-Home Accounting Collector (HAC)- Consolidation Accounting Collector (CAC). Message Handling Service. Overview of Message Handling Services-Message Structure- Message Transfer Agent (MTA)-User Agent (UA)-Message Store (MS). Directory Services. The Directory-The Directory Model-The CDPD Directory Service. Summary. 8. Mobile Applications. Categories of Mobile Applications. Push or Pull: Mobile Application Information Access-Vertical or Horizontal Nature of Mobile Applications. Vertical Applications. Field Service-Mobile Professional-Transportation- Point-of-Sale (POS)-Telemetry-Government. Horizontal Applications. Messaging and email-Limited Size Messaging. Applications-Enabling Protocols. Limited Size Remote Operation Service (LSROS)-Status Notification Service-Subscriber Area Location Service. 9. Non-Cellular Approaches to Mobile Data Networking. Background. Wireless LANs and Metropolitan Networks. Infrared Systems-Narrowband RF Systems-Spread Spectrum Systems-Metricom Ricochet. Paging Systems. One-Way Paging Systems-Two-Way Paging Systems. Private Wireless Packet Data Systems. Public Wireless Packet Data Services. Advanced Radio Data Integrated System (Ardis)-RAM Mobile Data (Mobitex)-RadioMail. Satellite-Based Systems. Summary. 10. Future Directions in Mobility. Mobility under IPv4. The Mobile IP Standards Process-Overview of Draft Version 16 of the IETF IP Mobility Support-Implementations Based on Mobile IP Drafts. Mobility under IPv6. The IPv6 Standards Process-Overview of Mobility Support in IPv6. Comparison of Mobile IP and CDPD. Objectives, Goals and Assumptions-Technical Architecture and Design-Model and Terminology-Operational Assumptions- Standardization Process-Potential. Bibliography. Glossary. Index.

Internetwork mobility : the CDPD approach

Conventional cellular wireless networks were designed with the purpose of providing high throughput for the user and high capacity for the service provider, without any provisions of energy efficiency. As a result, these networks have an enormous Carbon footprint. In this paper, we describe the sources of the inefficiencies in such networks. First, we present results of the studies on how much Carbon footprint such networks generate. We also discuss how much more mobile traffic is expected to increase so that this Carbon footprint will even increase tremendously more. We then discuss specific sources of inefficiency and potential sources of improvement at the physical layer, as well as at higher layers of the communication protocol hierarchy. In particular, considering that most of the energy inefficiency in cellular wireless networks is at the base stations, we discuss multi-tier networks and point to the potential of exploiting mobility patterns in order to use base station energy judiciously. We then investigate potential methods to reduce this inefficiency and quantify their individual contributions. By a consideration of the combination of all potential gains, we conclude that an improvement in energy consumption in cellular wireless networks by two orders of magnitude, or even more, is possible.

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Quantifying Potential Energy Efficiency Gain in Green Cellular Wireless Networks

The greatest single factor in enhancing spectral efficiency of a network is the mass deployment of microcells. By this simple technique we can repeatedly and efficiently reuse the precious spectrum. The number of users a network can support is fundamentally dependent on the common air interface (CAI) over which users communicate. User capacity is dependent on many factors, but the cardinal ones are the amount of spectrum the regulators allocate, the size of the radio coverage area from a base station (BS), and the amount of interference a particular radio link can tolerate. In this article we are primarily concerned with the system aspects associated with the CAI. We focus on the critical importance of BS siting. Starting with existing large cells, we deliberate on the problems that might arise in siting BSs in three dimensional microcells, in order to consider suitable multiple access methods for future cellular environments. >

J. Whitehead

Papers

System aspects of cellular radio