A Practical Perspective on Cellular Digital Packet Data (CDPD) Systems

The Cellular Digital Packet Data (CDPD) system provides a digital data overlay for the AMPS cellular system. CDPD can operate either in dedicated or non-dedicated channel mode at the base station. This paper examines the performance of CDPD over fading channels for both dedicated and non-dedicated channels with Nakagami-faded interference.

A web-based camera (webcam) is expected to enhance construction site monitoring, which may result in better project control. However, in most cases, webcams are located on the outside of a building because their mobility is limited by cable wiring, thus occasionally the view of the camera is blocked as the project develops. If a webcam is integrated with emerging wireless network technologies such as IEEE 802 or Cellular Digital Packet Data (CDPD), construction professionals may be able to utilize the webcam to monitor interior construction operations without worrying about getting the network cables wired on the congested and dynamic construction job site. Especially, the CDPD technology should enable the webcam to transmit captured photos from any construction site as far as the cellular phone service is available. However, with the speed of CDPD (19.2 Kilobits per second), it would take as long as 6 minutes to send one Mega pixel digital image. One may ask if construction professionals could figure out operations implemented at the job site by observing a 6 minute interval time-lapsed photo set. How many mistakes should we anticipate when interpreting the time-lapsed photo set with this time interval? To what extent can the frame rate of the webcam be lowered for monitoring construction operations at the job site? To answer these questions, we then produced time-lapsed photos of brickwork at three different construction sites with various time intervals and investigated error rates in identifying construction crew’s productivity using these time-lapsed photos. This paper presents a preliminary result of our investigation.

Cellular Digital Packet Data (CDPD) is a technology that provides digital packet-switched data services through standard analog cellular channels. CDPD is implemented as an overlay to existing cellular networks allowing data to be sent in packets during idle times on the cellular voice channels. This overlay implementation makes use of existing cellular infrastructure, simultaneously transmitting voice and data from the same device. A cellular communication network has significant advantages over its wireline counterparts. Mobility and ease of use are two particularly attractive features to a large population of field employees. Based upon well known world standards, CDPD will provide connectivity anywhere anytime-a true realization of the well sought dream of having information at your fingertips. >

We present an end to end adaptive video coding and transmission system that is designed for the Cellular Digital Packet Data (CDPD) wireless networks. The proposed system consists of (1) an embedded wavelet bit-plane coding algorithm, which is capable of adapting the compression ratio to the available bandwidth; (2) an efficient and error resilient fixed-length packetization scheme based on randomization in the wavelet domain; and (3) a feedback rate control algorithm, which is capable of estimating the available network bandwidth based on the acknowledgement information received by the server. Experimental results show that our system achieves good perceptual quality while maintaining high bandwidth utilization.

The authors first discuss the basic cellular digital packet data (CDPD) architecture and its authentication protocols. They then present threats to the network. Next, they investigate the basic requirements of the security architecture and goals in light of attacks. Then they present the improved authentication protocol in operation, and how it deals with faults. Next, they add authenticated key exchange for confidentiality, followed by anonymity provisions. Then, they summarize the design and present the complete protocol, and identify which protocol transmissions goes on which CDPD message. Finally, they present further issues and concerns that are beyond the scope of this protocol.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

The Cellular Digital Packet Data (CDPD) system is the first public wireless data ever deployed in the US. As its traffic continues to grow, potential new customers require to know the platform's quality-of-service (QoS) performance data prior to subscribing to the service. Consequently, network planners are searching for a simple model which can provide QoS analysis instantly, rather than conducting long (and costly) simulations. This paper provides such model. CDPD uses a random-access MAC layer protocol known as the DSMA/CD, to control the users packet transmission on the reverse link. In general, the success of the transmitted packets, as well as the delay incurred, depends heavily on both: the efficiency with which the DSMA/CD controls packet collisions, and the degree of error-free reception provided by the physical layer. Therefore, one must consider the joint operation of the two in order to produce quotable realistic traffic performance figures. This paper focuses on the joint operation of the two named layers.

There is no doubt about it: Asynchronous Transfer Mode (ATM) traffic will soon connect to the wireless network. Its characteristics are very well adapted to provide a well-balanced mix of voice and data communications. The question here is where will adaptation layers be processed? Should the Wireless Carrier be burdened with converting ATM-based traffic in other interfaces such as Cellular Digital Packet Data, a solution leading to multiple and possibly unmanageable gateway functions? Or should an Air Interface be developed to carry ATM traffic? Pushing ATM adaptation layers closer to the point of consumption of voice, data or video holds many advantages. This paper attempts to shine some light on the subject.

Mobile IP is a proposed standard protocol that builds on the Internet Protocol by making mobility transparent to applications and higher level protocols like TCP. Mobile IP (RFC 2002) is a standard proposed by a working group within the Internet Engineering Task Force; it allows the mobile node to use two IP addresses: a fixed home address and a care-of address that changes at each new point of attachment. The article presents the Mobile IP standard in moderate technical detail and points the reader toward a wealth of further information. Is also describes how Mobile IP will change with IP version 6, the product of a major effort within the IETF to engineer an eventual replacement for the current version of IP. Although IPv6 will support mobility to a greater degree than IPv4, it will still need Mobile IP to make mobility transparent to applications and higher level protocols such as TCP. There is a great deal of interest in mobile computing and apparently in Mobile IP as a way to provide for it. A quick Web search for items related to Mobile IP returned over 60,000 hits-impressive even given the notorious lack of selectivity for such procedures. Mobile IP forms the basis either directly or indirectly of many current research efforts and products. The Cellular Digital Packet Data (CDPD), for example, has created a widely deployed communications infrastructure based on a previous draft specification of the protocol. In addition, most major router vendors have developed implementations for Mobile IP.

Cellular digital packet data (CDPD) utilizes sleep mode mechanism to conserve the power of mobile end systems (M-ESs). A timer called T203 determines how quick an M-ES enters the sleep mode, and another timer called T204 determines how often the M-ES wakes up. A large T204 value and a small T203 value can effectively reduce the power consumption at the cost of degrading the frame transmission performance, i.e., more lost frames, longer frame waiting times, and larger waiting variance. When the power consumption budget is determined in a CDPD system design, our study provides guidelines to determine the timer values as well as the buffer size to optimize the frame transmission performance.

At Carnegie Mellon University in Pittsburgh, staff and students are using mobile computers for various tasks such as transferring lecture notes, sending e-mails, or surfing the net. This possible due to the installation of a wireless network which will cover all 28 academic and administrative buildings on the 40-hectare campus, and provide service to 10000 people. As long as they are on campus, the university community will be able to take advantage of the network. The high speed wireless infrastructure installed at Carnegie Mellon is called Wireless Andrew. Started as a National Science Foundation-funded research network to support Carnegie Mellon's wireless research initiative, the network originally provided coverage in seven campus buildings. The challenges in building such a large network are far from trivial. They include designing the network so that coverage blankets the entire campus, providing enough capacity to handle the campus-wide traffic load. Further, the network must provide highly reliable service. It builds on the university's wired network infrastructure, which currently provides 10-Mb/s and 100-Mb/s Ethernet service. To supply high-speed wireless service to the campus, Lucent WaveLAN equipment has been installed, which uses direct sequence spread-spectrum radio to provide a raw data rate of 2 Mb/s. For wireless access off campus or otherwise out of the range of the WaveLAN network, cellular digital packet data is used.

To design a cellular radio network (GSM, UMTS, WiFi ?) it is indispensable today to use a radio planning software. In current commercialized tools, radio network planning is based on a numerical evaluation of a set of radio metrics, directly linked to quality of service notion, such as interference, throughput, coverage, capacity ? The network configurations produced by such tools are generally faced with the human expert judgment who attaches great importance to the organizational aspects such as cells size and the topology. In other words, all those concepts related to the visual cells shape and geometry. In this article we emphasize the simplicity and the strength by which the geometrical concepts helps to bring out good network properties which are not taken into account by conventional radio criteria. On one hand, well-formed cells lead to reduce the number of handover calls, and to form transition zones between cells allowing proper completion of the handover procedure. On the other hand, cell geometry optimization produce performing network schemes in which the frequencies reuse (frequencies planning in GSM, WiFi) is simplified. We describe in this paper an original and practical modeling of the cellular geometry criteria granting the integration of this concept into the automatic planning process of mobile radio networks. The relevance of this criterion is assessed on three different levels. On a local level, we first establish the correlation between the geometric criteria and the improvement of point-by-point radio quality indicators. We secondly show geometry impact on radio frequency planning and the improving of the handover zones. Finally we analyze the impact of geometric criterion on improving indoor positioning systems.

Optimal planning of cellular networks is one of the most fundamental problems in network design. This paper discusses cell planning problems for the fourth generation (4G) cellular networks. We describe important planning aspects derived by the anticipated 4G technologies and model several relevant cell planning problems. We then review several algorithmic techniques for solving these problems.

In the planning of cellular networks, link budget calculation is the first step to get the maximum allowable cell radius that guarantees a target signal to interference plus noise ratio (SINR) with a certain level of outage probability at the cell border. The interference margin as one of key inputs for link budget is used to compensate for co-channel interference. In this paper, a mathematical analysis for interference margin as a function of system load is proposed in orthogonal frequency division multiple access (OFDMA) cellular networks. The analysis is derived from OFDMA features based on a general expression of exponential effective SINR mapping (EESM). The proposed approach can be easily applied to the evaluation of interference from neighboring cells, and help to improve the accuracy of the link budget calculation in OFDMA systems. All the theoretical analysis given in this paper have been proved by Monte Carlo simulations.

Modeling and analysis tools are essential for the design and evaluation of complex systems. This is particularly true for cellular systems, where, for instance, a variety of handoff, channel allocation, and data-transmission algorithms have been proposed. The capabilities of Petri nets (PNs) are used as a novel approach in the analysis of handoff, dynamic channel allocation (DCA), and cellular digital packet data resource management problems. The generalized stochastic PN (GSPN) models are obtained and analyzed as continuous-time Markov chains (MCs) derived from the reachability graphs. Solution of the MC results in performance indicators, which show the impacts of different algorithms on the system behavior.

The paper studies the value of data transmission over idle channels within cellular systems using frequency hopping techniques. In the beginning it seemed very logical that data transmission over cellular channels did not reduce voice capacity by hopping among idle channels. Actually, the analysis in the present paper indicates that although the hopping scheme creates additional capacity, it degrades system performance due to the additional interference contributed by data transmission. To implement a dedicated cellular digital packet data channel eventually would be the proper choice.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>