Cellular Digital Packet Data CDPD

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.

Early Cellular Digital Packet Data (CDPD) deployments have been a valuable learning experience for the cellular carriers that established them. The purpose of this paper, is to discuss the practical aspects of CDPD systems, based on such experience. Guidelines for the planning, deployment and management of cellular data networks are presented. This paper is intended for cellular service providers but may also benefit application developers who wish to understand the issues faced by carriers with respect to wireless data. The specific topics covered in this paper include deployment strategies, frequency planning and customer engineering. The conclusion emphasizes the importance of a well-developed strategy, coupled with the adaptability to meet the changing needs of an evolving customer base.

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.

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.

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.

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.

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.

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.

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.

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>

Device-to-Device (D2D) communication was initially proposed in cellular\nnetworks as a new paradigm to enhance network performance. The emergence of new\napplications such as content distribution and location-aware advertisement\nintroduced new use-cases for D2D communications in cellular networks. The\ninitial studies showed that D2D communication has advantages such as increased\nspectral efficiency and reduced communication delay. However, this\ncommunication mode introduces complications in terms of interference control\noverhead and protocols that are still open research problems. The feasibility\nof D2D communications in LTE-A is being studied by academia, industry, and the\nstandardization bodies. To date, there are more than 100 papers available on\nD2D communications in cellular networks and, there is no survey on this field.\nIn this article, we provide a taxonomy based on the D2D communicating spectrum\nand review the available literature extensively under the proposed taxonomy.\nMoreover, we provide new insights to the over-explored and under-explored areas\nwhich lead us to identify open research problems of D2D communication in\ncellular networks.\n

Device-to-Device (D2D) communication is an emergent technology that provides many advantages for the LTE-A networks as higher spectral efficiency and wireless Peer-to-Peer services. It is considered as a promising technology used in many different fields like public safety, network traffic offloading, and social applications and services. However, the integration of D2D communications in cellular networks creates two main challenges. First, the interference caused by the D2D links to the cellular links could significantly affect the performance of the cellular devices. Second, the minimum QoS requirements of D2D communications need to be guaranteed. Thus, the synchronization between devices becomes a necessity while Radio Resource Management (RRM) always represents a challenge. In this paper, we study the RRM problem for Vehicle-to-Vehicle (V2V) communication. A dynamic neural Q-learning-based resource allocation and resource sharing algorithm is proposed for D2D-based V2V communication in the LTE-A cellular networks. Simulation results show that the proposed algorithm is able to offer the best-performing allocations to improve network performance.

Vehicle-to-everything (V2X) communications, which provide wireless connectivity among vehicles, roadside drivers, passengers, and pedestrians, are attracting great interest. In this paper, we propose an energy-efficient relay assisted transmission scheme based on V2X communications in the uplink cellular networks for delay insensitive applications. We aim to maximize energy efficiency of the uplink while considering both the circuit power and transmit power consumption, as well as the delay constraint. The optimal resource allocation for direct transmission mode and V2X-enabled transmission mode are derived. For the V2X-enabled transmission mode, we first consider the transmission without the delay constraint and obtain the corresponding optimal power allocation. Based on the obtained result, we further propose the optimal resource allocation policy that satisfies the delay constraint and minimizes the energy consumption. Simulation results show that there exists an energy-delay tradeoff and the proposed V2X-enabled scheme can achieve significant energy saving with an acceptable delay compared with the traditional direct scheme, the decoding-and-forward based transmission scheme, and the opportunistic store-carry and forward based transmission scheme, especially when the cell radius is not small.

Precipitation and evaporation are the two fluxes coupling the atmospheric and terrestrial compartments of the hydrologic cycle. Accurate and robust observations of the spatial and temporal variability of these two fluxes over the Earth’s continents is crucial to help understand the intricacies of land surface – atmosphere interactions. Improving our understanding and our ability to quantify these interactions is not only important for scientific purposes (such as developing better earth system models) but also for societally relevant applications (such as flood and drought forecasting). Here, we demonstrate the potential and address the limitations of microwave links from cellular communication networks for estimating both precipitation and evaporation.Previous research has shown that attenuation of microwave signals propagating through rainfall from the transmitting to the receiving antennas of microwave links can be related to the average rainfall intensity along the path between transmitter and receiver. Over the past two decades, this notion has been successfully applied to retrieve rainfall fields from existing microwave links which are part of cellular communication networks. Rain-induced signal loss due to absorption and scattering of microwave signals by raindrops, a source of “noise” for mobile network operators, has turned out to be a “signal” for hydrometeorological science and applications. The approach of using existing cellular communication infrastructure for environmental monitoring (in this case rainfall measurement) has been dubbed “opportunistic sensing”.However, atmospheric constituents between the transmitters and receivers of microwave links do not only affect signal propagation when it rains. When it is dry, refractive index fluctuations induced by temperature and water vapor variations resulting from rising turbulent eddies in the atmospheric boundary layer between transmitters and receivers cause received signals to “scintillate”. The variance of these scintillations has been shown to be related to the structure parameter of the refractive index, which in turn can be related to sensible and latent heat fluxes across the microwave link path using Monin-Obukhov Similarity Theory (and the aid of auxiliary information). This principle is used by microwave scintillometers, commercially available instruments for observing turbulent fluxes in the atmospheric boundary layer.Recent research results show that microwave links from cellular communication networks can, under certain conditions, also be employed as boundary layer scintillometers. Combining this notion with the previous finding that such microwave links can also be used as path-average rain gauges suggests that there is potential to use each of the roughly five million backhaul links from cellular communication networks worldwide as combined precipitation-evaporation sensors. Hence, gaining access to received signal level data from this enormous number of microwave links would allow large-scale rainfall and evaporation mapping, also for regions across the globe which are currently poorly served in terms of dedicated meteorological stations.We present both the physical basis of this approach and empirical results from previous and ongoing measurement campaigns to discuss the potential and challenges of opportunistic sensing of two hydrologic fluxes with one single instrument: precipitation and evaporation.