CDPD performance: a joint analysis of the physical and MAC layers

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.

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. >

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.

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.

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>

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.

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.

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.

Problem statement: The demand for multimedia applications in WiMAX networks is growing at a rapid pace. A method for guaranteeing Quality of Service (QoS) for different classes of traffic is therefore gaining importance. Hence desi gning and analyzing multimedia traffic and QoS parameters has become central to this problem. In t his study, we propose a cross layer frame work in which a coordination between the Medium Access Control layer (MAC) and the Physical layer (PHY) is established for guaranteeing the QoS requirement in a multiclass traffic WiMAX environment. Two traffic classes' real time Polling Service (rtPS) a nd non real time Polling Service (nrtPS) are considered for analyzing the performance. Approach: The objective of study is to guarantee QoS for multiple service class traffic in a multiple connec tion environment in WiMAX network. A cross layer design approach is used for this purpose. A priorit y scheduler at the MAC layer schedules the traffic based on channel state information. The Adaptive modulation and coding scheme is used at the physical layer that adapts to the scheduled traffic to stabilize the QoS requirements of different tra ffic classes. Results: The Priority value is estimated using the Friis eq uation that calculates the received power and determines the SNR. The average throughput, average bytes received and the packet loss are plotted against time. This indicated that these QoS parameters are stable over a period of time. Conclusion: A cross layer frame work was developed based on a scheduler for QoS stability that uses CSI at the MAC layer and an AMC at the PHY layer in WiMax Networks. The scheduler enjoyed flexibility and scalability, whose performance was evaluated against existing systems through simulati on.

Applying multimedia to Wireless Sensor Network (WSN) adds more challenges due to WSN resource constraints and the strict Quality of Service (QoS) requirements for multimedia transmission. Different multimedia applications may have different QoS requirements, so routing protocols designed for Wireless Multimedia Sensor Network (WMSN) should be conversant of these requirements and challenges in order to ensure the efficient use of resources to transfer multimedia packets in an utmost manner. The majority of solutions proposed for WMSN depends on traditional layered based mechanisms which are inefficient for multimedia transmission. In this paper we propose a cross-layer Ant based Routing Protocol for WMSN (CARPM) by using modified ant colony optimization (ACO) technique to enhance the routing efficiency. The proposed protocol uses an improved ACO to search for the best path that are satisfied with the multimedia traffic requirements. While making best decision the weightage is given to energy consumption, and queuing delay. The proposed cross layer scheme works between the routing, MAC, and physical layers. Since, the remaining power and timestamp metrics are exchanged from physical layer to network layer. Dynamics duty cycle assignment is proposed at MAC layer which changes according to traffic rate. The presented algorithm is simulated using NS2 and is proven to satisfy its goals through a series of simulations.

Multimedia transmissions over wireless networks need continuous media play out. In order to meet best Quality of Services, higher layers data depend on lower layer parameters. That is readily known as cross-layer design. Our cross-layer design model optimizes the physical layer, MAC layer and application layer. Video summary frames are transmitted via MIMO transmit/receive diversity with AMC at the physical layer and Payload and data rate adaptation at the MAC link layer and source coding at the application layer. We, first model the finite-state Markov chain (FSMC) for the physical layer service and based on that, we then characterize the Lagrangian relaxation and Dynamic programming to find the optimal shortest path. The source coding as well as retransmission requests are based on the channel-state information (CSI) and the system controller is implemented in all the three physical, MAC layer and application layers. The numerical results revealed that our proposed cross-layer design can efficiently achieve the effective throughput and distortion gain.

Channel quality has a great influence on bit error rate (BER) of received signal. The scheme to efficiently ensure four kinds of data services provided by IEEE 802.16 standards is an interesting research issue. In this paper, we propose an adaptive scheduling algorithm cross physical (PHY) layer and MAC layer for IEEE 802.16 BWA system. The Signal to Noise Ratio (SNR) on wireless fading channels determines the modulation and coding (AMC) scheme and the quantity of transmitted packets at the PHY layer. The objective of the AMC coding scheme is maximize packets throughput while maintaining the BER requirement. At the MAC layer, the algorithm scheduling the packets to ensure diverse QoS requirements for multiple connections, e.g., delay for rtPS, throughput for nrtPS, and fairness for BE. To obtain optimal scheduling, we define the cost function for each connection based on channel condition, service status, throughput or deadline. We also verify the analytic results using computer simulation. The simulation results show that our proposed scheduler can provide diverse QoS guarantees, maximum throughput and achieve an optimal tradeoff between throughput and fairness.

In this paper, we propose a novel adaptive carrier sense multiple access scheme with collision avoidance (CSMA/CA) to perform efficient and reliable data transfer with increased throughput across multiple coexisting wireless body area networks (BANs) in a tiered architecture. We investigate the proposed scheme using two distributed cross-layer optimized dynamic routing techniques, i.e., shortest path routing (SPR) and cooperative multi-path routing (CMR). The channel state information from the physical layer is passed on to the network layer using an adaptive cross-layer carrier sensing mechanism between the physical and MAC layer, which adjusts the carrier sense threshold (e.g., RSSI) periodically based on the slowly-varying channel condition. An open-access experimental dataset of 'everyday' mixed-activities is used for analyzing the cross-layer optimization. Our proposed optimization using adaptive carrier sensing performs better than static carrier sensing with CSMA/CA as it reduces the continuous back-off duration and latency as well as significantly increases the throughput (in successful packets/s) by more than 50%. Adaptive CSMA/CA also shows 20% and 6% improvement over a coordinated TDMA approach with higher duty cycle for throughput and spectral efficiency, respectively, and provides acceptable packet delivery ratio and outage probability with respect to SINR.