The problem min-power k-connectivity seeks a power assignment to the nodes in a given wireless ad hoc network such that the produced network topology is k-connected and the total power is the lowest. In this paper, we present several approximation algorithms for this problem. Specifically, we propose a 3k-approximation algorithm for any k /spl ges/ 3, a (k + 12H (k))-approximation algorithm for k(2k - 1) /spl les/ n where n is the network size, a (k + 2 [(k + 1)/2])-approximation algorithm for 2 /spl les/ k /spl les/ 7, a 6-approximation algorithm for k = 3, and a 9-approximation algorithm for k = 4.

We consider the traffic grooming problem on general topology WDM networks. The problem is: given a set of t connections and their routes, and the grooming factor g, to find an optimal wavelength assignment and grooming such that the number of wavelengths required in the network is minimized. We first formulate this problem as an integer linear programming problem, and then propose a heuristics method to solve it. Our simulation results show that an increase of the grooming factor can considerably decrease the number of wavelengths required in the system.

We propose a new type of wireless system, which is to provide for multimedia, bandwidth upon demand and quality of service (QoS) to the user. The system proposes to disable the problem caused by the unavailability of wired access by providing large bandwidths upon demand to individual users. The scheme proposes the use of optical beams in interconnecting mobile-telephone-switching-offices (MTSO) with each other using distinct WDM measures in a multihop scenario. Small microcells capable of growing themselves and reducing back to their macro size are employed. Traffic is dealt with by the anomalous expansion and contraction of these cells. A high data rate to individual users is provided by a FH-CDMA based system whereby the chip rate becomes proportional to the channel quality. This ad-hoc method of adaptive coding helps the user maintain a uniform data rate throughout time. The benefits of this approach are dealt with in great detail and issues of reliability and hand-off as well as system diversity are dealt with. As a further approach the authors suggest the interaction of this system with an ail-optical underlaying network.

Wireless Internet has become possible through the evolution of portable computers and wireless connections over a mobile telephone network. However the realization of a mobile computing environment requires a communication architecture which is not only compatible with the current architectures but also takes into account the specific features of mobility and wirelessness. In this paper, the main characteristics of Internet communications wireless networks and portable computers are examined. It is shown that to obtain a good quality of service on wireless Internet the challenge is to "hide" user mobility. However, in order to improve performance and obtain a reliable point-to-point communication in wireless networks, some modifications are necessary. Both examples of a cellular telephone network and a cordless telephone network are used to illustrate these concepts. Finally, the future of wireless Internet is envisioned and, more specifically, its necessary characteristics to obtain a reliable wireless Internet connection.

Consumers are demanding world-wide cellular access to the Internet. This requires a global standard and effective means of accessing the Internet from wireless devices. The IMT-2000 project attempted to fix the first problem by harmonizing all wireless interfaces into one global standard. However, this attempt failed and a new family of standards was issued. In response, the Operator Harmonization Group (OHG) is currently harmonizing two of the most popular CDMA standards: WCDMA and cdma2000. One major issue holding back complete harmonization is mobility management. WCDMA is used in Global System for Mobile Communications (GSM) systems where General Packet Radio Service/enhanced data for GSM evolution (GPRS/EDGE) protocols are currently being developed to act as the mobility manager. cdma2000 is designed for IS-95 and currently uses Mobile IP as its mobility manager. If one global standard is to be achieved, the same mobility management system has to be used by both WCDMA and cdma2000. The second problem deals with providing reliable access over unreliable wireless links. In this paper, a conceptual model integrating GSM and TCP/IP using Mobile IP as the mobility manager is presented. This model presents a method to implementing mobile IP over a GSM cellular network. The conceptual model also provides a solution to deploying TCP over wireless links. This model can serve as a useful starting place to harmonizing one global 3G standard.

The robustness of TCP has contributed to its success in the Internet environment. The role of communications is already well-established in the office environment. With the advent of cheap, affordable broadband communications and the increasing complexity of consumer goods, it seems natural to extend the network into homes. In-home networking means a high-speed communication among the digital appliances within a home. Introduction of applications over high-speed home networks using the TCP/IP protocol is increasing. The integrated environment of Internet and home network is demanding as well. We have validated a TCP model over a high-speed home network environment, investigated the throughput behavior of TCP over IEEE 1394 home networks, and evaluated a potential solution for high performance of TCP over IEEE 1394 home networks. The simulation model has produced several interesting results in the performance of TCP over IEEE 1394 home networks.