Tài liệu Sổ tay của các mạng không dây và điện toán di động P3 pptx

... and code division can be used in order to divide the radio spectrum. In fre- quency division, the spectrum is divided into frequency bands. In time division, the us- age of the channel is divided ... growth of radio traffic, and other fac- tors. A given radio spectrum (bandwidth) dedicated for cellular communications can be divided into a set of disjoint and noninterfering radio channels. ......

Ngày tải lên: 15/12/2013, 05:15

... Usually, the hard handoff can be further divided into two different types—intra- and intercell handoffs. The soft handoff can also be divided into two different types—multiway soft handoffs and softer ... strategies during overloading, might influence the overall performance. In the next section, we introduce different types of possible handoffs. In Section 1.3, we describe different handoff...

Ngày tải lên: 15/12/2013, 05:15

... traveled maximal distance exceeds the last reported maximal distance. The paging operation is based on the last reported cell and the maximal distance R. The system will search all R rings surrounding the ... the cells within a distance of D from the last reported cell. The distance-based strategy is dynamic, and the distance threshold D can be determined on a per-user basis depending on his/...

Ngày tải lên: 15/12/2013, 05:15

... Unit Disk Graphs Unit disk graphs are intersection graphs of equal sized disks in the plane. It is easy to see that given the distance model, multicoloring is equivalent to coloring for unit disk ... disk graph is the intersection graph of disks of equal diameter in the plane. They can also be described in terms of distance or proximity models, which consist of a value d Ն 0 and an embedding...

Ngày tải lên: 15/12/2013, 05:15

... one, which indicates that channels assigned to the corresponding cells must be distinct, is often referred to as a cochannel constraint. An intersite constraint of two, which codifies the requirement ... node or to dif- ferent nodes. More precisely, c i represents the constraint between nodes at graph distance i from each other. The reuse distance of G equals k + 1, the minimum graph distance...

Ngày tải lên: 15/12/2013, 05:15

... fixed Algorithm complexity medium medium high high Communication complexity low medium high medium Channel utilization medium high medium high Control overhead medium high high medium introduced in Sections ... broadcast problem in mobile radio net- works, Distributed Computing 10, 3, 129–135, April 1997. 26. I. Cidon and M. Sidi, Distributed assignment algorithms for multihop packet radio n...

Ngày tải lên: 24/12/2013, 13:16

... transmitting. If the medium is found to be idle for an interval that exceeds the distributed interframe space (DIFS), the station continues with its transmission.* On the other hand (when the medium is busy), ... WLANs 155 Physical Layer Distributed Coordination Function Point Coordination Function Contention-free Contention Figure 7.6 IEEE 802.11 architecture. *To guarantee fair access to t...

Ngày tải lên: 24/12/2013, 13:16

... prediction model is used to determine whether a flow perceives a clean or dirty channel during each slot. (If the channel is dirty, we assume that the channel prediction model can also predict ... receive additional service only when leading flows relinquish slots. As a consequence of its compensation model, CIF-Q provides a graceful linear degra- dation in service for leading flows. Addition...

Ngày tải lên: 24/12/2013, 13:16

... words, the RN with no-CD cannot distinguish between ambient noise and two or more transmissions colliding on the channel. A number of radio and cellular networks in- cluding AMPS, GSM, ALOHA-net, ... Fifer and F. J. Bruno, Low cost packet radio, Proceedings of the IEEE, 75, 33–42, 1987. 20. M. Gerla and T C. Tsai, Multicluster, mobile, multimedia radio network, Wireless Networks, 1, 255–265,...

Ngày tải lên: 24/12/2013, 13:16

... this chapter, we focus on single-channel, single-hop radio networks. Single-hop radio networks are the basic ingredients from which larger, multi-hop radio networks are built [3, 22]. As customary, time ... least 1 – 1/f for any f Ն 1. 10.6 CONCLUDING REMARKS AND OPEN PROBLEMS A radio network is a distributed system with no central arbiter, consisting of n radio trans- ceivers, referred to a...

Ngày tải lên: 24/12/2013, 13:16