... máy di động •Hỗ trợ cuộc gọi đang di n ra trong quá trình chuyển giao•Giao tiếp với mạng có dây –Phát triển các giao thức và giao di n cho phép thiết bị di động kết nối với mạng có dây •Vấn ... nghệ không dây, mạng không dây, kiến trúc và các ứng dụng2Truy nhập không dây •Hàng triệu người sử dụng thiết bị cầm tay truy nhập Internet•Nỗ lực nghiên cứu và triển khai mạng khôngdây ... và triển khai mạng khôngdây và di động •Tốc độ truyền dữ liệu của mạng không dây, có dây và các ứng dụng•HDTV (High Definition TeleVision), FDDI (Fiber Distributed Data Interface), ISDN,...
... nghệ Khôngdây - Mạng Không dây Công nghệ khôngdây sử dụng sóng radio trong khi các công nghệ truyền thống sử dụng các loại cable làm phương tiện truyền dữ liệu. Phạm vị của công nghệ không ... KHÔNGDÂY VÀ CÁC ỨNG DỤNG CHO THIẾT BỊ DIĐỘNG Lê Viết Hà MSV: 0121869 Email: ha.leviet@gmail.com 1. Giới thiệu Công nghệ khôngdây cho phép ta liên kết nhiều thiết bị bằng sóng radio ... phát triển liên tục của các thiết bị di động, nền tảng mạng diđộng và cả nhu cầu của người sử dụng, lĩnh vực phát triển ứng dụng cho công nghệ khôngdây đã được mở ra nhiều hướng đầy tiềm...
... Usually, thehard 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 andsofter ... QHis filled.In this case, we consider the case for MO= 0. The two-dimensional state-transition dia-gram becomes one-dimensional ( j = 0). Therefore, the state probabilities can easily be ... basic concept of handoff in mobile cellular radio systems has been introduced. Sever-al different traffic models have been described and briefly discussed. Four conventionalhandoff schemes in...
... the cells within a distance of D from the lastreported cell. The distance-based strategy is dynamic, and the distance threshold D can bedetermined on a per-user basis depending on his/her mobility ... mobile station at and around its predicated location in descending probability un-til the mobile station is found. Their simulation results show that the predictive distance-based scheme performs ... reasons. First, someimportant distributions such as the exponential, Erlang, and Chi-square distributions arespecial cases of the Gamma distribution. Second, the Gamma distribution has a simpleLaplace–Stieltjes...
... 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 bedivided into a set of disjoint and noninterfering radio channels. ... using different bench-marks following extended simulations with a variety of assumptions regarding the mobileradio environment. Some of these assumptions might be the cellular topology, the differ-ent...
... Unit Disk GraphsUnit disk graphs are intersection graphs of equal sized disks in the plane. It is easy to seethat given the distance model, multicoloring is equivalent to coloring for unit disk ... onenode of each distinct base color, except for two pairs of heavy nodes, each correspondingto a base color different from v’s and from each other; (b) at most one node of each dis-tinct base ... of theFPA strategy discussed earlier has a performance ratio of k/2. In what follows, we discusssome specific classes of graphs that have been studied in the context of radio channel as-signment....
... and P. Spirakis, Frequency assignment in mobile and radionetworks, in Proceedings of the Workshop on Networks in Distributed Computing, DIMACS Se-ries. AMS, 1998. 11. D. A. Fotakis and P. ... 15. J. R. Griggs and R. K. Yeh, Labeling graphs with a condition at distance 2, SIAM J. Discr. Math.,5: 586–595, 1992. REFERENCES115directly to the following bound, adapted from [12]. For any ... one, which indicatesthat channels assigned to the corresponding cells must be distinct, is often referred to as acochannel constraint. An intersite constraint of two, which codifies the requirement...
... fixedAlgorithm complexity medium medium high highCommunication complexity low medium high mediumChannel utilization medium high medium highControl overhead medium high high medium20. I. Chlamtac ... 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 networks,IEEE Trans. ... Timedivision duplexing (TDD) alternates transmission and reception at different time instantson the same frequency band, whereas frequency division duplexing (FDD) separates thetwo into different...
... focus on the radio interface adopted in the TD-CDMA system. This in-terface is named UMTS terrestrial radio access—time division duplex (UTRA-TDD). Tosupport data connections with different bit ... to in-dicate readiness to receive the data. This mechanism can be used to capture the channel con-trol before the transmission of long packets, thus avoiding “long collisions.” In addition, ... transmitting. If the medium is found to be idle for aninterval that exceeds the distributed interframe space (DIFS), the station continues with itstransmission.* On the other hand (when the medium is busy),...
... prediction model is used to determine whether a flow perceives aclean or dirty channel during each slot. (If the channel is dirty, we assume that the channelprediction model can also predict ... receive additional service only when leadingflows relinquish slots.As a consequence of its compensation model, CIF-Q provides a graceful linear degra-dation in service for leading flows. Additionally, ... a leading flow denotes the amount of additional service that the flow hasto relinquish in the future in order to compensate for additional service received in the past. There are two distinct...
... accordingly the value of its prefix sum. Inone additional time slot, station Skreveals its identity.The reader should have no difficulty confirming that when the protocol terminates,conditions ... set N ǟN + 1endifall stations set L ǟL – 1endifendwhile204RANDOMIZED INITIALIZATION PROTOCOLS FOR RADIO NETWORKSFigure 9.1 Illustrating a partition tree. 13. J. L. Bordim, J.Cui, T. ... 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,...
... thischapter, we focus on single-channel, single-hop radio networks. Single-hop radio networksare the basic ingredients from which larger, multi-hop radio networks are built [3, 22].As customary, time ... least 1 – 1/f for any fՆ 1. 10.6 CONCLUDING REMARKS AND OPEN PROBLEMSA radio network is a distributed system with no central arbiter, consisting of n radio trans-ceivers, referred to as stations. ... activity.We noted that by extending the leader election protocols for single-hop radio networksdiscussed in this chapter, one can obtain clustering protocols for multihop radio networks,in which every...