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Handover Decision in Multi-cell Ultra-High-Throughput WLAN

Handover Decision in Multi-cell Ultra-High-Throughput WLAN. Date: 2013-1 1 -3. Nov . 2013. Authors:. Slide 1. Weiwei Xia (SEU). Content. Motivation Proposed Handover Decision in Multi-Cell Ultra-High-Throughput WLAN Network topology Proposed angle of handover index

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Handover Decision in Multi-cell Ultra-High-Throughput WLAN

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  1. Handover Decision in Multi-cell Ultra-High-Throughput WLAN Date: 2013-11-3 Nov. 2013 Authors: Slide 1 Weiwei Xia (SEU)

  2. Content • Motivation • Proposed Handover Decision in Multi-Cell Ultra-High-Throughput WLAN • Network topology • Proposed angle of handover index • Load balance index • Proposed handover decision scheme • Summary • References Nov. 2013 Slide 2 Weiwei Xia (SEU)

  3. Motivation Traditional handover strategies based on several elements such as RSSI, SINR, QoS and so on. As low frequency spectrum has been used fully, more and more wireless communication technologies aiming at higher frequency spectrum and lower power will be applied by considering green communication. Thus these will result in the radius of a cell getting smaller and more frequent handovers will occur. Traditional handover decision scheme chooses the target cell which has the maximal RSSI or SINR value, so thatthe traditional schemes cannot decrease handover times effectively. Nov. 2013 Slide 3 Weiwei Xia (SEU)

  4. Network topology of multi-cell handover architecture in Ultra-High-Throughput WLAN Nov. 2013 • Network topology • AP of each cell provides service to all the users in the cell , • A user can locate its position accurately with GPS receiver and send this information to the AP via the uplink channel, • Each user moves from its initial position to the destination, thus it will not change its direction randomly between two adjacent times, Fig.1. Handover scheme in multi-cell network Slide 4 Weiwei Xia (SEU)

  5. Proposed angle of handover index Nov. 2013 • A Cartesian coordinates is established for the entire network. • Every AP has its own location and can be recorded. Fig.2. Cartesian coordinates of the entire networks Slide 5 Weiwei Xia (SEU)

  6. Proposed angle of handover index Nov. 2013 A register can be used to record the recent location information of the user, thus the increment of horizontal coordinates and vertical coordinates can be obtained, respectively. So that, we can derivate the instantaneous direction angle. Fig.3. Instantaneous direction angle Slide 6 Weiwei Xia (SEU)

  7. Proposed angle of handover index The average direction angle, which indicates the tendency of user movement angle, can be calculated through linear weighted method as follows Nov. 2013 (1) • Given , the movement vector of use k can be determined and the direction vector from user to AP can also be obtained as follows, (2) Slide 7 Weiwei Xia (SEU)

  8. Proposed angle of handover index A direction angle for user k in cell i, which is the angle between the above two vectors,can be gotten as follow Nov. 2013 (3) Fig.4. Handover angle index Slide 8 Weiwei Xia (SEU)

  9. Proposed angle of handover index Nov. 2013 • To evaluate the level of direction angle index in the entire network at time t, a new index of angle of handover (AHO) for the whole network is defined as (4) Slide 9 Weiwei Xia (SEU)

  10. Load balance index Nov. 2013 The load index of cell i at time t (5) resources allocated to user k by AP i at time t the total resources of cell i at time t the load of cell i at time t (6) Slide 10 Weiwei Xia (SEU)

  11. Proposed handover decision scheme Nov. 2013 A practical scheme is proposed. The scheme consists of three stages: handover trigger process, handover decision process and call admission control process • Handover Trigger Process A user k is triggered to make handover if and only if its receiving SINR from the original cell i SINRi,k is lower than the threshold ,( ) holding for a trigger time (TT). TT is used to reduce possible ping-pong effect. The TT decreases with the increase of user’s velocity. Slide 11 Weiwei Xia (SEU)

  12. Proposed handover decision scheme Nov. 2013 • Handover Decision Process The optimal objective is to maximize the handover gain of the whole network. Assuming that user k is switched from its serving cell i to cell j, which is one of the candidate cells set. Together with angle of handover index and load balance index, we can obtain, (7) and are used to represent the load balance index and angle of handover index in the entire network, when the handover user communicates with cell i. At each handover time, user chooses the target cell with the maximal handover gain among the candidate cells set , where (8) Slide 12 Weiwei Xia (SEU)

  13. Proposed handover decision scheme Nov. 2013 • Call Admission Control Process A new user k will be admitted to access cell j only if its receiving SINR transmitted from cell j is larger than the access threshold and there are enough time-frequency resources to satisfy the quality of services of user k. However, if none adjacent cell can afford the required value of SINR, the user k will hold on in its serving cell. Procedure of the total handover scheme with proposed decision scheme is illustrated in Fig. 5. Slide 13 Weiwei Xia (SEU)

  14. Proposed handover decision scheme Nov. 2013 Fig. 5. Procedure of proposed handover decision scheme Slide 14 Weiwei Xia (SEU)

  15. Summary • This proposal formulates handover decision scheme in multi-cell Ultra-High-Throughput WLAN based on a novel proposed angle of handover index and load balance index together with QoS constrains. Nov. 2013 Slide 15 Weiwei Xia (SEU)

  16. References • [1] H. Choi,“An optimal handover decision for throughput enhancement,”IEEE Commun. Lett.,vol. 14, no. 9, p p. 851-853, Sept. 2010. • [2] G.Tamea, M. Biagi and R.Cusani, “Soft multi-criteria decision algorithm for vertical handover in heterogeneous networks,”IEEE Commun. Lett., vol. 15, no. 11, pp. 1215-1217, Nov. 2011. • [3] D.Xenakis, N. Passas and C. Verikoukis,“A novel handover decision policy for reducing power transmissions in the two-tier LTE network,”inproc. IEEEICC, June. 2012, pp. 1352-1356. • [4] H. Ge, X. Wen and etal,“A history-based handover prediction for LTE systems,”inproc. IEEE CNMT,Jan. 2009, pp. 1-4. • [5] T. Kim, Q. Yang and etal,“A mobility management Technique with simple handover prediction for 3G LTE systems,”inproc. IEEE VTC, Sept. 2007, pp. 259-263. • [6] D.Chiu and R. Jain, "Analysis of the increase and decrease algorithms for congestion avoidance in computer networks," Computer Networks and ISDN Systems, 1989. 17(1): p. 1-14. • [7] H. Wang, L. Ding and etal, “QoS-aware load balancing in 3GPP long term evolution multi-cell networks,”inproc. IEEE ICC, June. 2011, pp. 1-5. • [8] Zh. Li, H. Wang and etal, “Joint optimization on load balancing and network load in 3GPP LTE multi-cell networks,” in proc. IEEE WCSP, Nov. 2011, pp. 1-5. Nov. 2013 Slide 16 Weiwei Xia (SEU)

  17. Oct. 2013 Thank YOU Slide 17 Weiwei Xia (SEU)

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