Optimized Sectoring A CDMA Network Architecture

(1)

Optimized Sectoring A CDMA Network Architecture

R. Vijai

1

_{, K. Thangadurai}

2

_{, T. P. Udhaya Sankar}

3

1, 2 _{Assistant Professor, Department of Computer Science and Engineering, Annapoorana Engineering College,}

Salem

3 _{Associate Professor, Department of Computer Science and Engineering, Annapoorana Engineering College, Salem}

---***---Abstract: In this paper, we propose organize engineering for

code-division numerous entrance (CDMA)- construct cell frameworks situated in light of versatile area scope. We demonstrate that there is a limit confine for a CDMA framework, which for a delicate point of confinement is genuinely hard. We additionally demonstrate that for a non homogeneous activity, changing the region of scope for every part in a sectored cell can ingest the flow of the movement. For a cell of a settled sweep, isolated into segments, it is conceivable to choose the edges of scope of every segment to keep away from unnecessary obstructing because of transitory non uniformity of movement over the cell. This outcome depends on the way that for a given arrangement of framework parameters (transfer speed, bit rates, , and so forth.), a specific measure of territory is secured. Subsequently, the correct state of the cell/part isn't critical. The thought introduced is appeared to be pertinent to covering parts.

Key Words — Call Admission Control (CAC), Cell Design,

Code Division Multiple-Access (CDMA) Capacity, Coverage Angle.

I. INTRDUCTION

ONE of the remarkable highlights of code-division various access (CDMA) systems is the adaptability in their designing and the subsequent versatility to growing client base and new advancements. It adjusts well to the irregularity of way misfortune and the subsequent non uniform scope territory. Customarily, hexagonal cell geometry has been received for limited and time-division various access (FDMA and TDMA) frameworks. In any case, as portrayed in Fig.1, the real cell shape is very indiscriminate because of the way that way misfortune and blurring differ as an element of nature and additionally the moving articles in the region. This outcomes in an inconsistency in the anticipated and genuine framework execution. We will find in this paper in CDMA systems, such contrasts of execution expectation can be overwhelmed by utilizing the way that a very much characterized geometric shape isn't vital for foreseeing the framework conduct. As appeared in the accompanying sections, the CDMA cell covers a specific region for a given measure of greatest power. The state of the region may not be vital from a framework execution perspective. As exhibited by various analysts, the client limit in CDMA frameworks is of a delicate sort. Notwithstanding, we will appear in the area to take after that, for a settled edge, as far as possible is much the same as the TDMA frameworks.

In this manner, the "delicate quality" of the CDMA limit is as adaptable as the dependability of the edge. This outcome is an expanded thinking given in [2]. we demonstrate the reliance of scope edge on,

Fig. 1: (a) Ideal hexagonal layout of cells

(b) with ideal isotropic antennas

(c) actual coverage.

[image:1.595.347.520.254.371.2]

(2)

pillar width, or by basically having covering areas.

The blackout condition decides the limit of a CDMA cell [5]. A blackout condition is said to happen if the bit vitality to add up to impedance in addition to warm clamor thickness proportion is not as much as an edge got from the correspondences framework plan. Let be the power got by the base-station handset from the portable client " ." Then , that is, the for the client can be helpfully composed as [4] where add up to number of meddling clients in the cell under thought; warm commotion control; , where is the framework transmission capacity and is the (white) clamor control thickness; preparing addition of the client " ," where is the bit rate; For a solitary client class with data bit rate ; other cells' impedance; discourse action factor of the client. are expected to have a typical likelihood mass capacity given by for something else.

CDMA Network Architecture using Optimized Sectoring

In the accompanying, (1) will be utilized to demonstrate that the most extreme number of calls show in a phone is given by the connection where is the viable greatest power, is the action factor, and because of the broken idea of transmission and . is the base (edge) required . A bar over shows the mean esteem.

Evidence: Let be the required for a solid operation. At the end of the day, we say a blackout happens if the genuine piece vitality tointerference proportion . To additionally clear up this point, let the review of administration (GoS) be the likelihood that the objective isn't met. At that point, the framework is steady as long as the accompanying condition holds:

GoS: Subsequently, from (1) and (3), the accompanying should hold with likelihood .

1-GoS: Give us a chance to accept that is settled and gotten from the adjustment conspire. Letting , taking the desire on the two sides of (3a) and reworking terms, we acquire where and are for the most part uncorrelated [4] for , and ,where an over head bar indicates expectation. in the above condition is limited by most extreme power transmitted , that is, , which gives the statement which, after substitutions and , gives (2). Moreover, the normal estimation of the outside cell impedance is given from [3] where . The real estimation of relies on variables, for example, cell geometry and recurrence arranging. The amount is an upper bound on and is given by the equity sign in (5). Clearly, this bound could be very free, as the real power transmitted is significantly less than the . Utilizing the fairness of (2) and substituting for , from (6) we get where is the warm clamor control equivalent to that. Now, we may compare1 (7) with the shaft limit given in [2]. In [2], the creators have considered a solitary cell

case, rendering , and a most extreme energy of , which influences the second term in (7) to vanish. Along these lines, (7) is just a more summed up adaptation of the shaft limit. Nonetheless, it gives a more clear definition. From this condition, we can characterize the post limit as the limit of a CDMA framework when all clients in all cells are transmitting at their pinnacle control. In determining (7), we have accepted that the flag powers are uncorrelated. In the event that that isn't the situation, at that point the meaning of post limit may require assist change or may even change. Most extreme Erlang activity that can be conveyed would now be able to be computed by utilizing Erlang-B equation simply like in TDMA or FDMA frameworks. For an IS-95-like framework, with ostensible parameters of MHz, kbps, and dB and a GoS of 1%, is 41, expecting [4] and mW. It must be accentuated here that the above furthest reaches of is legitimate just (1-GoS) part of the time, similar to the case with .

[image:2.595.328.537.340.459.2]

IEEE Transactions on Vehicular Technology

Fig. 2: % versus for an IS-95-like system.

% and % the corresponding traffic load. For example, for % % and , we find that % and% (9)

By defining the coverage angle being the cell radius, we have to modify (9) to reflect %, the coverage angle guaranteed with probability %, as follows: %if % % otherwise.

(3)

density function (pdf) of the random variable coverage angle derived in Appendix I. For example, for , corresponding to six sectors, the probability that the angle of coverage is greater than 3 tends to zero for that.

From this figure, one can find the optimum sectoring angles, given call intensity and assuming equal sector coverage. Thus, if the call density gets very high in some areas, such as thickly populated urban areas, or during a busy hour, the sectors should be shrunk according to the new values of . The inevitable result of not shrinking the coverage is excessive blocking. For the range of for which the curves do not leave the upper limit of , calls can be accepted without a control. The control region starts at these points and is bounded by the lower limits of when sector angles should be redefined.

Fig. 3: f(;)=Pf g as a function

II. CALL ADMISSION CONTROL BY OPTIMIZED SECTORING

As observed over, the ideal division coverageis firmly identified with the call power. In a phone that has every part with an alternate guest thickness, it isn't ideal to have areas of equivalent edges of scope. The negative impact of equivalent scope points appears when one of the parts is congested. One answer for this issue is to have covering areas and apportion calls by utilizing some sort of channel obtaining.

It will be demonstrated later that this divert acquiring technique has in truth an indistinguishable impact from changing scope point. Another component, and power-wise a more effective one, is to change the genuine edge of scope of radio wires adaptively, as portrayed beneath. In the assumed framework, there are radio wires at first divided with measure up to scope points. The greatest number of calls that can be served is acquired from the upper bound given by or from the blackout condition given in a few messages and papers on CDMA limit (see, for instance, [4]). The zone secured by every radio wire is at first given by, where is the span of the cell. Let be the quantity of calls that can be acknowledged with the uniform scope edge. At that point the radio wire scope will stay uniform until the point when the primary area has the set call.

By then, the scope points are balanced with a specific end goal to oblige the new call that may some way or another come up short the framework because of blackout. In this way, the calculation will assess the new point of scope of the reception apparatuses growing the scope edge of at least one recieving wires and contracting the same for others, contingent on their guest densities. By contracting the beam width, one takes into account a handoff of the additional call/s without having the divisions to cover. The advantage of such a framework can be seen from the trunking proficiency thinking on the grounds that in the ideal sectoring case, a call won't be hindered insofar as there are not as much as brings in a phone of divisions. In scientific terms, for a GoS of , the normal activity conveyed by a segment in settled segments (say, ) and with ideal sectoring (say) is given from the Erlang-B recipes also, that..

A. Main Function of the Algorithm

Similarly sectored recieving wires, each will cover a point of 2 radians. Further, let be the call power for division number with units of calls/zone in the start of cell operation and be the new call force after some time when the new edge of scope must be computed. Let be the underlying or "current" territory of the segment, be the present edge of scope of the part, and be the region and edge of scope to be resolved. At the point when every division has a similar edge, it covers a region of, where is the cell span. By picking, the call force can be accepted to have the units of calls/radian and the region secured point secured. Let be the Erlang movement conveyed per segment as per the Erlang-B equation got from the GoS and . For whatever length of time that the quantity of brings in all phones is underneath , no control of the scope point is upheld. When the main part gets the st call, the accompanying advances are performed. 1) Check if the aggregate number of dispensed directs in all segments is . If not, at that point obstruct the call; generally, go to following stage. 2) Once a channel is accessible anyplace, the new edges of scope are to be controlled by utilizing the instrument given in the subsection to take after. 3) Once the edges have been changed, a few mobiles will consequently get a more grounded motion from the new "more extensive" segments, and a (delicate) handoff may continue now. Along these lines, the vacillation in client power has been caught up in change of the secured region.

B. Evaluation of the Coverage Angle

[image:3.595.52.273.291.409.2]

(4)

than the greatest, no measure is helpful. add up to movement steady. At the end of the day, the change can be spoken to by the accompanying:

The above condition can be utilized as a part of numerous approaches to assess as the heap vacillates. Following is a basic strategy. We begin by letting where for . The above will ensure that . Next, we should circulate among the rest of the divisions. We can continue as takes after. 1) Excess Angle: We have an over the top edge of to be shared by the rest of the areas. This edge can be suited by part as long as . In this way, the following stage is to retain into (1) areas. For , this might be finished by utilizing the accompanying connection: , for , though given for it . It can be instinctively asserted that the ideal sectorization brings about the economy of scales by packaging the impact of the considerable number of diverts in all areas together. That is the wellspring of pick up.

C. Illustration Calculations

In this area, we will show the advantage of utilizing advanced sectoring by taking three cases. For all cases, let there be three parts, i.e., and , which compares to a GoS %. The arrangement of load can be composed as. By at first expecting , we can compose .

1) Case I: One Lightly and One Heavily Loaded Sector: Let be the new call powers when division number 2 would typically hinder various calls. This relates to demonstrating that area number 2 has 150% of the most extreme movement that can be conveyed for a 1% GoS. Be that as it may, utilizing the streamlined sectoring, the points will be changed as takes after: from (12), . . Since every single other power are either not exactly or equivalent to the greatest for rescheduling a scope edge, the relating divisions will retain the exorbitant edge of 2 9 as indicated by (13), which gives and . Henceforth, the new scope is . As needs be, when the pillar width changes, every area has an aggregate heap of . To figure the investment funds in blocking, we definitely realize that after re sectoring, the blocking likelihood stays unaltered to 1%.

D. Receiving wire Design for Optimized CAC

The specific reception apparatuses expected to understand the design depicted above have officially gotten much consideration in CDMA systems and different applications. The motivation behind such receiving wires in CDMA frameworks has been to separate a client from meddling clients. Such receiving wires, called savvy radio wires, comprise of a variety of reception apparatus components, each transmitting a marginally extraordinary way. The client is dispensed a keen pillar, in this manner confining it from different clients. The adjustments required in such a radio wire would identify with one of the few conceivable outcomes, for example, exchanging on a specific number of tight pillars to frame a division of a given scope or utilizing

stage shifters to control shaft width. The CAC gives criticism to the reception apparatus to this reason. The shrewd radio wire innovation is financially developed and a lot of research work is accessible on this subject. For instance, see [7]– [9]. Another reception apparatus write would be one in which the bar width can be differed persistently between two points of confinement. Such reception apparatuses additionally have application in telemetry following frameworks and have been the subject of research in that field. Achievement has been accounted for in the outline of such recieving wires in numerous papers, for example, [14]– [21]. Other than the particular reception apparatuses required for this design, there are different tradeoffs also. Two essential impacts are the expanded impedance in the covered zones (see next area) and less recieving wire pick up.

III. APPLICATION TO OVERLAPPING SECTORS

The possibility of variable area estimate is relevant to cells with settled size areas too. Such is the situation insofar as there is a cover between adjoining divisions. To expound further, we will begin with a documentation to portray such a framework. Fig. 5 demonstrates a roundabout cell with three segments. In the event that divisions are of equivalent width without covering, every area will be of (for this situation ) radians to cover the entire cell. Be that as it may, with a covering of a radians, every division has a greatest scope of . We can speak to as far as given in the accompanying. Halfway covered. where is the quantity of parts, which is three in Fig.5. ( 1) is the circumstances an area is ally covered by other segment/s and is given from being the biggest whole number littler than or equivalent to . In Fig. 5, . is the covering edge at the part limits inside the phone. One imperative ramifications of (14) is that, given and , one instantly knows what number of parts exist anytime in the phone, to be specific, inside and ( 1) inside the edge on the segment limits with neighboring divisions in a similar cell. For instance, in the above case, , bringing about one segment accessible inside and two parts accessible on the covered limits. in Fig. 5 is another amount that should be considered. It is the base size of a segment and is given by the accompanying condition:

A. Cases of Overlapping Sectors

(5)

Sectors

From the above cases, it might be seen that every division in covered areas can be thought of as of variable width. The scope is given by a part in the range . Along these lines, if the activity force in a specific area is clients per radian, the segment can be stacked anyplace from to Erlangs, contingent upon the GoS. This resembles having variable beamwidth radio wires with shafts controllable inside . A hotspot can be considered as a division whose scope is contracted. This system of dealing with the hotspot activity is more productive and less perplexing than having a microcell inside a macrocell, as proposed in [10]. The motivation behind why covered segments are more effective than a hotspot microcell is that in a microcell, additional handling and hardware is required, much the same as having an additional cell. Then again, in covered sectoring, a "virtual segment" with a scope anyplace between can serve the hotspot. We will expound the idea of "virtual part" in more detail in the accompanying section.

C. Virtual Sectors

In the event that a cell has covering segments, at that point it is normal that a client sooner or later in space may have a place with any of the more than one potential segments. In a circumstance like this, the movement power exhibit in an area isn't the same as the heap conveyed by the segment. Assume that we have a cell partitioned into covering areas, each having an edge of scope radians. Let be the movement force in part . In the event that is the heap conveyed by segment , then the accompanying condition characterizes the virtual division with scope edge :subject to the conditions and Note that (16), alongside the conditions, makes it fundamental that there be no covering among the virtual segments.

It is anything but difficult to demonstrate that , for every virtual segment.

Definition: Let be the movement force display in an area with a scope point of radians. On the off chance that the force of the calls that are apportioned assets in a similar division is , then the virtual segment edge is given by (16) and (17). The possibility of virtual part will be utilized as a part of future research to think of numerical models for the designing of covered areas to expand framework asset usage.

IV. CONCLUSION AND FUTURE ENHANCEMENT

It has been demonstrated that under shifting activity power, the scope zone of a CDMA cell changes. This data can be utilized to have versatile sectoring in which the area point is changed by the activity power in a division. It has been exhibited that utilizing such a system for call affirmation control can bring about noteworthy change in the GoS of cells with some over-burden sectors. Such an investigation is likewise relevant to covering parts. If there should be an

occurrence of covering divisions, the covering can be utilized to execute a comparable call confirmation control system. Definitely, if every one of the divisions are completely stacked, the framework backpedals to the underlying state of equivalent edges of scope. This will bring about neither pick up nor loss of the improved sectoring at this stacking. Along these lines, it is truly in the middle of the road instances of load progression when the streamlined sectoring holds guarantee. In any case, the advantages that can be gotten are adequately huge to warrant a need.

REFERENES

[1] R. Kuruppillai, M. Dontamsetti, and F. J. Cosentino, Wireless PCS. New York: McGraw-Hill, 1997.

[2] P. Tran-Gia, N. Jain, and K. Leibnitz, “Code division multiple access wireless network planning considering clustered spatial customer traffic,” in Proc. 8th IEEE Telecommunications Network Planning Symp., Oct. 1998.

[3] A. J. Viterbi, A. M. Viterbi, and E. Zehavi, “Other-cell interference in cellular power-controlled CDMA,” IEEE Trans. Commun., vol. 42, pp. 1501–1504, Apr. 1994.

[4] A. M. Viterbi and A. J. Viterbi, “Erlang capacity of a power controlled CDMA system,” IEEE J. Select. Areas Commun., vol. 11, pp. 892–900, Aug.1993.

[5] K. S. Gilhousen, I. M. Jacobs, R. Padovani, A. J. Viterbi, L. A. Weaver Jr., and C. E. Wheatly, “On the capacity of a cellular CDMA system,” IEEE Trans. Veh. Technol., vol. 40, pp. 303– 312, May 1991.

[6] A. Papathanasiou, I. Furio, J. J. Blanz, and P. W. Baier, “Smart antennas with two-dimensional array configuration for performance enhancement of joint detection CDMA mobile radio system,” Wireless Personal Commun., vol. 11, no. 1, pp. 89–108, Oct.1999.

[7] G. V. Tsoulos, M. A. Beach, and S. C. Swales, “Performance enhancement of DS-CDMA PCS cellular networks with smart antennas,” in IEEE Global Telecommun. Conf., New York, 1995, pp.231–217.

[8] M. J. Feuerstein, “Applications of smart antennas in cellular networks,” in Proc. IEEE Antenna and Propagation Society Int. Symp. 1999, Piscataway, NJ, 1999, pp. 1096– 1099.

[9] C. Braun, M. Nilsson, and R. D. Murch, “Measurement of interference capability of smart antennas on mobile telephones,” in Proc. IEEE 49th Vehicular Technology Conf., Piscataway, NJ, 1999, pp. 1068–1073.

(6)

algorithm considering nonuniformity of traffic and base station locations,” IEICE Trans. Fundamentals Electron., Commun. Comput. Sci., vol. E81-A, no. 7, pp. 1367–1377, July 1998.

[12]C. U. Saraydar and A. Yener, “Adaptive cell sectorization for CDMA systems,” IEEE J. Select. Areas Commun., to be published.

[13] M. Mahmoudi, E. S. Sousa, and H. Alavi, “Adaptive sector size control in a CDMA system using Butler matrix,” in Proc. IEEE 49th Vehicular Technology Conf., vol. 2, 1999, pp. 1355– 1359.

[14] D. J. Kozakoff and P. P. Britt, “A 94-5 GHz variable beamwidth zoned lens monopulse antenna,” presented at the Proc. Southeastconf’80, New York,

1980.

[15] A. D. Olver and J. U. I. Syed, “Variable beamwidth reflector antenna by feed defocusing,” in Proc. Inst. Elect. Eng. Microwaves, Antennas Propagation, vol. 142, Oct. 1995, pp. 394–398.

[16] E. A. Parker, B. Philips, and R. J. Langley, “Experimental variable beamwidth horn,” Electron. Lett., vol. 31, no. 18, pp. 1539–1540, Aug. 1995.

[17] J. U. I Syed and A. D. Olver, “Variable beamwidth dual reflector antenna,” in Proc. Inst. Elect. Eng. 9th Int. Conf. Antennas and Propagation, vol. 1, 1995, pp. 92–96.

[18] E. A. Parker, B. Philips, S. B. Savia, and R. J. Langley, “A study of variable beamwidth horns,” in Proc. Inst. Elect. Eng. 10th Int. Conf. Antennas and Propagation, vol. 1, 1997, pp. 55–60.

[19] U. O. Sterr, A. D. Olver, and P. J. B. Clarricoats, “Variable beamwidth cornerreflector antenna,”Electron. Lett., vol. 34, no.11, pp.1050–1051, 1998.

[20] S.B.SaviaandE.A. Parker, “Radiationpatterns of a variablebeam width ferrite-loaded waveguide horn antenna,” Microwave Optical Technol. Lett., vol. 17, no. 4, Mar. 1998.