MXPA98006616A - Allocation of dynamic channel in macroceldas with exclusion determinista to enable autonomous microclasses subyacen - Google Patents

Abstract

Co-Existence Dynamic Channel Assignment (DCA) techniques are described for superimposed macrocell systems, which facilitate the coexistence of embedded microcellular (ie, internal), self-contained underlying systems. The coexistence of the two systems without excessive mutual interference is obtained by means of the systematic deterministic exclusion of predefined subsets of the universal channel set, from the dynamic assignment to the superposed macro cells. The set of channels is made available to the underlying systems. The exclusion is made with minimal degradation of the performance of the ACD. Multiple methods of exclusion are also described

Description

ALLOCATION OF DYNAMIC CHANNEL IN MACROCELDAS WITH EXCLUSION DETERMINISTA GOES TO ENABLE AUTONOMOUS MICROCLASSES SUBYACENTS Technical Field of the Invention This invention relates generally to wireless systems and more specifically to an apparatus and method for providing Dynamic Channel Allocation (DCA) for macrocell systems, which facilitate the coexistence of embedded microcellular autonomous environments.

BACKGROUND OF THE INVENTION Existing and emerging internal / microcellular systems (such as PBX (Private Branch eXchange) Private branch exchange An internal telephone switching system that electronically interconnects one telephone extension to another, as well as to the external telephone network. ) wireless, private wireless networks in fields, in buildings or factories), frequently try to autonomously reuse the channels assigned to external / macrocellular systems. The prevention of mutual interference between an internal microcell and external macrocells can be easily obtained with the conventional Fixed Channel Assignment (FCA), where only part of the entire spectrum is assigned to each of the external macrocells. REF. 28082 An internal microcell that starts inside an external macrocell or at the borders common to two or more cells has a lot of spectrum for use without mutual interference with external mobile conversations. With the appropriate adjustments in the power levels and the choice of frequencies for the internal cells, the two systems can be adjusted for an interference-free operation. Dynamic Channel Allocation (DCA) is being adapted to improve spectral utilization and to facilitate frequency planning in wireless networks. For example, see the articles by Chih-Lin I. and P. Chao, "Local Packing-Distributed Dynamic Channel Allocation at Cellular Base Station," Proc. GLOBCOM 1993 and "Local Packing-Distributed Dynamic Channel Allocation with Cosite Adjacent Channel Constraints," Proc. IEEE PIMRC 1994 and article by M. Haleem, K. Cheung and J. Chuang, "Aggressive Fuzzy Distributed Dynamic Channel Assignment for PCS," Proc. ICUPC '95, pp. 76. These DCA algorithms range from the simple selection of a feasible channel (S-DCA) to a maximum packet where a request is called only when there is no feasible channel with all possible rearrangements. The advantage of the DCA is that each cell is free to choose any channel of the universal set of channels available for the network, the only restriction is imposed by means of the interference of the cells that are within the frequency reuse distance . This capacity provides capacity gain in addition to solving the radio frequency planning. In contrast to the above advantages, the microcells in a given location in the macrocellular radio environment with. DCA may experience interference over any part of the assigned frequency spectrum. This phenomenon can prevent the internal autonomous wireless system from finding available channels in real time. The coordination required to avoid mutual interference becomes a challenge.

BRIEF DESCRIPTION OF THE INVENTION In accordance with the present invention, an apparatus for and method of providing dynamic channel allocation (DCA) for macrocellular systems, which facilitate the coexistence of autonomous microcellular underlying environments, is described. The DCA (dynamic channel allocation) coexistence (CE-DCA) technique is referred to, because it prevents mutual interference between macrocellular wireless systems (also referred to herein as an overlay system) and the autonomous microcellular wireless system (which is also referred to herein as an underlying system). The CE-DCA technique enables superposed system macrocells, while the DCA in operation, to be excluded from the use of a small part of the spectrum which is made available to the coexisting underlying system. The exclusion simultaneously assures at least certain numbers of available channels to the underlying system (s), wherever they exist, and ensures minimum capacity degradation in the overlapping system that puts the new DCA into operation (assignment dynamic channel). The CE-DCA technique can also use any of the well-known efficient DCA techniques (eg, local packet (LP-DCA). More particularly, according to the present invention, the apparatus and method allows a predetermined number of channels are excluded from one or more macrocells of the overlay system, which overlap one or more cells of the underlying system.This allows excluded channels to be used by the underlying system (for example, by assigning to the underlying autonomous system or allow these channels to be explored and taken (or captured) by the underlying system.) The predetermined number of channels to be excluded are systematically selected to meet deterministically with only one of a group of requirements, which include: 1) satisfy both equations 1 (EQUATION 1) and 2 (EQUATION 2), (2) violate EQUATION 1 and satisfy the EQUATION 2; and (3) satisfy EQUATION 1 and violate EQUATION 2, where EQUATION 1 \ \ = Nm? N where Nm2n is the minimum number of channels available for the underlying system, where P is the set of cells that can cause interference to the underlying system and where E_ is the set of channels to be excluded from a macrocell i of the system superimposed and EQUATION 2 f Ei = f where f is the null set and where O is a set of macrocells belonging to the cluster or universal group, the universal group is the minimum set of macrocells in a cluster or group without any common exclusion channel.

According to other features, the DCA can be 1) centrally controlled by a centralized access controller, 2) controlled in a distributive manner by base stations of the one or more macrocells which overlap the one or more cells of the underlying system or 3) provided by having the underlying system to be scanned to determine the predefined number of channels that have been excluded from the overlay system.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings, Figure 1 shows an idealized physical arrangement illustrative of a wireless communication system in which the present invention can be used, Figure 2 shows an illustrative block diagram of a base station of a cell , Figure 3 shows the topology for a "6-Min exclusion" configuration with a minimum size of the universal cluster or group of 4, Figure 4 illustrates the exclusion configuration that satisfies the condition in (EQUATION 1) while has a universal group size of 4, Figure 5 shows a "3-Min" exclusion configuration where each cluster or group of 6 cells satisfies the (EQUATION 2), Figure 6 shows a 2-Min exclusion configuration, where a cell will be excluded from two of the three subsets and where each group of 6 cells satisfies the (EQUATION 2), Figures 7a and 7b illustrate examples of finite projection planes q = l and q = 2 respectively; Figure 7c shows a representation of the exclusion channel sets to an FPP of order 2; Figure 7d shows an illustrative exclusion of 7 channel sets. { ci, ..., c7} in a group of 7 cells to provide joint exclusion of a common channel for alternative triplets of cells; Figure 8a shows an FPP exclusion obtained with sets of 14 channels of size Nm? N; Figures 8b and 8c respectively show the configuration of co-exclusion channel cells (shaded) in 6-Min and FPP exclusion schemes; Figure 9 shows distributions of common exclusion channel set sizes for mutually adjacent cells under static CE-DCA; and Figure 10 shows a table in deterministic schemes with parameters that are optimized or improved; Figure 11 shows, for the description in the Appendix, the corresponding areas in a macrocell centered by a microcell superimposed on one, two and three macrocells.

Detailed Description 1. General In the following description, each item or block of each figure has a reference designation associated with it, the first number of which refers to the figure in which that item is located first (for example, 110 is located in figure 1). Figure 1 shows an idealized physical arrangement illustrative of a wireless communication system in which the present invention can be used. While the physical layout of the cell is shown as a regular hexagonal grid, for purposes of illustration and analysis, it must be understood that in reality the physical disposition does not need to be regular and that the cells can be of any form and not They need to be uniform in size. The size and shape of the cells are usually determined by geographical factors and other environmental factors. As an example, the use of a 7-cell frequency reuse as reference, cells are identified by different numbers (eg, 101-107) are members of the same set of groups or clusters and must be serviced by different channel frequency sets to avoid interference problems. Cells in other group sets can use the same sets of channel frequencies. Thus, cell 106a can use the same frequency set as cell 106. Each cell includes a base station (e.g., Base 1, 111) to control communications to a plurality of mobile stations or users (e.g., Ul and U2) inside his cell. As shown, one or more cells, for example, 102, may include underlying microcellular systems located completely within "a", in a common border to two neighboring cells "b" or in a common corner to three mutually adjacent cells "c " These microcells also use sets of frequency channels for communications between users, mobile phones inside and outside the microcell. To help distinguish cells from the cell type system, reference will also be made to the group of hexagonal cells (cells) as superimposed and / or external macrocell systems and reference will be made to the underlying microcells as microcell systems and / or internal systems. In one embodiment of the present invention, a centralized access controller 110 is used to provide the Dynamic Channel Assignment (Co-Existence DCA or CE-DCA) technique between macro cells of each set of groups or clusters (e.g., macrocells). 101-103) of superimposed macrocellular systems to facilitate the coexistence of embedded, autonomous, microcellular systems (a, b and c). The coexistence of the two types of systems, without excessive mutual interference, is obtained by means of the systematic exclusion of predefined subsets of the universal channel set, from the dynamic assignment to the macrocells. The set of channels thus excluded results in a guaranteed number of channels available to an embedded microcellular autonomous system (for example, an internal system). When using the CE-DCA technique, exclusion is made with minimal performance degradation of the DCA (Dynamic Channel Assignment) in macrocell systems (usually an external system). An illustrative block diagram suitable for representing a base station, for example, 111 and an access controller 110, is shown in Figure 2. As shown, a modulated signal carrier signal is received at the antenna 201 and is processed by the receiver 202, under the control of the processor 203 and the programs stored in the memory 204. The transmitter 205 transmits a signal carrier modulated signal via the antenna 211 under the control of the processor 203. The transmitter 205 and the receiver 202 of the base station function to send / receive mobile station communication signals, also as control signals. The transmitter 205 and the receiver 202 of the access controller 110 function to send / receive control signals to / from the base stations. The standard wireless operation of the base station 111 is well known and is dependent on the communication characteristics of the particular system and is not further described herein. In one embodiment, the base station 111 is also communicated and put into operation under the control of the centralized access controller 110 of FIG. 1, which controls the channel assignment functions for the overlay system. In such an arrangement, the centralized access controller 110 receives a request for an autonomous subjacent system embedded by a predetermined number of communication channels. In response to the received request, the centralized access controller 110 excludes a predetermined number of channels of use by the one or more macro cells of the overlay system, which overlap one or more cells of the underlying system. It can be selected that the excluded channels meet deterministically with only one of a group of requirements that include: (1) satisfying both equations 1 (EQUATION 1) and 2 (EQUATION 2), (2) violate EQUATION 1 and satisfy EQUATION 2; and (3) satisfy EQUATION 1 and violate EQUATION 2. After this, the base station for each of the one or more macrocells receives signals to exclude excluded channels. Then, the processor 203 of the base station 111 is responsive to the commands or commands of the access controller 110, to assign and exclude frequency channels to the mobile users that are inside its cell 101. The centralized access controller 110 also sends an allocation signal to the underlying system making the request, which identifies that the frequency channels excluded from the macrocells are going to be assigned to the underlying system for communications. In another distributed control mode, none of the base stations 111-113 is put into operation under the control of the access controller 110 for the channel allocation functions, but, rather, they communicate with each other to coordinate the actions of channel and channel exclusions. The operation begins when one or more of the base stations of the overlay system receives a broadcast request from an autonomous subjacent system embedded by a predetermined number of communication channels. In response to the received request, the receiving base station (s) determines (in), in conjunction with other base stations of the one or more macro cells of the overlay system, which overlap one or more cells of the embedded autonomous sub-system, which predetermined number of channels must be excluded by those macrocells. Again, the excluded channels are selected to comply deterministically with a requirement of the previously described group of requirements. The previous two modalities of the base station are used with the systematic planned exclusion techniques, described in later paragraphs. In still other modalities, random exclusion techniques, instead of a deterministic technique, as described in a later paragraph, are used to define the exclusion of channels. These random modes can be put into operation either in a centralized manner, where the access controller 110 controls the exclusion of channels or in a distributed manner, where the base stations jointly determine the channels to be excluded. The operation for both modalities, centralized and distributed random, works in a similar way to the centralized and deterministic distributed modalities described previously. However, in the centralized and random distributed modes, the excluded channels are selected to statistically satisfy the EQUATION 1 and the EQUATION 2. In the access controller 110, the processor 203 is arranged to provide the standard access control functions for the The underlying macrocellular system of Figure 1 and further, if required, can be arranged to provide any of the enhanced CE-DCA functions to facilitate the coexistence of embedded microcellular autonomous systems as described above. 2. DCA Co-existing Since the frequency spectrum assigned to the macrocell system of Figure 1 is divided into frequency channels and in turn into time segments, the following discussion is carried out in terms of channels and channel sets. The advantage of the Dynamic Channel Allocation (DCA) lies in the fact that each cell is free to choose any channel of the universal set of channels available to the network, the only restriction is imposed through the interference of neighboring cells / interferers in the same network. This capacity provides capacity gain as well as ease of radiofrequency planning. Furthermore, it makes it very difficult for an internal autonomous wireless system (ie, microcell) to find available channels. To accommodate the coexisting internal wireless systems, for example, ac microcells of Figure 1, the invention describes a unique technique for excluding subsets of channels in each macrocell of the superimposed system, of the universal set of channels, U. It is started by defining the designation of CE-DCA as "the search for channel exclusion configurations to minimize the loss of capacity in a macrocellular system superimposed, while maximizing the number of channels acquired by the underlying microcellular system". Such an exclusion configuration must provide a sufficient number of channels to an underlying microcellular system, wherever located, within the superposed macrocell system. In other words, the set of channels available for each underlying microcellular system are those never used by their nearby superposed macro cells, which may otherwise cause mutual interference. The above objective can be obtained by excluding sets of channels in those macrocells in the neighboring system of the underlying microcellular system. The intersection of those exclusion sets must be large enough to provide the required number of channels to the underlying microcellular environment. The technique of the present invention ensures that this new restriction causes minimal degradation in performance, compared to conventional ACDs (Dynamic Channel Allocation) (without exclusion). As a stand-alone underlying system, an internal wireless environment can be initiated within a cell ("a" of figure 1) or in a common border to two or more cells ("b" or "c" of figure 1). By using the idealized hexagonal cell topology of Figure 1, a microcell can exist in no more than 3 mutually adjacent cells, shown as c in Figure 1. (In practice, a microcell can sometimes be overlapped with coverage areas of more than three macrocells). Let E_ be the set of excluded channels in the macrocell i when the DCA is executed, Nm? N the minimum number of channels required for an internal mobile environment (for example, c of figure 1), then the requirement is, EQUATION 1 | f Ei \ = Nm? n? .l 'where P is the set of cells that can cause mutual interference to the underlying microcellular system. The same logic and formulation extends directly to a complete macrocell system which can accommodate multiple independent underlying microcellular systems. In addition to the requirement expressed in equation (1), additional criteria are introduced that redefine the strategies of channel exclusions. First, it is intuitively obvious that the size of the exclusion set per cell must be minimized, \ E_ \. Second, the sizes of the intersections of the exclusion channel sets, | | j £ / | for | C |, < \ P \ also plays a role i. C important, because while it can be kept smaller, the macrocells will retain a higher capacity. Also, remember one of the fundamental differences between the DCA and the FCA concerning the use of channels. With the FCA, the minimum set of W cells, which can be used by all U-channels, form a group or cluster of frequency reuse; while with the DCA, each cell is allowed to use the entire U. It is called O the group or universal cluster, asi | O | It is normally 7 in the FCA and 1 in the DCA. The "group or universal cluster" in the context of the EC-DCA, is the "minimum set of cells in a group without any common exclusion channel", that is, EQUATION 2 Ei = f? .Q. where, f is the null set. The requirement raised by equation (1) determines that | O | > \ F. It is obvious that | W | it should be kept as small as possible and definitely smaller than that of the FCA. Having identified the above parameters, that is, Nmm, and | O |, which determine the performance of the CE-DCA algorithms (dynamic coexistence channel assignment), it is quite intuitive to see that an increase in the values of the previous parameters would have a negative effect on superimposed macrocellular systems. However, for an Np? n given, \ E_ \ and I \ \ Ei | for \ C \ < \ P \ must be large enough i.C to satisfy the requirements of an underlying microcellular system. On the other hand, | O | whose minimum value is | P | +1, is easily independent of Nm n, Finally, the channel exclusion configurations that minimize the values of the previous parameters, while satisfying the requirement in equation (1), can give as a result a different | [j Ei I, called the Channel extension requirement. By definition I [Ei \, it should not be greater than \ U \. Thus, the channel extension is a factor that determines the maximum Nmin obtainable for a given \ U \. The initial problem formulation is based on the parameters as identified above. As will be seen from the simulation study in the following section, there are additional factors that determine the performance of the CE-CDA algorithms. In particular, there are two algorithms, characterized by exactly the same values of the previous parameters, that provide a drastically different performance. The investigations carried out reveal that they differ in a new factor, called the physical disposition of co-cana exclusion cell, defined as "the configuration of a particular channel that is excluded in the physical disposition of the cell". The co-channel exclusion cells are the set of cells with j. identical. It seems that the more compact this physical arrangement is, the better the performance of the CE-DCA. Without loss of generality, the following description is based on a regular hexagonal cell topology with 2-cell buffer. In the case of the FCA, this physical disposition and restriction correspond to a group or reuse cluster of 7 conventional cells. As illustrated in Figure 1, a microcellular system can be located in three types of locations, called a, b, and c. The number of available channels for the microcells with each CE-DCA depends on the type of location where they are located, while a minimum of Nmin channels must be guaranteed by the CE-DCA (dynamic coexistence channel assignment) in the location of the worst case (that is, in c). Thus, the present invention focuses on | P | = 3 in this description and extensions can be made to physical arrangements with different \ P \ similarly. 3. Exclusion schemes for CE-DCA Two classes of CE-DCA algorithms are presented in this section, that is, statisticians and determinists. The deterministic class includes six different algorithms. The design of each CE-DCA is described along with the motivation for the specific design in the following subsections. 3. 1 CE-DCA Statistics The statistical method is designed to preserve one of the advantages that conventional DCAs offer, that is, no frequency planning in any form. Each cell independently and randomly makes a maximum of one exclusion set Ei of the universal channel set, U. All U channels are chosen with uniform probability. In this case, the requirements posed by equation (1) are satisfied only in the statistical sense. One of the implications is that | E, |, must be large enough to result in Niun channels available to the microcells with the required level of confidence. In order to investigate this question, the probability distributions of common exclusion channel set sizes are derived, | \ \ Ei | for several \ C \, in the Appendix A. With \ U \ = 420 channels in the universal set, Figure 9 shows typical size distributions, for several I £ I of mutually adjacent mutually adjacent channel sets, triplets and groups of 7 cells. The first two sets of distributions indicate the number of available channels for a microcellular system that overlaps with two and three macrocells respectively. Note that the average is large enough to provide channels for the underlying microcellular systems, while the standard deviation is favorably small to obtain a high level of confidence in the availability of channels. The third distribution shows the degree to which | O | < 7 is satisfied.

Note that the size of the average common exclusion set for a group of 7 cells and their standard deviation appear to be small even with very large values of \ E1 \ / \ U \. These properties are highly desirable and encouraging. Thus, it is expected that the EC-DCA statistics will provide favorable performance. 3. 2 CE-DCA Determinist Although the above discussion is encouraging, the purely statistical procedure does not provide direct control over the parameters identified in the previous section. From here, we proceed to look for deterministic methods, which will provide the ability to design values of objective parameters. You start by examining the range of the | W | in which exchanges can be made. At one extreme, if I i I = N-in, each cell would exclude the same set of channels with a size of Nmin. This is called the "common exclusion", which counts to truncate U by Nmlr channels and the performance degradation is exactly the difference between the capabilities of the DCA when using the channels \ U \ and \ U \ - Nm? N respectively , | O | = 8 in this case. On the other hand, ideally, one must have the ability to design exclusion configurations where each group of 3 cells has a common exclusion set of min size, while each group of 4 or more cells has the ability to use the set universal channel. In this case | O | is 4, which is the minimum value that can be obtained following the basic requirement of the CE-DCA.

In this subsection, six deterministic CE-DCAs are presented which attempt to optimize some of the parameters identified in the previous section. Common, 2-Min, 6-Min, 3-Min, FPP and CE-DCA of reverse FCA exclusion. While the FCA Reverse exclusion scheme does not satisfy the basic requirement in (1), it is presented as a reference case. Table 1 shown in Figure 10 summarizes the parameters that are optimized or improved in each algorithm. In the random exclusion scheme, the base station in each cell of Figure 1 independently determines which channel frequencies will be assigned to the microcell and hence will not be used by the DCA. The FCA-Inverse, 6-Min-3-Min, and 2-Min exclusion methods are planned systematic channel exclusions, where the base stations of Figure 1 do not independently determine which channels are to be assigned to the microcell and excluded from the DCA in the macrocells. In such an arrangement, the access controller 110 of Figure 1 can centrally control the planned channel exclusion for each of the cells and communicate the information to each base station. Alternatively, the base stations can communicate with each other to decide among themselves regarding the systematic channel exclusions. Each algorithm together with its design motivation is presented in the following paragraphs.

CE_DCA with common exclusion By definition, equation (1) determines that \ E \ is at least Nmin. The simplest method is to exclude a single set with Nmip channels from all macrocells, in such a way that the set is available to service the internal systems at any location. However, as discussed above, | O | = 8 in this case, so its spectral use is inefficient. The performance of the CE-DCA in the external system is simply that of the conventional reference DCA algorithm, with the truncated U. This loss of capacity may not be acceptable to the external service provider, even if some of the internal systems are put into operation by independent parties.

CE-DCA with 2-Min exclusion With the minimum possible value of I Ei | , this is, Nm? n, the common exclusion is inefficient with respect to all other key parameters. It leads to the hypothesis that the optimal strategy for CE-DCA would be one with \ Ei \ = kNmin, where k > l. It is found that the next smallest integer value of k, that is 2, ensures proper tiling of the exclusion sets between the macrocells, while satisfying equation (1) and results in a better | O |. As illustrated in Figure 6, this algorithm requires three mutually exclusive subsets, ie a, b, and c of size Nmin. Each macrocell will be excluded from using two of the three sets of channels. With this exclusion setting, each group of 6 cells satisfies equation (2). Thus, it is considered | O | = 6, which is close to the maximum value, 7, since | O | = 7 in the Conventional DCA. In addition, groups of 4 cells with certain orientation also satisfy equation (2).

CE-DCA with 6-Min Exclusion The 2-Min exclusion scheme provides a higher value for | Ej, but not the group size | O | . To optimize this, an exclusion configuration is designed, where each group of 3 cells has a common exclusion set of size Nmin, while each group of four or more cells is capable of using the universal set of channels; so | O | = 4. It is found that the size of exclusion set per cell, I Ei I for this case is 6 Nmin. This strategy is called the "6-Min exclusion". Figure 3 shows the topology for a "6-Min Exclusion" configuration with a minimum universal group size of 4. As shown in Figure 3, for every three mutually adjacent cells to have a common exclusion set Ci in size Nm? N, the three cells must be excluded from the set c ?; whereas for every four cells to have no common exclusion set, we must assign to each corner of a hexagon a different common exclusion set Ci, i = 1, ... 6, and the cell with those six corners You have to have all six sets excluded. Note that the reuse of any set Ci in another corner will result in a universal group size | O | greater than 4. In order to have a reuse group size | O | of 4, a different set of c ± channels of size Nmin must be assigned to the remaining 5 corners of the middle cell. From here, the middle cell must be excluded from a set of channels of size 6 Nmin. Figure 4 illustrates the exclusion configuration that satisfies the condition in (EQUATION 1), as long as it has a universal group size of 4. It is obtained by defining sets of 18 mutually exclusive channels of size Nm p within the universal set. To maintain the minimum value of | O |, sets of 18 mutually exclusive channels of size Nmin are required within U. Hence, this 6-Min exclusion requires a set of universal channels large enough, U, to satisfy the condition | U | > 18 Nmin. As shown in Figure 4, a 6-Min exclusion configuration is obtained with sets of 18 channels of size Nmin. An exclusion set chosen from the set of channel sets is assigned to each corner of a hexagon. { to , . . . , f; a j. . . f j a ", ..., f"). The exclusion set thus assigned to a corner is excluded in all three cells with the corner in common. This configuration ensures a reuse group size of 4 and has an exclusion set size of 6 Nmin per cell. Compared to the 2-Min Exclusion which optimizes I Ei | , but sacrifices | O |, the 6-Min exclusion seems to optimize | O | at the expense of I E | .

CE-DCa with 3-Min Exclusion In the search to reduce | Ei | and the I M E / I minimum required, an exclusion configuration is further designed that requires an exclusion configuration that excludes only 3Nmin channels per cell, that is I? i I = 3 Nmin, and requires only 4 sets of mutually exclusive Nmin channels within the universal set U , this is | [J E / | = 4.? N Figure 5 shows a 3-Min exclusion configuration obtained with sets of 4 channels of size Nmin. An exclusion set chosen from the set of channel sets is assigned to each corner of a hexagon. { a, b, c, d} . The exclusion set thus assigned to a corner is excluded in all three cells with the corner in common. This configuration ensures a universal group size of 6 and requires an exclusion set size of 3 Nmin per cell. This design can accommodate a much larger value of Nmin for a given universal channel set size, compared to the 6-Min exclusion; specifically, it only requires | U | > 4 Nmin. However, although all groups of 4 cells and 5 cells with certain shapes and orientations are allowed to have access to all U-channels, not every group of 5 cells has that property (such as shading). Any group of 6 cells such as A is able to use U. Thus | O | = 6 as in the 2-Min exclusion. With \ E \ greater than the latter, this scheme is expected to work better by excluding 2-Min.

CE-DCA excluding finite projection plane (FPP) Among the exclusion schemes presented above, 6-Min is the only one that minimizes | O | . However, its performance is delayed behind other schemes as will be seen in the next section. An additional disadvantage of 6-Min is that it requires a large space of the set of channels. In search of techniques to improve performance and reduce this spacing, we reach an exclusion scheme based on finite projection plane (FPP) which not only cuts the spacing from 18 Nm to 14 Nmin but also improves performance significantly. The FPP exclusion is similar to 6-Min in that I E | and it is still very different in its selection of E_. The method of selecting the exclusion set in this scheme comes from the theory of finite projection planes [for example, see the article by Yoshihiko Akaiwa and Hidehiro Andoh, "Channel Segregation - A Self-Organized Dynamic Channel Allocation Method: Application to TDMA / FDMA Microcellular Systm, "IEEE J. Sel. Areas in Comm. , Vol. 11,? O. 6, August 1993, pp. 949-954; and the article by Albert, A. A., and Sandler, R., "An Introduction to Fini te Proj ective Planes," Holt, Rinehart, and Winston,? ew York, 1968]. The definition of FPP is as follows: Definition: An FPP of order q consists of q2 + q + l points and those many lines. Any line is incident with q + 1 points and any point is incident with q + 1 lines. The simplest example of FPP is the FPP of order 1, which is represented by the 3 lines and 3 points in a triangle. Figures a and 7b show FPP examples of orders 1 and 2 respectively. Notice in Figure 7b, that the 7 lines and 7 points in the FPP of order 2 include a circle representing the seventh line. The FPP has been used to design new FCA schemes with improved frequency reuse efficiency [for example, see the article by Ueberberg, J., "Interactive Theorem Proving and Finite Projective Plans," Proc. Int. Conf. AISMC-3, "96, pp. 240-257.] Applies to the CE-DCA which leads to a physical layout of efficient co-exclusion channel cells.The channel exclusion with optimal | O | (= 4 ) can be represented on an FPP of order 2 in the following way: Consider 7 different sets of channels {.c \,..., C?) and represent on 7 points in the FPP, as illustrated in figure 7c 7 subsets (lines) of 3 sets of channels (points) are formed, each in such a way that any set of channels (point) c_, i = l, ..., 7 is found in 3 of the 7 subsets (lines) These 7 subsets can be assigned to a group of 7 cells, so that triplets of alternative cells share a commonly excluded channel set, that is, cl f c6 and c-as shown in Figure 7d The procedure will be repeated with a different set of 7 channel sets to provide common exclusions for the remaining triplets. ite with a 7-cell re-exclusion configuration. Note that only three of the six cell triplets of interest in Figure 7d obtain the common exclusion due to the fact that each point (set of channels) in this FPP of order 2 (group of 7 cells) is incident (shared) by only three lines (cells) and that each line (cell), which includes the circle (central cell), contains only three points (channels). To provide sets of channels commonly excluded from the three triplets of remaining cells of interest, the same process is repeated with a second set of 7 channel sets. The resulting exclusion configuration is shown in Figure 8a. As shown in Figure 8a, the exclusion of FPP is obtained with sets of 14 channels of size Nmin. Each corner of a hexagon is assigned an exclusion set chosen from the set of channel sets (a, ..., g, a ', ..., g'.}. The exclusion set thus assigned to a corner is excluded in all three cells with the corner in common.This configuration ensures a reuse group size of 4 and has an exclusion set size of 6 Nmin per cell.The exclusion scheme is derived from the concept of projection plane For pleasure and surprise, the FPP exclusion scheme proves to offer a traffic performance quite superior to that of the 6-Min exclusion. Since the two schemes have | E | | identical and | O | identical, but a physical layout of drastically different co-exclusion channels (see figures 8b and 8c), it is assumed that the more compact co-exclusion channel cell configuration of the FPP exclusion, which leads to more efficient channel reuse distances dynamically, is the main contributor to its high performance. Figures 8b and 8c respectively show the configuration of co-exclusion channel cells (shading) in 6-Min and FPP exclusion schemes.

CE-DCA excluding inverse FCA Another possibility of obtaining \ Ei \ = Nm? N, that is, a set of minimum exclusion per cell, while minimizing | O | is to define N sets of mutually exclusive channels of size Nmin and then each cell is excluded from the use of a set, with a re-exclusion setting that is the same as the FCA configuration, with the reuse factor of 7. This procedure results in | O | = 2 which is less than the minimum value that has been previously identified. Note that the constraint in equation (1) is violated in this scheme that leads to potentially poor microcellular performance. It is expected to offer higher performance of the DCA for the macrocell system, but the availability of channels in the underlying microcells may not be satisfactory if the ratio of the cell radius is not significantly smaller than one. However, since this scheme is characterized by a physical layout of highly efficient co-exclusion channel cells, similar to the FPP exclusion, it supports even more traffic than the reference DCA algorithm without exclusions. 4. Conclusion Many microcellular systems, mostly internal, operate within the same external macrocellular network spectrum autonomously. Its operations are based on the assumption that there are sets of relatively stationary channels never used by local macrocells. This assumption is true when the macrocell system operates under FCA. However, when noting the advantages of the DCA, such as its capacity gain and frequency planning facility, the external / macrocell systems move away from the FCA to the DCA and the sets of stationary channels available in the locality of the systems autonomous underlies will no longer exist. To satisfy the conflicting needs of both systems, the coexistence DCA algorithms (CE-DCA) are used, a new class of DCA algorithms for external / macrocellular wireless systems to allow the coexistence of internal / micro-cellular systems autonomous. The key factors that determine the relative performance of CE-DCA algorithms in external / macrocell systems are: the size of the macro-cell exclusion set, the size of the universal group, and the physical layout of the co-channel cell. exclusion. The first is determined mainly by the minimally required number of channels available in the microcells. On the other hand, the second and third parties vary with the type of exclusion algorithms. The amount of spectrum acquired by a microcell is determined by the type of algorithm, as well as the relative position of the microcellular system within the macrocellular environment. Among the algorithms presented in this description, the simplicity of a CE-DCA with common exclusion is shaded by its poor performance, except when the microcells need only a very small number of channels. Among other deterministic CE-DCA algorithms presented, it is found that 2-Min is characterized with an optimal exclusion set size per macrocell of twice the minimum requirement. As expected, it is found that this algorithm shows excellent performance. The CE-DCA excluding ß-Min provides the smallest universal group size and very good performance, with the caveat that its universal set size must be at least 18 times the number of channels that microcells need. Furthermore, it is found that its performance is quite inferior to the 2-Min strategy due to the fact that the size of the macro-exclusion set is much larger than in the case of 2-Min and also due to the contributions of the provision physicality of the coexclusion channel cells. Although the CE-DCA excluding 6-Min and similar FPP-based exclusion except for the difference in the physical layout of co-exclusion channel cells, the FPP shows a rather superior performance. This reveals the fact that the physical layout of the co-exclusion channel cells has a greater contribution towards the performance improvement of the CE-DCA algorithms. This conclusion is further reinforced by the performance of CE-DCA with the exclusion of inverse FCA. However, the exclusion of FCA-inverse does not satisfy the requirements and is described here only for the purpose of comparison. In conclusion, it seems that EC-DCA excluding FPP is the most efficient procedure. If microcellular systems are reasonably small in radius compared to macrocells, as would be true in most cases of interest, EC-DCA with random exclusion is recommended. The random EC-DCA also preserves the advantage of not requiring global frequency planning. It is envisioned that, higher CE-DCAs are possible with the use of channel segregation techniques where each channel is assigned a priority factor for allocation in each microcell. Such factors are updated following an adaptation procedure, which leads to an improved DCA performance, with respect to a superposed macrocell system, while leaving stationary channels for the use of underlying microcellular systems. On the statistical procedure side, there is a possibility of performance improvements by intelligently choosing the probability distributions during the selection of the exclusion channel sets, instead of selecting them according to an assumption of equal probability. The choice of such a probability distribution should ensure sizes of common exclusion channel sets for adjacent pairs and triplets of cells, which correspond to the probability of placing a microcell system, to lead to an expected optimized amount of channels for the microcells. The choice of selection probabilities must take into account the effects on macrocells. Such a strategy would have complexities that fall between purely random schemes and purely deterministic schemes in terms of the amount of combination and autonomy. What has been described is only illustrative of the application of the principles of the present invention. Other arrangements and methods may be increased by those skilled in the art without deviating from the spirit and scope of the present invention.

Appendix i) Common exclusion channel sets under random excitation: Any macrocell i is excluded from a set of channels, the f of size m, which is chosen randomly from the universal set of channels U. The probabilities of having k . { < m) channels in common between two and three such exclusion sets are [see Chih-Lin I and P. Chao, "Local Packing-Distributed Dynamic Channel Allocation with Cosite Adjacent Channel Constraints," Proc IEEE PIMRC 94: In general, the probability that k of m channels in En are in E_: I = 1,. . . , n-l is approximated by the Bernoulli distribution with probability of success (m / M) n ~ l, the hope and the variance of which are a m, respectively. This result was derived in the form of all against all as follows. Be Cj '. j = l, ..., M any channel in U.

Then, the probability that any channel is in an exclusion set is given by Pr. { ck € Ej_) = m / M. We have randomly selected m channels for all, minus the last cell n. This is equivalent to the repeated selection n-l of m of M objects with replacement. The probability that any channel Cj is in Ei for all i = 1, ..., n-l, can be expressed as Pr ..., n-1) = (m / M) ~ 1. This situation is similar to having a box of M objects where each of them has a certain color with probability of success p = (m / M). Then for M »m, if m objects are randomly selected, the probability that k of m objects is of the mentioned color, is provided frtJ by the Bernoulli probability, consequent, for M» m the selection of m channels for the n- This cell after the selection m channels for all nl cells is similar to this and from here the required distribution is given by, ii) Probability distribution of the localization of the microcellular system: For simplicity, macrocells are represented by hexagons and microcells by circles. The probabilities of a microcellular system to be superimposed with one, two or three macrocells correspond to the fractional areas shown in figure 11. Let the radii of the macrocell and the microcell R and aR be. If the center of a microcell is in the internal hex with radius (1-b) R, it is enclosed within the individual macrocell. A microcell with its center placed inside ABCDEF will be superimposed with three macrocells. The remaining area corresponds to microcells that overlap with two mutually adjacent macrocells. Thus, when considering the relative areas, it can be demonstrated that, ft - 3 -2a) Pi (6- (4 3 + p) a) a + 8 U [a - 0.5] A 3 3 P3 = 2 (2 l + p) a2 - 8 U [a-0.5]? where 0 < a < 0.7 is the ratio of microcell radii to macrocell, U [aJ is a stage function (1 unitary and A = ^ 1 a2 cos- 'Q -Q.5"• Note that P1> P2> PJ - 2a, It is noted that, in relation to this date, the best method known to the applicant to carry out the aforementioned invention is that which is clear from the present description of the invention. The invention having been described as above, property is claimed what is contained in the following

Claims (12)

Claims 1. A method for providing dynamic channel allocation (DCA) for at least a portion of a macrocellular system superimposed to facilitate the coexistence of at least one autonomous microcellular underlying system, characterized in that it comprises the steps of: excluding a predetermined number of channels of one or more macrocells of the superimposed system which overlap one or more cells of the underlying system, where Ei is the set of channels to be excluded from a macrocell i of the overlay system, assigning the predetermined number excluded from channels for use by the underlying system or allow those channels to be explored and taken by an independent underlying system and wherein the predetermined number of channels to be excluded from one or more cells of the overlay system is selected in such a way as to comply deterministically with only one of a group of requirements that include: (i) satisfaction both equations 1 (EQUATION 1) and 2 (EQUATION 2), (ii) violate EQUATION 1 and satisfy the EQUATION 2; and (iii) satisfy EQUATION 1 and violate EQUATION 2, where
1. EQUATION 1 \ f] Ei \ = Nm ¡.I 'where Nmin is the minimum number of channels available for the underlying system, where P is the set of cells that causes interference to the underlying system and where E_ is set size of exclusion in the macro cell iy
2. EQUATION 2 f] Ei = f where ? is the null set and where O is a set of macrocells belonging to a cluster or universal group, the universal group is the minimum set of macrocells in a group without any common exclusion channel. 2. The method according to claim 1, characterized in that the location of at least a part of the underlying system is selected from a group of locations that include (i) only within a cell of the macrocellular system, (ii) such so that it is superimposed on two mutually adjacent macrocells of the superposition system, and (iii) in such a way that it overlaps into three mutually adjacent macrocells of the superposition system and where | O | is greater than 3. The method according to claim 1, characterized in that it also comprises the step of selecting the size of the universal group, OR to be selected from a group of sizes, in which are included (i) that has an O as small as possible, (2) having 2 < O < 7 and (iii) that has an O as large as possible. 4. The method of compliance with the claim 1, characterized in that the size of the macrocell exclusion set, \ E_ \ is as small as possible. 5. The method according to claim 1, characterized in that the common exclusion set per group C, O-EZ? for all | C | < | O |, is as small as it is possible . 6. An apparatus for use in at least part of a macrocellular system superimposed to provide Dynamic Anal Allocation (DCA) to allow the coexistence of at least one autonomous underlying microcellular system, characterized in that it comprises: means for excluding a predetermined number of channels of one or more macrocells of the overlay system which overlap one or more cells of the underlying system, where E_ is the set of channels to be excluded from a macrocell i of the overlay system, means to allocate the excluded channels to be assigned by the underlying system or allow those channels to be explored and taken or captured by an independent underlying system, and wherein the predetermined number of channels to be excluded from each of the one or more macrocells is selected in such a way as to comply in a deterministic way with only one of a group of requirements that include: (i) satisfaction er both equations 1 (EQUATION 1) and 2 (EQUATION 2), (ii) violate EQUATION 1 and satisfy the EQUATION 2; and (iii) satisfy EQUATION 1 and violate EQUATION 2, where
3. EQUATION 1 l f | E / | > Nm? N where Nm? N is the minimum number of channels available for the underlying system, where P is the set of cells that causes interference to the underlying system and where E_ is the set of channels to be excluded from a macrocell and of the superimposed system and EQUATION 2) E / = fi < _OR where f is the null set and where O is a set of macrocells belonging to the universal group, the universal group is the minimum set of macrocells in a group without any common exclusion channel. 7. The method according to claim 1 and the apparatus according to claim 6, characterized in that the EQUATION 1 is violated and the EQUATION 2 is satisfied and the exclusion stage used an FCA exclusion technique (channel assignment). fixed) inverse. The method according to claim 1 and the apparatus according to claim 6, characterized in that EQUATION 1 is satisfied and the EQUATION 2 is violated and the exclusion stage uses a common exclusion technique. 9. A centralized access controller apparatus for providing Dynamic Channel Allocation (DCA) for macrocells of at least a portion of a superimposed system to facilitate the coexistence of at least one autonomous underlying system, the centralized access controller apparatus is characterized because it comprises: (A) means for receiving a request from a predetermined number of communication channels of an autonomous underlying system having one or more cells of the underlying system, which overlap one or more macro cells of the overlapping system, (B) means, responsive to the received request, to exclude a predetermined number of channels from use by the one or more macrocells of the overlapping system, the excluded channels are selected in such a way that they meet in a deterministic manner with only one of a group of requirements in the which include: (i) satisfying both equations 1 (EQUATION 1) and 2
4. (EQUATION 2), (ii) violate EQUATION 1 and satisfy the EQUATION 2; and (iii) satisfy EQUATION 1 and violate EQUATION 2, where
5. EQUATION 1 \ f] Ei \ = Nmin where Nmin is the minimum number of channels available for the underlying system, where P is the set of cells that can cause interference to the underlying system and where Ei is the size of the exclusion set in macro-cell i of the overlay system and
6. EQUATION 2 | E / = f iO where f is the null set and where O is a set of macrocells belonging to the universal group, the universal group is the minimum set of macrocells in group without any common exclusion channel, (C) signaling a station basis for each macrocell for the one or more macrocells of the overlay system, to exclude the predetermined number of channels of use for each macrocell, (D) means for sending an allocation signal to the underlying requesting system, which identifies the predetermined number of channels that are going to be used for communications. 10. A base station apparatus for providing Dynamic Channel Allocation (DCA) for a macrocell of at least a portion of an overlay system, to facilitate the coexistence of at least one underlying system, characterized in that it comprises: (A) means for receiving a broadcast request for a predetermined number of communication channels of an embedded embedded autonomous system having one or more cells of the underlying system which overlap one or more macro cells of the overlapping system, (B) means for determining, in conjunction with other base stations of the one or more cells of the underlying system, which predetermined number of channels should be excluded from use by the one or more macrocells of the overlapping system, the excluded channels are selected in such a way that they comply deterministically with only one of a group of requirements that includes: (i) satisfying both equations 1 (EQUATION 1) and 2 (ECU ATION 2), (ii) violate EQUATION 1 and satisfy the EQUATION 2; and (iii) satisfy EQUATION 1 and violate the
7. EQUATION 2, where
8. EQUATION 1 \ \ Ei \ = Nm II 'where Nm? N is the minimum number of channels available for the underlying system, where P is the set of cells that cause interference to the underlying system and where E_ is the size of the set of exclusion in the macro cell iy
9. EQUATION 2 f where f is the null set and where O is a set of macrocells belonging to the universal group, the universal group consists of the minimum set of macrocells in a group without any common exclusion channel, and (D) s to send a signal of assignment to the underlying requesting system, which identifies the excluded channels that are going to be used for communications by the underlying system. 11. An apparatus of an overlay system having at least part of it that includes a plurality of cells, to provide a predefined exclusion of communication channels, to facilitate the coexistence of at least one autonomous subjacent system, characterized in that it comprises: (A) in a base station of each one of one or more macrocells of the superposed system which overlap one or more cells of an overlay system, s to exclude a predetermined number of communication channels of the one or more macrocells of the system superimposed, the excluded channels to be used by the underlying system, where the excluded channels are selected in a deterministic manner in such a way that they meet only one of a group of requirements that include: (i) satisfying both equations 1 ( EQUATION 1) and 2 (EQUATION 2), (ii) violate EQUATION 1 and satisfy the EQUATION 2; and (iii) satisfy EQUATION 1 and violate EQUATION 2, where
10. EQUATION 1 \ f] Ei \ = Nmin? .l 'where Nmin is the minimum number of channels available for the underlying system, where P is the set of cells that cause interference to the underlying system and where Ei is the size of the exclusion set in the macro cell iy
11. EQUATION 2 | E / = f i.a where f is the null set and where O is a set of macrocells belonging to the universal group, the universal group consists of the minimum set of macrocells in a group without any common exclusion channel, and (B) in a base station of the underlying system , s to explore the communication channels, to determine the channels excluded from use by the underlying system.
12. 12. The method of compliance with the claim 1 and the apparatus according to claims 6, 9, 10, and 11, characterized in that EQUATION 1 and EQUATION 2 are satisfied and wherein the exclusion technique of a group of techniques including at least one exclusion is selected. of 2-Min, a 3-Min exclusion, a 6-Min exclusion and an exclusion technique based on the Finite Projection Plan (FPP).