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1、小区分层结构(精阅)（Residential hierarchical structure (read carefully)）Hierarchical structure of a cellHierarchical structure of a celldownloadI. IntroductionMany large business solutions employ small cell structures to obtain sufficient capacity. Small antennas with low antennas are often subject to covera
2、ge, so there must be a large number of cells for better coverage. CELL. There is a way to reduce the cell number of small CELL provides the main service area coverage, and coverage of CELL small CELL signal strength is not enough, in order to achieve this goal, the need for a distribution service be
3、tween large and small CELL CELL logic. The hierarchical structure (HCS) of the cell provides this logic. This function is implemented in BSC.Two, backgroundThe first GSM positioning operation is based on the best service, which means that under normal circumstances the mobile station selection area
4、is MS the current location on the transmission power of the highest area, so if you want to achieve small CELL for business and CELL absorption to cover the idea, must be in the same area having different size the cells are mixed together, it will not be easy. Despite the large signal received from
5、the neighboring large CELL, if the place is less disturbed, the small CELL is also of sufficient quality. Suppose a mobile station is locked in a small CELL and moves to a large CELL, and when the big CELL gets better, the mobile station will switch to the big CELL even if the small CELL can provide
6、 acceptable quality.Another additional reason for adopting tier cell is capacity redundancy backup. If the maximum amount of traffic in a network is designed to be calculated only with a small CELL, then a high-rise cell will be used to share part of the business during peak traffic. The cell hierar
7、chical structure allows a network to have two or three cell structures, which are used for large CELL, and a lower cell for small CELL.The hierarchical cell function is a complete part of the localization operation.Three, how to achieve this function?The cell layering function provides the possibili
8、ty of distinguishing the cell level in the network and can be divided into two or three layers. The upper layer is used for large CELL, while the lower layer is used for small CELL. For example, when in a small (normal) to provide coverage gap coverage to add a large CELL CELL network, the size of t
9、his area will become a umbrella CELL. Another example is when a micro CELL is added to a normal CELL network to address business hotspots, then for micro CELL, normal CELL is like a umbrella CELL. This HCS coverage area network function of large and cells. The small in regulation and district planni
10、ng are of great help, at the same time, although the service is not always the best residential area, but also to ensure the quality of the network.The layer structure can also be viewed without a priority level. The lower level is higher than the higher priority. This means that the HCS function is
11、 not only an application mentioned above, but also has other uses. It can also be used to divide cells into several priority classes regardless of their size. For example, in a dual band system used in 1800 MHz and 900 MHz cells, the single band 900 MHz mobile station cannot access the 1800 MHz cell
12、. Therefore, the dual frequency mobile station should select the 1800 MHz cell as much as possible to prevent unnecessary congestion on the 900 MHz frequency band. For this reason, the 1800 MHz cell has a high priority level. Here, micro cells (priority level 1 cells) is called layer 1 cell; normal
13、cells (priority level 2 cells) is called layer 2 cell; umbrella cells (priority level 3 cells) is called layer 3 cell.The HCS function is the same as in the localization algorithm of localization algorithm to consider, know the district belongs to one layer, when the switch when the first cell line
14、will put this information into the calculation, which is described in detail in the cell line.In the use of HCS function, usually the allocation of mobile stations locked in the lower level of the district. Then, the high-level (layer 2 and 3) cell will be used in the following situations:1, coverin
15、g the gap in the wireless network, if the signal strength is lower than a threshold value, will be switched to the high-rise district.2. Provide spare capacity. When the low level area congestion, if assigned to the inferior cell function allows, even if the higher quality of the district than the s
16、ervice district is poor, will also choose high-rise district.3,Providing service when the wireless link is disturbed. When the quality of emergency switch can switch to the high-rise residential.Four, brief technical introduction1, general provisionsThere is a signal strength threshold in the cells
17、in layer 1 and 2. It is used to decide to switch to / to a high level cell. When the signal strength of a lower level cell (layer 1 or 2) is lower than this threshold, there is no suitable cell in the same layer or lower layer, and a handover to the high-level cell will be performed.Only when the lo
18、wer cell generates a signal strength higher than the corresponding threshold value can the normal handover of the lower cell be cut back.2, operationIn the cells 1 and 2, there is a signal strength threshold LEVTHR and a hysteresis value LEVHYST. It is used to convert between three layers of cells.
19、The threshold value LEVTHR and the hysteresis value LEVHYST are used for switching between the cell layers. The actual switching threshold is:LEVTHRs - LEVHYSTs (switch to service cell)LEVTHRs + LEVHYSTs (switching to adjacent cells)The following example illustrates switching between cells in differ
20、ent layers:An upward example:The service area is the 1 layer cell, if the signal intensity of the service area is reduced to LEVTHRs - LEVHYST, localization will be the candidate object with switchable high-rise residential high-rise residential, but even in the base station line than the low layer
21、area before, but the priority signal intensity on LEVTHRn + LEVHYSTn layer 1 adjacent residential high-rise residential is still high. If the service area is a layer of 2 cells, its regularity is the same as above. Note that signal strength is included in the penalty value.An example of a downward l
22、ayer:If the service area is 3 quarters, when in the signal intensity of layer 1 and 2 adjacent cells increased to LEVTHRn + LEVHYSTn value above the adjacent cell will be used as the candidate base station, then, even in the base station in the adjacent area than the current cell line row, lower pri
23、ority priority layer cell is still present the high layer cell.After the base station queues in the positioning operation, the cells are divided into three groups, each of which is a group. This condition is still applied to all cell groups, even though there is only one service cell in a group. Bet
24、ter layer 1 is called 1b; the poor layer 1 is called 1 W and so on. Figure 2 illustrates this rule in detail. Service area here is a layer of 2 district.The adjacent cells of each group are further subdivided on or above the threshold according to the signal strength, and the purpose is to define th
25、e priority of each group. This priority must be avoided by Ping Pong effects between the layers.Table 1 lists all possible categories. Thus, the final candidate base station table is formed, consisting of a selection of different groups. For example: 1bo, 2BO, 3BO and so on. Choose which group and d
26、etermine the following, depending on the following circumstances:1) what level of community does the service area belong to?.2)The service cell companion strength in the above or below LEVTHRs - LEVHYSTs.3) do you have a pointer to arrive at the allow or not?.4) emergency (inferior or TA too large).
27、5) do you need cell switching?.6) does the subcell cell transform need to be used?.In an emergency switch, or when it is allowed to be referred to the inferior cell and a pointing request arrives, all cells in the base station queuing table are always included in the candidate base station table. Th
28、e establishment of the queue table of the base station and the organization of the candidate base station table are executed in the positioning operation.Description CategoryBetter layer 1, cells, above, their, own, threshold, 1boBetter layer 1, cells, below, their, own, threshold, 1buWorse layer 1,
29、 cells, above, their, own, threshold, 1woWorse layer 1, cells, below, their, own, threshold, 1wuBetter layer 2, cells, above, their, own, threshold, 2BOBetter layer 2, cells, below, their, own, threshold, 2buWorse layer 2, cells, above, their, own, threshold, 2WOWorse layer 2, cells, below, their, o
30、wn, threshold, 2wuBetter layer 3 cells 3BWorse layer 3 cells 3WServing cell s3, the management of the fast-moving mobile stationThere is a method for preventing fast movement of MS from handover to lower cell, which adopts a penalty value of signal strength. The parameter PSSTEMP is a OFFSET value t
31、hat penalizes the signal strength, and the parameter PTIMTEMP is the penalty time value. The cell will be in a penalty state within the time specified in the system start parameter PTIMTEMP from the result of measurement information in an adjacent cell. This is only valid if the adjacent cell is low
32、er than the cell level of the current service cell. Therefore, only 1 and 2 of the district can be punished.The cell in the temporary penalty table will be penalized. This table can contain all the cells at the same time. That is, up to 64 adjacent cells. On the ultra TA value switch and the quality
33、 difference emergency switch, this table will be appended to the cells normal penalty table after the handover failure.A cell can be included in both of the two tables. In this case, two kinds of punishments are executed simultaneously.4, different from CME20 R5No,5, additional functions in CME20 R6
34、No,Five. Engineering Guide1 、 apply microcells in HCS function(1) description of the layer (Level)If the HCS function is added to the microcells in the network, the macrocells is defined as layer 2 cell (LEVEL = 2), and the microcells is defined as layer 1 cell (LEVEL = 1).(2) adjustment of the micr
35、ocells service areaBecause the microcells antenna is low and the output power is small, its coverage is usually relatively small. The limited coverage area of Microcellr is one reason for the increase in system capacity, which can be overcome by increasing the number of microcell in the network. Set
36、 a microcell for two reasons, one is the solution of a business focus, one is a large area of less traffic in the network, set it to microcell cell, the volume of business it around the macrocell district to attract part of. Therefore, the use of macrocells can attract large enough traffic, which is
37、 very important for network regulation.If you do not consider the HCS function, and that is the use of K algorithm in localization algorithm (signal intensity, then the service queue) area of the macrocell cell is limited to macrocell cell signal strength than the surrounding area a large area, for
38、a close around the district planning network or a similar macrocell dominant area this area is too small. The HCS function provides a way to expand the coverage area of microcell cells in areas where macrocell cell coverage is predominant. If you want to use a microcell cell to attract the load arou
39、nd the macrocell cell, the value of the parameter LEVTHR should be set as low as possible, but to meet the requirements of the C/I and C/A levels on the microcell cell boundary. Since the HCS function does not follow the best service principle, you should pay special attention to the interference of
40、 C/I and C/A. If the microcell cell is protected and the interference level is low. The value of the parameter LEVTHR can be set to a lower value. If the interference level is higher, the parameter LEVTHR should not be too low and should be increased.(3) dedicated frequency band for level 1 cellFrom
41、 a full cell planning point of view, the HCS operation would be better if the microcells cell had a dedicated sub-band instead of the band borrowed from the macro network. If the microcell cell has its own dedicated frequency band, then the value of the parameter can be set lower and can be as low a
42、s -95 dBm. If the frequency reuse of microcell cell is close, the value of parameter LEVTHR should be higher, which is due to the same frequency interference between microcell cells.(4) the layers 1 and 2 share one frequency bandWhen the frequency is borrowed from the macrocell cell layer, the setti
43、ngs for the parameter LEVTHR are the same as those assigned in the microcell, depending on the macrocell cell around it. Generally speaking, it is very difficult to select low frequency interference for a microcell cell in an environment with a smaller macrocell and a more compact frequency reuse en
44、vironment. In addition, business density is very high in a tightly planned high-capacity network, and the microcell cell does not need much to get enough traffic. There are several different schemes for configuring frequencies for microcell cells. One scheme is to assign one or two good frequencies,
45、 that is, frequencies at lower levels of interference in the area of the microcell service. Another scheme is to allocate each frequency other than the very bad frequency, and use synthetic frequency hopping to perform frequency hopping at more frequencies.As macrocell cell frequency reuse, paramete
46、rs of LEVTHR should be under a typical signal intensity (0 10 dB (close multiplexing) multiplexing less closely), the signal strength, signal strength in the boundary region between the macrocell area. In any case, the parameter values do not take into account the environment of the macrocell cell,
47、and its value must not be less than -95 dBm.Different LEVTHR corresponding to different distance between stations are given in Table 2 and macrocell around the value of the network settings, as well as corresponding to its relationship with the two different types of frequency reuse, reuse and reuse
48、 is not close close type type. The compact macrocell cell frequency reuse model defined here is the macrocell cell layer whose frequency is a multiplexing type of about 9 (for example, a 3/9 multiplexing type) or a lower type.The non compact macrocell cell frequency reuse model defined here is the macrocell cell layer whose frequency is a multiplexing type of about 12 (such as a 4/12 multiplexing type) or a higher type.If the quality of voice and connection is satisfactory, then the microcell cell needs to increase traffic, when the value of the parameter can be lowered,