CN101801049A - Switching optimization method between macro cell and family base station cell - Google Patents

Abstract

The embodiment of the present invention relates to a handover optimization method between a Home eNodeB (Home Evolved Node B) and an eNodeB (Evolved Node B) in a next generation mobile communication system (LTE/LTE-Advanced). The method includes that the eNodeB and the HomeeNodeB obtain speed information and service status information (real-time service or non-real-time service) of a wireless transmitting/receiving unit (WTRU), and when the measurement result is lower than a threshold value, for the user belonging to the home base station, The handover decision is made by comprehensively considering the load conditions of the macro cell and the home base station cell in LTE/LTE-Advanced, the speed of wireless transmission/reception/unit, and the type of user service. The example of the present invention can optimize the handover of the terminal between the macro cell and the home base station cell in LTE/LTE-Advanced, improve the handover success rate, and reduce unnecessary handover.

Description

A handover optimization method between a macro cell and a home base station cell

technical field

The present invention relates to the technical field of mobile communication, more particularly, the present invention is used in the communication between eNodeB (evolved Node B) and Home eNodeB (Home Evolved Node B) in the next generation mobile communication system (LTE/LTE-Advanced) A handover optimization method.

Background technique

With the widespread commercialization of the third generation mobile communication system and the release of the LTE (Long Term Evolution) standard, the standard formulation of the fourth generation mobile communication system has also reached a critical stage. As the mainstream technology in the fourth generation mobile communication, 3GPP leads the formulation LTE-Advanced technology has high expectations. LTE-Advanced is the evolution of LTE. Its official name is Further Advancements for E-UTRA. It is one of the two mainstream technical solutions collected by ITU-R's IMT-Advanced.

In LTE-Advanced, new frequency bands and large bandwidth applications are effectively supported, the peak rate is greatly increased, the spectral efficiency is also improved, the bandwidth is wider, and the rate is faster. At the same time, better network coverage has become one of the important requirements. According to Relevant statistics at home and abroad show that 70% of voice services and 90% of data services in the 3G era take place indoors. Sufficient indoor coverage can not only provide users with more convenient services, but also save operators’ fixed capital investment costs and improve Operator's revenue. In order to achieve better indoor network coverage and network capacity expansion, LTE-Advanced introduced the Home eNodeB (Home Evolved Node B, also known as Femtocell, home base station, HeNB), compared to the evolved Node B in LTE/LTE-Advanced (eNodeB), home base stations are small in size, low in transmission power, plug and play, convenient for users to install and maintain, and save operators' operating costs, and are likely to be deployed on a large scale in the near future. At present, many multinational companies and major domestic operators and equipment manufacturers have given great attention to femtocells.

With the large-scale deployment of femtocells, terminal mobility management has become a thorny issue, especially when the terminal moves from the source macro cell of LTE/LTE-Advanced to the femtocell, a handover will be necessary Problems, such as high-speed users may not need to switch, due to the limited coverage of home base stations, switching high-speed users will result in two unnecessary handovers, unnecessary switching strategies between real-time users and non-real-time users under medium speed conditions It may lead to a series of problems such as handover failure, unnecessary handover, and call drop rate. Low-speed users may want to handover to the home base station cell as soon as possible and stay as long as possible; in addition, the power of the home base station is small. However, the evolved Node B in LTE/LTE-Advanced has relatively large power, and the capacity of the two is also quite different. If the difference in capacity and power between the two is not considered during the handover process, it may cause ping-pong handover, etc., affecting users. However, in the current handover between the macro cell and the home base station cell, there is no handover method that can deal with different user speeds and business status information and take into account the capacity and power differences between the two.

Contents of the invention

The present invention aims to solve the problem of handover between LTE/LTE-Advanced macro cell and home base station cell that cannot be well solved in the existing mobile communication handover technology, and proposes a method based on the current load of the cell, user speed and business status information. switching method.

In order to achieve the above object and solve corresponding technical problems, the present invention is achieved through the following technical solutions:

Step 1: The source eNodeB controls the WTRU (Wireless Transmitting/Receiving Unit) to send the load information, speed information and service status information of the terminal to the source eNodeB in an event-triggered, periodic-triggered or periodic-time-triggered manner.

Step 2: When the source eNodeB receives the reference signal reception strength or reference signal reception quality sent by the WTRU to meet the handover condition, when the source eNodeB makes a decision to handover to the HNB cell, the source eNodeB sends a handover request Send to the femtocell gateway system (or other femtocell handover judgment system), and at the same time send the WTRU speed and service status information to the femtocell gateway system (or other femtocell handover judgment system), and enter the next step.

Step 3: Determine whether the home base station allows the user to access. If the home base station adopts the CSG (closed subscriber group) mode, the home base station gateway system first determines whether the WTRU belongs to the closed subscriber group or whether the home base station adopts an open access mode. In the access mode, the WTRU belongs to the closed subscriber group or the home base station adopts the open access mode, then proceed to the next step.

Step 4: Determine whether to perform handover according to the load conditions of the current LTE/LTE-Advanced source macro cell and the HNB cell, the speed status of the WTRU, and the service information status. If the handover condition is met, the WTRU is handed over from the source macro cell to the target base station cell, and if it is not met, the handover is not performed. During the handover decision process, the load conditions of the source macro cell and target HNB cell involved in the handover are considered comprehensively, and it is realized by processing the handover measurement information. The load status of the LTE/LTE-Advanced source macro cell and HNB cell and the reference signal reception strength of the WTRU Or the received quality of the reference signals is combined as an input for the handover decision.

In step 4, consider the handover of the load conditions of the source macro cell and the target Femtocell. Specifically, the handover decision input is proportional to the respective reference signal strength or reference signal quality of the source macro cell and the target Femtocell, and inversely proportional to the source macro cell and the target home base station. The respective cell load factors of the base station cells are proportional to the respective maximum load capacities of the source macro cell and the target home base station cell.

Step 5: In the above technical solution, the home base station gateway makes a decision on whether to accept the handover decision according to the user identity, speed and service status information. Specifically, the WTRU speed is divided into three categories: high speed, medium speed and low speed; the WTRU service state is divided into two types: real-time service and non-real-time service. When the conditions in step 4 are met, high-speed real-time and high-speed non-real-time WTRUs do not switch, medium-speed real-time users switch, medium-speed non-real-time users do not switch, and low-speed real-time users switch between low-speed non-real-time users.

In Step 5, the WTRU speed can also be simplified into two categories: high speed and low speed. At this time, high speed users do not switch, and low speed users switch. Thereby reducing unnecessary switching, lowering the call drop rate, and realizing the optimization of switching between LTE/LTE-Advanced macro cells and home base station cells.

It can be seen from the above technical solutions that the technical solution of the present invention assists in making handover decisions based on comprehensive consideration of LTE/LTE-Advanced macro cell and home base station cell load, user speed information status, and service information status. In this way, handover optimization from the macro cell to the HNB cell is realized.

The technical solutions of the present invention will be further described below with reference to the drawings and specific embodiments.

Description of drawings

In order to explain the embodiments of the present invention and the existing technical solutions more clearly, the accompanying drawings for explaining the technical solutions of the present invention and the accompanying drawings used in the description of the prior art are briefly introduced below. Obviously, without paying Under the premise of creative work, those skilled in the art can obtain other drawings through this drawing.

FIG. 1 is a flow chart of switching based on network load, user speed and service status in Embodiment 1 of the present invention;

FIG. 2 is a flow chart of switching based on network load, user speed and service status in Embodiment 2 of the present invention;

Fig. 3 is a flow chart of switching based on network load, user speed and service status in Embodiment 3 of the present invention.

Detailed ways

In order to make the description of the advantages of the technical solution of the present invention more clear, the specific implementation of the present invention will be further elaborated below in conjunction with the accompanying drawings. Obviously, the described embodiments are only some of the embodiments of the present invention, not all of them. For example, the location where the embodiment of the present invention is deployed is moved to the MME or the home base station. According to the embodiments of the present invention, those skilled in the art can realize all other embodiments of the present invention without creative efforts, which all belong to the protection scope of the present invention.

The main idea of the present invention is to determine whether it is necessary for the user to switch from the LTE/LTE-Advanced macro cell according to the network load conditions of the current LTE/LTE-Advanced macro cell and the home base station cell, the speed status information of the user, and the service status information. Handover to the home base station cell, reducing unnecessary handover, thereby optimizing the handover from the LTE/LTE-Advanced macro cell to the home base station cell.

References below to "WTRU" pertain to, but are not limited to, pagers, mobile stations, cellular telephones, netbooks, mobile stations, fixed or mobile subscriber units, personal digital assistants (PDAs), computers, or other user equipment or terminal. The term "evolved Node B" referred to below includes but does not belong to eNodeB, base station, evolved base station, site controller, node B, access point (Access Point) or any other interface that can work in a wireless environment equipment.

Fig. 1 is the specific flow chart of embodiment one of the present invention, specifically includes:

Step 101: The eNodeB receives the report of the WTRU's measurement information and speed and service status information.

The service state information in this step can be reported by the WTRU to the eNodeB through a simple identifier, and the speed state information of the WTRU can be obtained by GPS or estimated according to Doppler frequency shift.

Step 102: Whether the signal quality or strength measured by the WTRU meets the handover threshold.

Considering that the power of the home base station is small, in order to realize the fairness of the handover, the present invention adopts the following processing method for the signal strength and signal quality measurement values reported by the WTRU:

$\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; o</span>}}}{\mathrm{<span\; class="notranslate">\; log</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; e</span>}<span\; class="notranslate">\; *</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; *</span>\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; *</span>\mathrm{<span\; class="notranslate">\; G</span>}$

The value of Mo is the value of RSRP (Reference Signal Received Power) or RSRQ (Reference Signal Received Quality) of the home base station cell or LTE/LTE-Advanced macro cell measured and reported by the WTRU, and log(e*k+n) is the value of the home base station The load factor of the cell and the LTE/LTE-Advanced source macro cell, e is a constant 2.7182818284590 (where e can be replaced by other values greater than e), n is the home base station cell or LTE/LTE-Advanced source macro cell The number of WTRUs (that is, cell load), k is an adjustment factor designed according to different cell types/scales, N is the maximum capacity of an LTE/LTE-Advanced macro cell or a home base station cell, and G is an adjustment factor.

Finally, M is used for judgment, and it is judged whether the M value of the source macro cell meets the handover threshold, and the next step is entered if it is satisfied.

Step 103: Whether the HNB is in the open mode or the WTRU belongs to the user white list of the closed mode, if yes, go to the next step.

Step 104: Whether the WTRU is a high-speed user (for example, 30 kilometers per hour) and accepting non-real-time services (such as download services), then enter the next step.

Step 105: The WTRU switches from the LTE/LTE-Advanced source macro cell to the target HNB cell.

Fig. 2 is a specific flowchart of Embodiment 2 of the present invention, specifically including:

Step 201: The eNodeB receives the report of the WTRU's measurement information and speed and service status information.

The service state information in this step can be reported by the WTRU to the eNodeB through a simple identifier, and the speed state information of the WTRU can be obtained by GPS or estimated according to Doppler frequency shift.

Step 202: Whether the signal quality or strength measured by the WTRU meets the handover threshold.

Considering that the power of the home base station is small, in order to realize the fairness of the handover, the present invention adopts the following processing method for the signal strength and signal quality measurement values reported by the WTRU:

$\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; o</span>}}}{\mathrm{<span\; class="notranslate">\; log</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; e</span>}<span\; class="notranslate">\; *</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; *</span>\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; *</span>\mathrm{<span\; class="notranslate">\; G</span>}$

The value of Mo is the value of RSRP (Reference Signal Received Power) or RSRQ (Reference Signal Received Quality) of the home base station cell or LTE/LTE-Advanced macro cell measured and reported by the WTRU, and log(e*k+n) is the value of the home base station The load factor of the cell and the LTE/LTE-Advanced source macro cell, e is a constant 2.7182818284590 (where e can be replaced by other values greater than e), n is the home base station cell or LTE/LTE-Advanced source macro cell The number of WTRUs (that is, cell load), k is an adjustment factor designed according to different cell types/scales, N is the maximum capacity of an LTE/LTE-Advanced macro cell or a home base station cell, and G is an adjustment factor.

Finally, M is used for judgment, and it is judged whether the M value of the source macro cell meets the handover threshold, and the next step is entered if it is satisfied.

Step 203: Whether the HNB is in the open mode or the WTRU belongs to the user white list of the closed mode, if yes, go to the next step.

Step 204: Whether the WTRU is a high-speed user (for example, 30 kilometers per hour, the threshold is adjustable), then go to the next step.

Step 205: The WTRU switches from the LTE/LTE-Advanced source macro cell to the target HNB cell.

Fig. 3 is a specific flowchart of Embodiment 3 of the present invention, specifically including:

Step 301: The eNodeB receives the report of the WTRU's measurement information and speed and service status information.

The service state information in this step can be reported by the WTRU to the eNodeB through a simple identifier, and the speed state information of the WTRU can be obtained by GPS or estimated according to Doppler frequency shift.

Step 302: Whether the signal quality or strength measured by the WTRU meets the handover threshold.

Considering that the power of the home base station is small, in order to realize the fairness of the handover, the present invention adopts the following processing method for the signal strength and signal quality measurement values reported by the WTRU:

$\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; o</span>}}}{\mathrm{<span\; class="notranslate">\; log</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; e</span>}<span\; class="notranslate">\; *</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; *</span>\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; *</span>\mathrm{<span\; class="notranslate">\; G</span>}$

The value of Mo is the value of RSRP (Reference Signal Received Power) or RSRQ (Reference Signal Received Quality) of the home base station cell or LTE/LTE-Advanced macro cell measured and reported by the WTRU, and log(e*k+n) is the value of the home base station The load factor of the cell and the LTE/LTE-Advanced source macro cell, e is a constant 2.7182818284590 (where e can be replaced by other values greater than e), n is the home base station cell or LTE/LTE-Advanced source macro cell The number of WTRUs (that is, cell load), k is an adjustment factor designed according to different cell types/scales, N is the maximum capacity of an LTE/LTE-Advanced macro cell or a home base station cell, and G is an adjustment factor.

Finally, M is used for judgment, and it is judged whether the M value of the source macro cell meets the handover threshold, and the next step is entered if it is satisfied.

Step 303: Whether the HNB is in the open mode or the WTRU belongs to the user white list of the closed mode, if yes, proceed to the next step.

Step 304: Whether the WTRU is a high-speed user (such as 30 kilometers per hour, the threshold is adjustable) or a medium-speed user (such as 15 kilometers per hour to 30 kilometers per hour, the threshold is adjustable) non-real-time user, then Go to the next step.

Step 305: The WTRU switches from the LTE/LTE-Advanced source macro cell to the target HNB cell.

The above is a specific description of the core idea of the embodiment of the present invention without limitation. In the specific implementation process, appropriate improvements can be made to the method of the present invention to meet the needs of specific situations. Those of ordinary skill in the art can refer to the embodiment of the present invention Through simple replacement and modification, it does not depart from the scope of the technical solution of the present invention.

Claims (10)

1. A handover processing method, characterized in that it comprises the following steps: Step 1: The WTRU reports the speed information and service status information of the WTRU to the source eNodeB. Step 2: The source eNB judges whether the handover decision input obtained from the received signal strength or signal quality of the LTE/LTE-Advanced source macro cell and the home base station cell and the load factors of the respective cells satisfies the handover condition, and if the handover condition is met, proceed Next step. Step 3: Whether the home base station allows the WTRU to access, and if the WTRU is allowed to access, go to the next step. Step 4: Determine whether the speed status and service information status of the WTRU are suitable for handover, if so, switch, and enter the next step. Step 5: The WTRU switches from the source macro cell to the target femto cell. 2. The handover processing method according to claim 1, characterized in that: In the step 1, the WTRU reports to the source eNB that the speed information and the service status information of the WTRU are included in the message. 3. The handover processing method according to claim 1, characterized in that: In the step 2, the load conditions of the LTE/LTE-Advanced source macro cell and the home base station cell and the WTRU's reference signal reception strength or reference signal reception quality are combined as a handover decision input, and the source eNodeB judges that it does not meet the handover condition , then return to step 1; if the switching condition is met, go to step 3. 4. The handover processing method according to claim 3, characterized in that: The method of combining the load conditions of the LTE/LTE-Advanced source macro cell and the HNB cell with the received reference signal strength or received reference signal quality of the WTRU as the handover decision input method is specifically as follows: The handover decision input is proportional to the respective reference signal strength and reference signal quality of the source macro cell and the target Femtocell, inversely proportional to the respective cell load factors of the source macro cell and the target Femtocell, and proportional to the respective maximum load capacity. 5. The handover processing method according to claim 4, characterized in that: The respective cell load factors of the LTE/LTE-Advanced source macro cell and the target home base station cell are specifically: the respective cell loads of the LTE/LTE-Advanced source macro cell and the target home base station cell (the number of WTRUs residing in the current cell) or the LTE/LTE An expression of the respective cell loads (number of WTRUs residing in the current cell) of the LTE-Advanced source macro cell and the target HNB cell. 6. The handover processing method according to claim 1, characterized in that: In the step 3, the specific method of whether the home base station allows the WTRU to access is that the WTRU is in the white list of the home base station, or the home base station adopts the open mode, then return to step 1. 7. The handover processing method according to claim 1, characterized in that: The step 4 is specifically, the principle of determining whether the speed state and service state of the WTRU is suitable for handover is that the high-speed WTRU does not handover, the medium-speed non-real-time WTRU does not handover, the medium-speed real-time WTRU handovers, and the low-speed WTRU handover. 8. The handover processing method according to claim 7, characterized in that: The principle for judging whether the speed state and service state of the WTRU are suitable for handover can be simplified as follows: high-speed WTRUs do not handover, low-speed WTRUs handover, regardless of WTRU service information. 9. The handover processing method according to claim 7, characterized in that: The defined value range of high-speed WTRU is above 30 km/h, the defined value range of medium-speed WTRU is between 15 km/h and 30 km/h, and the speed value range of low-speed WTRU is between 0 and 15 km/h meters per hour. 10. The handover processing method according to claim 8, characterized in that: The determination threshold of a high-speed WTRU and a low-speed WTRU ranges from 15 km/h to 30 km/h, a low-speed WTRU is lower than this threshold, and a high-speed WTRU is higher than this threshold.

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