KR101393141B1 - Method to multi rat choosing access and simultaneous access and load balancing in heterogeneous cellular network - Google Patents

Method to multi rat choosing access and simultaneous access and load balancing in heterogeneous cellular network Download PDF

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KR101393141B1
KR101393141B1 KR1020130038481A KR20130038481A KR101393141B1 KR 101393141 B1 KR101393141 B1 KR 101393141B1 KR 1020130038481 A KR1020130038481 A KR 1020130038481A KR 20130038481 A KR20130038481 A KR 20130038481A KR 101393141 B1 KR101393141 B1 KR 101393141B1
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access point
user
access
user terminal
primary
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KR1020130038481A
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Korean (ko)
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최완
채승호
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한국과학기술원
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W28/00—Network traffic management; Network resource management
    • H04W28/02—Traffic management, e.g. flow control or congestion control
    • H04W28/08—Load balancing or load distribution
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W40/00—Communication routing or communication path finding
    • H04W40/02—Communication route or path selection, e.g. power-based or shortest path routing
    • H04W40/12—Communication route or path selection, e.g. power-based or shortest path routing based on transmission quality or channel quality
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W48/00—Access restriction; Network selection; Access point selection
    • H04W48/20—Selecting an access point
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W88/00—Devices specially adapted for wireless communication networks, e.g. terminals, base stations or access point devices
    • H04W88/02—Terminal devices
    • H04W88/06—Terminal devices adapted for operation in multiple networks or having at least two operational modes, e.g. multi-mode terminals

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  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Computer Security & Cryptography (AREA)
  • Mobile Radio Communication Systems (AREA)

Abstract

A method, user equipment, and a system for multi-radio access in heterogeneous cellular networks are disclosed. According to one embodiment, the method comprises applying a weight by radio access technology (RAT) to reception power of a received signal, determining a main access point (AP) to be accessed according to a level of the reception power which is applied with the weight, determining whether user equipment is a cell boundary user with respect to the main access point, and accessing to the main access point and at least one additional access point using a RAT different from that of the main access point.

Description

[0001] METHOD FOR MULTI RAT CHOOSING ACCESS AND SIMULTANEOUS ACCESS AND LOAD BALANCING IN HETEROGENEOUS CELLULAR NETWORK [0002]

Disclosed is a technique for providing multiple radio access technology (RAT) in a heterogeneous cellular network.

In recent years, with the development of various devices such as smart phones, paradigm shifts gradually from voice-centric communication to traffic / data-centric communication. Correspondingly, as Wi-Fi access points (APs) are installed to meet data demands, the heterogeneity of networks is increasing. In addition, various radio access technologies (RAT, such as LTE, Wi-Fi, 802.11 (a), 802.11 (g), etc.) have been developed and mixed in the network. Therefore, recently, many industrial organizations and academies are interested in research on a multi-radio access technology of a heterogeneous cellular network.

Most of the previous researches focused on how users select and connect to one wireless access technology, and seamless handover between heterogeneous wireless access technologies depending on user mobility. There are various advantages such as increasing the data rate that a user can acquire by using the wireless access technology at the same time or increasing the number of services that can be received at a time, compared to a method of selectively connecting one wireless access technology.

However, in recent years, there has been a growing interest in using multiple wireless access technologies simultaneously in industrial organizations. However, up to now, research on simultaneous use of wireless access technologies is relatively early in the research. Therefore, there is a need for techniques for simultaneous use of multiple wireless access technologies that enable load balancing.

According to an exemplary embodiment, a weight may be applied to a signal received from an access point (AP) that provides radio access technology (RAT).

According to an exemplary embodiment, multiple access may be performed when a cell boundary user is determined according to a data rate.

According to an exemplary embodiment, when it is determined that the cell is a user within a cell according to a data rate, selective access is possible.

According to an embodiment, multiple access to a plurality of access points can be performed using unique numbers.

According to an exemplary embodiment, a step of applying a weight according to a radio access technology (RAT) to a reception power of a received signal, a step of determining a main access point (AP) to be connected according to a magnitude of reception power to which a weight is applied Determining whether the user terminal is a cell boundary user for the primary access point, and determining whether the user terminal is a cell boundary user, when the mobile terminal user is determined to be a cell boundary user, accessing at least one additional access point using a different radio access technology from the primary access point and the primary access point A method of wireless connection in a heterogeneous cellular network environment may be provided.

According to another embodiment of the present invention, the step of applying the weighting to the reception power of the received signal according to the radio access technology (RAT) may include a step of, in accordance with a predetermined probability, A method of wireless connection in a heterogeneous cellular network environment including applying a weight that is determined to be determined as a point.

According to another embodiment of the present invention, the step of determining whether the user terminal is a cell boundary user for a primary access point includes the steps of: if the data rate acquired from the primary access point is less than a target threshold, And determining that the cell is a cell boundary user.

According to another embodiment of the present invention, there is provided a method for wireless connection in a heterogeneous cellular network environment, further comprising the step of selectively accessing a primary access point when the user terminal is determined to be a cell inside user for the primary access point.

According to another embodiment of the present invention, the step of multi-accessing at least one access point using a wireless access technology different from that of the primary access point and the primary access point, And accessing multiple access points in a heterogeneous cellular network environment.

According to another embodiment, the multiple access to the primary access point and the secondary access point using the unique number may include transmitting multiple accesses to the primary access point and the secondary access point, A step of receiving different unique numbers, and a step of sharing and pairing the unique numbers to the primary access point and the secondary access point, in a heterogeneous cellular network environment.

According to an embodiment of the present invention, a signal receiving unit for receiving a signal broadcast at each access point, a weight applying unit for applying different weights to the reception power of the signal for each wireless access technology, a weight applying unit for assigning a primary access point to which the user terminal will connect, A cell boundary determination unit for determining whether the user terminal is a cell boundary user for the primary access point and a cell boundary determination unit for determining whether the user terminal is a cell boundary user, A plurality of access points connected to at least one additional access point using the technique of the present invention can be provided with a wireless connection in a heterogeneous cellular network environment.

According to another embodiment, the weight application unit applies a weight value determined to be determined as a primary access point according to a predetermined probability of an access point using a predetermined wireless access technology, and a user terminal wirelessly connecting in a heterogeneous cellular network environment is provided .

According to another embodiment, when the data rate obtained from the primary access point is smaller than the target threshold value, the cell boundary determination unit determines that the user terminal is a cell boundary user, and a user terminal that performs wireless connection in a heterogeneous cellular network environment is provided .

According to another embodiment, the target threshold value may be a value set such that the number of user terminals that are multiple connected to at least one access point using different radio access technologies is set to a predetermined number of users. In a heterogeneous cellular network environment, May be provided.

According to another embodiment of the present invention, when the user terminal is a cell internal user, the cell boundary determining unit may further include a selective connection unit that selectively connects to the primary access point, and if the data rate acquired from the primary access point is not smaller than the target threshold value, It is possible to provide a user terminal wirelessly connecting in a heterogeneous cellular network environment in which it is determined that the terminal is a cell internal user.

According to yet another embodiment, a multiple access unit may be provided with a user terminal wirelessly connecting in a heterogeneous cellular network environment in which multiple accesses are made to a primary access point and an additional access point using a unique number.

According to another embodiment, the multiple access unit includes a multiple access transmission unit for transmitting multiple access to the primary access point and the additional access point, a unique number receiving unit for receiving different unique numbers from the primary access point and the additional access point, And a unique number sharing unit for sharing the common access point and the additional access point by sharing the common access point and the additional access point in a heterogeneous cellular network environment.

According to an embodiment, a primary access point for broadcasting a signal with a predetermined wireless access technology, a secondary access point for broadcasting a signal using a wireless access technology different from the predetermined wireless access technology, and a reception An access point determination unit for determining a primary access point to be connected according to a size of power and a multiple access unit for performing multiple access to a primary access point and a secondary access point when the user terminal is determined as a cell boundary user for the primary access point, A wireless access system may be provided in a heterogeneous cellular network environment including a terminal.

According to another embodiment, a multiple access unit may be provided with a wireless access system in a heterogeneous cellular network environment in which multiple accesses are made to at least one additional access point to the extent that the normalized throughput is greater than a predetermined throughput.

According to an exemplary embodiment, a weight may be applied to a signal received from an access point (AP) that provides radio access technology (RAT) to perform load control.

According to one embodiment, the outgoing probability of the user terminal can be improved through multiple connections.

According to one embodiment, it is possible to improve the QoS of cell boundary users through multiple connections and to control the number of user terminals accessing each access point.

According to an exemplary embodiment, since the user only receives one parameter value for cell boundary determination from the access points serving the wireless access technology, the complexity may be low.

According to one embodiment, it is possible to guarantee the normalized QoS of the entire network user terminal through multiple connections.

According to one embodiment, the load of an access point that services each wireless access technology can be controlled through multiple accesses.

1 is a diagram illustrating a configuration in which a user terminal according to an exemplary embodiment of the present invention performs multiple connections with an access point (AP) using a radio access technology (RAT).
2 is a flow chart illustrating a method of wireless connection in a heterogeneous cellular network environment according to an embodiment.
3 is a diagram illustrating a configuration in which a user terminal according to an embodiment has multiple accesses to an access point based on a weight.
4 is a diagram illustrating a wireless access system in a heterogeneous cellular network environment in accordance with one embodiment.
5 is a diagram illustrating a user terminal wirelessly connecting in a heterogeneous cellular network environment according to an exemplary embodiment.

Hereinafter, embodiments will be described in detail with reference to the accompanying drawings.

1 illustrates a configuration in which user terminals 131 and 132 according to an embodiment perform multiple connections with access points (APs) 110 and 120 using radio access technology (RAT) FIG. Here, a first access point 110 serving a first wireless access technology and a second access point 120 serving as a second wireless access technology to an nth wireless access technology, which are different from the first wireless access technology, Points may exist respectively. In FIG. 1, a first access point 110 and a second access point 120 may be illustrated.

According to one embodiment, among the first to nth access points, the access point having the largest received power and received by the user terminals 131 and 132 is transmitted to the main access point Can be determined. Also, in addition to the primary access point, the remaining access points to which the user terminals 131 and 132 are multiplexed can be represented as additional access points.

Here, the primary access point may be an access point to which the user terminals 131 and 132 basically connect, and the secondary access point may be an access point Lt; / RTI > At this time, each of the access points 110 and 120 can arbitrarily select and service one user terminal 131 or 132.

For example, each user terminal 131, 132 connects to the nearest access point, cell edge users connect to the first access point 110 and the second access point 120 at the same time, Cell inner users can select and access one access point. Here, the cell boundary user may be a user judged to be located at a boundary of a cell served by each access point, and a cell user may be a user judged to be located inside a cell served by each access point.

Specifically, in FIG. 1A, the user terminal 132 can selectively access the second access point 120 serving as a second access technology as a primary access point. 1B, the user terminal 131 can access the first access point 110 serving as the first wireless access technology as a primary access point and the second access point 120 as an additional access point. 1C, the user terminal 131 at the cell boundary for the first access point 110 accesses the first access point 110 and the second access point 120, The user terminal 132 in the cell can selectively connect to the first access point 110. [

According to one embodiment, the wireless access technology provided by each access point can be modeled as follows. In the following, it is assumed that the system herein includes two types of access points serving two different wireless access technologies. However, the present invention is not limited to this, and may include first to nth access points that service n different radio access technologies. Here, n may be an integer of 2 or more.

First, a downlink environment of a heterogeneous cellular network in which access points that service two wireless access technologies coexist can be considered. Each wireless access technology has unique characteristics, and the characteristics of the kth wireless access technology (RAT k) can be expressed as follows. For example, the transmit power for the k < th >

Figure 112013030673760-pat00001
, The channel coding loss is
Figure 112013030673760-pat00002
, The bandwidth is
Figure 112013030673760-pat00003
, Bandwidth efficiency
Figure 112013030673760-pat00004
, The transmission loss index
Figure 112013030673760-pat00005
.

Where the access points for each wireless access technology can be modeled as a 2D homogeneous Poisson point process (PPP). According to one embodiment, access points per unit area

Figure 112013030673760-pat00006
Density, and the group of access points
Figure 112013030673760-pat00007
. Where the location of the first access point 110 serving the first wireless access technology may be independent of the location of the second access point 120 serving the second wireless access technology.

According to one embodiment, the user terminals 131 and 132 may be modeled as a 2D homogenous PPP similar to the access point described above. Here, the density of the user terminals 131 and 132 per unit area is

Figure 112013030673760-pat00008
, And the user's channel may be modeled as Rayleigh fading. Each of the user terminals 131 and 132 can select or simultaneously access an access point serving one wireless access technology according to an embodiment, and a detailed procedure will be described in detail with reference to FIG.

2 is a flow chart illustrating a method of wireless connection in a heterogeneous cellular network environment according to an embodiment.

In step 210, the user terminal may receive a signal from each access point. Specifically, each access point may broadcast a pilot sequence according to a wireless access technology to be serviced. Here, the pilot sequence may be a pilot signal, which is a promised signal between each access point and a user terminal (e.g., a signal that is known in advance). According to an exemplary embodiment, a user terminal can acquire channel information up to each access point by receiving a pilot signal broadcast at an access point. Also, since the signal size must be measured from the access points serving each wireless access technology, the pilot sequence may be different for different wireless access technologies.

Where the nearest access point serving the k < th > wireless access technology

Figure 112013030673760-pat00009
The reception SINR of a user connected to the base station (assuming that it is located at the origin) can be expressed by Equation (1).

Figure 112013030673760-pat00010

In Equation (1)

Figure 112013030673760-pat00011
Are interference sources using the same radio access technology as the user terminal
Figure 112013030673760-pat00012
Lt; / RTI > and < RTI ID =
Figure 112013030673760-pat00013
The distance to the access point serving the wireless connection technology connected with the user,
Figure 112013030673760-pat00014
Is the noise spectral density,
Figure 112013030673760-pat00015
May represent the channel gain. here
Figure 112013030673760-pat00016
Is modeled by Rayleigh fading with unit intensity (
Figure 112013030673760-pat00017
). Here, exp (1) of the Rayleigh fading model can mean an exponential distribution of intensity 1,
Figure 112013030673760-pat00018
. And
Figure 112013030673760-pat00019
The transmission power,
Figure 112013030673760-pat00020
The transmission loss index w,
Figure 112013030673760-pat00021
Can represent the bandwidth.

In step 220, the user terminal may apply a weight according to the radio access technology to the received power of the received signal through the processor. Specifically, different weights may be applied to the received power for each wireless access technology applied to the received signal. For example, the received power of a signal received with the first wireless access technology includes a first weight

Figure 112013030673760-pat00022
), And the reception power of the signal received by the second wireless access technology includes the second weight
Figure 112013030673760-pat00023
) Can be applied. According to one embodiment, the application of the weight can be performed by multiplying the received power by a weight.

According to an embodiment, the probability of determining a primary access point can be adjusted to a weight. Hereinafter, a process of applying a weight value set to be connected to a primary access point using a predetermined wireless access technology according to a predetermined probability will be described in detail with reference to FIG.

Then, in step 230, the user terminal may determine a primary access point to access according to the magnitude of the received power weighted through the processor. Herein, the user terminal can determine, as the primary access point, the closest access point of the wireless access technology having the largest received power with the weighted value of the access points.

In step 240, the user terminal may determine whether the user terminal is a cell edge user for the primary access point. Here, the user terminal may determine itself as a cell boundary user and a cell inner user according to the positional relationship in the cell served by the primary access point. At this time, the user terminal can recognize the unique characteristics of each wireless access technology in advance.

According to an exemplary embodiment, a user terminal can basically access the nearest access point while servicing the wireless access technology having the largest received power. At this time, if the data rate obtainable by the user terminal is smaller than the target threshold, the user terminal can be determined as the cell boundary user. Here, the relationship between the data rate and the target threshold value may be expressed by Equation (2).

Figure 112013030673760-pat00024

In Equation (2)

Figure 112013030673760-pat00025
Bandwidth efficiency,
Figure 112013030673760-pat00026
Bandwidth,
Figure 112013030673760-pat00027
SINR < / RTI >
Figure 112013030673760-pat00028
Is the channel coding loss rate,
Figure 112013030673760-pat00029
May represent a target threshold value used as a criterion for determining the user terminal as a cell boundary user in the i < th > wireless access technology. If the data rate is not smaller than the target threshold value, it can be regarded as a cell internal user. For example, if the user terminal is regarded as a cell boundary user, the user terminal can simultaneously access two access points serving different wireless access technologies.

Here, a throughput that can be obtained when a single access point serving a first wireless access technology is accessed can be expressed by the following equation (3).

Figure 112013030673760-pat00030

Also, the throughput when two access points serving different radio access technologies are simultaneously connected can be expressed by the following equation (4).

Figure 112013030673760-pat00031

According to an exemplary embodiment, a cell boundary user can simultaneously access two access points through multiple accesses, thereby increasing the data rate that can be obtained and increasing the probability of satisfying the user's QoS (Quality of Service). In this case, in the case of a cell internal user, QoS can be satisfied with a high probability because an appropriate reception power is ensured. In contrast, when a cell boundary user accesses one access point using only one wireless access technology, a lower data rate can be obtained as compared with a cell user. In a case where two wireless access technologies are used at the same time through multiple access according to an embodiment, the probability of satisfying the QoS can be greatly improved due to the effect of using two bandwidths at the same time.

Here, the probability that the user terminal connected to the first access point serving the first wireless access technology determines that the user terminal is the cell boundary user can be expressed by Equation (5).

Figure 112013030673760-pat00032

The probability that the user terminal connected to the second access point serving the second wireless access technology determines that the user terminal itself is the cell boundary user can be expressed by Equation (6).

Figure 112013030673760-pat00033

Then, in step 251, if the user terminal is a cell boundary user, the user terminal may have multiple access to a plurality of access points. Specifically, when the user terminal determines itself as a cell boundary user through the processor, the user terminal can simultaneously access the at least one additional access point using a different radio access technology from the main access point and the main access point.

According to an exemplary embodiment, a user terminal determined to be a cell boundary user can access multiple accesses to a primary access point and an access point using a unique number. Specifically, each user terminal using each of the multiple access technologies can transmit the selected access or multiple access to the corresponding access points. And a unique number can be given from the corresponding access points. At this time, a cell boundary user who makes multiple connections can be given a different unique number from each of the access points (for example, the primary access point and the secondary access point). The unique number may then be shared and paired with each access point.

In step 252, if the user terminal is a cell internal user, the user terminal can select and access one access point. Specifically, if the user terminal determines itself as a cell user through the processor, the user terminal can selectively access the primary access point.

3 is a diagram illustrating a configuration in which a user terminal 330 according to an embodiment has multiple accesses to an access point based on a weight. Here, it is possible to determine that the access point using the predetermined radio access technology is determined as the main access point according to a predetermined probability. Accordingly, the number of user terminals 330 can be off-loaded or load-balancing by predetermining a primary access point to which the user terminal 330 accesses.

According to one embodiment, all of the user terminals 330 may connect to the nearest access point serving the wireless access technology with the largest received power. When the user terminal 330 accesses the nearest access point serving the i < th > wireless access technology, it can be expressed as Equation (7).

Figure 112013030673760-pat00034

In the above-mentioned equation (7)

Figure 112013030673760-pat00035
Is the connection weight for the k-th wireless access technology, K is a collection of wireless access technologies (e.g., K = {1,2}),
Figure 112013030673760-pat00036
Is the distance from the user to the nearest access point among the k access points serving the k < th > wireless access technology.

Specifically, the weights in multiple connections can be set as follows. 1) The weight

Figure 112013030673760-pat00037
, The user terminal 330 may determine only the distance to access the nearest access point. And 2)
Figure 112013030673760-pat00038
, The user terminal 330 can connect to the access point having the largest received power of the signal received through each wireless access technology. Also, 3)
Figure 112013030673760-pat00039
The user terminal 330 can access the access point serving the radio access technology having the largest received power.

Here, 3)

Figure 112013030673760-pat00040
Each user terminal 330 can access the access point through the wireless connection technology having the largest received power. In this case, 2)
Figure 112013030673760-pat00041
Quot;
Figure 112013030673760-pat00042
The number of user terminals 330 using each wireless access technology can be adjusted according to the value of the user terminal 330.

For example, in practice, if the received power from the first wireless access technology is greater than the received power from the second wireless access technology (e.g.,

Figure 112013030673760-pat00043
), And can access the first access point 310 serving the first wireless access technology. here
Figure 112013030673760-pat00044
(For example,
Figure 112013030673760-pat00045
The received power is virtually multiplied by the value, so that the second wireless access technology is used, so that the number of the user terminals 330 connecting to each wireless access technology can be arbitrarily controlled.

According to one embodiment, in accordance with the access method criterion according to this weighted received power magnitude, each user terminal 330 can determine to one access point to connect. Figure 3a shows

Figure 112013030673760-pat00046
= 3
Figure 112013030673760-pat00047
= 10, all of the user terminals 330 are connected to the second access points 320 serving the second wireless access technology. Figure 3b
Figure 112013030673760-pat00048
= 100
Figure 112013030673760-pat00049
= 10, it can be seen that more user terminals 330 than shown in FIG. 3A connect to first access points 310 serving first wireless access technology. For example, offloading may have occurred.

The parameters used for each modeling are shown in FIG. 3A

Figure 112013030673760-pat00050
= 30 dB,
Figure 112013030673760-pat00051
= 0.1,
Figure 112013030673760-pat00052
= 3,
Figure 112013030673760-pat00053
= 15 dB,
Figure 112013030673760-pat00054
= 0.6,
Figure 112013030673760-pat00055
= 10, and in Fig. 3b
Figure 112013030673760-pat00056
= 30 dB,
Figure 112013030673760-pat00057
= 0.1,
Figure 112013030673760-pat00058
= 100,
Figure 112013030673760-pat00059
= 15 dB,
Figure 112013030673760-pat00060
= 0.6,
Figure 112013030673760-pat00061
= 10.

4 is a diagram illustrating a wireless access system 400 in a heterogeneous cellular network environment in accordance with one embodiment. The wireless access system 400 may include a first access point 410, a second access point 421 to an nth access point 422, and a user terminal 430. In the following equations, n is assumed to be 2, but the present invention is not limited thereto.

The first access point 410, the second access point 421 to the nth access point 422 can broadcast signals using different radio access technologies. Among the access points, the access point having the largest received power in the signal received by the user terminal 430 may be determined to be the primary access point, and the access point to which multiple access is additionally determined as the secondary access point. For example, the primary access point may broadcast a signal including a pilot sequence with a predetermined radio access technology. Further, the access point can broadcast a signal with a radio access technology different from a predetermined radio access technology.

The user terminal 430 determines the primary access point to be connected according to the magnitude of the received power of each signal to which different weights are applied for each wireless access technology. If the user terminal 430 determines that the user terminal 430 is the cell boundary user for the primary access point, Multiple access to the access point and the additional access point.

According to one embodiment, the outage occurs when the user terminal 430 receives a service from the wireless access technology and the data rate that the user terminal 430 can obtain is less than a specific target rate. . The outage probability can represent the probability that such an outage occurs. Specifically, the probability that the user terminal is connected to the first access point 410 serving the first wireless access technology and the outage occurs when it is determined that the user is an intra-cell user can be expressed by Equation (8).

Figure 112013030673760-pat00062

Also, the probability of occurrence of the outage when connected to the second access point 421 can be expressed by the following equation (9).

Figure 112013030673760-pat00063

In the case of a cell boundary user connected to two access points connected to the first access point 410 serving as the first wireless access technology and identified as the cell boundary, the outage probability is represented by the following equation (10) .

Figure 112013030673760-pat00064

In the above Equation (10), the cell boundary user can simultaneously use the first wireless access technology and the second wireless access technology. Accordingly, the user terminal 430 determined as the cell boundary determines that the sum of the data rates obtained from the first wireless access technology and the second wireless access technology is less than the target QoS

Figure 112013030673760-pat00065
An outage occurs, and the outage probability can be improved accordingly.

According to one embodiment, the average number of user terminals 430 using the first wireless access technology is

Figure 112013030673760-pat00066
, And the number of average user terminals 430 using the second radio access technology is
Figure 112013030673760-pat00067
Lt; / RTI > here
Figure 112013030673760-pat00068
The probability of accessing the first access point 410,
Figure 112013030673760-pat00069
Lt; RTI ID = 0.0 > 421 < / RTI > At this time, since the cell boundary users simultaneously use different radio access technologies, the average number of user terminals 430 may increase. For example, the user terminal 430 determined to be the cell boundary among the user terminals 430 using the second radio access technology accesses simultaneously with the first radio access technology, so that all the user terminals 430 using the first radio access technology 430) can be expressed by the following Equation (11).

Figure 112013030673760-pat00070

The number of all user terminals 430 using the second radio access technology in a similar manner can be expressed by Equation (12).

Figure 112013030673760-pat00071

here,

Figure 112013030673760-pat00072
and
Figure 112013030673760-pat00073
Lt; RTI ID = 0.0 > threshold < / RTI >
Figure 112013030673760-pat00074
and
Figure 112013030673760-pat00075
(E.g., load balancing) the number of user terminals 430 of other wireless access technologies by adjusting the values of the parameters. For example, if the target threshold is
Figure 112013030673760-pat00076
The number of the user terminal 430 connected to the second access point 421 serving the second wireless access technology may be zero. For example, if the target threshold value is set greater than 1, the user terminal 430 may be added to another wireless access technology with a probability of zero or more. Specifically, the target threshold value may be set such that the number of user terminals 430 that are connected to at least one access point using another wireless access technology is a predetermined number of users.

According to the embodiment, unlike the general user offloading or load balancing concept, the number of the user terminals 430 that are connected to one additional access point in a state of being connected to one main access point, Can be controlled.

Also, according to one embodiment, prior to multiple access,

Figure 112013030673760-pat00077
The number of user terminals 430 to be connected first can be adjusted, so that the number of users offloading can also be applied. For example, if a predetermined target threshold value that determines the cell boundary is stored in the user terminals 430,
Figure 112013030673760-pat00078
It may be determined whether or not the access point serving as a wireless access technology of the first wireless access technology or the second wireless access technology is determined as a cell boundary. Accordingly, multiple connections according to one embodiment may also include offloading or load balancing concepts.

According to an embodiment, since each access point transmits data to one user terminal 430 at every time among connected user terminals, a user inside a cell connected to the first access point 410 obtains The average throughput can be expressed as: " (13) "

Figure 112013030673760-pat00079

In the above-mentioned equation (13)

Figure 112013030673760-pat00080
Can represent a SINR and a symbol representing an average of the distance. The average throughput that can be obtained by a user inside a cell connected to the second access point 421 in a similar manner can be expressed by Equation (14).

Figure 112013030673760-pat00081

The average throughput that a cell boundary user of the first access point 410 can obtain can be expressed by Equation (15).

Figure 112013030673760-pat00082

The first term in Equation (15) may be obtained when the second access point 421 serves another user, even though the user terminal 430 is determined to be the cell boundary and simultaneously accesses the access points, Lt; RTI ID = 0.0 > 410 < / RTI > And the second term may indicate a case in which a service is simultaneously received from the first access point 410 and the second access point 421 through a simultaneous connection. Similarly, the average throughput obtained by the cell boundary user of the second access point can be expressed by the following equation (16).

Figure 112013030673760-pat00083

As described above, as the number of users simultaneously using the first access point 410 and the second access point 421 increases, the throughput is normalized to the RAT load, The normalized throughput of the cell boundary user may be reduced.

Where the normalized throughput of all user terminals 430 when the user terminal 430 is selectively connected and multiple connections is greater than a predetermined amount of throughput (e.g.,

Figure 112013030673760-pat00084
) Can be expressed by the following Equation (17). &Quot; (17) "

Figure 112013030673760-pat00085

According to one embodiment, a cell boundary user (such as a user terminal that does not get more than a certain target rate) can be a plurality of users (e.g., a user terminal that does not get more than a certain target rate), to the extent that the normalized throughput Access points at the same time. This greatly improves the QoS of cell boundary users and can control the number of user terminals 430 accessing each access point.

5 is a diagram illustrating a user terminal 530 that wirelessly connects in a heterogeneous cellular network environment according to one embodiment. The user terminal 530 according to one embodiment includes a signal receiving unit 531, a weight applying unit 532, an access point determining unit 533, a cell boundary determining unit 534, a multiple access unit 535, (Not shown).

The signal receiving unit 531 can receive a signal broadcast at each access point. The signal broadcast here may include a pilot sequence and may exhibit other unique characteristics depending on the wireless access technology served by the transmitted access point.

The weight applying unit 532 may apply different weights to the reception power of the signal depending on the radio access technology. Here, the weight applying unit 532 may apply a weight that is determined to be determined by the primary access point 510 according to a predetermined probability of the access point using the predetermined wireless access technique.

The access point determining unit 533 may determine the primary access point 510 to which the user terminal 530 will connect based on the magnitude of the received power to which the weight is applied.

The cell boundary determination unit 534 can determine whether the user terminal 530 is a cell boundary user for the primary access point 510. [ The cell boundary determination unit 534 may determine that the user terminal 530 is a cell boundary user if the data rate obtained from the primary access point 510 is smaller than the target threshold value. According to another embodiment, if the data rate obtained from the primary access point 510 is not smaller than the target threshold value, the user terminal 530 may be determined to be a cell internal user.

Herein, the target threshold may be a value set such that the number of user terminals 530 that are connected to at least one access point using another wireless access technology is a predetermined number of users.

The multiple access unit 535 may be connected to at least one access point 520 using a different radio access technology from the primary access point 510 and the primary access point 510 if the user terminal 530 is a cell boundary user . According to one embodiment, the multiple access unit 535 can access multiple accesses to the primary access point 510 and the secondary access point 520 using a unique number.

More specifically, the multiple access unit 535 includes a multiple access transmission unit (not shown), a primary access point 510 and a secondary access point 520 that transmit multiple accesses to the primary access point 510 and the secondary access point 520, And a unique number sharing unit (not shown) that shares a unique number with the primary access point 510 and the secondary access point 520 and pairs the unique number with the primary access point 510 and the secondary access point 520 .

According to one embodiment, the multiple connections 535 may be multiple-connected to at least one additional access point to the extent that the normalized throughput is greater than a predetermined amount of processing.

A selective connection (not shown) may selectively connect to the primary access point 510 if the user terminal 530 is a cell internal user.

A user terminal 530 may include a computer readable storage medium having stored thereon one or more programs including instructions for performing a method of wireless connection in a heterogeneous cellular network environment in accordance with an embodiment.

As various radio access technologies are developed, a plurality of different radio access technologies may be mixed. However, since most of the technologies are limited to the selection of wireless access technologies, technologies for selecting and simultaneously accessing wireless access technologies may be required to cope with heterogeneous communication environments.

According to an exemplary embodiment, a user terminal can provide a low-complexity method of selecting or simultaneously accessing an access point serving a wireless access technology while performing load control between wireless access technologies.

Here, in an environment where a plurality of wireless access technologies exist, it is possible to design a wireless access technology selection or a simultaneous access for all user terminals in order to optimize the overall network throughput. However, in order to schedule selective access or simultaneous access to all access points in a large-scale (such as an infinite area) and a user terminal connected to each access point, central unit may be additionally required. Also, such a central control unit must report various factors such as the number of user terminals and channels from all access points, and this method is complex and may not be realized realistically.

According to an exemplary embodiment, since the user only receives one parameter value for cell boundary determination from the access points serving the wireless access technology, the complexity may be low.

According to an exemplary embodiment, user terminals that can not achieve a specific QoS by selectively accessing a single wireless access technology can simultaneously use a plurality of wireless access technologies, thereby assuring a specific QoS.

According to one embodiment, normalized QoS of the entire network user terminal can be guaranteed. Further, by controlling the number of user terminals simultaneously using the multiple radio access technology, it is possible to control the load of the access point serving each radio access technology.

The apparatus described above may be implemented as a hardware component, a software component, and / or a combination of hardware components and software components. For example, the apparatus and components described in the embodiments may be implemented within a computer system, such as, for example, a processor, a controller, an arithmetic logic unit (ALU), a digital signal processor, a microcomputer, a field programmable array (FPA) A programmable logic unit (PLU), a microprocessor, or any other device capable of executing and responding to instructions. The processing device may execute one or more software applications that are executed on an operating system (OS) and an operating system. The processing device may also access, store, manipulate, process, and generate data in response to execution of the software. For ease of understanding, the processing apparatus may be described as being used singly, but those skilled in the art will recognize that the processing apparatus may have a plurality of processing elements and / As shown in FIG. For example, the processing unit may comprise a plurality of processors or one processor and one controller. Other processing configurations are also possible, such as a parallel processor.

The software may include a computer program, code, instructions, or a combination of one or more of the foregoing, and may be configured to configure the processing device to operate as desired or to process it collectively or collectively Device can be commanded. The software and / or data may be in the form of any type of machine, component, physical device, virtual equipment, computer storage media, or device , Or may be permanently or temporarily embodied in a transmitted signal wave. The software may be distributed over a networked computer system and stored or executed in a distributed manner. The software and data may be stored on one or more computer readable recording media.

The method according to an embodiment may be implemented in the form of a program command that can be executed through various computer means and recorded in a computer-readable medium. The computer readable medium may include program instructions, data files, data structures, and the like, alone or in combination. Program instructions to be recorded on the medium may be those specially designed and constructed for the embodiments or may be available to those skilled in the art of computer software. Examples of computer-readable media include magnetic media such as hard disks, floppy disks and magnetic tape; optical media such as CD-ROMs and DVDs; magnetic media such as floppy disks; Magneto-optical media, and hardware devices specifically configured to store and execute program instructions such as ROM, RAM, flash memory, and the like. Examples of program instructions include machine language code such as those produced by a compiler, as well as high-level language code that can be executed by a computer using an interpreter or the like. The hardware devices described above may be configured to operate as one or more software modules to perform the operations of the embodiments, and vice versa.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. For example, it is to be understood that the techniques described may be performed in a different order than the described methods, and / or that components of the described systems, structures, devices, circuits, Lt; / RTI > or equivalents, even if it is replaced or replaced.

Therefore, other implementations, other embodiments, and equivalents to the claims are also within the scope of the following claims.

410: 1st access point
421: Second access point
422: nth access point
430: User terminal

Claims (15)

Applying a weight according to radio access technology (RAT) to the received power of the received signal;
Determining a primary access point (AP) to be connected according to the magnitude of the received power to which the weight is applied;
Determining whether the user terminal is a cell boundary user for the primary access point; And
Accessing at least one additional access point using a different radio access technology from the main access point and the main access point when it is determined to be a cell boundary user
Lt; RTI ID = 0.0 > a < / RTI > heterogeneous cellular network environment. The method according to claim 1,
The step of applying a weight to the received power of the received signal according to a radio access technology (RAT)
Applying a weight value determined to be determined to the primary access point according to a predetermined probability of an access point using a predetermined wireless access technology
Lt; RTI ID = 0.0 > a < / RTI > heterogeneous cellular network environment. The method according to claim 1,
Wherein determining whether the user terminal is a cell boundary user for the primary access point comprises:
Determining that the user terminal is the cell boundary user if the data rate acquired from the primary access point is less than a target threshold;
Lt; RTI ID = 0.0 > a < / RTI > heterogeneous cellular network environment. The method according to claim 1,
Selecting and accessing the primary access point when it is determined that the user terminal is a cell internal user;
Lt; RTI ID = 0.0 > a < / RTI > heterogeneous cellular network environment. The method according to claim 1,
The step of multiple accessing at least one access point using a different radio access technology from the main access point and the main access point,
A step of multiple accessing the primary access point and the secondary access point using a unique number
Lt; RTI ID = 0.0 > a < / RTI > heterogeneous cellular network environment. 6. The method of claim 5,
Wherein the multiple access to the primary access point and the secondary access point using the unique number comprises:
Transmitting to the primary access point and the secondary access point whether multiple access is made;
Receiving different unique numbers from the primary access point and the secondary access point; And
Sharing and sharing the unique number with the primary access point and the secondary access point
Lt; RTI ID = 0.0 > a < / RTI > heterogeneous cellular network environment. A signal receiving unit for receiving a signal broadcast at each access point;
A weight applying unit for applying different weights to the reception power of the signal by wireless connection technology;
An access point determining unit for determining a primary access point to which the user terminal will connect based on the magnitude of the received power to which the weight is applied;
A cell boundary determining unit for determining whether the user terminal is a cell boundary user for the primary access point; And
Wherein the access point is a cell boundary user and the access point is a cell boundary user, the access point is connected to at least one access point using a different radio access technology from the access point and the access point,
Wherein the wireless terminal accesses the wireless terminal in a heterogeneous cellular network environment. 8. The method of claim 7,
Wherein the weight applying unit comprises:
The method comprising: applying a predetermined weight to an access point using a predetermined wireless access technology,
A user terminal wirelessly connected in a heterogeneous cellular network environment. 8. The method of claim 7,
The cell boundary determination unit may determine,
And determining that the user terminal is the cell boundary user if the data rate obtained from the primary access point is smaller than the target threshold value,
A user terminal wirelessly connected in a heterogeneous cellular network environment. 10. The method of claim 9,
The target threshold value may be calculated by:
Wherein the number of user terminals that are connected to at least one access point using the other wireless access technology is a predetermined number of users,
A user terminal wirelessly connected in a heterogeneous cellular network environment. 8. The method of claim 7,
When the user terminal is a cell internal user, a selective connection
Further comprising:
The cell boundary determination unit may determine,
And determining that the user terminal is an in-cell user if the data rate acquired from the primary access point is not smaller than the target threshold value,
A user terminal wirelessly connected in a heterogeneous cellular network environment. 8. The method of claim 7,
The multi-
And accessing the primary access point and the secondary access point by using a unique number,
A user terminal wirelessly connected in a heterogeneous cellular network environment. 13. The method of claim 12,
The multi-
A multiple access transmission unit transmitting multiple access to the primary access point and the secondary access point;
A unique number receiver for receiving different unique numbers from the primary access point and the secondary access point; And
A unique number sharing unit that shares the unique number with the primary access point and the secondary access point,
Wherein the wireless terminal accesses the wireless terminal in a heterogeneous cellular network environment. A primary access point for broadcasting a signal with a predetermined wireless access technology;
An access point for broadcasting a signal with a radio access technology different from the predetermined radio access technology; And
An access point determination unit for determining the primary access point to be connected according to a magnitude of reception power of each signal to which different weights are applied for each wireless access technology; and an access point determination unit for determining, if the user terminal is a cell boundary user for the primary access point, And a multiple access unit for multiple access to the access point
Lt; RTI ID = 0.0 > heterogeneous < / RTI > cellular network environment. 15. The method of claim 14,
The multi-
Accessing at least one additional access point within a range ensuring that the normalized throughput is equal to or greater than a predetermined throughput,
A wireless access system in a heterogeneous cellular network environment.
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JP2001078243A (en) 1999-09-02 2001-03-23 Nec Mobile Commun Ltd Branch control system and method
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Publication number Priority date Publication date Assignee Title
JP2001078243A (en) 1999-09-02 2001-03-23 Nec Mobile Commun Ltd Branch control system and method
JP2010239417A (en) 2009-03-31 2010-10-21 Kddi Corp Base station controller, and base station cooperative communication control method

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