KR20150093876A - System and method for deciding energy efficient hand-over using a protocol characteristic - Google Patents

Abstract

The present invention relates to an energy efficient hand-over decision system and a method thereof. According to the present invention, the system comprises: a mobile terminal using a real-time or a non-real-time traffic, and being communicable with any wireless access point; a serving wireless access point which requests for checking a kind of traffic to the mobile terminal, and deciding whether the hand-over is performed or not, and a target wireless access point depending on the kind of traffic responding to the request in order to notify a hand-over message to the mobile terminal; and a target wireless access point for responding to which the confirmed hand-over message is received from the mobile terminal that receives a hand-over request, in order to indicate the data path switch. Accordingly, energy efficiency can be increased by avoiding power consumption caused by collision occurrence during the hand-over.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an energy efficient handover determination system and method using protocol characteristics,

The present invention relates to a mobile communication system, and more particularly, to a method for maximizing a lifetime of a mobile terminal by dividing traffic used by the mobile terminal into real-time and non-real- The present invention relates to an energy efficient handover determination system and method for allocating a backoff window size when a mobile terminal uses a handover request to avoid power consumption due to a collision during handover.

In mobile communication, when a mobile node (MN) in a busy state moves out of a cell boundary of a corresponding base station and moves to a neighbor base station service area, the mobile station is automatically tuned to a new communication channel of an adjacent base station, This is the function that maintains the call status.

The current handover method is operated to handover to a higher signal strength depending on RSSI (Received Signal Strength Indicator) signal strength. In general, communication with a wireless access point with a high RSSI signal strength reduces power consumption of the terminal and ensures maximum transmission speed of the wireless technology.

However, the power consumption of the wireless network is affected not only by the RSSI signal intensity but also by the contention based on the number of terminals connected to the wireless access point and the channel occupancy status. Since the conventional technology relies only on RSSI signal strength, a user may be confused with a specific wireless access point. When two or more terminals are connected to one wireless access point, contention for using a channel occurs, As the number of connected terminals increases, the probability of collision due to contention increases. At this time, the backoff algorithm procedure is performed as the contention occurs. For example, in order to transmit data to a wireless access point, the terminal performs a signaling operation for data transmission such as RTS (Request To Send), CTS (Clear To Send), and ACK (Acknowledge) , And when the contention occurs, the signaling operation is repeatedly performed during the backoff algorithm until the channel is allocated, thereby consuming unnecessary transmission energy.

Therefore, in order to reduce retransmission caused by a channel occupation failure of a terminal, that is, a collision, and to reduce energy consumption, the present invention provides a non-real- A contention window allocation and a method for reducing energy consumption through a handover control algorithm.

Korean Patent Publication No. 10-2010-0115991 (published on October 29, 2010) Korean Patent Publication No. 10-2011-0020398 (published March 23, 2011) Korean Patent Publication No. 10-2011-0036188 (Published on April 07, 2011)

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and it is an object of the present invention to provide a mobile terminal which is using non-real time traffic in a situation where two or more wireless access points coexist and handover of the mobile terminal is possible There is provided an energy efficient handover decision system and method for allocating a contention window to prevent participation of a channel occupancy contest for a predetermined time and reducing energy consumption due to a retransmission attempt when there is no channel available for a wireless access point attempting handover .

However, the objects of the present invention are not limited to the above-mentioned objects, and other objects not mentioned can be clearly understood by those skilled in the art from the following description.

According to an aspect of the present invention, there is provided an energy efficient handover determination system including: a mobile terminal that is using real-time or non-real-time traffic and can communicate with any wireless access point; A serving radio access point for determining a handover status and a target radio access point according to a type of traffic responding to the request and notifying the handover message to the mobile terminal, and a handover confirmation message And a target wireless access point that specifies a data path switch in response to the request.

Advantageously, the serving wireless access point performs a handover regardless of the channel state of the target wireless access point when the traffic type is real-time traffic, and if the traffic type is non-real- (EN) An Energy Efficient Vertical Hand-over Decision Controller (EEVHDC) that allocates a maximum contention window when there is no available channel system.

According to another aspect of the present invention, there is provided a method of determining an energy efficient handover, the method comprising: determining a traffic type of a mobile terminal; determining a channel state of a target wireless access point; determining a channel state of the traffic type and a target wireless access point; And determining whether to perform handover according to an energy efficient vertical handover decision control algorithm to be referred to.

Advantageously, the energy efficient vertical handover decision control algorithm performs a handover regardless of the channel state of the target wireless access point when the traffic type is real-time traffic, and if the traffic type is non- And a maximum contention window is allocated when there is no channel to which the channel state of the wireless access point can be allocated.

As described above, according to the energy efficient handover determination system and method of the present invention, the non-real-time traffic using terminal that attempts handover to a wireless access point with no channel margin allocates contention windows and handover The control algorithm can reduce the energy consumption due to the retransmission attempt.

1 is a configuration diagram illustrating a network environment and a protocol stack according to an embodiment of the present invention.
2 is a block diagram illustrating a traffic information delivery protocol according to an embodiment of the present invention.
FIG. 3 is a flowchart illustrating an algorithm procedure of an energy efficient Vertical Handover Decision Controller (EEVHDC) according to an embodiment of the present invention.

Hereinafter, an energy efficient handover determination system according to the present invention will be described in detail with reference to the accompanying drawings.

1 is a configuration diagram illustrating a network environment and a protocol stack according to an embodiment of the present invention.

The network environment 1 according to an embodiment of the present invention includes a network 100, a mobile node 200, a serving wireless access point 300, and a target wireless access point 400 .

The network 100 according to an exemplary embodiment of the present invention may be a Universal Mobile Telecommunications System (UMTS) network. The mobile terminal 200 may use real-time or non-real-time services and may communicate with any wireless access point Do. In addition, the serving radio access point 300 requests the mobile terminal 200 to confirm the traffic type, determines whether to perform handover according to the traffic type responding to the request, notifies the handover message to the mobile terminal 200, The wireless access point 400 designates a data path switching (Path Switch) in response to receiving a handover confirmation message from the mobile terminal 200 that has received the handover request. Each of the wireless access points 300 and 400 includes an energy efficient Vertical Handover Decision Controller (EEVHDC) 310 and 410, and uses different standards such as 802.11 and Wi-MAX, respectively. .

The MN protocol stack of the mobile terminal 200 is composed of an application layer, a link layer and a physical layer, and includes an application layer and a link layer There may be a media-independent hand-over function (MIHF).

The EEVHDC protocol stack of the wireless access points 300 and 400 includes an energy efficient Vertical Handover Decision Controller algorithm EEVHDC algorithm, A link layer and a physical layer, and an energy efficient vertical handover decision controller algorithm (EEVHDC algorithm) and a medium independent handover function (MIHF) may exist on a link layer. Detailed operation of the energy efficient vertical handover decision controllers 310 and 410 of the wireless access points 300 and 400 is described below in FIG.

2 is a block diagram illustrating a traffic information delivery protocol according to an embodiment of the present invention.

The fields of the traffic information delivery protocol are Type 200, A 201, Reserved 202, Identification 203 and Data 204. Type 200 is a field for indicating the type of message. Hello, Registration, Trigger, and Query. A field 201 is an Acknowledge request bit included in a Trigger message. The Reserved 202 field is a 7-bit field for classifying the traffic used by the mobile terminal 200 into real-time and non-real-time traffic. For example, 0000011 for real-time traffic and 0000010 for non real-time traffic. Identification 203 is a trigger acknowledgment message, which is a 16-bit field generated by the server used for trigger message matching. Data 204 is a field including a link layer event.

Hereinafter, the energy efficient handover determination method of the present invention using the system configured as described above will be described.

FIG. 3 is a flowchart illustrating an algorithm procedure of an energy efficient Vertical Handover Decision Controller (EEVHDC) according to an embodiment of the present invention.

Referring to FIG. 3, it is assumed that the mobile terminal 200 accesses the serving radio access point 300 and receives a service. When a handover request is generated from the mobile terminal 200 under this assumption (S302), the mobile terminal 200 determines whether the traffic type of the mobile terminal 200 is real-time or non-real-time and reports it according to the measurement result Command. Accordingly, the mobile terminal 200 measures the type of traffic using a traffic information delivery protocol or the like of FIG. 2 and transmits the result to the serving wireless access point 300 (S303).

Then, when the serving wireless access point 300 checks the traffic of the mobile terminal 200, if the traffic of the mobile terminal 200 is real-time traffic, it determines the target wireless access point to be handed over and performs handover (S305 If the traffic of the mobile terminal 200 is non-real time traffic, the flow advances to step S304 to check the channel state of the current wireless access point, i.e., the target wireless access point 400, without performing the handover.

In step S304, if the channel of the target wireless access point 400 has a margin to be allocated, the handover is performed (S305). Otherwise, a maximum contention window is allocated to the non-real-time traffic (S306). At this time, by allocating the maximum contention window for the non-real-time traffic, the intervals of retransmission attempts of the non-real-time traffic are increased, and the energy consumption due to retransmission attempts can be reduced.

The handover process of step S305 will be further described. In step S305, the serving radio access point 300 transmits a handover request message to the mobile terminal 200. [ This handover request message includes information on the determined target wireless access point 400. [ Upon receiving the handover request message, the mobile station 200 transmits a handover confirmation message to the target wireless access point 400 to notify that the handover has been performed. The target wireless access point 400 then requests a path switch to the gateway and requests the target wireless access point 400 to change the data path to the serving wireless access point 300. The gateway then switches the data path from the serving wireless access point 300 to the target wireless access point 400, thereby terminating the series of handover processes (S307).

In addition, according to the energy efficient vertical handover decision control algorithm procedure according to another embodiment of the present invention, the range of the contention window allocated in step S306 may be randomly determined. However, if another mobile terminal 200 attempts handover while waiting for a contention window with a timer in the mobile terminals 200 and 200, it detects that another mobile terminal 200 handover It is possible to reduce the energy consumption due to the retransmission attempt while allowing the longest waiting mobile terminal to have priority by stopping the remaining time slot by stopping the timer.

In addition, according to the energy efficient vertical handover decision control algorithm procedure according to another embodiment of the present invention, the range of the contention window allocated in step S306 is randomly determined, and the channel of the target wireless access point has a margin If it is detected that the mobile terminal is not present, the timer can be operated again so that the mobile terminal having the longest wait time can have priority and energy consumption due to the retransmission attempt can be reduced.

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, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the invention.

100: Network
200: mobile terminal
300: serving wireless access point
400: Target wireless access point
310, 410: Energy Efficient Vertical Handover Controller

Claims (8)

A handover determination system of a mobile communication system,
A mobile terminal that is using real-time or non-real-time traffic and is capable of communicating with any wireless access point;
A serving radio access point for requesting a check of a traffic type to the mobile terminal, determining a handover status and a target radio access point according to a traffic type responding to the request, and notifying a handover message to the mobile terminal; And
A target wireless access point that designates a data path switch in response to receiving a handover acknowledgment message from a mobile terminal that has received a handover request;
The handover decision system comprising:
The method according to claim 1,
The serving wireless access point,
Wherein the handover is performed regardless of a channel state of the target wireless access point when the traffic type is real-time traffic, and when the traffic type is non-real-time traffic and there is no channel to which the channel state of the target wireless access point can be allocated, Characterized in that it comprises an energy efficient vertical hand-over decision controller (EEVHDC), which assigns a contention window to the handover decision window.
The method according to claim 1,
The serving wireless access point,
An Energy Efficient Vertical Handover Decision Controller (EEVHDC) that randomly allocates a contention window when the traffic type is non-real time traffic and there is no channel to which the channel state of the target wireless access point can be allocated. ),
The mobile terminal,
And a timer for stopping a remaining time slot when detecting a handover attempt of another mobile terminal while waiting for the allocated contention window.
The method according to claim 1,
The serving wireless access point,
And an Energy Efficient Vertical Hand-over Decision Controller (EEVHDC) that randomly allocates a contention window when the traffic type is non real-time traffic,
The mobile terminal,
And a timer operative when the channel of the target wireless access point is detected as unrecoverable.
A handover determination method of a mobile communication system,
Determining a type of traffic the mobile terminal is servicing;
Determining a channel state of the target wireless access point; And
Determining whether to perform a handover according to an energy efficient vertical handover decision control algorithm that refers to the traffic type and a channel state of a target wireless access point;
The handover determination method comprising:
The method according to claim 5,
The energy efficient vertical handover decision control algorithm comprises:
Handover is performed regardless of a channel state of the target wireless access point when the traffic type is real-time traffic,
Wherein the maximum contention window is allocated when the traffic type is non-real time traffic and there is no channel to which the channel state of the target wireless access point can be allocated.
The method according to claim 5,
The energy efficient vertical handover decision control algorithm comprises:
Handover is performed regardless of a channel state of the target wireless access point when the traffic type is real-time traffic,
Randomly allocating a contention window when the traffic type is non-real time traffic and there is no channel to which the channel state of the target wireless access point can be allocated,
Wherein when a handover attempt of another mobile station is detected while waiting for the allocated contention window, the remaining time slot is stopped.
The method according to claim 5,
The energy efficient vertical handover decision control algorithm comprises:
Handover is performed regardless of a channel state of the target wireless access point when the traffic type is real-time traffic,
If the traffic type is non real-time traffic, a contention window is randomly allocated,
And when the channel state of the target wireless access point is detected as having no assignable channel, the timer of the allocated contention window is activated.

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