KR20160064935A - Method and system for controlling transmission of code words during handover in a wireless network - Google Patents

Abstract

Embodiments provide a method and a system for controlling transmission of code words during a handover in a wireless network including a plurality of base stations. The method comprises receiving a signal-to-interference-plus-noise ratio (SINR) related to user equipment serviced by one base station. The user equipment is associated with a plurality of cooperative transmission modes. The cooperative transmission modes represent whether the user equipment receives the whole or a portion of the code words from the base stations based on a cooperative transmission threshold criterion and whether the user equipment receives a combination of the whole of the code words from any base stations or receives a portion of the cord words from a set of other base stations. In addition, the method comprises determining whether the SINR meets the cooperative transmission threshold criterion so as to select a cooperative transmission mode for transmission of the cord words from the base stations to the user equipment.

Description

METHOD AND SYSTEM FOR CONTROLLING TRANSMISSION OF CODE WORDS DURING HANDOVER IN A WIRELESS NETWORK BACKGROUND OF THE INVENTION [0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention generally relates to a wireless communication system, and more particularly, to handover with base stations (BSs) of a user equipment (UE).

In general, handover (HO) is an important procedure in cellular transmission because it enables the continuity of services within the same Radio Access Technology (RAT) or across different RATs. In the existing system, one hard handover (HO) and one soft handover (soft HO) are used for the MS to switch from one source base station to one target base station It is possible. Thereby maintaining the continuity of the service. In a soft handover, a terminal having a radio link with both a source base station and a target base station receives downlink data from a plurality of base stations while a handover procedure follows, i.e., during a handover time. If the terminal is connected to two or more base stations, the terminal will receive the entire codeword from the source and the target base station during the handover as shown in FIG. 1A.

In hard handover, the terminal must disconnect the radio link with the source base station before a new radio link is established with the target base station. That is, at a certain point in time, as shown in FIG. 1B, the terminal has a radio link with only one base station. In hard handover, inter-frequency handovers in the Global System for Mobile Communications (GSM), Long Term Evolution (LTE) and Code Division Multiple Access (CDMA) If the MS satisfies the handover condition in the base technology, the MS will transmit a signal strength measurement report of the neighbor BS in which the signal strength is increased as compared with the source BS. Based on the report, the source base station will provide the terminal with information about the radio link of the target base station. The terminal will disconnect the link with the source base station and establish a new link with the target base station. Hard handover of LTE is one of the causes of the ping-pong effect which causes overhead in signaling. One possible solution to mitigate the ping-pong effect is to perform joint transmission during handover. During handover, the combined transmission of the entire codeword from the serving base station and the target base station will increase the usage of the sparse spectrum resource and reduce the cell overall spectral efficiency.

The processing of the combination from multiple base stations may be in the form of dynamic point switching (DPS) dynamically. Here, only one base station can transmit to the terminal or a combined transmission can be made at a given time. Here, all the base stations included in the transmission set simultaneously transmit the same data to the terminal. In both transmission modes, a data packet for a terminal is available at all base stations included in the transmission set. The combined transmission is better in terms of link fragility in a millimeter wave system. Soft handover is preferable to hard handover due to link vulnerability. In the currently known soft handover scheme, complete data is transmitted by a plurality of base stations participating in a HO procedure. Therefore, there is an overhead both during transmission of data as well as during handover. Considering the link vulnerability of millimeter-wave systems and the need for small cells, the number of handovers will increase. As a result, the throughput during handover will be greatly reduced by increasing the number of handover and overhead.

The above information is provided only as background information in order to facilitate understanding of the present invention. Applicant makes no decision or assertion as to whether any of the above-mentioned contents can be applied as prior art to this application.

Embodiments of the present invention provide a method and system for controlling transmission of codewords during a handover in a wireless network.

Other embodiments of the present invention provide for multiple cooperative transmission modes in which the UE receives the entire codeword from the base station based on the cooperative transmission threshold criterion, Whether to receive the combination of the entire codeword from the base station or from which base station, and whether to receive the partial codeword from another base station set.

Embodiments of the present invention provide a method for controlling transmission of codewords at handover or in a wireless network including a plurality of base stations. The method includes receiving a signal-to-interference-plus-noise ratio (SINR) associated with a User Equipment (UE) served by a base station. The terminal is associated with multiple cooperative transmission modes. In this regard, whether the UE receives the entire codeword from the base station or whether the partial codeword is received from the base station or whether the entire codeword combination is received from one or more base stations or the coordinated transmission threshold criteria Is related to the receipt of a partial codeword in another set of base stations. The method also includes determining whether the SINR meets a cooperative transmission threshold criterion for selecting a cooperative transmission mode for transmitting a codeword from a base station to a terminal.

An embodiment of the present invention provides a system for controlling the transmission of codewords in a wireless network comprising a plurality of base stations during a handover, wherein each base station receives an SINR associated with a terminal served by the base station Wherein each base station is configured to determine whether each base station transmits an entire codeword and a partial codeword to a terminal based on a cooperative transmission threshold criterion, It is associated with multiple transmission modes. The control unit is further configured to determine whether the SNIR meets the cooperative transmission threshold criterion to select the cooperative transmission mode for transmission of codewords from the base station to the terminal.

Here, SINR is an example of channel quality information, and other types of channel quality information such as Carrier to interference plus noise ratio (CINR) may be applied.

These and other aspects of the embodiments herein will be better understood in consideration of the accompanying drawings, together with the following description. It is to be understood, however, that the following description, while indicating preferred embodiments and numerous specific details, is given by way of illustration and is not intended to limit the scope of the invention. Many modifications and variations are possible within the scope of the embodiments without departing from the spirit of the invention, and the above embodiments include all such modifications.

According to the embodiment of the present invention, it is possible to reduce the ping-pong effect through handover according to the type of codeword transmitted in the cooperative transmission mode, and to reduce the amount of resources used for information transmission between the base station and the terminals .

The invention is illustrated in the accompanying drawings, wherein like reference numerals designate corresponding parts in the various figures. BRIEF DESCRIPTION OF THE DRAWINGS Embodiments of the invention will now be better understood by reference to the following description taken in conjunction with the accompanying drawings, in which: FIG.
Figures 1A and 1B illustrate a handover mechanism in a mobile communication system as described in the prior art.
2 shows an overview of the high level of a system for controlling the transmission of codewords to one terminal according to an embodiment of the present invention.
FIG. 3 illustrates various modules within a base station 104 or base station 106 in accordance with an embodiment of the invention.
FIG. 4 illustrates various modules within terminal 102 in accordance with an embodiment of the present invention.
5 illustrates an example of a state transition scenario for controlling transmission of a codeword to one terminal during one or more cooperative transmission modes according to an embodiment of the present invention.
6 is a flow diagram illustrating a method for controlling transmission of a codeword in a wireless network during handover according to an embodiment of the present invention.

Embodiments of the invention and the details of the various functions and advantages will be described in more detail with reference to the non-limitative embodiments shown in the accompanying drawings, and are illustrated in the following description. Descriptions of well-known components and processing techniques are omitted to avoid obscuring the present embodiments unnecessarily. Furthermore, the various embodiments described herein are not mutually exclusive, and some embodiments may be combined with one or more other embodiments to form a new embodiment. Unless stated otherwise, 'or' used herein means non-exclusive. The examples used herein are merely set forth to assist those of ordinary skill in the art in readily understanding and easily carrying out the embodiments. Accordingly, the embodiments should not be construed as limiting the scope of the embodiments.

Embodiments of the present invention represent a method and system for controlling the transmission of codewords in a wireless network including handover or multiple base stations. The method includes receiving a signal-to-interference-plus-noise ratio (SINR) associated with a terminal served by one or more base stations. The base stations are associated with a number of coordinated transmission modes. The coordinated transmission mode indicates whether each base station transmits an entire codeword or a partial codeword to the terminal based on a transmission threshold criterion. The method also includes determining if the SINR satisfies the coordinated transmission threshold criteria to select one or more cooperative transmission modes for transmitting codewords from the base stations to the terminal . In an embodiment, the cooperative transmission threshold criterion includes a time reference. Here, SINR is an example of channel quality information, and other types of channel quality information such as Carrier to interference plus noise ratio (CINR) may be applied.

The method and system are simple, robust to control the transmission of codewords for handover in a wireless network.

Unlike existing systems, resources are conserved and signaling overhead is reduced. The handover is no longer limited to the base station change serving for the terminal. During handover involving joint transmission, the length of the codeword transmitted by each base station is not the same. The handover is similar to soft handover in that the codewords transmitted from various base stations are not the same length. For example, if one base station transmits the entire codeword and another base station transmits a code shorter than the entire codeword, the DL transmission overhead in the downlink is greatly reduced.

BRIEF DESCRIPTION OF THE DRAWINGS Referring now to the drawings, and more particularly to FIGS. 2-6, wherein like reference numerals identify features consistent with the drawings in a consistent manner, there are shown preferred embodiments.

FIG. 2 illustrates a high level overview of a system 200 for controlling codeword transmissions to a terminal in accordance with the described embodiments. In an embodiment, system 200 may be configured to include terminal 102, base station 104, and base station 106.

The terminal 102 described herein may be, but is not limited to, a mobile phone, a mobile station, a smart phone, a Personal Digital Assistants (PDA), a tablet, a phablet, . As shown in FIG. 2, the terminal 102 may be configured to receive a service from the base station 104 through a link-A in a downlink and to receive a service from the base station 106 via a link-B.

The base station 104 and the base station 106 form a transmission set for transmitting the full or partial codeword to the terminal 102. The base station 104 and the base station 106 may transmit a codeword to the terminal 102 via "Link-A" and "Link-B ". For purposes of transmission to the terminal 102, the transmission set may have a leader called a master base station (master BS). In an embodiment, the master base station may be one of the transmit sets (i.e., the base station 104 or the base station 106), or may be determined to be separate from the base station 104 and the base station 106 in the transmit set. The base station 104 and the base station 106 may be configured to be associated with a plurality of Coordinated Transmission Modes. Where the cooperative transmission mode indicates whether the base station 104 and the base station 106 transmit the entire codeword or the partial codeword based on coordinated transmission threshold criteria. In an embodiment, the master base station may be required to have centralized scheduling for the terminal 102. In another embodiment, the master base station may be optional if distributed scheduling is used.

The base station 104 and the base station 106 may be configured to receive information related to the SINR or other measurement data of the terminal 102 via a centralized or distributed mechanism. For example, in a centralized mechanism, the information may be provided to either the base station 104 or the base station 106. In addition, the base station 104 or the base station 106 may be configured to receive the SINR associated with the terminal 102. The base station 104 or the base station 106 may also receive the coordinated transmission threshold criteria to select the cooperative transmission mode for transmitting the codeword from the base station 104 and the base station 106 to the terminal 102 Or not. For example, in the cooperative transmission mode, either the base station 104 or the base station 106 may transmit the partial code word or partial information corresponding to the code word. In another cooperative transmission mode, either the base station 104 or the base station 106 can transmit the entire codeword to the terminal 102. [ For example, a scenario may be considered in which two base stations (i.e., a first base station and a second base station) can be served solely or jointly to the terminal 102. The types of possible cooperative transmission modes are as follows.

The first type is only one of the first base station or the second base station transmits the entire codeword to the terminal 102. The second type is that both the first base station and the second base station transmit the entire codeword to the terminal 102. The third type is also characterized in that while the second base station transmits a partial codeword or a source code word shorter or equal in length to the code word transmitted by the first base station, It is a type of transmitting a word. The fourth type is the type in which the first and second base stations transmit the partial codeword. Here, the partial code word may be part of the original code word, or the length of the partial code word may be the original code word which is absolutely short compared to the entire code word.

Also, the terminal 102 may be configured to maintain a set of timer values and Radio Link Failure (RLF) counters at the base station for the handover based on the selected cooperative transmission mode. The timer value for the terminal 102 to switch from one cooperative transmission mode to another cooperative transmission mode is as follows:

● S ₁₂ : T ₁₁ for all base stations transmitting the codeword, and the entire codeword For all transmitting base stations, t ₁₂

● S ₁₃ : t ₂ ,

● S _14: t ₃ ,

● S ₂₁ : t ₄ ,

● S _23: t ₅ ,

● S _24: t ₆ ,

● S _31: t ₇ ,

S _32: t ₈₁ for all base stations transmitting the partial codeword, t ₈₂ for all base stations transmitting the entire codeword,

● S _34: t ₉ .

Figure 2 shows a limited overview of the system 200. However, it should not be understood as a limitation of another embodiment. The system 200 may also include other base stations that communicate with each other according to different hardware or software components.

3 illustrates various modules in base station 104 or base station 106, in accordance with the described embodiment. In an embodiment, the base station 104 or base station 106 may be configured to include a receive (Rx) module 302, a control module 304, a storage module 306, and a transmit module (Tx) 308.

The receiving module 302 may be configured to receive the SINR associated with the base station 104 or the terminal 102 served by the base station 106. In an embodiment, the terminal 102 determines whether the terminal 102 receives the entire codeword from the base station or receives a combination of the entire codeword from which base station, and receives a partial codeword from another base station set based on the cooperative transmission threshold criterion Or < / RTI > The receiving module 302 may also be configured to send a received SINR associated with the terminal 102 to the control module 304. Upon receiving the SINR, the control module 304 determines whether the SINR satisfies the cooperative transmission threshold criterion to select the cooperative transmission mode for transmitting the codeword from the base station 104 or the base station 106 to the terminal 102 . ≪ / RTI >

In an embodiment, determining whether the SINR satisfies the cooperative transmission threshold criterion to select the cooperative transmission mode for receiving the codeword from the base station 104 or the base station 106 to the terminal 102 may comprise determining whether the SINR satisfies the cooperative transmission threshold criterion And determining by the control module 304 whether it is within a first cooperative transmission threshold. The first cooperative transmission threshold value is associated with a first cooperative transmission mode in one or more cooperative transmission modes. The first cooperative transmission mode is selected after determining whether the SINR is within the first cooperative transmission threshold and the first cooperative transmission mode allows the base station 104 and the base station 106 to transmit the entire codeword to the terminal 102 .

In another embodiment, if the control module 304 determines that the SINR is within a second cooperative transmission threshold criterion after determining that the SINR exceeds the first cooperative transmission threshold (the second cooperative transmission threshold is a multiple And is associated with a second cooperative transmission mode in cooperative transmission mode), then the second cooperative transmission mode is selected. And the second cooperative transmission mode allows the base station 104 or the base station 106 to transmit the entire codeword and the partial codeword to the terminal.

In another embodiment, after the control module 304 determines that the SINR exceeds the second cooperative transmission threshold, if the SINR is determined to be within the third cooperative transmission threshold (the third cooperative transmission threshold is a multiple cooperative transmission threshold And is associated with a third cooperative transmission mode in the transmission mode), a third cooperative transmission mode is selected. And the third cooperative transmission mode allows the base station 104 and the base station 106 to transmit the partial code word to the terminal.

In another embodiment, the control module 304 is configured to determine whether the SINR exceeds the third cooperative transmission threshold and then select a fourth cooperative transmission mode. The fourth cooperative transmission mode allows the base station 104 or base station 106 to transmit the entire codeword to the terminal 102.

The storage module 306 is configured to store a cooperative transmission threshold criterion for each cooperative transmission mode. The storage module 306 is configured to store control commands for performing various operations. The transmitting module 308 is configured to transmit the entire codeword or partial codeword to the terminal 102 based on the determined cooperative transmission mode.

FIG. 3 shows a limited overview of the base station 104 or base station 106. However, this should not be understood as a limitation of the embodiment. The base station 104 or base station 106 may also include any module that communicates with other configurations of the system 200.

4 illustrates various modules at the terminal 102, in accordance with the described embodiment. In an embodiment, the terminal 102 may be configured to include a receive (Rx) module 402, a control module 404, a storage module 406, and a transmit module (Tx) 408.

The receiving module 402 receives a signal transmitted from another device. For example, the receiving module 402 may be configured to receive a full codeword or a partial codeword according to the cooperative transmission mode from the base station 104 or the base station 106 at the terminal 102. The control module 404 controls the overall functions of the terminal 102. For example, the control module 404 can receive and transmit signals by controlling the receiving module 402 and the transmitting module 408. [ In addition, the control module 404 can store and read data in the storage module 406. The storage module 406 is configured to store control commands for performing various operations. The transmitting module 408 is configured to transmit the SINR to the base station 104 or 106.

In an embodiment, the terminal 102 determines whether the terminal 102 receives the entire codeword from the base station or receives a combination of the entire codeword from which base station, and receives a partial codeword from another base station set based on the cooperative transmission threshold criterion Or < / RTI >

FIG. 4 shows a limited overview of the terminal 102. However, this should not be understood as a limitation of the embodiment. In addition, the terminal 102 may include any module communicating with other configurations of the system 200.

5 illustrates an example scenario of a state transition for controlling the transmission of a codeword for a terminal between one or more cooperative transmission modes, as in an embodiment of the present invention. In an embodiment, different cooperative transmission modes during the handover procedure are shown in FIG. 5 below. The Y axis represents an increase in the signal strength value. Where X1, X2, X3, and X4 are the four cooperative transmission modes.

Here, X1 denotes a mode for transmitting all codewords by all base stations for the UE, X2 denotes a mode for transmitting a partial codeword by some base stations for the UE and a mode for transmitting the entire codewords by the remaining base stations Means a transmission mode. X3 denotes a mode for transmitting the partial codeword by all the base stations for the UE, and X4 denotes a mode for transmitting the entire codeword by only one base station for the UE.

T1, T2, and T3 are the cooperative transmission threshold criterion, and delta is the bias value of a particular state. If the strength of the signal is very low, the base station 104 and the base station 106 will transmit the entire codeword to the terminal 102. For example, if the SINR of the terminal 102 is within the first cooperative transmission threshold T1 (the first cooperative transmission threshold T1 is associated with a first cooperative transmission mode X1), the first cooperative transmission Mode X1 is selected, which allows the base station 104 and the base station 106 to transmit the entire codeword to the terminal 102. [ Also, after determining that the SINR exceeds the first cooperative transmission threshold T1, if the strength of the signal exceeds the first cooperative transmission threshold T1 and increases to the second cooperative transmission threshold T2 (i.e., 102 < / RTI > is within the range of the second cooperative transmission threshold T2), the second cooperative transmission mode X2 is selected. Accordingly, either the base station 104 or the base station 106 can transmit the entire codeword to the terminal 102, and either the base station 104 or the base station 106 can transmit the partial codeword to the terminal 102 . For example, in the second cooperative transmission mode X2, the base station 104 may transmit the entire codeword to the terminal 102, and the base station 104 may transmit the partial codeword to the terminal 102. As another example, in the second cooperative transmission mode X2, the base station 104 may transmit the partial codeword to the terminal 102, and the base station 104 may transmit the entire codeword to the terminal 102. [

After determining that the SINR exceeds the second cooperative transmission threshold T2, if the strength of the signal exceeds the second cooperative transmission threshold T2 and increases to the third cooperative transmission threshold T3 (i.e., And the SINR is within the range of the third cooperative transmission threshold value T3), the third cooperative transmission mode X3 is selected. Accordingly, the base station 104 and the base station 106 can transmit the partial code word to the terminal 102. Further, if the strength of the signal exceeds the third reception threshold T3 (i.e., the SINR of the terminal 102 exceeds the third cooperative transmission threshold T3), the fourth cooperative transmission mode X4 is selected do. This only allows the base station 104 or the base station 106 to transmit the entire codeword to the terminal 102. For example, in the fourth cooperative transmission mode X4, the base station 104 may only transmit the entire codeword to the terminal 102. Another example is that in the fourth cooperative transmission mode X4, only the base station 106 may transmit the entire codeword to the terminal 102.

In another example, if the SINR of the terminal 102 is within the range of the first cooperative transmission threshold T1 (the first cooperative transmission threshold T1 is associated with the first cooperative transmission mode X1) Cooperative transmission mode X1 is selected. This allows the base station 104 and the base station 106 to transmit the entire codeword to the terminal 102. Also, after determining whether the SINR exceeds the first cooperative transmission threshold value T1 and the second cooperative transmission threshold value T2, if the signal strength is increased to the third cooperative transmission threshold value T3 If the cooperative transmission threshold T1 and the second cooperative transmission threshold T2 are exceeded, that is, if the SINR of the terminal 102 is within the range of the third cooperative transmission threshold T3), the third cooperative transmission mode X3 is selected . This allows the base station 104 and the base station 106 to transmit the partial code word to the terminal 102.

In an embodiment, the switch from one cooperative transmission mode to another cooperative transmission mode of the terminal 102 is associated with the terminal after receiving the entire codeword or partial codeword from the base station 104 and the base station 106, Depends on the received SINR. A validly received SINR (also referred to as post-processing SINR) is the length of the codeword selected for transmission of the partial codeword and the length of the codeword co-operating in the transmission of the codeword It depends on the number. The notation SINRi represents the average SINR at the terminal from the base station i. For example, SINR1 indicates the average SINR at the terminal 102 from the base station 104. [ In another example, SINR2 represents the average SINR at the terminal 102 from the base station 106. [ A method for determining a possible cooperative transmission mode and a method for determining the length of a codeword from each base station will be described below.

The length of each of the code words from all the base stations and at least "should _{be" l 1 "", | B} | The number of base stations transmitting data from the base station must be smaller than "a" and "I" is the number of codewords from each base station Xi maximizing the utility function (f) The length is measured as shown in the following equation.

Also, the length is quantized as follows to match the transport block size (TBS).

Also, the effective SINR is obtained as follows with a newly quantized length.

The effective SINR will satisfy the conditions for switching from one cooperative transmission mode to another cooperative transmission mode.

The total codeword by the base station: SINR _C

T1

The entire code by a portion of the code word and the another base station due to any base station words: T1 <SINR _C

T2

Partial codeword by all base stations: T2

SINR _C

T3

The total codeword by the base station: SINR _{C >} T3

The timer value for the transition of the terminal from one cooperative transmission mode to another cooperative transmission mode must satisfy the conditions described in connection with Fig.

The conditions of each cooperative transmission mode (i.e., X1, X2, X3, and X4) in the embodiment are described below. Here, the base station 1 may be the base station 104, and the base station 2 may be the base station 106.

Here, S ₁₂ indicates a transition of the UE from the first cooperative transmission mode X 1 to the second cooperative transmission mode X 2. S ₂₁ represents a switching terminal in the second transmission mode X2 cooperation with the first transmission mode in cooperation X1.

_S13 indicates the switching of the UE from the first cooperative transmission mode "X1" to the third cooperative transmission mode "X3", and _S31 indicates the first cooperative transmission mode "X1" in the third cooperative transmission mode "X3" Indicates the switching of the terminal.

S ₁₄ is the first in a cooperative transmission mode "X1" represents a terminal transition to the fourth cooperative transmission mode "X4", S ₄₁ is the fourth first cooperative transmission mode from the cooperative transmission mode "X4""X1" Indicates the switching of the terminal.

S ₂₃ is the second in the cooperative transmission mode "X2" in the third cooperation transmission mode "X3" denotes a transition of the UE, S ₃₂ is the second cooperative transmission mode "X2" in the third cooperation transmission mode "X3" To indicate the switching of the terminal.

S ₂₄ is the second in the cooperative transmission mode "X2" in the fourth cooperative transmission mode "X4" denotes a transition of the UE, S ₄₂ is the second cooperative transmission mode "X2" in the fourth cooperative transmission mode "X" To indicate the switching of the terminal.

S ₃₄ is the third in the cooperative transmission mode "X3" in the fourth cooperative transmission mode "X4" denotes a transition of the UE, S ₄₃ is the third cooperation transmission mode "X3" in the fourth cooperative transmission mode "X4" To indicate the switching of the terminal.

In yet another embodiment, the average SINR is calculated, which is required to determine a cooperative transmission mode. For all sub-bands (or entire bands) assigned to the terminal, the SINR should be considered. The SINR over the reference symbols of previous sub-frames N1 (or the minimum time-frequency unit of scheduling) located apart from sub-frames N2 should be considered. The average SINR _i is calculated as follows.

As shown in Equation (5), in order to lower the speed of the terminal to v1 m / s, one sample average is taken. Here, """"indicates the index of the subframe. i - N ₂ * a> 0, and 1 <a <W.

In order to keep the speed of the terminal between v1 and v2 m / s, if the coefficient of variation (meaning the ratio of the standard deviation) of the SINR sample (which is used for the sum in Eq.1) Critical criterion) If T1 or less, the sample mean of SINR is calculated by Eq.1. Otherwise, the median of the sample is reported.

For speeds above v2 m / s, one of the following options can be selected:

The minimum value of the SINR from the sample shown in Eq.1

In an embodiment, as described above, the effective SINR must satisfy the value for the time interval given by the timer value. Here, a single timer value in LTE will be the set of timer values according to the signal strength (in the transmit set) from the base station and the respective base station in the transmission set in the transmission set.

In an embodiment, if the strength of the signal decreases below a threshold _Qout , the terminal may be said to have entered a Radio Link Failure State (RLF). A single counter is used to count the number of RLF measurements. If the number of counts is satisfied, the UE must initiate an RRC Connection Re-establishment procedure. In the case of partial transmission of information, the RLF is declared only when the RLF condition is satisfied from all base stations in the transmission set. Also, if there are "K" base stations in the transmission set, there are K different counters that determine the RLF, and each counter corresponds to the number of base stations that can actively transmit. Thus, for RLF there will be k thresholds. The RLF condition is met with a "K" threshold using the corresponding counter.

In another embodiment, the handover method may be executed at the terminal, or may be executed at the base station if the base station has appropriate information. The terminal evaluates the validity of the received SINR from each base station connected during cooperative transmission.

In another embodiment of the present invention, all k (k = 1 to 7) may have the same value and may have a value of zero. The thresholds are for an SINR value averaged at the appropriate time or frequency. The determination of switching of the terminal can be performed without considering the effective SINR. The duration for checking the signal strength can be set by the network or can be selected by the terminal.

Unlike existing systems, partial information transmission at one base station can only transmit a portion of the codeword for the terminal (possibly even a function of the codeword), other base stations can transmit the entire codeword, The portion for full code word transmission by another base station is a function of the signal reported by the terminal 102. The ping-pong effect of the soft handover can be reduced and also the number of resources for partial information transmission can be reduced when the link is being achieved.

6 is a flow diagram illustrating a method for controlling transmission of a codeword in a wireless network during handover according to an embodiment of the present invention.

In step 502, the method 500 includes receiving an SINR associated with the terminal being served by one or more base stations. The base stations may be associated with multiple cooperative transmission modes. The multiple cooperative transmission modes indicate whether the base stations transmit the entire codeword or the partial codeword to the terminal based on a transmission threshold criterion. The method 500 allows the control module 304 to receive the SINR associated with the terminal served by the base stations at the base station. In step 504, the method 500 includes determining whether the SINR is within a first cooperative transmission threshold. The first cooperative transmission threshold criterion may be associated with the first cooperative transmission mode from the plurality of cooperative transmission modes. The method 500 allows the control module 304 to determine whether the SINR is within a first cooperative transmission threshold.

If it is determined in step 506 that the SINR is within the first cooperative transmission threshold, the method 500 in step 508 allows the first cooperative transmission mode to be selected. The first cooperative transmission mode allows all base stations to transmit the entire codeword to the terminal. The method 500 allows the control module 304 to select the first cooperative transmission mode in which all base stations transmit the entire codeword to the terminal. If it is determined in step 506 that the SINR exceeds the first cooperative transmission threshold, the method 500 in step 510 includes determining whether the SINR is within the second cooperative transmission threshold. The second cooperative transmission threshold may be associated with a second cooperative transmission mode (in the plurality of cooperative transmission modes). The method 500 allows the control module 304 to determine whether the SINR is within the second cooperative transmission threshold. In step 512, if it is determined whether the SINR is within the second cooperative transmission threshold and exceeds the first cooperative transmission threshold, then the method 500 includes selecting a second cooperative transmission mode do. The second cooperative transmission mode allows some base stations to transmit the entire codeword to the terminal and some base stations to transmit the partial codeword to the terminal. The method 500 allows the control module 304 to select the second cooperative transmission mode, which allows some base stations to transmit the entire codeword and the partial codeword to the terminal.

If it is determined in step 512 that the SINR exceeds the second cooperative transmission threshold, the method 500 in step 516 includes determining whether the SINR is within a third cooperative transmission threshold. The third cooperative transmission threshold may be associated with a third cooperative transmission mode (in multiple cooperative transmission modes). The method 500 allows the control module 304 to determine whether the SINR is within the third cooperative transmission threshold. If it is determined in step 518 that the SINR is within the third cooperative transmission threshold and exceeds the second cooperative transmission threshold, then the method 500 includes selecting the third cooperative transmission mode . The third cooperative transmission mode allows all base stations to transmit the partial code word to the terminal. The method 500 allows the control module 304 to select the third cooperative transmission mode, which allows all base stations to transmit the partial code word to the terminal. If it is determined in step 518 that the SINR exceeds the third cooperative transmission threshold, then in step 522 the method includes selecting a fourth cooperative transmission mode. The fourth cooperative transmission mode allows only one base station to transmit the entire codeword to the terminal. The method 500 allows the control module 304 to select a fourth cooperative transmission mode (only one base station allows the terminal to transmit the entire codeword). In an embodiment, the terminal may be configured to maintain an RLF counter and a set of timer values for handover based on the selected cooperative transmission mode at the base station.

The various acts, behaviors, blocks, steps, and the like in method 500 may be performed in the order presented, in another order, or concurrently. Also, in some embodiments, certain behaviors, behaviors, blocks, steps, and the like may be omitted, added, modified, skipped, or the like, without departing from the scope of the present invention.

The embodiments disclosed herein may be realized through network management for controlling at least one software program and configuration executed on at least one hardware device. The configuration shown in Figures 2 and 3 includes at least one hardware device or a block that may be a combination of a hardware device and a software module.

The particular embodiments described above represent a general feature of embodiments of the present disclosure as a whole so that a third party can readily adapt and / or adapt various embodiments to such embodiments without departing from the generic concept, have. Thus, modifications of the embodiments and adaptations thereof are intended to be understood as being within the scope of equivalents and means of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and should not be regarded as limiting. While the foregoing embodiments of the disclosure have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments described herein may be practiced with modification within the spirit and scope of the embodiments herein.

Claims (18)

A method of operating a base station in a wireless network,
Receiving channel quality information associated with a terminal served by at least one base station,
Determining at least one cooperative transmission mode by a cooperative transmission threshold criterion to transmit a codeword to the terminal based on the channel quality information,
And transmitting the codeword according to the at least one cooperative transmission mode during handover of the terminal. The method according to claim 1,
The method of claim 1,
Determining whether the channel quality information is within a first threshold value,
Selecting a first cooperative transmission mode in response to a determination as to whether the channel quality information is within the first threshold,
Wherein the first threshold is associated with the first cooperative transmission mode in a plurality of cooperative transmission modes,
Wherein the first cooperative transmission mode is a mode in which each base station transmits an entire codeword to the terminal. 3. The method of claim 2,
The method of claim 1,
Determining whether the channel quality information is within a second threshold value by determining whether the channel quality information exceeds the first threshold value;
Selecting a second cooperative transmission mode in response to determining whether the channel quality information is within the second threshold,
Wherein the second threshold is associated with the second cooperative transmission mode in a plurality of cooperative transmission modes,
Wherein the second cooperative transmission mode is a mode in which at least one base station transmits a full codeword to the terminal and at least one base station transmits a partial codeword to the terminal. The method of claim 3,
The method of claim 1,
Determining whether the channel quality information is within a third threshold value in response to determining whether the channel quality information exceeds the second threshold value;
Selecting a third cooperative transmission mode in response to determining whether the channel quality information is within the third threshold,
Wherein the third threshold is associated with the third cooperative transmission mode in a plurality of cooperative transmission modes,
Wherein the third cooperative transmission mode is a mode in which all base stations transmit the partial code word to the terminal. 5. The method of claim 4,
The method of claim 1,
Selecting a fourth cooperative transmission mode in response to determining whether the channel quality information exceeds the third threshold,
Wherein the fourth cooperative transmission mode is a mode in which only one base station transmits the entire codeword to the terminal. The method according to claim 1,
Further comprising maintaining, for handover based on the cooperative transmission mode, a value of one of the set of timer values and a radio link failure (RLF) counter. The method according to claim 1,
Wherein the threshold criterion is constructed on a time basis. A method of operating a terminal in a wireless network,
Transmitting channel quality information related to a terminal served by a plurality of base stations,
Receiving codewords according to at least one cooperative transmission mode during handover,
Wherein the at least one cooperative transmission mode is determined by a cooperative transmission threshold criterion based on the channel quality information. 9. The method of claim 8,
Wherein the at least one cooperative transmission mode comprises:
A first mode in which each of the plurality of base stations transmits an entire codeword to the terminal,
A second mode in which some of the plurality of base stations transmit the entire codeword to the terminal and the remainder transmit the partial codeword to the terminal,
A third mode in which the plurality of base stations transmit the partial code word to the terminal,
And a fourth mode in which one of the plurality of base stations transmits the entire codeword to the terminal. A base station apparatus in a wireless network,
A receiving module for receiving channel quality information associated with a terminal served by at least one base station;
A control module for determining at least one cooperative transmission mode by a cooperative transmission threshold criterion to transmit a codeword to the terminal based on the channel quality information;
And a transmitting module for transmitting the codeword according to the at least one cooperative transmission mode during handover of the terminal. 11. The method of claim 10,
Wherein the control module is further configured to determine whether the channel quality information is within a first threshold and to select a first cooperative transmission mode in response to determining whether the channel quality information is within the first threshold,
Wherein the first threshold is associated with a first cooperative transmission mode in a plurality of cooperative transmission modes,
Wherein the first cooperative transmission mode is a mode in which each base station transmits the entire codeword to the terminal. 12. The method of claim 11,
Wherein the control module determines whether the channel quality information is within a second threshold value by determining whether the channel quality information exceeds the first threshold value and if the channel quality information is within a second threshold value, A second cooperative transmission mode is selected in response to the determination as to whether or not it is within the value,
Wherein the second threshold is associated with the second cooperative transmission mode in a plurality of cooperative transmission modes,
Wherein the second cooperative transmission mode is a mode in which at least one base station transmits a full codeword to the terminal and at least one base station transmits a partial codeword to the terminal. 13. The method of claim 12,
Wherein the control module determines whether the channel quality information is within a third threshold value in response to the determination that the channel quality information exceeds the second threshold value, The third cooperative transmission mode is selected in response to the determination of the &lt; RTI ID = 0.0 &gt;
Wherein the third threshold is associated with the third cooperative transmission mode in a plurality of cooperative transmission modes,
And the third cooperative transmission mode is a mode in which all base stations transmit the partial code word to the terminal. 14. The method of claim 13,
The control module selects a fourth cooperative transmission mode in response to the determination of whether the channel quality information exceeds the third threshold,
Wherein the fourth cooperative transmission mode is a mode in which only one base station transmits the entire codeword to the terminal. 11. The method of claim 10,
And maintains a value of one of the set of timer values and a radio link failure (RLF) counter for handover based on the cooperative transmission mode. 11. The method of claim 10,
Wherein the threshold criterion is configured on a time basis. A terminal apparatus in a wireless network,
A transmission module for transmitting channel quality information related to a terminal served by multiple base stations,
And a receiving module for receiving a codeword according to at least one cooperative transmission mode during handover,
Wherein the at least one cooperative transmission mode is determined by a cooperative transmission threshold criterion based on the channel quality information. 18. The method of claim 17,
Wherein the at least one cooperative transmission mode comprises:
A first mode in which each of the plurality of base stations transmits an entire codeword to the terminal,
A second mode in which some of the plurality of base stations transmit the entire codeword to the terminal and the remainder transmit the partial codeword to the terminal,
A third mode in which the plurality of base stations transmit the partial code word to the terminal,
And a fourth mode in which one of the plurality of base stations transmits an entire codeword to the terminal.

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