KR101764779B1 - Apparatus and method for transmitting uplink channel of remote node - Google Patents

Abstract

The present invention relates to a method and apparatus for transmitting a channel adaptive reverse channel to a host node by a remote node, and a remote node necessarily receives It is possible to minimize the transmission power of the remote node by transmitting the reverse channel when the channel state is good by measuring the state of the forward channel and determining whether the reverse channel is to be transmitted It is possible to reduce the overall power consumption of the remote node transmitting the reverse channel by preventing unnecessary power from being consumed in the channel state measurement.

Description

[0001] APPARATUS AND METHOD FOR TRANSMITTING UPLINK CHANNEL OF REMOTE NODE [0002]

The present invention relates to a channel transmission apparatus and method, and more particularly, to a channel transmission apparatus for adaptively transmitting an uplink channel from a remote node to a host node in consideration of a state of a communication channel in communication between a host node and a remote node , A method and a recording medium on which the method is recorded. In particular, the present invention relates to a method for optimizing the power consumption of a remote node in transmitting a reverse channel.

The development of electronic technology has facilitated the development of telecommunication through electromagnetic waves, and is being widely used today in various forms of wireless communication. Such wireless communication basically modulates the information to be transmitted as a radio wave to transmit the radio wave through a power amplifier (PA), and the receiving side demodulates the received radio wave to acquire information.

In order to improve the efficiency of wireless communication, scholars have developed a concept of time division in which each message is temporally separated into one transmission medium and the message channels are composed of different message channels in a time- Respectively.

By using this time division, pulses of different communication paths can be inserted by using the idle time between the pulses of one communication path and the pulse, so that multiple communication in different time is possible.

Particularly, a time division duplex (TDD) is a method of performing bidirectional communication with one frequency by dividing the inside of one frame into transmission and reception in the time division transmission method. Generally, different frequencies are used for transmission and reception in wireless communication, but time division duplex (TDD) is characterized in that bidirectional communication is possible by dividing the same frequency into time division and transmission / reception.

Meanwhile, a time division duplex (TDD) wireless communication system and a remote node (e.g., a wireless communication terminal) utilized therein receive signals from a host node and transmit their signals to a host node .

However, as the functions of the remote node have diversified and the structure has become complicated, it has been difficult to manage the power of the remote node itself relatively. Particularly, as the function of the remote node becomes more advanced, various studies have been proposed to save power consumed in the process of mutual communication with the host node as the power consumption of the remote node increases have.

For example, in a non-patent document, Hichan Moon, Suhan Choi, " Channel adaptive random access for TDD-based wireless systems ", IEEE Trans. Vehicular Tech., Pp. 2730-2741, Node transmits a Random Access Channel (RRC) only when the channel state of the forward link is good, and it is proposed to reduce the power consumption of a transmitter of a remote node required for RRC transmission have. However, excessive power is still consumed in the reverse channel transmission from the remote node to the host node, and a method for reducing the power consumption of such a remote node is required.

It is an object of the embodiments of the present invention to provide a wireless communication system in which a remote node transmits a reverse channel immediately after receiving a forward channel from a host node without considering the state of the channel, And unnecessary power dissipation caused by not considering the power consumed in the measurement of the forward channel received from the host node is blocked and the remote node considers the change of the channel state And to overcome the limitation of transmission performance by transmitting an uplink channel without transmitting the uplink channel.

In addition, the present embodiments are intended to reduce the power consumption of a receiver used for channel measurement in measuring a forward channel by a remote node.

One embodiment includes the steps of: a remote node intermittently receiving a forward channel from a host node; Measuring a state of the forward channel; Estimating a state of the reverse channel from the measured state of the forward channel; And transmitting an uplink channel to a host node when the estimated state of the uplink channel satisfies a preset channel condition, wherein the step of measuring a state of the forward channel includes: It is possible to provide a reverse channel transmission method of a remote node that measures the state of the forward channel in the reverse channel.

In the reverse channel transmission method of the remote node, the step of measuring the state of the forward channel may measure the state of the forward channel in a period in which the paging message is received from the host node in the interval in which the forward channel is intermittently received, The state of the forward channel can be measured at a predetermined time interval between a period of receiving a paging message from the node and a period and a period for measuring the state of the forward channel through the control message received from the host node have. Then, the remote node can transit to the sleep state in a period other than the designated period in which the state of the forward channel is measured.

In the reverse channel transmission method of the remote node, the step of measuring the state of the forward channel may measure the state of the forward channel in an interval during which the beacon is received from the host node during a period in which the forward channel is intermittently received.

In the reverse channel transmission method of the remote node, the step of measuring the state of the forward channel may increase a time interval between intervals for measuring a forward channel in proportion to a time allowed to transmit the reverse channel, It is possible to reduce a time interval between intervals in which a forward channel is measured when a predetermined time elapses.

In the reverse channel transmission method of the remote node, when the estimated reverse channel condition satisfies a preset channel condition, the step of transmitting the reverse channel to the host node may include a step of determining a quality of a service requested by the user, The Doppler frequency estimated from the change of the Doppler frequency is used to set the channel condition, and if the estimated state of the reverse channel satisfies the set channel condition, the reverse channel can be transmitted to the host node.

Another embodiment includes: a receiving unit for intermittently receiving a forward channel from a host node; A channel estimator for measuring a state of a forward channel in a predetermined interval of an interval during which the forward channel is intermittently received and estimating a state of the reverse channel based on the measured state of the forward channel; A controller for determining whether a state of the estimated reverse channel satisfies a preset channel condition and determining whether to transmit the reverse channel; A transmitter for transmitting an uplink channel to the host node according to the determination of the controller; And a Doppler frequency estimator for estimating a Doppler frequency through a change in the signal received by the receiver.

In this remote node, the channel estimator may set a period and a period for measuring the forward channel according to the control message received from the host node. In the interval during which the forward channel is intermittently received, in the interval for receiving the paging message, The state can be measured.

According to the present embodiments, the remote node receives the forward channel from the host node and does not immediately respond to the forward channel, but delays the reverse channel transmission considering the state of the channel, thereby transmitting the channel transmission efficiency And unnecessary power consumed in channel measurement can be reduced by intermittently measuring a forward channel received from a host node. By setting a channel condition variably in consideration of a change in a channel state, Performance can be optimized.

According to the embodiments, in order to determine whether or not a remote node transmits a reverse channel, a period for operating a receiver for measuring a state of a forward channel is minimized to reduce the total power consumption of the remote node It can be optimized.

1 is a diagram illustrating an example of a signal transmission structure of a forward channel and a reverse channel in a wireless communication system according to the present embodiments.
2 is a diagram illustrating an example of a structure of an access probe (AP) transmitted on a reverse channel in a wireless communication system according to the present embodiments.
FIG. 3 and FIG. 4 are views illustrating an example of a reference signal transmitted in a forward direction and a file channel transmitted in the wireless communication system according to the present embodiments.
5 is a diagram illustrating an example of intermittently receiving a forward channel according to the present embodiments.
6 to 8 are views illustrating an example of measuring the state of a forward channel in a section in which a remote node is designated according to the present embodiments.
9 shows a beacon frame of 802.11.
FIG. 10 and FIG. 11 are flowcharts illustrating a process of a reverse channel transmission method of a remote node according to the present embodiments.
12 is a block diagram showing a configuration of a remote node communicating with a host node according to the present embodiments.

Hereinafter, some embodiments of the present invention will be described in detail with reference to exemplary drawings. In the drawings, like reference numerals are used to denote like elements throughout the drawings, even if they are shown on different drawings. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

In describing the components of the present invention, terms such as first, second, A, B, (a), and (b) may be used. These terms are intended to distinguish the components from other components, and the terms do not limit the nature, order, order, or number of the components. When a component is described as being "connected", "coupled", or "connected" to another component, the component may be directly connected or connected to the other component, Quot; intervening "or that each component may be" connected, "" coupled, "or " connected" through other components.

Before describing the embodiments, a brief description will be given of a wireless communication environment in which the embodiments are implemented, and an overview of implementation problems occurring in an environment in which the embodiments are implemented and solutions for the same.

The present embodiments are widely applicable to wireless communication systems using Time Division Duplex (TDD). For example, the present invention is applicable to a mobile communication system such as 3GPP W-CDMA, LTE, or CDMA2000 of 3GPP2. The present embodiments focus on the case of transmitting a random access channel in such a mobile communication system But is not limited to this.

In this specification, a host node refers to a node that transmits a signal through a forward link (downlink), and a base station may correspond to the node. A remote node refers to a node that transmits a signal through a reverse link (uplink), and may correspond to a mobile node.

Hereinafter, random access channel transmission will be described assuming a W-CDMA system with reference to FIG.

FIG. 1 illustrates an example of a signal transmission structure of a forward channel and an reverse channel in a wireless communication environment in which the present embodiments are implemented. As shown in FIG. 1, a remote node transmits a random access channel Lt; / RTI >

1, it is assumed that a forward channel is an Access-Preamble-Acquisition Indication CHannel (AP-AICH), and a reverse channel is a random access channel (RACH).

As shown in FIG. 1, a remote node transmits AP0 100, which is an access probe including a preamble, to a host node through an arbitrary access channel for initial synchronization of communication, Lt; / RTI > For example, a remote node transmits an access probe configured as a preamble through a random access channel, as shown in FIG. 2A.

When the remote node does not receive a response signal to the access probe AP0 100 from the host node for tp-p time, the AP1 100 increases the transmission power of the access probe AP0 100 by AP (110) on the random access channel. At this time, the access probe AP1 110 includes a preamble configured with the same signature as the access probe AP0 100 transmitted previously.

At this time, when the host node receives the access probe AP1 110 through the random access channel, the same signature as the access probe AP1 110 received after waiting for the time tp-ai is transmitted to the AICH 120 to the remote node.

Then, the remote node demodulates the signal received through the AICH 120 to check a signature and an acquisition indicator (AI, not shown). If the ACK signal of the host node is confirmed through the acquisition acknowledgment, the remote node waits for the tp-mag time again and transmits a message including the reverse data through the Random Access Channel to the host node Node. For example, a remote node transmits an access probe including a message configured as shown in FIG. 2 (B) on a random access channel. At this time, the remote node transmits the corresponding access probe with the transmission power corresponding to the access probe AP1 (110).

FIG. 2 is a diagram illustrating an example of a structure of an access probe transmitted over a reverse channel in the wireless communication environment of FIG. 1, assuming CDMA2000 of 3GPP2.

In the 3GPP2 CDMA2000, the remote node transmits an access probe including the message shown in FIG. 2 (B) through the random access channel, and when the host node successfully receives the forwarding probe, And notifies the remote node of the reception via the common channel. That is, the AICH is not transmitted, and this signal is transmitted as a message to the forward common channel.

As mentioned above, most random access channels are an essential element of a wireless communication system, and arbitrary access channels are implemented in various ways.

In spite of these various implementations, the conventional random access channel transmits an access probe immediately when an event to transmit an arbitrary access channel in an upper layer occurs, without taking the channel state of the reverse link into consideration. However, the transmission of such an arbitrary random access channel has a problem that excessive transmission power is required.

In order to solve such a problem, in a time division duplex (TDD) wireless communication system, a state of a forward channel is measured to acquire information of an uplink channel state. Only when the acquired information satisfies a specific transmission condition, A kind of transmission delay scheme can be proposed.

As described above, it is determined whether to transmit the random access channel according to the channel state. If the transmission condition is not satisfied, the transmission of the random access channel access probe is delayed, thereby greatly reducing the transmission output. Further, the coverage radius of the communication system can be greatly expanded under the condition of the same maximum or average transmission power.

In the present embodiments, the channel state means the propagation attenuation of the radio channel between the transmitter and the receiver. This includes a change in the channel gain for a relatively short period of time, such as Rayleigh Fading, as well as Path Loss, which is attenuation by path. Another meaning of the channel state may be a received signal-to-noise ratio (SNR) in the case of transmitting a constant power signal.

In general, in the time division duplex (TDD) scheme, it can be assumed that the channel gain is similar to the forward link and the reverse link. In the present embodiments, the channel gain of the forward channel is measured by using this property, the channel gain is defined as the channel state, and an efficient method of transmitting the reverse random access channel only when the channel state is good is limited.

In summary, in the channel adaptive random access channel transmission method described above, when a remote node determines a random access channel transmission condition in advance and measures a state of a forward channel, if the forward channel satisfies a transmission condition Only the random access channel is transmitted, and otherwise, the random access channel transmission is delayed. That is, the random access channel can be transmitted only when the channel state is good, and the transmission power used for transmission can be greatly reduced.

However, the power consumed by the remote node may consume not only the transmit power of the random access channel, but also the operation of the receiver by the remote node to measure the state of the forward channel . In the above-described simple channel adaptive random access channel transmission scheme, the power consumed for the measurement of the forward channel is not considered.

On the other hand, in such a channel adaptive random access channel, it is not considered to optimize the performance after changing the transmission condition once after determining the transmission condition. Therefore, it is impossible to flexibly cope with a change in the channel state.

In this regard, in many wireless communication systems, there may be a requirement to transmit a message of a random access channel within a predetermined time. If the transmission of the random access probe is delayed due to poor channel conditions under such circumstances, the performance of the channel adaptive random access channel can be further improved by changing the transmission conditions according to the elapsed time or the time remaining for the future random access channel transmission .

FIGS. 3 and 4 illustrate examples of a reference signal transmitted in a forward direction and a file channel transmitted in a wireless communication environment in which the present embodiments are implemented.

Generally, in many wireless communication systems, a host node transmits a pilot or a reference signal continuously or periodically on a forward link. In this wireless communication environment, the remote node according to the present embodiments measures the forward channel transmitted from the host node and grasps the state of the reverse channel based on the measured forward channel.

3 shows an example of a pilot channel transmitted in CDMA2000 or W-CDMA.

Referring to FIG. 3, when a pilot channel exists as one code channel, it is always transmitted continuously. Therefore, the remote node can measure the pilot channel to grasp the state of the forward channel.

As described above, when an arbitrary access channel is transmitted in a conventional CDMA2000 or W-CDMA system, an arbitrary access channel is immediately transmitted as soon as an event triggering an arbitrary access channel occurs in an upper layer. At this time, the state of the forward channel is measured to determine the transmission power for transmitting the random access channel. That is, it is used to determine the transmission power of the random access channel by continuously measuring the pilot channel transmitted on the forward link. Therefore, it can be seen that the power consumption of the remote node due to the reception of the forward channel may occur in the process of transmitting the reverse channel (random access channel).

FIG. 4 shows an implementation example of a reference signal transmitted in a forward direction in 3GPP LTE.

Referring to FIG. 4, one subframe is transmitted with a length of 1 ms, and each subframe is composed of 14 OFDM symbols. Among them, the reference signal is transmitted only during some symbol intervals.

In the LTE system, the reference signal is transmitted to every 1, 5, 8, and 12th OFDM symbols, and the state of the forward channel can be measured using the reference signal. However, when the transmission of the random access channel is required, the remote node continuously monitors the forward channel.

For convenience of explanation, FIG. 4 shows a case where a reference signal is transmitted in only two symbols in one subframe. That is, although only one subframe is shown in FIG. 4, the structure of such a subframe in the time axis is infinitely repeated. Therefore, the remote node can measure the state of the forward channel in all subframes.

Now, it is assumed that an event of an upper layer occurs in the above-described wireless communication environment. In the conventional random access channel transmission scheme, when an event of an upper layer occurs, the random access channel is immediately transmitted.

On the other hand, in the channel adaptive random access channel adopted by the present embodiments, the access probe of the random access channel is transmitted only when the predetermined channel condition is satisfied, otherwise, the transmission of the access probe is delayed.

If it is desired to transmit a random access channel only in a channel with a very good status in order to minimize the transmission power, it may take a very long time before transmitting the access probe. In this case, the power required to measure the forward channel at the total consumed power of the remote node may be relatively larger than the transmission power. In particular, in the case of a channel adaptive random access channel transmission, the transmission delay of the access probe can be as short as several ms to as long as several seconds as a characteristic of the operation. In this case, if the remote node continuously measures the state of the forward channel by operating the receiver, there is a concern that the power consumption of the receiver of the remote node may be a main factor of the total power consumption .

The embodiments of the present invention propose an adaptive channel transmission method of a remote node to solve such a problem. The channel transmission method reduces the transmission power required for the Random Access Channel transmission in the mobile communication field, The transmit power or average transmit power can be used to extend the Coverage Radius of the limited Remote Node. In addition, the present embodiments can be utilized in all communication systems and terminals that need to minimize the power required for communication such as a sensor network, a wireless LAN, machine-to-machine communication, and communication between medical equipments.

FIG. 5 illustrates an example of a method for intermittently receiving a forward channel adopted in the present embodiments, and is an operation diagram of a receiver provided in a remote node.

Basically, the present embodiments estimate the state of the reverse channel through reception and measurement of the forward channel, and transmit the reverse channel considering the estimated channel state and the set channel condition. However, in this case, it is pointed out that there is a fear that the power consumed in the reception and measurement of the forward channel is wasted depending on the state of the channel. In order to solve such a problem, the present embodiments repeatedly operate the receiver of the remote node for a certain period of time without measuring the state of the forward channel by repeating the process of not operating the receiver, A method for reducing power consumption of a remote node is proposed.

First, when a remote node needs to transmit a random access channel, the remote node measures the state of the forward channel and determines whether to transmit the random access channel. The remote node performs the measurement of the forward channel for some time interval and determines whether to transmit the access probe based on the measurement result. Also, power consumption of the remote node can be reduced by not operating the receiver of the remote node during the time when the status of the forward channel is not measured.

Particularly, during the time when the remote node does not measure the state of the forward channel, except for a part essential for the operation of the remote node such as a clock measuring the time of the remote node, The power consumption can be minimized. That is, the remote node operates similar to the sleep state of the mobile communication terminal, thereby reducing power consumption.

FIG. 5 is a diagram illustrating a state in which a remote node measures the state of a forward channel every predetermined period. In FIG. 5, measurement intervals are set so that all measurement intervals maintain a constant time interval (T1 = T2).

Referring to FIG. 5, a remote node performs a state measurement of a forward channel for a predetermined time at time t0, t1, and t2. The section for performing the channel measurement is shown in Fig. 5 as a hatched square. The remote node measures the channel state in each channel measurement interval and determines whether to transmit the RBO based on the measured channel state. Also, the remote node transitions to a sleep state during the remaining time interval to minimize the total power consumption.

As described above, intermittent channel state measurements can reduce power consumption compared to continuous channel state measurements. However, in determining the transmission of the RBD, the power consumption of the remote node may be changed depending on the state of the forward channel at a certain point in time. That is, in a wireless communication system, there is a time interval in which a remote node necessarily measures the state of a forward channel. When a channel measurement is performed in this interval, a remote node actually measures a forward channel state It may not cause any additional power consumption.

For example, in a mobile communication system, a remote node has to check whether a paging message is transmitted to a remote node every predetermined time. Therefore, the remote node of all the mobile communication systems awakes from the sleep state for every predetermined paging interval and receives the forward channel. In a typical mobile communication system, this is performed at intervals of 1 second or 2 seconds. However, in the IoT environment, the period for checking the paging message may be one hour, one day, or more. Further, the remote station needs to perform measurement of the synchronization confirmation channel environment with the system every predetermined period. In another embodiment, it is necessary to check a message transmitted from a host at a predetermined time or to check whether a host transmits a message.

In the present embodiment, the state of the forward channel is measured at a time when the remote node of the mobile communication system checks whether or not the paging message is received, and determines whether the reverse channel is transmitted based on the measured state. That is, the remote node measures the state of the forward channel during a period of checking whether or not the paging message is transmitted, and determines whether or not the reverse channel is transmitted based on the measured state. Thus, the power consumed by the receiver Can be minimized.

FIG. 6 illustrates an example of measuring a forward channel state according to the present embodiments. FIG. 6 illustrates the LTE mobile communication system as a standard or may be commonly applied to other wireless communication systems.

Referring to FIG. 6, a host node transmits a paging message to a remote node at regular intervals, and performs a function of notifying that a message to be transmitted to the corresponding remote node exists . Slotted paging is a method of transmitting a paging message at a predetermined time according to the predetermined period.

In the embodiment shown in FIG. 6, the remote node periodically operates the receiver to receive the paging message, and thus measures the state of the forward channel while the receiver is operating to receive the paging message. And determines whether the reverse channel is transmitted based on the measured state of the forward channel, where the reverse channel may be a random access channel that transmits in the reverse direction.

According to the embodiment shown in FIG. 6, a remote node measures a state of a forward channel at a time when a receiver operates to receive a message indicating whether to paging. This eliminates the need for additional receiver power consumption for forward channel state measurements. If further power consumption of the receiver is to be further reduced, it is possible to check whether the forward channel is paged every integer multiples of the paging cycle of the forward channel, and simultaneously measure the state of the forward channel.

In the above-described embodiment, the remote node measures the state of the forward channel only at the time of operating the receiver to confirm the message informing whether or not to paging. However, if the channel status is measured only at the time of receiving a message informing whether or not to paging, the power consumption of the remote node can be minimized, but the time delay of the random access channel transmitted on the reverse link may become excessively long .

Therefore, in the case of the service sensitive to time delay, the present embodiments operate not only the time when the remote node operates the receiver to check the message informing of whether the paging is paged, but also the operation of the receiver N between the two paging messages And provides an embodiment for measuring channel conditions.

FIG. 7 illustrates an example in which a channel status is measured between intervals during which a remote node receives a paging message according to the present embodiments.

Referring to FIG. 7, a remote node not only measures a channel state when receiving a paging message, but performs a channel measurement additionally at a point located at the middle of a period in which a paging message is received. That is, this embodiment shows the case where N = 1. This additional channel measurement is performed to provide an embodiment that can reduce the power consumption of the remote node and reduce the reception delay of the Random Access Channel.

At this time, the host node can designate the period of the channel state measurement performed by the remote node for the adaptive random access channel transmission through the control message. That is, the host node can designate a cycle for transmitting a paging message and a period for a remote node to wake up from a sleep state for channel measurement, respectively.

For example, as in the embodiment shown in FIG. 6, a remote node may simultaneously perform channel state measurement for random access channel transmission while receiving a paging message. Alternatively, as in the embodiment shown in FIG. 7, the interval at which the remote node awakes from the sleep state in order to receive the paging message may be set to an integer multiple of the period in which the remote node awakes from sleep for channel state measurement. FIG. 7 is an example of a case where the paging message reception period is set to twice the channel state measurement period.

That is, in the present exemplary embodiment, the remote node receives the paging message designated by the host node and performs channel state measurement for random access channel transmission during the time of receiving the paging message. Also, it awakes from the sleep state and performs channel state measurement according to the channel state measurement period for random access channel transmission designated by the host node.

The present embodiments are applicable not only to a mobile communication system but also to a wireless communication system operating in a license-exempt band.

FIG. 8 shows an embodiment in which a remote node measures channel conditions in an 802.11 wireless LAN system.

In an 802.11 wireless LAN system, an access point (AP) transmits a beacon periodically. The beacon not only secures time synchronization of the wireless LAN system, but also measures a channel state with an AP. The beacon frame includes the information of the traffic indication map (TIM) of the AP and is transmitted. The TIM contains information about whether the AP has buffered data to send to each node. Figure 9 shows a portion of the beacon frame used in 802.11.

In the 802.11 standard, an AP periodically transmits a beacon frame, and each node is in a sleep state to reduce power consumption, and when the beacon transmission time is reached, the receiver operates and receives a beacon. Also, the presence or absence of data transmitted to the node is checked. The present embodiments can be applied to a wireless communication system of 802.11. In this case, a host node becomes an AP and a remote node becomes an STA (station).

Each remote node receives a beacon frame transmitted at a period called a beacon interval and measures the channel state between the host node and the remote node by utilizing the beacon frame. Here, the channel state may be a channel gain between two nodes, a received SNR, or the like.

FIG. 8 illustrates an embodiment in which a remote node operates a receiver to receive a beacon at each beacon interval in 802.11, and measures a channel state with an AP using a beacon frame during the time interval. Determines whether an uplink channel is transmitted based on the measured channel state, and performs transmission of a reverse random access channel only when a channel gain between an AP and a remote node satisfies a predetermined channel condition.

If the service needs to transmit random access within a short time delay, additional channel state measurements may be performed N times between the beacon and the beacon. Alternatively, if the remote node has to maximize the waiting time, it can reduce the power consumption of the remote node by receiving the beacon once only at M beacon receiving periods without receiving all the beacons.

In the present exemplary embodiment, a channel state measurement is performed for a random access channel transmission in a time interval during which a remote node receives a beacon. The measurement period and the beacon reception period are determined by a host node through a control message It can inform the remote node.

That is, as in the above-described embodiments, in the wireless communication system, there are signals that each remote node must receive. During the time interval, the status of the forward channel is measured to determine whether the RRC is transmitted It is possible to reduce the power consumption of the remote node by preventing power consumption due to the operation of the additional receiver. In addition, by performing additional channel state measurement according to the time delay required according to the service, the power consumption of the remote node is reduced, and the time delay of random access channel transmission can be minimized.

In addition, the embodiments can adjust the time interval between intervals measured according to other variables.

For example, the time interval between state measurement intervals of the forward channel can be adjusted in proportion to the time allowed to transmit the random access channel. That is, if the allowed transmission time is large, it is not necessary to shorten the period for measuring the state of the forward channel. Therefore, if the allowed transmission time is long, the time interval between the measurement intervals is set long, and if the allowed transmission time is small, the time interval between measurement intervals is set to be short and finally the remote node The power consumed can be optimized.

The method of setting the time interval between measurement intervals can be fixedly used until the time interval set in the beginning is transmitted until the access probe is transmitted. However, it is possible to perform a more efficient random access channel transmission by changing the time interval of the channel state measurement over time, and the embodiments also provide a method of applying the time interval variably.

For example, the time between measurement intervals can be variably set according to the elapsed time from the time when the event for the first time to transmit the random access channel occurs, or the remaining time allowed to finally transmit the random access channel. If the elapsed time from the time of the first transmission event is large or the allowed remaining time is decreased, the time interval of the measurement interval may be set to be shorter so that more channel state measurement can be performed.

That is, according to the present embodiments, a forward channel state measurement interval for transmitting an arbitrary access channel of a remote node is a receiving period of a signal that must be received from a host node, The power consumption of the remote node can be minimized and the forward channel state measurement interval can be variably adjusted to optimize the power consumption of the remote node and the time delay of the random access channel transmission, ) To transmit a random access channel.

10 and 11 illustrate an example in which a remote node according to the present embodiment transmits a random access channel. FIG. 10 illustrates a state in which a remote node receives a paging message, FIG. 11 illustrates a case in which a remote node performs channel state measurement in addition to a period in which the remote node receives a paging message.

10, a host node generates a control message for specifying a forward channel state measurement interval and a measurement period of a remote node (S1000), and transmits the generated control message to a remote node. (S1001).

The remote node sets a forward channel state measurement interval and a measurement interval according to the control message received from the host node (S1002).

For example, FIG. 10 shows a case where a remote node measures a state of a forward channel by operating a receiver only in a period in which a paging message is received from a host node. Sets a time point at which a paging message is received according to a control message, and performs forward channel state measurement only in an interval in which a paging message is received.

The remote node operates the receiver at the reception time of the paging message set according to the control message (S1003).

When the host node transmits a paging message to a remote node (S1004), the remote node measures the state of the forward channel in the interval in which the paging message is received (S1005) (S1006).

If the channel condition of the remote node does not satisfy the predetermined channel condition, the remote node stops the operation of the receiver and waits until the next paging message reception time.

The remote node operates the receiver at the reception time of the next paging message (S1007) and receives the paging message from the host node (S1008).

The remote node measures the forward channel state in the reception interval of the paging message (S1009), and determines whether to transmit the random access channel according to whether the measured channel condition satisfies the preset channel condition (S1010).

The remote node transmits the random access channel to the host node when the measured channel condition meets a preset channel condition (S1011).

Therefore, the remote node can minimize the transmission power by transmitting an arbitrary access channel only when the channel state is good, and can measure the channel state only in a section receiving the paging message from the host node, The power consumed in the measurement can be minimized.

11 is a diagram illustrating a case where additional channel state measurement is performed between receiving intervals of a paging message so as to reduce a reception delay of a Random Access Channel in a case of a service sensitive to time delay. And the channel state measurement is additionally performed.

Referring to FIG. 11, a host node generates a control message for specifying a period and a period for measuring a channel state of a remote node (S1100) and transmits the control message to a remote node (S1101 ).

The remote node operates the receiver at the set time according to the control message (S1103). When the host node transmits the paging message (S1104), the remote node measures the state of the forward channel in the reception interval of the paging message S1105) It is determined whether or not the random access channel is transmitted (S1106).

If the measured channel condition does not satisfy the preset channel condition, the remote node stops the operation of the receiver and waits until the next channel condition measurement interval.

At this time, the remote node operates the receiver at the set time according to the control message before the interval in which the next paging message is received (S1107), and the host node measures the channel state of the remote node (S1108), and receives the reference signal to measure the state of the forward channel (S1109).

Here, the reference signal is a signal for measuring the quality of a channel by a remote node (for example, a CRS (Common Reference Signal) or a CSI-RS (Channel State Information-RS) And may include a pilot signal. The remote node may measure the channel quality using a reference signal received power (RSRP) or a reference signal received quality (RSRQ) of the reference signal or may use a channel quality measurement procedure in each mobile communication system .

The remote node determines whether to transmit the random access channel according to the measured channel state (S1110). If the measured channel state does not satisfy the predetermined channel condition, the remote node stops the operation of the receiver, .

At this time, if the measured channel condition satisfies the preset channel condition, the remote node transmits an arbitrary access channel to the host node and transmits the random access channel in a shorter time than the reception period of the paging message The time delay of random access channel transmission can be reduced.

The remote node operates the receiver at the time of receiving the next paging message (S1111), and when the host node transmits the paging message (S1112), the remote node measures the state of the forward channel during the reception period of the paging message (S1113 ) Random access channel (S1114). If the measured channel condition satisfies the predetermined channel condition, the arbitrary access channel is transmitted (S1115).

Accordingly, the remote node can perform additional channel state measurement a predetermined number of times during the reception interval of the paging message, thereby reducing power consumption according to the channel state measurement of the remote node, Thereby minimizing the time delay of the < / RTI >

12 shows a configuration of a remote node communicating with a host node according to the present embodiments.

12, a remote node 1200 according to the present embodiment includes an antenna 1210, a receiver 1220, a transmitter 1230, a channel estimator 1240, and a controller 1250 , And a Doppler frequency estimating unit 1260. Since each configuration of the remote node of Fig. 12 corresponds to the above-described series of channel transmission methods, in order to avoid unnecessary duplication, the device characteristic is focused on and only the outline thereof is described.

An antenna 1210 receives a signal transmitted through a wireless channel and transmits a signal to be transmitted by a remote node.

The receiving unit 1220 intermittently receives a forward channel transmitted from a host node (not shown).

At this time, the receiver 1220 measures the state of the forward channel by operating only in the designated interval according to the control message received from the host node, and does not operate in the interval other than the designated interval and does not measure the state of the forward channel . Therefore, it is desirable to keep the consumed power to a minimum in a section in which the receiving section 1220 does not operate, and a section for measuring the channel state and a section for not measuring can be repeatedly arranged in accordance with the passage of time, May be set to be variable.

From an implementation point of view, such a receiver 1220 may include an RF receive block, a demodulation block, a channel decoding block, etc. to recover data from the signal provided from the antenna 1210. The RF receiving block may be composed of a filter and an RF preprocessor and the demodulation block may be configured by an FFT operator for extracting data on each subcarrier when the wireless communication system uses the orthogonal frequency division multiplexing method, The channel decoding block may be composed of a demodulator, a deinterleaver and a channel decoder.

The channel estimation unit 1240 estimates the state of the reverse channel from the remote node to the host node based on the forward channel received through the receiver 1220. [ For example, the channel estimator 1240 can estimate the received power of the received signal using the pilot of the forward signal.

The remote node may include a Doppler frequency estimating unit 1260. The Doppler frequency estimating unit 1260 estimates the Doppler frequency using a received signal received from the receiving unit 1220, And estimates a Doppler frequency between nodes (Remote Node). That is, the Doppler frequency estimator 1260 estimates the Doppler frequency based on the change of the signal received through the forward channel, and provides the control unit 1250 with a judgment basis.

The control unit 1250 determines whether the state of the reverse channel estimated through the channel estimation unit 1240 satisfies a preset channel condition, and determines whether to transmit the reverse channel according to the determination result.

For example, it is determined whether to transmit the reverse channel by comparing the state estimate of the reverse channel calculated based on the channel gain of the received forward channel with a threshold indicating the channel condition. At this time, it is preferable that the channel condition is variably reset depending on the passage of time. Meanwhile, the controller 1250 may set a threshold considering the quality of service (QoS) of a service requested by the user, or may set a threshold using the Doppler frequency estimated by the Doppler frequency estimator 1260.

The controller 1250 controls the operation period of the receiver 1220 according to the control message received from the host node. The determination parameters may include a Doppler frequency of the received forward channel, a time allowed to transmit the reverse channel, a time at which an event for transmitting the reverse channel is generated A time elapsed from time to time, a requested level of QoS set, and a request from a host node.

Accordingly, the decision parameter can be received from a host node or input from the outside of the remote node by a user, and can be based on a forward channel received via the receiver 1220 and one or more preset constraints And may be calculated by the control unit 1250.

The transmitter 1230 adaptively transmits the reverse channel according to the determination of the controller 1250. For this purpose, the transmitter 1230 generates a signal to be transmitted to the host node through the random access channel under the control of the controller 1250. That is, the transmitting unit 1230 converts a signal to be transmitted to a host node through a random access channel into a form for transmission over a radio resource only when the control unit 1250 permits the random access channel transmission, (1210).

From an implementation point of view, the transmitter 1230 may include a signal generation block, a channel code block, a modulation block, an RF transmission block, and the like. The channel coding block may be configured by a modulator, an interleaver, a channel encoder, and the like. The modulation block may include an IFFT operator for mapping data to each subcarrier when the wireless communication system uses the orthogonal frequency division multiplexing method. The RF transmission block may be composed of a filter and an RF preprocessor.

According to the above-described embodiments, after the remote node receives the forward channel from the host node, it does not immediately respond and transmits the reverse channel considering the state of the channel, thereby improving the efficiency of channel transmission , It is possible to reduce unnecessary power consumed in channel reception by intermittently measuring the forward channel received from the host node. In particular, by measuring the channel state in a reception period of a signal that must be received from the host node, power consumed in channel state measurement can be minimized. Accordingly, the operation time of the terminal can be greatly improved when the battery is used in the mobile communication terminal or the like.

In addition, according to the present embodiments, the performance of the reverse channel transmission can be optimized by variably setting the channel condition in consideration of the change of the channel state. That is, it is possible not only to increase the detection probability of the host node against the same transmission output, but also to reduce the transmission power of the remote node at the same performance. This enables more efficient, low power channel adaptive random access channel transmission.

In the meantime, the embodiments can be embodied in a computer-readable code on a computer-readable recording medium. At this time, the computer-readable recording medium includes all kinds of recording apparatuses in which data that can be read by a computer system is stored. Examples of the computer-readable recording medium include a ROM, a RAM, a CD-ROM, a magnetic tape, a floppy disk, an optical data storage device, and the like in the form of a carrier wave (for example, transmission over the Internet) . In addition, the computer-readable recording medium may be distributed over network-connected computer systems so that computer readable codes can be stored and executed in a distributed manner. And functional programs, code, and code segments for implementing the embodiments can be deduced by the programmers of the art to which the embodiments belong.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit and scope of the invention as defined by the appended claims. The embodiments of the present invention are not intended to limit the scope of the present invention but to limit the scope of the present invention.

1200: Remote Node
1210: Antenna 1220: Receiver
1230: Transmitting section 1240: Channel estimating section
1250: Control section 1260: Doppler frequency estimating section

Claims (19)

Receiving a paging message from a host node by intermittently receiving a forward channel by operating a receiver in a period during which the remote node receives a paging message from the host node;
Measuring a state of the forward channel in a period in which the paging message is received;
Estimating a state of the reverse channel from the measured state of the forward channel;
Comparing a state of the estimated reverse channel with a predetermined channel condition to determine whether to transmit the reverse channel to the host node; And
And transmitting an uplink channel to the host node if the estimated state of the uplink channel satisfies the preset channel condition.
delete The method according to claim 1,
The step of measuring the state of the forward channel comprises:
And the receiver measures the state of the forward channel by operating the receiver in a predefined interval between the intervals of receiving the paging message from the host node.
The method of claim 3,
The step of measuring the state of the forward channel comprises:
And setting a period and a period for measuring a state of the forward channel through a control message received from the host node.
The method according to claim 1,
The step of measuring the state of the forward channel comprises:
And measuring a state of the forward channel in a predetermined interval and period according to a control message received from the host node.
The method according to claim 1,
The step of measuring the state of the forward channel comprises:
And measuring a state of the forward channel in an interval during which the beacon is received from the host node during a period of intermittently receiving the forward channel.
The method according to claim 1,
The step of measuring the state of the forward channel comprises:
And increasing a time interval between intervals in which the forward channel is measured in proportion to a time allowed to transmit the reverse channel.
The method according to claim 1,
The step of measuring the state of the forward channel comprises:
And decreasing a time interval between intervals in which the forward channel is measured when a transmission event of the reverse channel occurs and a predetermined time elapses.
The method according to claim 1,
The step of measuring the state of the forward channel comprises:
Wherein the remote node transitions to a sleep state in a period other than a predetermined period that measures the state of the forward channel.
The method according to claim 1,
And transmitting the reverse channel to the host node if the estimated state of the reverse channel satisfies a preset channel condition,
The channel condition is set using a Doppler frequency estimated from a quality of a service requested by a user or a change in a signal received through the forward channel, and if the estimated reverse channel condition satisfies the set channel condition, And transmitting the reverse channel to the node.
A receiver intermittently receiving a forward channel by operating a receiver in an interval of receiving a paging message from a host node;
A channel estimator for measuring a state of the forward channel in an interval for receiving the paging message and estimating a state of the reverse channel based on the measured state of the forward channel;
A controller for determining whether a state of the estimated reverse channel satisfies a predetermined channel condition and for determining whether to transmit an uplink channel; And
And a transmitter for transmitting the uplink channel to the host node when the controller determines that the estimated state of the uplink channel satisfies the preset channel condition,
.
12. The method of claim 11,
Wherein the channel estimator comprises:
Wherein the remote node measures a state of the forward channel by operating a receiver in a predetermined interval between intervals in which the paging message is received from the host node.
12. The method of claim 11,
Wherein the channel estimator comprises:
And setting a period and a period for measuring the forward channel according to a control message received from the host node.
12. The method of claim 11,
The receiver may further comprise:
Wherein the channel estimator maintains the power consumption at a minimum in an interval in which the state of the forward channel is not measured.
12. The method of claim 11,
And a Doppler frequency estimator for estimating a Doppler frequency through a change in a signal received by the receiver.
16. The method of claim 15,
Wherein,
The remote node determines whether to transmit the uplink channel by comparing the quality of the service requested by the user or the estimated uplink channel with a threshold set using the estimated Doppler frequency. The method according to claim 1,
Wherein determining whether to transmit an uplink channel to the host node comprises:
And determining whether to transmit a reverse random access channel to the host node.
18. The method of claim 17,
Further comprising delaying transmission of the RBs if the estimated state of the RBs does not satisfy the preset channel condition.
12. The method of claim 11,
Wherein,
Determining whether or not to transmit a reverse random access channel if the estimated reverse channel condition satisfies the preset channel condition, and if the estimated reverse channel condition does not satisfy the preset channel condition, A remote node deferring transmission of a reverse random access channel.

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