KR20170012528A - Multi-channel low energy communication method and apparatus - Google Patents

Abstract

An embodiment of the present invention relates to a multi-channel low power communication method for low power communication and an apparatus thereof. The multi-channel low power communication method comprises the steps of: transmitting a request to send (RTS) to a receiver through each of a plurality of communication channels; receiving a clear to send (CTS) from the receiver in response to the RTS; and transmitting a data packet through the whole or a part of at least one communication channel, receiving the CTS, among the plurality of communication channels.

Description

[0001] MULTI-CHANNEL LOW ENERGY COMMUNICATION METHOD AND APPARATUS [0002]

An embodiment of the present invention relates to a multi-channel low-power communication method and apparatus for low-power communication.

As the number of mobile internet users continues to increase due to the widespread use of smart devices, and as real-time traffic such as high-volume multimedia applications such as voice and video is increasing, bandwidth and speed of network devices are increasing to accommodate them. With the rapid spread of high-performance intelligent mobile terminals, users' desires are also constantly diversifying and increasing.

However, energy consumption is also increasing in proportion to the performance of network devices. Because wireless communication devices equipped with advanced communication technologies use a powerful processor, a large memory, a large screen, and an open operating system, the energy budget of the wireless communication interface under limited battery capacity is very limited. Wireless communication systems continue to evolve rapidly to accommodate additional components and technologies for new functionality and performance improvements, but battery size and capacity are slowly evolving. Therefore, a method of efficiently using a limited battery capacity for a longer period of time is becoming an essential and important issue in wireless communication systems.

2. Description of the Related Art [0002] Recently, since the capacity of a wireless communication portable terminal is limited, studies for reducing energy consumption have been actively conducted. It is known that most energy is inefficiently consumed in a wireless communication interface in portable devices such as smart phones, tablets, notebooks, and sensors.

Since the battery capacity of portable terminals and sensors is limited, it is essential to minimize energy consumption. In this mobile node, most of the energy is consumed in the CPU and the wireless communication interface. The CPU can save energy by adjusting the clock frequency and supply voltage variably according to the load to be processed and the requirements of the application program. That is, if it is possible to operate the CPU with low frequency and low voltage, or if there is no work to be done, the operation is stopped until something needs to be done.

The wireless interface, on the other hand, reduces power usage by the following three techniques.

1) Stay awake only if there is data to exchange with another wireless device; otherwise, keep the low power mode and reduce energy consumption.

2) If received packet is different from its ID, do not process data and reduce energy consumption.

3) Techniques such as the above 1 and 2 make the mobile node operate without considering the given environment and constraints, which is inefficient. Therefore, in the existing wireless modem physical layer, it is necessary to design a low operating frequency, minimize the supply voltage, design a lower complexity, and adjust the clock frequency and supply voltage variably according to the load to be processed, have.

However, there are limitations in operating frequency, supply voltage, and complexity that can not be lowered due to limitations of existing semiconductor process technology. There is a trade-off relationship between these three factors and performance. have.

Typical limitations of wireless LAN technology include inefficient energy efficiency, interference problems, coverage, transmission capacity, and unstable transmission speed. Although a large number of APs are installed due to the spread of smart devices equipped with a wireless LAN chip, actual performance is increased due to a problem that overlapping service areas between APs and frequent collision of signals due to hidden node problems Does not meet the expected level.

In particular, the wireless LAN needs high frequency digital processing to support high performance services. Therefore, the biggest problem is that the power consumption is very high because the hardware size is very large and the use voltage is relatively high.

In order to overcome this problem, the power saving protocol of the MAC level is defined as a sleep mode, and when there is no packet to be exchanged, the power saving mode is switched to the sleep mode to cut off unnecessary circuit clock or voltage supply to save power . In the MAC layer, energy is wasted only when there is data to be exchanged with another wireless device by using a separate control signal transmitted / received periodically. Otherwise, energy consumption can be reduced by maintaining a low power mode.

At this time, the control signal usually has a relatively long time period because of the hardware and software interrupt processing problems of the MAC layer. Because of the trade-off relation between performance (quality of service such as throughput and delay) and power consumption, There is a limitation in using the above.

In the active mode other than the sleep mode, since it is not always known whether a packet will be received, it should always be in a reception standby state. Even if a packet is received, there is no guarantee that the received packet is a packet that should be received by itself. There is a limitation in saving power as the existing technology.

Through the embodiments of the present invention, in a wireless communication system supporting multiple channels, power is reduced by controlling a transmission scheme based on power consumption efficiency of a hardware resource, channel environment, and battery information.

Basically, the power consumption of the wireless communication device increases in proportion to the hardware resources used and the operating frequency. As the frequency bandwidth used by the wireless communication device is wider, the power consumption increases. In addition, The more non-adjacent bands are used, the more hardware resources are used.

 The present invention can extend the battery life time of a wireless communication device by controlling a transmission mode based on power consumption efficiency, channel environment, and battery information in a battery-limited wireless communication device.

A multi-channel low-power communication method, comprising: transmitting a request to send (RTS) to a receiver via each of a plurality of communication channels; Receiving Clear to Send (CTS) from the receiver in response to the RTS; And transmitting a data packet through all or a part of at least one communication channel that has received the CTS among the plurality of communication channels.

In one aspect, the step of transmitting a data packet through all or a part of at least one or more communication channels that have received the CTS among the plurality of communication channels may include transmitting at least one communication channel ; And transmitting the data packet over the bonded communication channel.

In yet another aspect, at least one of the RTS and the CTS may comprise a multi-channel power save information field for multi-channel power save.

In another aspect, the multi-channel power save information field includes a multi-channel power save information field including at least one of a category of the multi-channel power save mode, whether the multi-channel power save information field supports the multi-channel power save mode, A band information field for adjacent channels and non-adjacent channels; An ID information field including destination information of the data packet; And a lifetime information field including at least one of a remaining lifetime of the transmitter and a remaining battery time of the transmitter.

In another aspect, the category of the multi-channel power save mode includes information on whether to recommend an adjacent channel bonding transmission scheme or a non-adjacent channel carrier aggregation transmission scheme; Information on selection of a channel according to a channel state; And information on selection of a channel according to a battery state.

In another aspect, the ID information includes a plurality of destination information, and each of the plurality of destination information may correspond to destination information related to the plurality of destination for each communication channel.

In another aspect, the data packet may not be transmitted to a communication channel that does not receive the CTS among the plurality of communication channels.

In another aspect, the step of transmitting a data packet through all or a portion of at least one or more communication channels that have received the CTS among the plurality of communication channels comprises the steps of carrier aggregating the non- , Controlling the input path chain for transmission of the data packet of each of the non-adjacent channels using a regulator.

Through the embodiments of the present invention, a power saving technique of the physical layer for wireless communication can be provided. The battery life time of the wireless communication device can be extended by controlling the transmission mode based on the power consumption efficiency, the channel environment, and the battery information in the battery-limited wireless communication device.

In addition, power consumption can be reduced by controlling a transmission method based on power consumption efficiency of a hardware resource, a channel environment, and battery information in a wireless communication system supporting multiple channels through embodiments of the present invention.

Basically, the power consumption of the wireless communication device increases in proportion to the hardware resources used and the operating frequency. The wider the frequency bandwidth used by the wireless communication device, the greater the power consumption. The more non-adjacent bands carrying non-adjacent channel carrier aggregation, the more hardware resources are used.

Therefore, the present invention can extend the battery life time of the wireless communication device by controlling the transmission mode based on the power consumption efficiency, the channel environment, and the battery information in the battery-limited wireless communication device.

1 shows an example of a channel allocation policy for a 5 GHz band channel allocation.
FIG. 2 is a diagram illustrating a PIFS-based multi-channel access method and a static bandwidth allocation method.
3 is a diagram for explaining a dynamic bandwidth allocation method in an embodiment of the present invention.
4 is a flowchart illustrating a multi-channel low-power communication method according to an exemplary embodiment of the present invention.
5 is a diagram for explaining a multi-channel low-power communication method in an embodiment of the present invention.
6 illustrates an example of a multi-channel low power communication method in an embodiment of the present invention.
FIG. 7 illustrates an embodiment in which a long aggregation packet is transmitted using data and an ACK signal in an embodiment of the present invention.
8 is a block diagram illustrating a configuration of an adjacent channel bonding transmitting and receiving apparatus according to an embodiment of the present invention.
9 shows a transmission spectrum used in an adjacent channel bonding transmission spectrum and a multi-channel power save mode in an embodiment of the present invention.
10 is a block diagram for explaining a configuration of a non-adjacent channel carrier aggregation transmission / reception apparatus in an embodiment of the present invention.
11 shows an example of a non-adjacent channel carrier aggregation spectrum and a non-adjacent channel carrier aggregation spectrum of a multi-channel power save mode, in an embodiment of the present invention.
12 to 16 illustrate an example of a multi-channel low-power communication method of non-adjacent channel carrier aggregation in an embodiment of the present invention.
17 is a diagram for explaining the configuration of a multi-channel power save information field in an embodiment of the present invention.
18 is a view for explaining an IEEE 802.11 physical layer structure in an embodiment of the present invention.
19 is a block diagram illustrating a configuration of a multi-channel low-power communication system according to an embodiment of the present invention.

Hereinafter, a multi-channel low-power communication method and a system thereof will be described in detail with reference to the accompanying drawings.

The WLAN system operates as a contention-based and collision-avoidance-based transmission scheme of the CSMA / CA (Carrier Sense Multiple Access / Collision Avoidance) protocol. That is, it is determined whether there is another signal for a predetermined time in the currently used channel, and if there is no signal, it is judged as an empty channel state (Idle) and transmission is attempted. If carrier sensing is performed, (Busy) and reserves transmission.

On the other hand, the wireless LAN system defines a power saving protocol that notifies whether there is a packet to be exchanged by using a beacon signal. When a beacon signal indicating that there is no packet to be exchanged is received, the terminal using the power saving mode switches to the sleep mode, consumes only the minimum power, waits until the next beacon, wakes up after a predetermined time, This power saving protocol is implemented in the MAC layer or higher, and always has to operate in the receive mode when the terminal is wake up and active in the packet to be exchanged.

1 shows an example of a channel allocation policy for a 5 GHz band channel allocation. The wireless LAN system has increased the data rate by expanding the channel bandwidth. The channel bandwidths are arranged so that they do not overlap in each bandwidth mode. Referring to the channel allocation policy of the 5 GHz ISM band as shown in FIG. 1, IEEE 802.11a has a bandwidth of 20 MHz, and IEEE 802.11n has a bandwidth of 20 MHz or 40 MHz. IEEE 802.11ac has a bandwidth of 20 MHz, 40 MHz, 80 MHz or 80 + 80 MHz and 160 MHz.

Hence, heterogeneous standard terminals may exist in the same / adjacent channel in the adjacent location. That is, the IEEE 802.11a terminal, the IEEE 802.11n terminal, the IEEE 802.11ac terminal, and the IEEE 802.11ac standard terminal may operate in the same service network area. This situation is the same in the 2.4 GHz band and the 1 GHz band and below. This situation is a cause of preventing the terminals that want to be provided with high-speed service by supporting wide bandwidth to easily obtain such opportunities due to the same / adjacent channel interference.

FIG. 2 is a diagram illustrating a PIFS-based multi-channel access method and a static bandwidth allocation method.

In a wireless LAN, a CSMA-based channel bonding protocol is used. As shown in (a) of FIG. 2, a terminal that transmits and transmits four channels is required to transmit not only primary channels but also primary channels The Channel Clear Assessment (CCA) is checked periodically and data can be transmitted using all four channels only when the channel is empty (AIFS + Backoff and PIFS) for a certain period of time.

However, as described above, it is very difficult to satisfy these conditions in a congested wireless channel situation. That is, if one of the channels to be bonded does not satisfy the condition (gray represents an interference signal) as shown in FIG. 2 (b), it is not possible to get a transmission opportunity and wait again. Only when all four channels are empty for a certain period of time, data can be transmitted using all channels.

To solve this problem, a dynamic bandwidth allocation method as shown in FIG. 3 can be used. In an embodiment, instead of using all four channels in an environment having four channels as a whole, a method of transmitting a channel by bonding only two channels satisfying the condition can be used. If another signal exists in a subchannel to which a channel is to be transmitted, other channels except the channel can be transmitted using the other channel.

4 is a flow chart for explaining a multi-channel low-power communication method in an embodiment of the present invention. The method according to the embodiment is for the case of using RTS (Request to Send) and CTS (Clear to Send) in the embodiment of FIG. May be performed between the transmitter and the receiver of the data.

In step 410, the transmitter may transmit the RTS to the receiver through each of the plurality of communication channels, and the receiver may receive the RTS transmitted from the transmitter. Also, in step 420, the receiver may select one or more communication channels from among the plurality of communication channels that received the RTS.

In step 430, the receiver may transmit the CTS to the transmitter in response to the RTS for the selected communication channel, and the transmitter may receive the CTS transmitted from the receiver. In step 440, The receiver may transmit the data packet to the receiver through all or a portion of the one or more communication channels that have received the data packet, and the receiver may receive the data packet from the transmitter.

In the embodiment, the method described with reference to FIG. 3 can effectively operate also in the case of using RTS and CTS. The dynamic bandwidth allocation protocol of FIG. 4 can be effectively operated by transmitting static / dynamic bandwidth allocation mode information and bandwidth mode information to a data packet, and FIG. 5 illustrates a dynamic bandwidth allocation method using RTS and CTS . The RTS and CTS include a multi-channel power save information field for multi-channel power save, the fields of which will be described in detail later.

In step 420, one or more communication channels among the plurality of communication channels receiving the RTS may be selected based on the respective channel states and interference states of the plurality of communication channels receiving the RTS.

Also, in step 440, the transmitter may bond the at least one communication channel that received the CTS and transmit the data packet over the bonded communication channel. Here, among the plurality of communication channels, it is possible not to transmit the data packet to the communication channel that does not receive the CTS.

The receiver may include determining one or more communication channels when receiving a data packet from a transmitter of the one or more communication channels selected in step 440. In an embodiment, a communication channel may be determined by identifying a CTS comprising information about one or more communication channels from which to receive data packets from a transmitter of the selected one or more communication channels.

The step of determining a communication channel may be determined based on a channel state of each of the selected one or more communication channels and a battery capacity (or energy budget information) of the transceiver, wherein the usage efficiency of the selected one or more communication channels, A higher channel may be determined as a communication channel from which to receive data packets from the transmitter. Alternatively, it may be determined for adjacent channels among the selected one or more communication channels.

Power efficiency is a consideration for the transmission method to efficiently use such channel bandwidth. It should be operated according to the battery condition of the transceiver, the performance target, and the surrounding situation. The higher the bandwidth used, the greater the power consumption of the wireless communication device. This is because the higher the bandwidth, the higher the processing speed (operating frequency) of the wireless communication circuit.

6 illustrates an example of a multi-channel low power communication method in one embodiment of the present invention. UB means a unit band supported by a wireless communication device. For example, in the case of a wireless LAN, UB is 20 because a minimum unit channel is determined in units of 20 MHz.

The secondary channel is defined as a secondary channel, the secondary channel is represented by a secondary UB, the secondary channel is represented by a secondary channel, and a secondary channel is defined by a tertiary channel and a quaternary channel . The multi-channel power save information A and B means an information field for transmission using a multi-channel power save technique.

6A shows an example of a multi-channel power save in which RTS is transmitted to four bands for aggregation and transmission of four bands, but communication is performed using only two bands. The transmitter may request the multi-channel power save via the multi-channel power save information field of the RTS, or the receiver may request through the multi-channel power save information field of the CTS.

By transmitting the RTS in this way, the transmitter can inform other nodes (receivers) included in the network that the channel is being used for power saving purposes, and the receiver can request the transmitter to reduce the transmission bandwidth for power save have.

6B uses less channels than the case of FIG. 6A. Therefore, if FIG. 6A reduces the operating frequency by 1/2, FIG. The effect of reducing the operating frequency can be obtained. Therefore, according to the present invention, the power consumption efficiency can be improved.

FIG. 6 (c) shows a case where a request is made to use a narrower channel for data packet transmission while transmitting the CTS. The channel state and network interference can be measured during the exchange of RTS and CTS, and the power save efficiency can be improved by using RTS and CTS considering the battery capacity and channel condition of the wireless device.

In an embodiment, a multi-channel low-power communication method can be performed over data packets and ACK frames without the use of RTS or CTS.

FIG. 7 illustrates an embodiment in which a long aggregation packet is transmitted using data and an ACK signal in an embodiment of the present invention.

FIG. 7A shows a case where the bandwidth is reduced to 1/2 of the available bandwidth to lower the operating frequency. FIG. 7B shows a case where a short data packet is transmitted before a long aggregation data packet is transmitted, After the save environment is set, a long aggregation data packet is transmitted through the determined channel.

Here, the short data packet is a data packet transmitted on all the channels in FIG. 7, and is transmitted before the long aggregation data packet is transmitted, compared with the long aggregation data packet transmitted after receiving the ACK frame It uses the term "short data packet" because it is relatively short. By transmitting a "short data packet ", the transmitter can receive from the receiver information about a channel suitable for power save among a plurality of channels. On the contrary, a long aggregation data packet means a data packet actually transmitted to a receiver, and the term is used because it is relatively long compared to a short data packet.

In a multi-channel low-power method using a data packet and an ACK frame, a transmitter transmits a long aggregation data packet through a bonded communication channel by bonding at least one communication channel that received a short data packet among a plurality of communication channels, Lt; / RTI > At this time, among the plurality of communication channels, a long aggregation data packet may not be transmitted to the communication channel that has not received the ACK frame.

Here, at least one of the short data packet and the ACK frame may include a (multi-channel power save) information field for multi-channel power save.

8 is a block diagram for explaining a configuration of an apparatus for transmitting and receiving an adjacent channel by bonding in an embodiment of the present invention. A baseband processor 805, and a sensor 806. The transmission / reception antenna 801, the front end module 802, the transmission / reception unit 803, the ADC and the DAC 804, the baseband processor 805,

The radio signal is transmitted and received via the antenna 801. The front end module 802 serves as an interface between the transmission / reception antenna 801 and the transmission / reception unit 803. The front end module 802 may include various external devices not included in the transmission / reception unit 803 or devices for performance enhancement and function expansion. For example, external transmit power amplifiers or external receive low noise amplifiers, switches, and the like may be included. The transmission / reception unit 803 modulates and transmits a packet to be transmitted, and performs a function of demodulating the received packet. The ADC and DAC 804 convert the signal form between the analog signal and the digital signal.

The baseband processor 805 performs a function of extracting information from a frame or generating a frame according to a transmission frame format, and compensating for a signal distorted by encoding and decoding, a channel or an analog device. The back-end processor of the baseband processor 805 performs processing for sampling and filtering at the forefront of the digital circuit, channel mixing, and sending it to the analog circuitry. Sampling, filtering, and channel mixing circuits use a clock controller and a mode controller to maintain the same signal format (bandwidth, etc.) even when the operating frequency of the wireless communication transceiver is changed. For example, if the operating frequency of a wireless communication system is reduced to ½, if there is no other processing, the bandwidth of the spectrum in the frequency domain is reduced to ½, and the sampling is doubled. It can maintain the same signal format as before changing the operating frequency.

The sensor 806 is a sensor module for sensing the battery information and the state of the wireless device, and informs the mode controller of the sensing result.

9 shows a transmission spectrum used in an adjacent channel bonding transmission spectrum and a multi-channel power save mode in an embodiment of the present invention. 9 (a), if the required operating frequency is f when four bands are bonded and transmitted, only one band is used as shown in FIG. 9 (b) by all of the multi-channel power save, In the case where the receiver is agreed, wireless communication is possible using only the operating frequency of f / 4.

10 is a block diagram for explaining a configuration of a non-adjacent channel carrier aggregation transmission / reception apparatus in an embodiment of the present invention. The adjacent channel bonding transmitting and receiving apparatus shown in FIG. 8 may be connected through a coordinator.

In the case of carrier aggregation and transmission of non-adjacent channels, energy consumption becomes very large because additional hardware resources need to be operated. This is because RF and ADC and DAC for each channel transmission and reception may be separately required because the interval between non-adjacent channels is considerably large. However, if the battery power resource is the primary criterion for determining the transmission mode, transmitting using this non-adjacent channel carrier aggregation scheme is very inefficient in terms of power efficiency.

The coordinator of FIG. 10 may control the input path chain for transmission and reception of each of the non-adjacent channels. According to this control, the mode controller of each path can control the clock controller and its peripheral devices.

11 shows an example of a non-adjacent channel carrier aggregation spectrum and a non-adjacent channel carrier aggregation spectrum of a multi-channel power save mode, in an embodiment of the present invention.

11 (a) shows a spectrum when carrier aggregation is performed on non-adjacent channels each of which is connected with four adjacent channels. The wireless terminal may select the best available band among the available bands to reduce battery usage, and transmit the selected band using a multi-channel power save technique in a narrow band.

11 (b) shows an example of carrier aggregation transmission using only one band among non-adjacent channels. 11C shows an example in which adjacent channel bonding transmission is performed by driving to one band rather than using twice the hardware resources to support transmission and reception of non-adjacent channel carrier aggregation. FIG. FIG. 11 (c) shows an example of operating in the lowest operating frequency mode to consume lower power.

12 to 16 illustrate an example of a multi-channel low-power communication method of non-adjacent channel carrier aggregation in an embodiment of the present invention.

Figure 12 is an example of a multi-channel power save of nonadjacent channel carrier aggregation. In this figure, BG represents a band gap indicating a frequency interval between non-adjacent channels. BO represents a Band Offset which means the interval between the center frequencies of non-adjacent channels. Basically, the wireless communication system periodically checks the battery usage and compares the remaining battery usage (energy budget) with the function that the wireless communication system has to perform and the target (life time, etc.) The channel power save transmission method is used to reduce the transmission bandwidth or to transmit the adjacent channel aggregation transmission method instead of the non-adjacent channel aggregation transmission method.

FIG. 13 shows an example of carrier aggregation transmission using only one of the non-adjacent channels, and FIG. 14 shows an example in which band allocation is performed in one band To perform adjacent channel bonding transmission.

Also, FIG. 15 shows an example of operating in the lowest operating frequency mode to consume lower power in FIG.

Figure 16 is for the case where an interference signal is present. The bandwidth to be used and the band to be used can be specified and used by using the multi-channel low-power communication method of the present invention. In the case where it is determined that not only the interference signal but also the usage efficiency of the corresponding channel is deteriorated as compared with the battery usage to be used according to the channel state, only a good channel is selected and transmitted.

17 is a diagram for explaining the configuration of a multi-channel power save information field in an embodiment of the present invention. The multi-channel power saving information field according to the embodiment includes multi-channel power save information 171, band information 172, ID 173, life time 174 ). ≪ / RTI >

The multi-channel power save information 171 includes information on whether the multi-channel power save mode is supported, i.e., whether the multi-channel power save mode is supported, Category) can be included. The multi-channel power save mode category is the recommended power save transfer method according to the multi-channel power save mode policy.

1) Multichannel power save policy information from the viewpoint of hardware power consumption efficiency: For example, information indicating whether the adjacent channel bonding transmission scheme or the non-adjacent channel carrier aggregation transmission scheme is further recommended. Since the power consumption of the hardware resource is different for each terminal, the power consumption efficiency of the adjacent channel bonding and the non-adjacent channel carrier aggregation transmission method will be different. This information can tell you which of these two is more recommended.

2) Multichannel power save policy information in view of network operation efficiency: It is information to support band selective transmission scheme according to channel state. That is, from the viewpoint of network operation efficiency, it would be energy efficient to use only a band having a good channel state.

3) Multichannel power save policy information based on battery information: It can support multi-channel power save transmission by providing information such as whether battery warning should be transmitted to minimize battery consumption or recommend direct transmission method.

The band information 172 may include band information of adjacent or non-adjacent channels. Band information 1 and band information 2 may include dynamic / static bandwidth allocation of adjacent bands, bandwidth, bandwidth category, band information to be used, and the like. Band Offset refers to the center frequency spacing of two non-adjacent bands.

The ID information 173 may include at least one or more of the non-adjacent channels in the multi-channel power save information field so as to distinguish the wireless communication devices having different destinations. For example, if ID 1 is for communicating with terminal 1 using the f1 frequency channel, then ID 2 may correspond to terminal 2 using the f2 frequency channel.

The lifetime 174 information field may include remaining lifetime of the wireless communication terminal that transmits the packet and battery margin information as to the required function.

18 is a view for explaining an IEEE 802.11 physical layer structure in an embodiment of the present invention. The physical layer structure of IEEE 802.11 is composed of PLME (Physical Layer Management Entity), PLCP (Physical Layer Convergence Entity) sublayer, and PMD (Physical Medium Dependent) sublayer. The PLME provides the management function of the physical layer by acting as an interface between the MAC Layer Management Entity (MLME) and the physical layer. The PLCP sublayer transmits an MPDU (MAC Protocol Data Unit) received from the MAC sublayer according to a signal generated by the control of the MAC layer between the MAC sublayer and the PMD sublayer, or transmits a frame from the PMD sublayer to the MAC sublayer . The PMD sublayer supports the physical layer so that it can transmit and receive between two terminals via the wireless medium as a PLCP lower layer. The MPDU transmitted by the MAC sublayer is called a physical service data unit (PSDU) in the PLCP sublayer. An A-MPDU that aggregates multiple MPDUs can be delivered.

The PLCP sublayer adds a field containing information required by the physical layer transceiver in the process of receiving the PSDU from the MAC sublayer to the PMD sublayer. The added fields include a PLCP preamble, a PLCP header, a tail bit for initializing the convolution encoder, and the like in the PSDU.

The PLCP preamble consists of a periodic and repetitive sequence to allow the receiver to synchronize, gain control, or know the channel state to successfully recover the PSDU. The PLCP header contains information necessary for restoring the PSDU.

For example, packet length, bandwidth, MCS, and techniques used for transmission. The data field may include a service field containing an initialization sequence for initializing the scrambler and a sequence encoded by appending tail bits. The data field is modulated, encoded and transmitted according to the transmission type contained in the PLCP header. The transmitting PLCP sublayer generates PPDUs and transmits them through the PMD sublayer. The receiving side receives the PPDUs, performs synchronization and gain control with the PLCP preamble, obtains channel status information, and transmits the PLCP header Obtain and restore information necessary for packet restoration.

The IEEE 802.11ac standard supports 80 MHz bandwidth while supporting the 20 MHz or 40 MHz bandwidth mode supported by the IEEE 802.11n standard. It is possible to transmit two non-contiguous 80 MHz simultaneously (non-contiguous 160 MHz) or a continuous 160 MHz bandwidth signal (Contiguous 160 MHz).

An AP supporting the IEEE 802.11ac standard can simultaneously transmit packets to at least one terminal using MU-MIMO (Multi-user MIMO) transmission technology. In a basic service set of a wireless LAN, an AP transmits data classified into different spatial streams to groups including at least one of a plurality of terminals associated with the AP. Can be transmitted simultaneously. The AP can also transmit data only to a UE using a single user MIMO (SU-MIMO) scheme.

If beamforming technology is supported between APs and terminals belonging to the network, the signal can be transmitted to a single terminal or terminal group of a specific target with high signal gain. In order to support MU-MIMO transmission, a group ID for a terminal group is allocated, and an AP transmits a group ID management frame to allocate and allocate a group ID. One terminal can be assigned a plurality of group IDs.

The functions of the WLAN terminal or the AP may differ depending on the vendor implementing the system and manufacturing the chip. In addition to the mandatory implementations, the standard specifies what to implement selectively, and the features supported by the version of the implementation may vary. Convolutional encoding, for example, is a mandatory implementation, but LDPC (Low Density Parity Check) is an optional implementation, and beamforming, MU-MIMO, and 160MHz bandwidth support are optional implementations.

When transmitting the PPDU, the WLAN system transmits the header information including the signal information for correctly restoring the PPDU in the header field. Since this signal information is very important for restoring PPDU data, it is transmitted to the lowest MCS so as to be strong against channel change and noise.

The VHT PPDU is divided into L-STF, L-LTF, L-SIG, VHT-SIGA, VHT-STF, VHT-LTF and VHT-SIGB data. The HT PPDU is divided into L-STF, L-LTF, L-SIG, HT-SIG, HT-STF and HT-LTF data. do.

The L-STF is used for carrier sensing to detect that a signal is present in the currently used channel, and to adapt the radio signal input to the antenna to the operating area of the analog circuit and the analog-to-digital converter (Automatic gain control), and frequency offset correction.

L-LTF is used for frequency offset correction and symbol synchronization, and is used for channel response estimation for demodulation of L-SIG field and HT-SIG field or VHT-SIG field. The signal-to-noise ratio can be estimated using the principle that the two symbols are repeated.

By using repetitive sequences such as L-STF and L-LTF, various characteristics of the channel such as interference, Doppler, and delay spread can be estimated.

Signal fields such as L-SIG, HT-SIG, and VHT-SIG include control information necessary for demodulating a PPDU receiving terminal or an AP receiving PPDU. Such as packet length, MCS, bandwidth and channel encoding scheme, beamforming, STBC, smoothing, MU-MIMO, and short guard interval mode. In case of VHT-SIG, it is divided into the VHT-SIGA field and the VHT-SIGB field separately for the common control information and dedicated information required for the specific MU group. But also ID information such as a group ID and a partial association ID (PAID).

The HT-STF or VHT-STF is used to improve the gain control performance of the AGC, and additional gain control is indispensable especially when the beam forming technique is used.

HT-LTF or VHT-LTF is used by the terminal or the AP to estimate the channel. Unlike the legacy standard, the 11n or 11ac standard increases the throughput by increasing the number of subcarriers used. Therefore, in addition to L-LTF, a new LTF is defined for data recovery. In the case of VHT-LTF, a pilot signal for offset correction is also included.

The data field includes data information to be transmitted. In this field, the MPDU of the MAC layer is converted into a PSDU and the service field and the tail bit are transmitted.

When the frame includes low power information to support the low power mode of the present invention, the transmitter and the receiver can communicate more efficiently. That is, the transmission method to be used can be selected based on the multi-channel power saving information included in the signal information of the received packet, the band use information, and the ID information. Particularly, the power consumption efficiency can be increased by reducing the bandwidth used for the low power transmission and transmitting the selectively determined channel through the data packet.

19 is a block diagram illustrating a configuration of a multi-channel low-power communication system according to an embodiment of the present invention.

The system 1900 according to the embodiment includes a transceiver antenna 1901, a front end module 1902, a transmitter / receiver 1903, a DAC / ADC 1904, a baseband processor 1905, a host interface 1906, And may further include a radio interface 1907, a processor 1908, a memory 1909, and an input / output interface 1910.

The data packet may be transmitted and received via one or more antennas 1901. [ The interface between the transmission / reception antenna 1901 and the transmission / reception unit 1903 can be handled by the front end module 1102.

The front end module 1902 may include various external elements not included in the transmitter / receiver unit 1903, or elements for performance enhancement and function extension. For example, an external transmission power amplifier or an external receiving low noise amplifier, a switch, or the like may be included.

The transmission / reception unit 1903 modulates and transmits a packet to be transmitted, demodulates the received packet, and the DAC / ADC 1904 can convert the signal format between the analog signal and the digital signal as needed have.

The baseband processor 1905 functions to generate a frame according to a transmission frame format or to extract information from a reception frame and to compensate for a signal distorted by encoding and decoding and a channel or an analog component. May serve as an interface between the wireless communication modem and the host interface 1906.

Processor 1908 may be configured to generate and transmit a PPDU format and may be configured to receive the transmitted PPDU and interpret the respective field information in the received packet to obtain control information and use it to restore data . The processor or transceiver may comprise an application specific integrated circuit (ASIC), a logic circuit, or a data processing device.

The memory 1909 may include at least one of a read only memory (ROM), a read access memory (RAM), a flash memory, a memory card, and a storage device. The input device to the input / output interface 1910 may be a keyboard, a keypad, a microphone, a camera, etc., and the output device may be a display means, a speaker, or the like.

Through the embodiments of the present invention, it is possible to provide a technique for power saving of the physical layer for wireless communication. In the embodiment, the battery life of the wireless communication device can be extended by controlling the transmission mode based on the power consumption efficiency, the channel environment, and the battery information in the battery-limited wireless communication device, In the communication system, power can be saved by controlling the transmission method based on the power consumption efficiency of the hardware resource, the channel environment, and the battery information.

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

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

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

Claims (8)

In a multi-channel low-power communication method,
Receiving information on a channel bandwidth of a transmitter from the transmitter; And
Determining a channel bandwidth for communicating with the transmitter based on the received information to reduce power consumption
/ RTI >
Channel low power communication method.
The method according to claim 1,
Wherein the determining comprises:
Determining a channel bandwidth less than a current channel bandwidth as a channel bandwidth for communicating with the transmitter
/ RTI >
Channel low power communication method.
The method according to claim 1,
Wherein the determining comprises:
Determining a channel bandwidth for communicating with the transmitter based on at least one of a battery state and an interference state
/ RTI >
Channel low power communication method.
The method according to claim 1,
Wherein the operating frequency of the receiver decreases with the determined channel bandwidth,
Channel low power communication method.
In a multi-channel low-power communication method,
Transmitting information on a channel bandwidth of a transmitter to a receiver; And
Communicating with the receiver in a power save mode using the channel bandwidth determined by the receiver
Lt; / RTI >
The receiver includes:
Determine a channel bandwidth for communicating with the transmitter to reduce power consumption based on information received from the transmitter,
A multi-channel low-power communication method of a transmitter.
6. The method of claim 5,
Wherein the receiver determines a channel bandwidth less than a current channel bandwidth as a channel bandwidth for communicating with the transmitter,
A multi-channel low-power communication method of a transmitter.
6. The method of claim 5,
Wherein the receiver determines a channel bandwidth for communicating with the transmitter based on at least one of a battery condition and an interference condition,
A multi-channel low-power communication method of a transmitter.
6. The method of claim 5,
Wherein the operating frequency of the receiver decreases with the determined channel bandwidth,
A multi-channel low-power communication method of a transmitter.

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