CN107005880B - Communication method, server, road side unit and node - Google Patents

Abstract

The application provides a communication method, an RRM server, an RSU and a node. The method comprises the following steps: the method comprises the steps that a Radio Resource Management (RRM) server segments a region in a communication network to form at least one segment for at least one RSU; the RRM server allocates a channel for the at least one segment; the RRM server transmits network segment information and channel allocation information to each of the at least one RSU, wherein the network segment information indicates a segment of the RSU and the channel allocation information indicates a channel allocated for the segment, so that the RSU communicates with nodes entering the segment through the channel allocated for the segment.

Description

Communication method, server, road side unit and node

Technical Field

The present invention generally relates to the field of communication technologies, and more particularly, to a communication method, a server, a road side unit, and a node.

Background

Vehicular Ad hoc Networks (VANET) enable communication between nearby vehicles and between vehicles and nearby fixed infrastructure. It is desirable to design a variety of applications to improve the safety of future transportation systems and to provide a number of industrial and entertainment services. Dedicated Short Range Communication (DSRC) is the primary Communication technology that enables vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I) communications to enable such applications. Due to the large number of vehicles and the complex road architecture, it is desirable to form large dense vehicle networks in motorways and urban VANETs, both in terms of large networks and large numbers of nodes.

The Medium Access Control (MAC) sublayer of a widely used DSRC system relies on random Access channel sharing techniques such as Carrier Sensing Medium Access/collision avoidance (CSMA/CA) and is extended with Enhanced Distributed Channel Access (EDCA) traffic differentiation and multi-channel functions. For example, network access in the Vehicular Environment (WAVE) and the European Telecommunications Standards Institute (ETSI) Intelligent Transportation Systems (ITS) G5 standard use the Institute of Electrical and Electronics Engineers (IEEE) 802.11p MAC sublayer with IEEE 1609.4 multi-channel functionality.

There are 6 traffic channels (SCH) and 1 Control Channel (CCH) in the existing standard, and the channel access time is divided into synchronization intervals. Each interval contains a guard interval and alternating fixed length intervals called CCH intervals and SCH intervals. The duration of the CCH interval and SCH interval is defined in the standard as 50 milliseconds (ms). During the CCH interval, all nodes monitor the CCH for the exchange of safety messages and other control packets (packets). During the SCH interval, the node transmits potentially non-secure application data on the SCH.

However, in the above-mentioned existing standards, radio resources adapted to such network conditions cannot be effectively utilized: in congested urban areas with dense VANET, a large number of safety and control messages need to be transmitted during the CCH interval. The fixed length of the CCH may not provide sufficient bandwidth in these scenarios, resulting in potential collisions and QoS degradation. On the other hand, if the node density is sparse, the CCH interval will be idle for a long period of time.

Disclosure of Invention

The embodiment of the invention provides a communication method, a server, a road side unit and a node which can improve the utilization rate of wireless resources.

In a first aspect, the present application provides a method of communication. The RRM server receives the network status information sent by the at least one RSU. The network state information sent by each of the at least one RSU indicates a density of nodes covered by the RSU. The RRM server segments the zones in the communication network according to the network state information to form at least one segment for the at least one RSU, respectively. The RRM server allocates a channel for the at least one segment. The RRM server transmits network segment information and channel allocation information to each of the at least one RSU. The network segment information indicates a segment of the RSU, and the channel allocation information indicates a channel allocated for the segment so that the RSU communicates with a node entering the segment through the channel allocated for the segment.

According to the embodiment of the present invention, the RRM server performs network segmentation and channel allocation on segments according to the network state information reported by the RSU, and notifies the RSU of the network segmentation information and the channel allocation information, so that the RSU communicates with a node entering the segment through the channel allocated for the segment, thereby reducing collision probability and quality degradation, and further improving utilization rate of radio resources.

According to a first implementation form of the method according to the first aspect, the density of nodes comprises a number of nodes within different distances from the RSU. In this case, before the RRM server segments the zone in the communication network, the RRM server further determines that the zone is congested according to the number of nodes within a different distance from the RSU. Therefore, instead of using a fixed-length CCH, segmentation and channel allocation are performed based on whether the region is congested, so as to reduce the probability of collision according to different network conditions, enabling dynamic channel allocation.

According to a second implementation of the method according to the first implementation, the method further comprises: the RRM server determines that the region becomes uncongested and sends segment revocation information to each of the at least one RSU. The segment revocation information indicates that the segment and channel allocation are revoked so that the RSU communicates with nodes entering the RSU's coverage through a legacy (legacy) channel. The solution of the present application may be compatible with conventional channel allocation solutions, since the segments may be dropped when the area becomes uncongested.

According to a third implementation of the method of the first aspect as such or any of the preceding implementations of the first aspect, the RRM server divides the area into squares, each square having a RSU in its center, the RSU (a) square having a side length L_SComprises the following steps:

L_S＝min(D_maxl), wherein:

D_max＝max({D_i|N_i≤N_desired(a)})

wherein (x)_a,y_a) Longitude and latitude, N, of RSU (a)_iIs the number of nodes, N, in different ranges of the RSU (a)_desired(a) Is the desired node density of the square of rsu (a). Due to the presence of L and D_maxAdjacent segments may use non-overlapping channels to avoid interference from nodes in adjacent segments.

In a second aspect, the present application provides a method of transmitting data. The RSU sends the network status information to the radio resource management RRM server. The network state information indicates a density of nodes covered by the RSU. And the RSU receives the network segmentation information and the channel allocation information sent by the server. The network segment information indicates a segment of the RSU, the channel allocation information indicates a channel allocated for the segment, and the segment is one of at least one segment respectively for the at least one RSU formed by the RRM server segmenting a region in the communication network. And the RSU sends network segmentation information and the channel allocation information to nodes covered by the RSU. The RSU communicates with nodes in the segment over the channel allocated for the segment.

According to the embodiment of the present invention, the RRM server performs network segmentation and channel allocation for segments according to the network state information reported by the RSU, and notifies the RSU of the network segmentation information and channel allocation information, so that the RSU can communicate with a node entering the segment through the channel allocated for the segment, thereby reducing collision probability and quality deterioration, and further improving utilization rate of radio resources.

The first implementation form of the method according to the second aspect, the method further comprises: and the RSU acquires network state information according to the report of the node covered by the RSU.

A second implementation of the method according to the second aspect as such or any preceding implementation of the second aspect, the density of nodes comprises a number of nodes within different distances from the RSU, and the method further comprises: and the RSU determines the coverage congestion of the RSU according to the number of nodes in different distances from the RSU.

A third implementation of the method according to the first aspect as such or any preceding implementation of the second aspect, the method further comprising: the RSU receives the segment revocation information from the RRM server and communicates with a node entering the coverage of the RSU by switching to a legacy channel. The segment revocation information indicates that the segment and channel allocation are revoked.

According to a fourth implementation of the method of the first aspect as such or any of the preceding implementations of the second aspect, the RSU reports the network state information to the NCC periodically, or when at least one of predetermined conditions is met.

In a third aspect, a method of transmitting data is provided. The method comprises the steps that a node receives network segmentation information and channel allocation information from a Road Side Unit (RSU), determines that the node is in a segment according to the network segmentation information, and communicates with the RSU through a channel allocated for the segment. The network segment information indicates a segment of the RSU, the channel allocation information indicates a channel allocated for the segment, and the segment is one of at least one segment respectively for the at least one RSU formed by the RRM server segmenting a region in the communication network.

According to a first implementation of the method of the third aspect, the method further comprises: the node receives segment revocation information from the RSU and communicates with the RSU over a legacy channel. The segment revocation information indicates that the segment and channel allocation are revoked.

In a fourth aspect, the present application provides a server. The server comprises means for performing the method of the first aspect.

In a fifth aspect, the present application provides an RSU. The RSU comprises means for performing the method of the second aspect.

In a sixth aspect, the present application provides a node. The node comprises means for performing the method of the third aspect.

In some embodiments, the node is a vehicle comprising an OBU.

In some embodiments, said allocating a channel for said at least one segment comprises: allocating a channel for the at least one segment from among one PCCH, two LCCHs, and four LSCHs, and allocating the PCCH, another LCCH, and another two LSCHs for another segment adjacent to the segment. The PCCH may be shared between adjacent segments for compatibility with legacy solutions. Within each segment, a node is allowed to use one LCCH and two LSCHs. Neighboring segments may use non-overlapping channels to avoid interference from nodes in neighboring segments. Since each segment is allocated with the LCCH for transmitting the control message, collision probability and QoS degradation are reduced, thereby improving utilization of radio resources. Further, if both LCCHs for the segment are occupied, the LCCHs may be used for data transmission to support more nodes in the segment.

Drawings

In order to more clearly illustrate the technical solution in the embodiments of the present invention, the drawings required in the embodiments will be briefly described below. It is obvious that the drawings described below are only some embodiments of the invention, and that for a person skilled in the art, other drawings can be derived from them without inventive effort.

Fig. 1 depicts an architecture diagram of a communication system in accordance with an embodiment of the present invention.

Fig. 2 depicts a schematic diagram of the functional entities of the communication system 100 according to an embodiment of the invention.

Fig. 3 depicts a schematic flow diagram of a communication method according to an embodiment of the invention.

Fig. 4 depicts a schematic flow chart of a communication method according to another embodiment of the invention.

Fig. 5 depicts a schematic flow chart of a communication method according to another embodiment of the invention.

Fig. 6 depicts a schematic flow chart diagram of a communication procedure according to another embodiment of the invention.

Fig. 7 depicts the format of packets sent from the RSU to the RRM server according to an embodiment of the present invention.

Fig. 8 depicts the format of packets sent from the RRM server to the RSU in accordance with an embodiment of the present invention.

Fig. 9 depicts the format of a packet sent from an RSU to a node according to an embodiment of the present invention.

Fig. 10 depicts an example table of the number of nodes at different distances from the RSU in accordance with an embodiment of the invention.

Fig. 11 depicts a schematic flow chart diagram of a communication procedure according to another embodiment of the invention.

Fig. 12 depicts the format of another packet sent from the RRM server to the RSU in accordance with an embodiment of the present invention.

Fig. 13 depicts a schematic flow diagram of segmentation of a network according to an embodiment of the invention.

FIG. 14 is a schematic network model according to an embodiment of the invention.

FIG. 15 is a simplified block diagram of a server according to an embodiment of the present invention.

Fig. 16 is a simplified block diagram of an RSU according to an embodiment of the present invention.

Fig. 17 is a simplified block diagram of a node according to another embodiment of the present invention.

FIG. 18 is a simplified block diagram of a computing device.

Detailed Description

The technical solution of the present invention will be described in detail with reference to the accompanying drawings. It will be clear that these embodiments are only some exemplary embodiments of the invention, which is not limited thereto. Other embodiments obtained by persons skilled in the art based on the embodiments of the present invention also belong to the protection scope of the present invention.

The technology to which embodiments of the present invention relate may be referred to as dynamic network segmentation based multi-channel MAC protocol (DNSM-MAC).

Fig. 1 depicts an architecture diagram of a communication system 100 in accordance with an embodiment of the present invention.

The communication system 100 may be a VANET including a Network Control Center (NCC)110, a plurality of Road Side Units (RSUs) 120, and a plurality of nodes (e.g., vehicles) 130. It should be understood that the nomenclature of these network nodes in communication system 100 is for identification only, and should not be construed as limiting.

The NCC 110 includes an RRM server 111 that plays a key role in implementation of the embodiment of the present invention and further implements other functions, however, for convenience of description, only the RRM server 111 is described in detail. The RRM server 111 is used to segment regions in the network and perform channel allocation for the segments.

The RSU120 is connected to the NCC 110 via a wired or wireless link, such as Long Term Evolution (LTE) or the internet 140. The RSUs 120 are typically located at the curb side, at a distance from each other. The distance between two RSUs 120 may be equal to the effective communication range of the underlying (undersying) DSRC technology (e.g., 500m for IEEE 802.11 p). RSU120 is used to collect network state information from node 130 within its coverage area and forward packets between node 130 and NCC 110.

Fig. 2 depicts a schematic diagram of the functional entities of the communication system 100 according to an embodiment of the invention.

Referring to fig. 2, the functional blocks of these entities are shown in fig. 2, including NCC 110, RSU120, and OBU 131 in node 130. The RRM server 111 is located in the NCC 110 and takes on the function of channel allocation. The network segmentation function is distributed between the RSU120 and the RRM server 111. Each node 130 is equipped with a DSRC network interface for communication with each other and with the RSU. The DSRC interface may include DNSM-MAC layers, 802.11p PHY layers, and other layers. And the RRM server and the RSU may communicate with each other through an internet interface.

Embodiments of the present invention provide an efficient dynamic technique for allocating channels in a multi-channel VANET, wherein the available channels are dynamically allocated to different segments of the network dynamically defined in the vicinity of the RSU depending on the network load (or node density) with the aid of the RSU and RRM server.

Fig. 3 depicts a schematic flow diagram of a communication method according to an embodiment of the invention. The method of fig. 3 is implemented by the RRM of fig. 1.

310. The RRM server receives the network state information transmitted by the at least one RSU, wherein the network state information transmitted by each RSU of the at least one RSU indicates a density of nodes covered by the RSU.

320. The RRM server segments the zones in the communication network according to the network state information to form at least one segment for the at least one RSU, respectively.

For example, the area may refer to a section of a highway or a city area. After segmentation, each RSU may correspond to only one segment, and each RSU may be located at the center of the segment. The segment sizes of different RSUs may be different or the same.

330. The RRM server allocates a channel for the at least one segment.

For example, the RRM server may allocate multiple channels for each segment, e.g., the allocated channels for each segment may include a common CCH, a local CCH, and two local SCHs. Adjacent segments may share a common CCH or may have different local CCHs and local SCHs.

340. The RRM server transmits to each of the at least one RSU network segment information indicating a segment of the RSU and channel allocation information indicating channels allocated for the segment so that the RSU communicates with nodes entering the segment over the channels allocated for the segment.

According to the embodiment of the invention, the RRM server carries out network segmentation and channel allocation on the segments according to the network state information reported by the RSU, and informs the RSU of the network segmentation information and the channel allocation information, so that the RSU communicates with the nodes entering the segments through the channels allocated to the segments, thereby reducing the collision probability and quality deterioration and further improving the utilization rate of wireless resources.

In particular, a node equipped with an on-board unit (OBU) may communicate with the RSU when the node is within a communication range or coverage of the RSU. The RSU may determine network state information from information reported by the nodes covered by the RSU and transmit the network state information to the RRM server. For example, in the normal state, during the CCH interval the RSU and the node monitor the CCH for the exchange of safety messages and other control packets, while during the SCH interval the RSU and the node transmit potentially non-safety application data onto the SCH. However, when the RRM server detects the congested region according to the network state information, the RRM server may perform network segmentation according to the network state information to provide a plurality of segments respectively centered on the RSUs and allocate a channel to each segment. The RRM server transmits segment information indicating segments of the RSU and channel allocation information indicating allocation of channels for the RSU, and the RSU broadcasts the segment information and the channel allocation information to nodes, and then the nodes communicate with the RSU through the channels allocated for the segments.

Optionally, as another embodiment, the density of nodes includes a number of nodes within a different distance from the RSU, and before 320, the method further comprises: the RRM server determines the zone congestion based on the number of nodes within different distances from the RSU.

For example, if the number of nodes within 50m of an RSU exceeds 10, or the number of nodes within 100m of the RSU exceeds 20, the coverage of the RSU is considered to be a congested area. Further, a plurality of thresholds may be set to determine the congestion area. The purpose of introducing multiple thresholds is to have some traffic flow beyond the popular area with more nodes than other areas. For example, the node density in town centers is much higher than that in subordinate rural areas. In order to avoid that some areas with more popular traffic flows are divided into ultra-small segments which cannot be supported by enough RSUs, and further, a plurality of problems of channel allocation, interference between adjacent segments, unknown CAM (computer aided manufacturing) from adjacent vehicles and the like occur, different threshold values can be set in the coverage range. Therefore, instead of using a fixed-length CCH, segmentation and channel allocation are performed based on whether the region is congested, so as to reduce the probability of collision according to different network conditions, enabling dynamic channel allocation.

Optionally, as another embodiment, the method of fig. 3 further includes: the RRM server determines that the region becomes uncongested and sends segment revocation information to each of the at least one RSU, wherein the segment revocation information indicates to revoke the segment and channel allocation so that the RSU communicates with nodes entering the coverage of the RSU over legacy channels. The solution of the present application may be compatible with conventional channel allocation solutions, since the segment may be dropped when the area becomes uncongested.

For example, if the number of nodes within 50m from the RSU is less than 10, or the number of nodes within 100m from the RSU is less than 20, the coverage of the RSU is considered to be an uncongested area. In this case, segmentation is not necessary, and thus, is undone. The RSU and vehicle are then switched to a legacy channel for listening to control messages and data, thereby providing a flexible channel allocation scheme.

At 320, the RRM server divides the region into squares, each square having an RSU at the center, the side length L of the square of RSU (a) being:

L_S＝min(D_maxl), wherein:

D_max＝max({D_i|N_i≤N_desired(a)})

wherein (x)_a,y_a) Longitude and latitude, N, of RSU (a)_iIs the number of nodes, N, in different ranges of the RSU (a)_desired(a) Is the period of square of RSU (a)And (5) observing the node density. Where N, a, b, c and i are all positive integers.

Due to the presence of L and D_maxAdjacent segments may use non-overlapping channels to avoid interference from nodes in adjacent segments.

In 330, the RRM server allocates channels for the at least one segment from among a common control channel PCCH, two local control channels LCCH and four local traffic channels LSCH, wherein the PCCH, one LCCH and two LSCHs are allocated for the segment, and the PCCH, another LCCH and another two LSCHs are allocated for another segment adjacent to the segment.

In a conventional channel allocation scheme, 7 channels (1 CCH and 6 SCH) are allocated for RSUs in a communication network. That is, two adjacent RSUs must share a CCH, which may not provide enough bandwidth in such scenarios, resulting in potentially high collision rates and QoS degradation. However, in the embodiment of the present invention, two LCCHs may be respectively allocated to two adjacent RSUs, so as to further reduce collision probability and QoS degradation, and implement dynamic channel allocation.

Fig. 4 depicts a schematic flow chart of a communication method according to another embodiment of the invention. The method of fig. 4 is implemented by the RSU of fig. 1.

410. A Road Side Unit (RSU) sends network status information to a radio resource management RRM server, wherein the network status information indicates a density of nodes covered by the RSU.

420. The RSU receives network segment information and channel allocation information transmitted by the RRM server, wherein the network segment information indicates a segment of the RSU, the channel allocation information indicates a channel allocated for the segment, and the segment is one of at least one segment formed by the RRM server segmenting a region in the communication network, each of the at least one segment being for the at least one RSU.

430. The RSU sends network segment information and channel allocation information to the nodes covered by the RSU. For example, the RSU may broadcast the segmentation information and the channel allocation information to nodes.

440. The RSU communicates with the nodes in the segment over the channel allocated for the segment.

According to the embodiment of the invention, the RRM server performs network segmentation and channel allocation on segments according to the network state information reported by the RSU, and notifies the RSU of the network segmentation information and the channel allocation information, so that the RSU communicates with a node entering the segment through a channel allocated for the segment, thereby reducing collision probability and quality deterioration, and further improving the utilization rate of radio resources.

Optionally, as another embodiment, the method of fig. 4 further includes: the RSU obtains network state information.

Optionally, as another embodiment, the density of nodes includes a number of nodes within different distances from the RSU, and before 430, the method of fig. 4 further includes: and determining the coverage congestion of the RSU according to the number of nodes in different distances from the RSU.

Optionally, as another embodiment, the method of fig. 4 further includes: the RSU receives segment revocation information indicating that the segment and channel allocation are revoked, from the RRM server, and communicates with a node entering the coverage of the RSU by switching to a legacy channel.

At 430, the RSU periodically reports network status information to the NCC.

Optionally, as another embodiment, in 430, when at least one of the predetermined conditions is met, the RSU reports the network status information to the NCC.

According to the embodiment of the invention, one common control channel PCCH, two local control channels LCCH and four local traffic channels are allocated to the at least one segment, one PCCH, one LCCH and two LSCHs are allocated to the segment, and the PCCH, the other LCCH and the other two LSCHs are allocated to another segment adjacent to the segment.

Fig. 5 depicts a schematic flow chart of a communication method according to another embodiment of the invention. The method of fig. 5 is implemented by the node of fig. 1.

510. The node receives network segment information and channel allocation information from a road side unit, RSU, wherein the network segment information indicates a segment of the RSU, the channel allocation information indicates a channel allocated for the segment, and the segment is one of at least one segment formed by segmentation of a region in a communication network by the RRM server, each for the at least one RSU.

520. The node determines that the node is in the segment based on the network segment information.

530. The node communicates with the RSU over the channel allocated for the segment.

According to the embodiment of the invention, the RRM server carries out network segmentation and channel allocation on the segments according to the network state information reported by the RSU, and informs the RSU of the network segmentation information and the channel allocation information, so that the RSU communicates with the nodes entering the segments through the channels allocated to the segments, thereby reducing the collision probability and quality deterioration and further improving the utilization rate of wireless resources.

Optionally, as another embodiment, the method of fig. 5 further includes: the node receives segment revocation information from the RRM server and communicates with the RSU through the legacy channel, wherein the segment revocation information indicates that the segment and channel allocation are revoked.

According to the embodiment of the invention, one common control channel PCCH, two local control channels LCCH and four local traffic channels are allocated to the at least one segment, one PCCH, one LCCH and two LSCHs are allocated to the segment, and the PCCH, the other LCCH and the other two LSCHs are allocated to another segment adjacent to the segment.

According to an embodiment of the invention, the node is a vehicle comprising an on board unit, OBU.

Fig. 6 depicts a schematic flow chart diagram of a communication procedure according to another embodiment of the invention.

610. The RSU collects node IDs and location information from nodes within the RSU's coverage area by grouping.

For example, once a new node (e.g., vehicle) enters the coverage (or communication range) of the RSU, each time a packet (e.g., ACK, RTS, CTS, DATA) is sent, the RSU obtains the node ID of the node and creates an entry for the node in the table. Then, when the node broadcasts a Cooperation Awareness Message (CAM) or a Decentralized Environment Notification Message (DENM), or transmits a packet by multicast/unicast, the RSU collects location information and motion information and updates an entry of the node in the table. This may be achieved, for example, by Local Dynamic Mapping (LDM) in ITS architecture ETSI TR 102863 (V1.1.1).

615. The RSU determines network state information based on the collected location information of the nodes.

For example, the RSU may determine the number of nodes within communication range and the number of nodes at different distances from the RSU based on the location information of the nodes.

Fig. 10 depicts a table indicating the number of nodes at different distances from the RSU in accordance with an embodiment of the present invention. Referring to fig. 10, the number of neighboring nodes of the RSU is 50 in the range 0-100m corresponding to the range index 1, the number of neighboring nodes of the RSU is 80 in the range 0-200m corresponding to the range index 2, and the number of neighboring vehicles of the RSU is 200 in the range 0-500m corresponding to the range index 3, and so on.

620. The RSU sends a report to the RRM server in the NCC.

The RSU may send a report to the RRM server in the NCC to help find the coverage of the appropriate network segment. The report includes network status information.

Fig. 7 depicts the format of packets sent from the RSU to the RRM server according to an embodiment of the present invention. Referring to fig. 7, a sender ID field 710 indicates an ID of an RSU, and the length of the field 710 may be 32 bits. The destination ID field 720 indicates the ID of RRM, and the length of field 720 may be 32 bits. Since embodiments of the present invention are implemented in the MAC sublayer, the MAC address can be used as the ID of the network node. The packet type field 730 indicates the type of the packet, e.g., the packet type indicates that the packet is an RSU report packet, and the length of the field 730 may be 4 bits. The length field 740 indicates the size of the packet, and the length of the field 740 may be 16 bits. The Range No. field 750 indicates the Range index 1 of the RSU, and the length of the field 750 may be 8 bits. The vehicle number field (No. of Veh.)760 indicates the number of active vehicles within the distance D1 corresponding to the range index 1Total, field 760 may be 16 bits in length. The range number field 770 indicates a range index n of the RSU, and the length of the field 770 may be 8 bits. The car number field 780 indicates the total number of active vehicles within the distance Dn corresponding to the range index 1, and the length of the field 780 may be 16 bits. For simplicity, similar range index fields 2 through n-1 and corresponding car number field D are omitted from FIG. 7₂To D_n-1Where n represents the number of coverage of the RSU, and n is a positive integer.

Furthermore, the RSU may send reports to the NCC periodically or only when certain trigger conditions (for sending network state information updates) are met. An example of the latter case is to define a set of predefined thresholds of network congestion levels that can be configured for the respective RSUs. The RSU can alert the RRM server only if the number of vehicles within the respective range of the RSU is greater than a predefined threshold.

It should be appreciated that each RSU in the communication network may collect position information and motion information from vehicles within the RSU's coverage area and send reports carrying network status information to the RRM server.

630. The RRM server detects a congested area of the network.

The RRM server may identify whether a region is congested according to the number of active nodes (node density) within the communication range of the RSU in the region. If the node density in a certain area is larger than a threshold value N_desired(which may be adjustable or preset) then congestion is identified.

Alternatively, as another embodiment, congestion may be identified for different ranges of each RSU. For example, thresholds for different communication ranges may be predefined in the RRM server.

640. The RRM server performs network segmentation if the RRM server determines that there is a congested area in the communication network.

The RRM may divide the congestion area into a plurality of segments, for example, into a plurality of squares, each square being centered on the RSU. Embodiments of the invention are not limited in this regard, for example, the segments may have other shapes, such as circular, hexagonal, etc.

In the following, a congested network segment is described, taking a square segment as an example.

First the RRM server calculates the side length L of a square (segment) centered on the RSU_s. The side length of the square may also be adapted to the presence of at least one of a neighboring RSU, a delay limit of ITS use case, and a node density.

Network segmentation is described below by way of example for the presence of a neighbor RSU and a node density network.

a) Consider the presence of a neighboring RSU:

if a plurality of RSUs are available in the congested area, the RRM server divides the area into a plurality of squares, each square is centered on an RSU, and the side length L is given by the following formula:

wherein (x)_a,y_a) Is the longitude and latitude of the rsu (a), and a, b, and c may be integers.

b) Consider the desired node density:

the RRM server calculates the side lengths taking into account the reported node densities around each RSU. The RRM server obtains the maximum distance D when the node density in a certain area meets the required node density by the following formula_max：

D_max＝max({D_i|N_i≤N_desired(a)})

Wherein N is_iIs a certain region (distance RSU (a) 0-D_iNumber of nodes in m), i may be an integer, N_desired(a) Is the desired node density for the square of rsu (a).

c) Finally, the RRM server selects D_maxAnd the minimum value between L is taken as the side length L of each segment_SThe final result of (1).

L_S＝min(D_max,L)

It should be understood that the above-described methods for performing segmentation are merely examples. Embodiments of the present invention are not limited thereto, and other segmentation methods (e.g., uniformly dividing the congested area) may also be employed.

650. The RRM server performs channel allocation for the network segment.

After the network segment, the RRM server may allocate a channel for the network segment. To be compatible with existing standards (e.g., IEEE 1609.4), 7 channels are still employed. One of the 7 channels is designated as a common control channel (PCCH) shared between adjacent segments. Of the remaining six channels, two of them are called Local Control Channels (LCCH), and the remaining four channels are used as local traffic channels (LSCH). In this embodiment, the vehicle initially operates with a multi-channel MAC. If a new vehicle (entering the network after segmentation) misses the information, the RSU in the segmented network occupies the common control channel (PCCH) to broadcast the segmentation information. Within each segment, a node is allowed to use one LCCH and two LSCHs. Neighboring segments may use non-overlapping channels to avoid interference from nodes in neighboring segments. For example, in the example scenario shown in FIG. 13, it is assumed that a region in road 1310 may be divided into segments 1311, 1312, and 1313, and another region in road 1320 may be divided into segments 1321, 1322, and 1323. Further, segment 1321 may be allocated LCCH 1, LSCH 1, and LSCH 2, and segment 1322 may be allocated LCCH 2, LSCH 3, and LSCH 4. The nodes in segment 1323 may then reuse the same channel as segment 1321 without causing any interference to the nodes in segment 1323 because the nodes in segment 1323 are far enough apart.

The LCCH is used as a segmented local CCH through which emergency messages, channel negotiation, and segmentation cancellation are transmitted, and the LSCH is used as the segmented local SCH for data transmission. There may be no channels for multiple pairs of nodes since only two traffic channels per segment may be used for data transmission. Thus, if both traffic channels of the segment are occupied at this time, the LCCH may be allowed for data transmission after a successful channel negotiation. The channel access mechanism within each segment is similar to the Asynchronous MultiChannel MAC (AMCMAC) scheme.

660. The RRM server transmits network segment information and channel allocation information to the RSU.

After network segmentation and channel allocation, the RRM server sends packets carrying network segmentation information and channel allocation information to each RSU. The network segment information includes a side length of a segment for the RSU and the channel allocation information includes a list of channels allocated for the segment.

Fig. 8 depicts the format of packets sent from the RRM server to the RSU in accordance with an embodiment of the present invention. Referring to fig. 8, a sender ID field 810 indicates an ID of an RRM server, and the length of the field 810 may be 32 bits. The destination ID field 820 indicates the ID of the RSU, and the length of the field 820 may be 32 bits. Since embodiments of the present invention are implemented in the MAC sublayer, the MAC address can be used as the ID of the network node. The packet type field 830 indicates the type of packet, and the length of the field 830 may be 4 bits. The LS field 840 indicates a side length of a segment for an RSU, and the length of the field 840 may be 12 bits. The channel field 850 indicates a list of channels allocated for the segment, and the length of the field 850 may be (8 bits) × the total number of channels allocated for the segment.

670. The RSU informs the nodes of the network segment information and channel allocation information.

Upon receiving the network segment information and channel assignment information from the NCC, the RSU will broadcast the network segment information and channel assignment information to the vehicles within its coverage area over the PCCH. The network segment information and channel allocation information may be carried in packets.

Fig. 9 depicts the format of a packet sent from an RSU to a node according to one embodiment of the invention.

Referring to fig. 9, a sender ID field 910 indicates an ID of an RSU, and the length of the field 910 may be 32 bits. The destination ID field 920 includes the ID of the vehicle, and the length of the field 920 may be 32 bits. The packet type field 930 indicates the type of the packet, and the length of the field 930 may be 4 bits. A center of segment (center of seg.) field 950 indicates the longitude and latitude of the center of the segment, and the length of the field 950 may be 64 bits (32 bits longitude and 32 bits latitude). The LS field 960 indicates a side length of a segment for an RSU, and the length of the field 960 may be 12 bits. The channel field 970 represents a list of channels allocated for the segment, and the length of the field 970 may be (8 bits) the total number of channels allocated for the segment.

680. After receiving the network segmentation information and the channel allocation information from the RSU, the node switches to the LCCH to monitor the control message.

Since no congestion occurs in the communication range of the RSU in the normal network state, the vehicle monitors the control message on the legacy CCH and the traffic data in the legacy SCH. In a congested state, the vehicle may receive network segment information and corresponding channel allocation information broadcast by the RSU on the PCCH. After receiving the segmentation information and the corresponding channel allocation information, the vehicle will immediately switch to the corresponding dedicated LCCH to monitor the control message. In addition, when updated network segmentation information and channel allocation information are received again, the vehicle shall update its own segmentation id (sid) according to the updated network segmentation information and channel allocation information, and immediately switch to the corresponding dedicated LCCH to monitor the control message.

Fig. 11 depicts a schematic flow chart diagram of a communication procedure according to another embodiment of the invention.

In this embodiment, assuming that the RRM server has already performed network segmentation and channel assignment to the congested area, if the congested area becomes uncongested, the network segmentation and channel assignment are revoked.

1110. The RRM server determines that the congested area becomes uncongested.

Also, as depicted in 630, the RRM server may identify whether a congested area becomes uncongested based on the number of active nodes (node density) within communication range of the RSUs in the area. For example, if the node density in a certain area is below a threshold N_desired(which may be adjustable or preset) it is identified that the congested area becomes uncongested. Optionally, as another embodiment, thresholds for different communication ranges may be predefined in the RRM server.

1120. The RRM server sends a segment revocation packet to the RSU.

After providing the network state information, the RRM server in the NCC determines that the network becomes uncongested and thus the previous segment is no longer needed. Thus, the NCC will send a segment retraction packet to the RSU to retract the previous segment and channel allocation.

Fig. 12 depicts the format of the packets sent from the RRM server to the RSU.

Referring to fig. 12, a sender ID field 1210 includes an ID of an RRM server, and the length of the field 1210 may be 32 bits. The destination ID field 1220 contains the ID of the RSU, and the length of the field 1220 may be 32 bits. The packet type field 1230 includes the type of packet to indicate that the packet is a network segment withdrawal message, and the length of the field 1230 may be 4 bits. The revocation flag field 1240 includes a side length of a segment of an RSU for indicating that the segment is revoked, and the length of the field 1240 may be 4 bits.

1130. The RSU sends segment withdraw packets to the nodes it covers.

Upon receiving the segment withdraw packet from the NCC, the RSU broadcasts the same packet to the vehicles within its coverage area.

1140. The node switches back to the legacy CCH to listen for control messages.

For example, the vehicle, upon receiving the packet, will switch back to listen for the legacy CCH and perform media access based on the multi-channel MAC protocol.

FIG. 14 depicts a schematic diagram of a network model, according to an embodiment of the invention. The scenario of fig. 14 considers a network with multiple hops within a large reference area.

In an exemplary scenario, the performance of an embodiment of the present invention is evaluated in terms of throughput, packet transfer rate, and transmission collision rate using a well-known simulation tool, NS-2.

For example, the area considered is a 500m 1500m area with manhattan grid pattern traffic, where nodes travel along the grid (i.e., representing lanes). It is assumed that RSUs are present in the system model. In urban areas, RSUs are typically used in busy/congested areas (e.g., traffic lights). In a highway scenario, RSUs are typically placed along a popular highway to assist ITS and to help collect and disseminate information for various applications. The segmentation mechanism is based on geographical location. Each segment uses one RSU as a local coordinator to facilitate forwarding of packets to distant hops, propagation of emergency messages, and as a service provider to provide information to ITS service subscribers. Assume that the RSU has another network interface (e.g., ethernet/LTE) in addition to DSRC access.

Considering different network sizes, i.e. different evaluations for single and multi-hop are performed. The single-hop scene covers an area of 500m × 500m, and the multi-hop scene is composed of three single-hop areas. Assuming that RSUs are placed every 500m along the zone boundary, the vehicles are randomly distributed in the grid as shown in fig. 14. The average speed of the node is 27mi/h, which is close to the speed limit of the urban traffic scene. The density of nodes in each sub-network is equal.

The overall throughput versus total number of nodes in the large-scale reference region results show that the DNSM-MAC scheme outperforms other multi-channel MAC schemes from small-scale to large-scale networks except for very sparse networks.

To analyze the actual system performance, the middle region is chosen as the reference region, since the nodes of this region naturally receive interference from nodes outside the region from both sides. The results of the normalized throughput of the nodes in the middle region versus the total number of nodes in the reference region show that the DNSM-MAC scheme achieves a normalized throughput higher than the other three benchmarking multi-channel schemes in all dense and sparse networks. In a network with 90 nodes, the DNSM-MAC scheme has a 357% higher normalized throughput than AMCP and AMCMAC.

Another result is obtained by comparing packet transfer rates and collision rates on traffic channels between different multi-channel MAC schemes in a large vehicle environment. This result shows that both the DNSM-MAC scheme and the AMCMAC scheme are superior to the other two multi-channel MAC schemes in terms of packet transfer rate and collision rate on the traffic channel. The DNSM-MAC scheme and the AMCMAC scheme have higher and more stable packet transfer rates on traffic channels than the AMCP scheme and the IEEE 1609.4 standard at different network scales. For the collision rate on the traffic channel, the proposed scheme achieves a lower collision rate compared to the AMCP scheme, maintaining a collision level similar to the standard IEEE 1609.4.

Another result of the cumulative penetration of the segmented information versus the number of times the information is broadcast in different network size scenarios is also obtained. It should be noted that, after the first two broadcasts of the segment information, more than half of the nodes can be penetrated in most scenarios.

Another result of the penetration rate versus time in milliseconds shows that the switching delay between different MAC modes (i.e., AMCMAC scheme and DNSM-MAC scheme) is less than 1ms and that all nodes can be informed of the segment of the reference network within 2 seconds.

The above-described process may be performed by a unit in an apparatus or a software module in a computing device. The following sections of this application will describe these apparatuses and computing devices.

FIG. 15 is a simplified block diagram of a server according to an embodiment of the present invention.

The server 1500 comprises a receiving unit 1510, a segmenting unit 1520, a distributing unit 1530 and a sending unit 1540.

The receiving unit 1510 is configured to receive network status information transmitted by at least one RSU, wherein the network status information transmitted by each RSU of the at least one RSU indicates a density of nodes covered by the RSU. The segmentation unit 1520 is configured to segment the region in the communication network according to the network status information to form at least one segment for the at least one RSU, respectively. The allocation unit 1530 is configured to allocate a channel for the at least one segment. The transmitting unit 1540 is configured to transmit network segment information and channel allocation information to each RSU of the at least one RSU, wherein the network segment information indicates a segment of the RSU, and the channel allocation information indicates a channel allocated for the segment, so that the RSU communicates with a node entering the segment through the channel allocated for the segment.

Optionally, the density of the nodes includes the number of nodes within different distances from the RSU, and the server further includes a determining unit 1550 configured to determine the area congestion according to the number of nodes within different distances from the RSU.

Optionally, the determining unit 1550 is further configured to determine that the region becomes non-congested, and the sending unit 1540 is further configured to send segment revocation information to each RSU of the at least one RSU, wherein the segment revocation information indicates to revoke the segment and channel allocation so that the RSU communicates with nodes entering the coverage of the RSU through the legacy channel.

Optionally, the segment is configured to be divided into a plurality of squares, each square having a RSU in the center, the side length L of the square of RSU (a)_SGiven by the following equation:

L_S＝min(D_maxl), wherein:

D_max＝max({D_i|N_i≤N_desired(a)})，

wherein (x)_a,y_a) Longitude and latitude, N, of RSU (a)_iIs the number of nodes, N, in different ranges of the RSU (a)_desired(a) Is the desired node density of the square of rsu (a).

Alternatively, the allocating unit 1530 allocates channels for the at least one segment from one common control channel PCCH, two local control channels LCCH and four local traffic channels LSCH, wherein the PCCH, one LCCH and two LSCHs are allocated for the segment, and the PCCH, another LCCH and another two LSCHs are allocated for another segment adjacent to the segment.

The server may perform each process of the method as shown in fig. 3, and thus, a detailed description thereof is omitted.

Fig. 16 is a simplified block diagram of an RSU1600 according to an embodiment of the present invention.

The RSU1600 includes a transmitting unit 1610, a receiving unit 1620, and a communication unit 1630.

The transmitting unit 1610 is configured to transmit network status information to the RRM server, wherein the network status information indicates a density of nodes covered by the RSU.

The receiving unit 1620 is configured to receive network segment information and channel allocation information transmitted by a server, wherein the network segment information indicates a segment of the RSU, the channel allocation information indicates a channel allocated to the segment, and the segment is one of at least one segment formed by segmentation of a region in a communication network by an RRM server, respectively for the at least one RSU, wherein the transmitting unit 1610 is further configured to transmit the network segment information and the channel allocation information to nodes covered by the RSU.

The communication unit 1630 is configured to communicate with the nodes in the segment through the channel allocated for the segment.

Optionally, the RSU1600 further comprises an acquisition unit 1640. The obtaining unit 1640 is configured to obtain network status information from the report of the RSU covered node.

Optionally, the density of the nodes comprises the number of nodes within different distances from the RSU, and the RSU further comprises a determining unit 1650. The determining unit 1650 is configured to determine the coverage congestion of the RSU according to the number of nodes within different distances from the RSU.

Optionally, the receiving unit 1620 is further configured to receive segment revocation information from the RRM server, wherein the segment revocation information indicates that the segment and the channel allocation are revoked, and the communicating unit 1630 is further configured to communicate with a node entering the coverage of the RSU by switching to a legacy channel.

Optionally, the transmitting unit 1610 is configured to: the RSU reports the network state information to the NCC periodically; or at least one of predetermined conditions is met, the RSU reports network status information to the NCC.

Optionally, one common control channel PCCH, two local control channels LCCH and four local traffic channels are allocated to the at least one segment, one PCCH, one LCCH and two LSCHs are allocated to the segment, and the PCCH, another LCCH and another two LSCHs are allocated to another segment adjacent to the segment.

The RSU may perform each process of the method as shown in fig. 4, and thus, will not be described herein.

Fig. 17 is a simplified block diagram of a node 1700 according to an embodiment of the present invention.

Node 1700 includes a receiving unit 1710, a determining unit 1720, and a communication unit 1730.

The receiving unit 1710 is configured to receive network segment information and channel allocation information from an RSU, wherein the network segment information indicates a segment of the RSU, the channel allocation information indicates a channel allocated for the segment, and the segment is one of at least one segment formed by segmentation of a region in a communication network by an RRM server, respectively for the at least one RSU.

The determining unit 1720 is configured to determine from the network segment information that the node is in the segment.

The communication unit 1730 is configured to communicate with the RSU through the channel allocated for the segment.

Optionally, the receiving unit 1710 is further configured to receive segment revocation information from the RSU, wherein the segment revocation information indicates that the segment and the channel allocation are revoked, and the communication unit 1730 is configured to communicate with the RSU over the legacy channel.

Optionally, one common control channel PCCH, two local control channels LCCH and four local traffic channels are allocated to the at least one segment, one PCCH, one LCCH and two LSCHs are allocated to the segment, and the PCCH, another LCCH and another two LSCHs are allocated to another segment adjacent to the segment.

Optionally, the node is a vehicle comprising an OBU.

The node may perform each process of the method as shown in fig. 5, and thus, will not be described herein.

It is noted that server 1500, RSU1600, and node 1700 are presented herein in the form of functional units. The term "unit" may refer to, without limitation, an Application Specific Integrated Circuit (ASIC), an electronic circuit, a processor (shared, dedicated, or group) and memory that execute one or more software or firmware programs, a combinational logic circuit, and/or other suitable components that provide the described functionality. In a particular example, those skilled in the art will appreciate that server 1500, RSU1600, and node 1700 may take the form of computing device 1800 of fig. 18. For example, the determining unit, the allocating unit, the segmenting unit, the obtaining unit, the communicating unit, and the like may be implemented by a processor, a storage unit, and a communication interface of the host, and specifically may be implemented by the processor executing modules in the storage unit.

Fig. 18 is a simplified block diagram of computing device 1800. The computing device includes a processor 1810 coupled to one or more data storage devices. Data storage devices may include storage medium 1850 and storage unit 1820. Storage medium 1850 may be read-only, such as read-only memory (ROM), or readable/writable, such as hard disk or flash memory. The storage unit 1820 may be a Random Access Memory (RAM). The storage unit 1820 may be physically integrated with the processor or internal to the processor or configured as a separate unit or units.

Processor 1810 provides sequencing and processing facilities for executing instructions, performing interrupt actions, providing timing functions, and possibly other functions. Optionally, processor 1810 includes one or more Central Processing Units (CPUs). Optionally, computing device 1800 includes more than one processor. The term "processor" refers to one or more devices, circuits, and/or processing cores configured to process data, such as computer program instructions.

Program code executed by processor 1810 may be stored in storage unit 1820 or in storage medium 1850. Alternatively, program code stored in storage medium 1850 may be copied into storage unit for execution by processor 1810.

Computing device 1800 also includes communication interface 1860 that enables direct communication with another device or system via an external network. Optionally, computing device 1800 also includes output device 1830 and input device 1840. An output device 1830 is coupled to processor 1810 and is capable of displaying information in one or more ways. An input device 1840 is also coupled to the processor 1810 and is capable of receiving input from a user of the computing device 1800 in one or more ways.

The aforementioned elements of computing device 1800 may be coupled to one another by a bus.

Computing device 1800 can be a general-purpose computing device or an application-specific computing device. As a practical example, the computing device described above may be a desktop computer, a laptop computer, a web server, a Personal Digital Assistant (PDA), a mobile phone, a tablet computer, a wireless terminal device, a telecommunication device, an embedded system, or any other device having a similar structure as shown in fig. 18. However, the present application is certainly not limited to any particular type of computing device.

As another embodiment, the present application provides a server. The functions of the server may be implemented by the computing device described in fig. 18.

The server includes: a storage unit storing computer executable program code, a communication interface, and a processor coupled to the storage unit and the communication interface, wherein the program code includes instructions that, when executed by the processor, cause the processor to: the method comprises the steps of receiving network state information sent by at least one RSU, segmenting regions in a communication network according to the network state information to form at least one segment aiming at the at least one RSU respectively, distributing channels for the at least one segment, and sending network segment information and channel distribution information to each RSU in the at least one RSU. The network status information sent by each of the at least one RSU indicates a density of nodes covered by the RSU. The network segment information indicates a segment of the RSU, and the channel allocation information indicates a channel allocated for the segment so that the RSU communicates with nodes entering the segment over the channel allocated for the segment.

Optionally, the density of nodes comprises a number of nodes within different distances from the RSU, and the program code further comprises instructions which, when executed by the processor, cause the processor to determine that a region in the communication network is congested based on the number of nodes within different distances from the RSU before segmenting the region.

Optionally, the program code further comprises instructions which, when executed by the processor, cause the processor to determine that the region becomes uncongested and send segment revocation information to each of the at least one RSU. The segment revocation information indicates that the segment and channel allocation are revoked so that the RSU communicates with nodes that enter the RSU's coverage over legacy channels.

According to an embodiment of the invention, when the processor executes the instructions, the processor is caused to divide the area into a plurality of squares, each square having an RSU in the center during the segmentation, the side length L of the square of RSU (a)_SComprises the following steps:

L_S＝min(D_maxl), wherein:

D_max＝max({D_i|N_i≤N_desired(a)})，

wherein (x)_a,y_a) Longitude and latitude, N, of RSU (a)_iIs the number of nodes, N, in different ranges of the RSU (a)_desired(a) Is the desired node density of the square of rsu (a).

According to an embodiment of the invention, the instructions, when executed by the processor, cause the processor to allocate channels for the at least one segment from among a common control channel PCCH, two local control channels LCCH and four local traffic channels LSCH, wherein the PCCH, one LCCH and two LSCHs are allocated for the segment and the PCCH, another LCCH and another two LSCHs are allocated for another segment adjacent to the segment.

The server may perform each process of the method as shown in fig. 3, and thus, will not be described herein.

As another embodiment, the present application provides an RSU. The functionality of the RSU may be implemented by the computing device described in fig. 18.

The server includes: a storage unit storing computer executable program code, a communication interface, and a processor coupled to the storage unit and the communication interface, wherein the program code includes instructions that, when executed by the processor, cause the processor to: the method comprises the steps of sending network state information to a Radio Resource Management (RRM) server, receiving network segmentation information and channel allocation information sent by the server, sending the network segmentation information and the channel allocation information to nodes covered by the RSU, and communicating with the nodes in the segments through channels allocated to the segments. The network state information indicates a density of nodes covered by the RSU. The network segment information indicates a segment of the RSU, the channel allocation information indicates a channel allocated for the segment, and the segment is one of at least one segment formed by the RRM server segmenting a region in the communication network, respectively for the at least one RSU.

Optionally, the program code further comprises instructions which, when executed by the processor, cause the processor to obtain network status information based on the report of the RSU covered node.

Optionally, the density of nodes includes a number of nodes within different distances from the RSU, and the program code further includes instructions that, when executed by the processor, cause the processor to determine the coverage congestion of the RSU based on the number of nodes within different distances from the RSU before sending the network status information to the RRM server.

Optionally, the program code further includes instructions which, when executed by the processor, cause the processor to receive segment revocation information from the RRM server and communicate with a node entering coverage of the RSU by switching to a legacy channel. The segment revocation information indicates that the segment and channel allocation are revoked.

According to an embodiment of the invention, the instructions, when executed by the processor, cause the processor to periodically report the network status information to the NCC, or report the network status information to the NCC when at least one of predetermined conditions is met.

According to the embodiment of the invention, one common control channel PCCH, two local control channels LCCH and four local traffic channels are allocated to the at least one segment, one PCCH, one LCCH and two LSCHs are allocated to the segment, and the PCCH, the other LCCH and the other two LSCHs are allocated to another segment adjacent to the segment.

The RSU may perform each process of the method as shown in fig. 4, and thus, will not be described herein.

As another embodiment, the present application provides a node. The functionality of the node may be implemented by the computing device described in fig. 18.

The node comprises: a storage unit storing computer executable program code, a communication interface, and a processor coupled to the storage unit and the communication interface, wherein the program code includes instructions that, when executed by the processor, cause the processor to: receiving network segment information and channel allocation information from a Road Side Unit (RSU), determining that a node is in the segment according to the network segment information, and communicating with the RSU through a channel allocated for the segment. The network segment information indicates a segment of the RSU, the channel allocation information indicates a channel allocated for the segment, and the segment is one of at least one segment formed by the RRM server segmenting a region in the communication network, respectively for the at least one RSU.

Optionally, the program code further includes instructions that, when executed by the processor, cause the processor to receive segment revocation information from the RRM server and communicate with the RSU over a legacy channel. The segment revocation information indicates that the segment and channel allocation are revoked.

According to the embodiment of the invention, one common control channel PCCH, two local control channels LCCH and four local traffic channels are allocated to the at least one segment, one PCCH, one LCCH and two LSCHs are allocated to the segment, and the PCCH, the other LCCH and the other two LSCHs are allocated to another segment adjacent to the segment.

According to an embodiment of the invention, the node is a vehicle comprising an on board unit, OBU.

The node may perform each process of the method as shown in fig. 5, and thus, will not be described herein.

According to the embodiments of the present invention, the RRM server performs network segmentation and channel allocation on segments according to the network state information reported by the RSU, and notifies the RSU of the network segmentation information and the channel allocation information, so that the RSU communicates with a node entering the segment through a channel allocated for the segment, thereby reducing collision probability and quality degradation, and further improving the utilization rate of radio resources.

It is clear to those skilled in the art that, for convenience and brevity of description, the specific working processes of the above-described systems, apparatuses and units may refer to the corresponding processes in the foregoing method embodiments, and are not described herein again.

In the several embodiments provided in the present application, it should be understood that the disclosed system, apparatus and method may be implemented in other ways. For example, the above-described apparatus embodiments are merely illustrative, and for example, the division of the units is only one logical division, and other divisions may be realized in practice, for example, a plurality of units or components may be combined or integrated into another system, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, devices or units, and may be in an electrical, mechanical or other form.

The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment.

In addition, functional units in the embodiments of the present application may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit. The integrated unit may be implemented in the form of hardware, or may be implemented in the form of a software functional unit.

When the integrated unit is implemented in the form of a software functional unit and sold or used as a stand-alone product, it may be stored in a computer-readable storage medium. Based on such understanding, the technical solution of the present invention may be substantially or partially embodied in the form of a software product, or all or part of the technical solution that contributes to the prior art. The computer software product is stored in a storage medium and includes instructions for causing a computer device (which may be a personal computer, a server network device, etc.) to perform all or a portion of the steps of the methods described in the various embodiments of the invention. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk or an optical disk, etc. that can store program codes.

The transmit diversity method, related apparatus and system according to the present invention have been described in detail above. Based on the spirit of the embodiments of the present invention, a person of ordinary skill in the art can modify the specific implementation and application scope of the present invention. Accordingly, the contents of the specification should not be construed as limiting the present invention.

The functions, if implemented in the form of software functional units and sold or used as a stand-alone product, may be stored in a computer readable storage medium. Based on such understanding, the technical solution of the present application or portions thereof that substantially contribute to the prior art may be embodied in the form of a software product stored in a storage medium and including instructions for causing a computer device (which may be a personal computer, a server, or a network device) to execute all or part of the steps of the method according to the embodiments of the present application. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk or an optical disk, and other various media capable of storing program codes.

The above description is only for the specific embodiments of the present application, but the scope of the present application is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present application, and shall be covered by the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims (24)

1. A method of communication, comprising:

receiving network state information sent by at least one RSU (road side unit), by a RRM (radio resource management) server, wherein the network state information sent by each RSU in the at least one RSU indicates the density of nodes covered by the RSU;

the RRM server segmenting regions in the communication network according to the network state information to form at least one segment for the at least one RSU, respectively;

the RRM server allocates a channel for the at least one segment;

the RRM server transmitting network segment information and channel allocation information to each of the at least one RSU, wherein the network segment information indicates a segment of the RSU and the channel allocation information indicates a channel allocated for the segment so that the RSU communicates with a node entering the segment through the channel allocated for the segment;

wherein the density of nodes comprises a number of nodes within different distances from the RSU, and before the RRM server segments a region in the communication network, the method further comprises:

and the RRM server determines the region congestion according to the number of nodes in different distances from the RSU.

2. The method of claim 1, further comprising:

the RRM server determining that the area becomes uncongested;

the RRM server sends segment revocation information to each of the at least one RSU, wherein the segment revocation information indicates that the segment and channel allocation are revoked so that the RSU communicates with nodes entering the coverage of the RSU through a legacy channel.

3. The method of claim 1, wherein the RRM server segments the regions in the communication network according to the network state information, comprising:

the RRM server divides the area into a plurality of squares, each square having an RSU at the center, the side length L of the square of RSU (a)_SComprises the following steps:

L_S＝min(D_max,L)

wherein the content of the first and second substances,

wherein (x)_a,y_a) Longitude and latitude, N, of RSU (a)_iIs the number of nodes, N, in different ranges of the RSU (a)_desired(a) Is the desired node density of said square of RSU (a), dist () denotes the distance between the nodes, D_iRepresenting different distances to the rsu (a) at said different ranges.

4. The method of any of claims 1-3, wherein the allocating channels for the at least one segment comprises:

allocating channels for said at least one segment from among one common control channel PCCH, two local control channels LCCH and four local traffic channels LSCH, wherein said PCCH, one LCCH and two LSCHs are allocated for said segment and said PCCH, one other LCCH and two other LSCHs are allocated for another segment adjacent to said segment.

5. A method of transmitting data, comprising:

the method comprises the steps that a RSU sends network state information to a RRM server, wherein the network state information indicates the density of nodes covered by the RSU;

the RSU receives network segment information and channel allocation information transmitted by a server, wherein the network segment information indicates a segment of the RSU, the channel allocation information indicates a channel allocated for the segment, and the segment is one of at least one segment formed by segmenting a region in a communication network by the RRM server and aiming at least one RSU respectively;

the RSU sends network segmentation information and the channel allocation information to nodes covered by the RSU;

the RSU communicates with nodes in the segment over the channel allocated for the segment;

further comprising:

and the RSU acquires network state information according to the report of the node covered by the RSU.

6. The method of claim 5, wherein the density of nodes comprises a number of nodes within different distances from the RSU, and before the RSU sends network status information to the RRM server, the method further comprises:

and the RSU determines the coverage area congestion of the RSU according to the number of nodes in different distances from the RSU.

7. The method of claim 6, further comprising:

the RSU receiving segment revocation information from the RRM server, wherein the segment revocation information indicates that the segment and channel allocation are revoked;

the RSU communicates with nodes that enter the RSU's coverage by switching to legacy channels.

8. The method of claim 5, wherein the transmitting network status information by the Road Side Unit (RSU) to a Radio Resource Management (RRM) server comprises:

the RSU periodically reports the network state information to a Network Control Center (NCC); or

The RSU reports the network status information to the NCC when at least one of predetermined conditions is met.

9. The method according to any of claims 5 to 8, wherein said at least one segment is allocated one common control channel, PCCH, two local control channels, LCCH, and four local traffic channels, LSCH, one PCCH, one LCCH, and two LSCH for said segment, and another segment adjacent to said segment is allocated said PCCH, another LCCH, and another two LSCH.

10. A method of transmitting data, comprising:

a node receives network segment information and channel allocation information from a Road Side Unit (RSU), wherein the network segment information indicates a segment of the RSU, the channel allocation information indicates a channel allocated for the segment, and the segment is one of at least one segment formed by a Radio Resource Management (RRM) server segmenting a region in a communication network and aiming at least one RSU;

the node determines that the node is in the segment according to the network segment information;

the node communicating with the RSU over the channel allocated for the segment;

further comprising:

the node receiving segment revocation information from the RSU, wherein the segment revocation information indicates that the segment and channel allocation are revoked;

the node communicates with the RSU over a legacy channel.

11. The method of claim 10, wherein the at least one segment is allocated one common control channel PCCH, two local control channels LCCH and four local traffic channels LSCH, the segment is allocated one PCCH, one LCCH and two LSCHs, and another segment adjacent to the segment is allocated the PCCH, another LCCH and another two LSCHs.

12. The method according to claim 10 or 11, wherein the node is a vehicle comprising an on board unit, OBU.

13. A server, comprising:

a receiving unit configured to receive network status information transmitted by at least one Road Side Unit (RSU), wherein the network status information transmitted by each RSU of the at least one RSU indicates a density of nodes covered by the RSU;

a segmentation unit configured to segment a region in the communication network according to the network state information to form at least one segment for the at least one RSU, respectively;

an allocation unit configured to allocate a channel for the at least one segment;

a transmitting unit configured to transmit network segment information and channel allocation information to each RSU of the at least one RSU, wherein the network segment information indicates a segment of the RSU, and the channel allocation information indicates a channel allocated for the segment, so that the RSU communicates with a node entering the segment through the channel allocated for the segment;

wherein the density of the nodes comprises the number of nodes within different distances from the RSU, and the server further comprises a determining unit configured to determine the zone congestion according to the number of nodes within different distances from the RSU.

14. The server according to claim 13, wherein the determining unit is further configured to determine that the area becomes uncongested, the transmitting unit is further configured to transmit segment revocation information to each of the at least one RSU, wherein the segment revocation information indicates that the segment and channel allocation are revoked so that the RSU communicates with nodes entering coverage of the RSU over legacy channels.

15. The server of claim 13, wherein the segment is configured to be divided into a plurality of squares, each square having an RSU at the center, the RSU (a) square having a side length L_SComprises the following steps:

L_S＝min(D_max,L)

wherein the content of the first and second substances,

wherein (x)_a,y_a) Longitude and latitude, N, of RSU (a)_iIs the number of nodes, N, in different ranges of the RSU (a)_desired(a) Is the desired node density of said square of RSU (a), dist () denotes the distance between the nodes, D_iRepresenting different distances to the rsu (a) at said different ranges.

16. The server according to any of claims 13 to 15, wherein the allocating unit allocates channels for the at least one segment from one common control channel, PCCH, two local control channels, LCCH, and four local traffic channels, LSCH, wherein the PCCH, one LCCH, and two LSCHs are allocated for the segment, and the PCCH, another LCCH, and another two LSCHs are allocated for another segment adjacent to the segment.

17. A roadside unit comprising:

a transmitting unit configured to transmit network state information to a radio resource management RRM server, wherein the network state information indicates a density of nodes covered by the RSU;

a receiving unit configured to receive network segment information and channel allocation information transmitted by a server, wherein the network segment information indicates a segment of the RSU, the channel allocation information indicates a channel allocated for the segment, and the segment is one of at least one segment respectively for at least one RSU formed by segmenting a region in a communication network by the RRM server, wherein the transmitting unit is further configured to transmit the network segment information and the channel allocation information to nodes covered by the RSU;

a communication unit configured to communicate with nodes in the segment through the channel allocated for the segment;

further comprising:

and the acquisition unit is configured to acquire the network state information according to the report of the node covered by the RSU.

18. The RSU of claim 17, wherein the density of nodes comprises a number of nodes within different distances from the RSU, and further comprising:

and the determining unit is configured to determine the coverage area congestion of the RSU according to the number of nodes in different distances from the RSU.

19. The road side unit of claim 18, wherein the receiving unit is further configured to receive segment revocation information from the RRM server, wherein the segment revocation information indicates that the segments and channel allocations are revoked, and the communication unit is further configured to communicate with nodes that enter coverage of the RSU by switching to legacy channels.

20. The roadside unit of claim 17, wherein the transmitting unit is configured to: the RSU periodically reports the network state information to a Network Control Center (NCC); or at least one of predetermined conditions is met, the RSU reports the network status information to the NCC.

21. The rsu of any of claims 17-20, wherein the at least one segment is allocated one common control channel, PCCH, two local control channels, LCCH, and four local traffic channels, LSCH, one PCCH, one LCCH, and two LSCHs, for the segment, and another segment adjacent to the segment is allocated the PCCH, another LCCH, and another two LSCHs.

22. A communication node, comprising:

a receiving unit configured to receive network segment information and channel allocation information from a road side unit, RSU, wherein the network segment information indicates a segment of the RSU, the channel allocation information indicates a channel allocated for the segment, and the segment is one of at least one segment respectively for at least one RSU formed by a RRM server segmenting a region in a communication network;

a determining unit configured to determine that the node is in the segment according to the network segment information;

a communication unit configured to communicate with the RSU through the channel allocated for the segment;

wherein the receiving unit is further configured to receive segment revocation information from the RSU, wherein the segment revocation information indicates that the segment and channel allocation are revoked, and the communication unit is further configured to communicate with the RSU over a legacy channel.

23. The node of claim 22, wherein the at least one segment is allocated one common control channel, PCCH, two local control channels, LCCH, and four local traffic channels, LSCH, one PCCH, one LCCH, and two LSCHs are allocated for the segment, and another segment adjacent to the segment is allocated the PCCH, another LCCH, and another two LSCHs.

24. A node according to claim 22 or 23, wherein said node is a vehicle comprising an on board unit, OBU.