阅读说明：本技术 一种处于不同局域网下的投屏方法、系统及智能装置 (Screen projection method, system and intelligent device under different local area networks ) 是由 杜兰涛 刘飞 赵宇峰 于 2019-12-04 设计创作，主要内容包括：本发明公开了一种处于不同局域网下的投屏方法，属于网络投屏技术领域，主要解决的是目前手机与智能电视或机顶盒不在同一局域网时手机上的视频应用不能投屏到电视或机顶盒的技术问题，所述方法为设置一网络连接移动终端局域网主交换机、电视设备局域网主交换机的投屏网关，移动终端依次通过所述移动终端局域网主交换机、投屏网关、电视设备局域网主交换机完成向电视设备投屏的功能。本发明还公开了一种处于不同局域网下的投屏系统以及一种处于不同局域网下的投屏智能装置。本发明可以实现跨网段投屏功能，网络结构简单。(The invention discloses a screen projection method under different local area networks, belongs to the technical field of network screen projection, and mainly solves the technical problem that video application on a mobile phone cannot be projected to a television or a set top box when the mobile phone and an intelligent television or the set top box are not in the same local area network at present. The invention also discloses a screen projection system under different local area networks and an intelligent screen projection device under different local area networks. The invention can realize the cross-network-segment screen projection function and has simple network structure.)

1. A screen projection method under different local area networks is characterized in that a screen projection gateway (C) which is connected with a mobile terminal local area network main switch (A) and a television equipment local area network main switch (B) through a network is arranged, and the mobile terminal (D) completes the screen projection function to the television equipment (E) through the mobile terminal local area network main switch (A), the screen projection gateway (C) and the television equipment local area network main switch (B) in sequence.

2. The screen-casting method under different local area networks according to claim 1, wherein the screen-casting gateway (C) comprises a mobile terminal gateway module for connecting at least one mobile terminal local area network master switch (a), a tv device gateway module for connecting at least one tv device local area network master switch (B), an M-SEARCH forwarding module operating according to HTTPMU and HTTPU protocols, and an HTTP forwarding module operating according to HTTP protocol, and the screen-casting process is as follows:

s1, the M-SEARCH forwarding module monitors a mobile terminal network port module, receives an M-SEARCH message of a mobile terminal (D) requesting screen projection, and forwards the M-SEARCH message to a television equipment local area network through a television equipment network port module;

s2, the M-SEARCH forwarding module waits for receiving an M-SEARCH response message replied by television equipment (E) capable of screen projection, and sends the updated Location field content in the M-SEARCH response message to a mobile terminal (D) requesting screen projection;

s3, after the HTTP forwarding module waits for receiving an HTTP request message sent by a mobile terminal (D) requesting screen projection, updating an HOST field in the HTTP request message, establishing TCP network connection with television equipment (E) capable of screen projection, and sending the HTTP request message to the television equipment (E) capable of screen projection;

and S4, the HTTP forwarding module waits for receiving an HTTP reply message replied by the television equipment (E) capable of screen casting and sends the HTTP reply message to the mobile terminal (D) requesting screen casting, so that the mobile terminal (D) can control the television equipment (E) to perform screen casting display and can acquire state information of the television equipment (E).

3. The method of claim 2, wherein in step S1, if the M-SEARCH message comes from a new mobile terminal (D), the M-SEARCH forwarding module creates an M-SEARCH forwarding thread corresponding to the new mobile terminal (D), and the new M-SEARCH forwarding thread forwards the M-SEARCH message to the local area network of the tv device.

4. The method of claim 3, wherein in step S2, the new M-SEARCH forwarding thread waits for receiving the M-SEARCH response message returned from the TV device (E) capable of screen-casting, and updates the Location field content in the M-SEARCH response message and sends the updated Location field content to the mobile terminal (D) requesting screen-casting.

5. The method of claim 3, wherein in step S2, the new M-SEARCH forwarding thread receives the M-SEARCH response message and controls the HTTP forwarding module to create a new HTTP forwarding thread corresponding to the new mobile terminal (D).

6. The method according to claim 5, wherein in step S3, the new HTTP forwarding thread waits for receiving the HTTP request message, updates the HOST field in the HTTP request message, establishes a TCP network connection with the screen-capable TV device (E), and sends the HTTP request message to the screen-capable TV device (E).

7. The method according to claim 5, wherein in step S4, the new HTTP forwarding thread waits for receiving the HTTP reply message and sends the HTTP reply message to the mobile terminal (D) requesting screen projection.

8. A screen projection system under different local area networks comprises a mobile terminal (D), a mobile terminal local area network main switch (A), a television device (E), a television device local area network main switch (B) and a screen projection gateway (C), wherein the screen projection system further comprises the screen projection gateway (C), and the mobile terminal (D) completes the screen projection function to the television device (E) through the mobile terminal local area network main switch (A), the screen projection gateway (C) and the television device local area network main switch (B) in sequence by using the screen projection method according to any one of claims 1 to 7.

9. The screen-casting system under different local area networks according to claim 8, wherein the screen-casting gateway (C) comprises a mobile terminal gateway module for connecting at least one mobile terminal local area network master switch (a), a tv device gateway module for connecting at least one tv device local area network master switch (B), an M-SEARCH forwarding module operating according to HTTPMU and HTTPU protocols, an HTTP forwarding module operating according to HTTP protocol; the M-SEARCH forwarding module is used for receiving the M-SEARCH message sent by the mobile terminal (D) and forwarding the M-SEARCH message to the local area network of the television equipment, and is used for receiving the M-SEARCH response message replied by the television equipment (E) and sending the updated content of the Location field to the mobile terminal (D); the HTTP forwarding module is used for receiving an HTTP request message sent by the mobile terminal (D), updating an HOST field in the HTTP request message, establishing TCP network connection with the television equipment (E), sending the HTTP request message to the television equipment (E), receiving an HTTP reply message replied by the television equipment (E) and sending the HTTP reply message to the mobile terminal (D), so that the mobile terminal (D) can control the television equipment (E) to perform screen projection display and obtain state information of the television equipment (E).

10. An intelligent screen projection device under different local area networks is characterized by comprising a mobile terminal network port module, a television equipment network port module, an M-SEARCH forwarding module and an HTTP forwarding module, wherein the mobile terminal network port module is used for being connected with at least one mobile terminal local area network main switch (A), the television equipment network port module is used for being connected with at least one television equipment local area network main switch (B), the M-SEARCH forwarding module works according to HTTPMU and HTTPU protocols, and the HTTP forwarding module works according to HTTP protocols; the M-SEARCH forwarding module is used for receiving an M-SEARCH message sent by a mobile terminal (D) and forwarding the M-SEARCH message to a television equipment local area network, and is used for receiving an M-SEARCH response message replied by the television equipment (E) and sending the M-SEARCH response message to the mobile terminal (D); the HTTP forwarding module is used for receiving an HTTP request message sent by the mobile terminal (D), updating an HOST field in the HTTP request message, establishing TCP network connection with the television equipment (E), sending the HTTP request message to the television equipment (E), receiving an HTTP reply message replied by the television equipment (E) and sending the HTTP reply message to the mobile terminal (D), so that the mobile terminal (D) can control the television equipment (E) to perform screen projection display and obtain state information of the television equipment (E) by using the screen projection method according to any one of claims 1 to 7.

Technical Field

The invention relates to the technical field of network screen projection, in particular to a screen projection method, a screen projection system and an intelligent device under different local area networks.

Background

With the continuous improvement of the technology of the processor chip of the mobile phone, the video decoding capability of the mobile phone is stronger, various video application software (such as love art, Tencent video, Youkou video and the like) are produced at a glance, the videos provided by the video platforms do not lack high-definition videos with the resolution ratio of 720P and 1080P, the high-definition videos are watched on a small screen such as the mobile phone, the visual experience is not optimal, and the high-definition videos can be better presented only by being played on a large screen such as a television.

At present, video application software on a smart phone basically provides a screen projection function, and the realization of the screen projection function requires that both the mobile phone and a television (or a set-top box) conform to the DLNA standard and are in the same local area network.

Dlna (digital Living Network alliance), a digital home Network alliance, establishes guidelines and specifications for media formats, transmission and protocol interoperability according to open industry standards, and aims to solve the interconnection and interworking between wireless networks and wired networks including personal PCs, consumer electronics, and mobile devices.

The various technologies and protocols selected by DLNA are widely used at present, and the UPnP protocol family is used in the discovery and control layer of the device.

UPnP (universal Plug and play), that is, universal Plug and play, the target of UPnP is that all devices on the network can know that a new device is added as soon as the device is connected to the network, and the devices can communicate with each other and can be used or controlled directly, and all devices do not need to be set and are completely Plug and play.

UPnP separates components in a network into three types: control points, devices and services, UPnP component schematic is shown in figure 1. The concept of the components in fig. 1 is as follows:

1. the root device/device, the device defined in the UPnP network, has a very broad meaning and a wide variety of appliances, computer peripherals, intelligent devices, wireless devices, personal computers, etc. may be referred to as devices. A UPnP device can be a carrier of multiple services or a nest of multiple sub-devices;

2. service, the functional service that the device can provide. The method comprises control service, event service and display service. The services are the minimum controllable units in the UPnP system, each service is externally represented as a specific behavior and mode, and the behavior and the mode can be described by using state and variable values;

3. the control point, i.e. the control device, may discover and control other devices, e.g. control video playing, pausing, etc. of other devices.

In the UPnP network, a device may be merged with a control point to be the same device, and has both the functions of the device and the functions of the control point, that is, the device may serve as a device and may also serve as a control point to discover and control other devices.

UPnP protocol Stack As shown in FIG. 2, the TCP/IP protocol is the basis of the UPnP protocol structure, and the HTTP protocol and its variation are constructed on top of the TCP/IP protocol, and this part is the core of UPnP, and all UPnP messages are encapsulated in the HTTP protocol and its variation. The variant of the HTTP protocol is HTTPU and HTTPMU, whose message formats follow the HTTP protocol, except that HTTPMU is transmitted by UDP multicast and HTTPU is transmitted by UDP unicast.

The Simple Service Discovery Protocol (SSDP) is built into HTTPU/HTTPMU and defines how services existing on the network can be discovered. Including in particular how the control point finds out which services are available on the network and the information of these services, and the control point itself announces which services it offers. This protocol is used in the device discovery part of the UPnP workflow.

The Simple Object Access Protocol (SOAP) defines how to perform Remote Procedure calls (Remote Procedure calls) using XML and HTTP. The method comprises the steps that how the control point sends a command message to the equipment, and how the equipment sends a response message to the control point after receiving the command message. The protocol is applied in the device control part of the UPnP workflow.

The Generic Event Notification Architecture (GENA) defines how a control point transmits subscription information and receives it when it wants to listen to the status of a certain service state variable of a device, and this protocol is applied in the Event subscription part of the UPnP workflow.

The work flow of UPnP is shown in fig. 3: first, both the control point and the device need to obtain the IP address. After obtaining IP address, the control point sends HTTPMU message to search UPnP device on the whole network, meanwhile, the device on the network also sends HTTPMU message to announce its existence, after receiving the search message, the device sends HTTPU message to the control point to inform the control point to obtain the path of its description information, the control point sends HTTP message to the device according to the path information to request to obtain device description, the device replies its description information to the control point after receiving the request, the control point analyzes the description information and then sends action information to the device, in addition, the control point monitors the state of the device, and when the state changes, corresponding processing action is made.

The process of screen projection by the mobile phone to the television is basically consistent with the process, in the process, the mobile phone is a control point, the television (or the set top box) is a device, when the screen projection function is selected in the video application of the mobile phone, the mobile phone firstly discovers the television (or the set top box) in the network in an HTTPMU mode, the television (or the set top box) in the network informs the mobile phone of the path of the description information in an HTTPU mode, the mobile phone requests the description information to the television (or the set top box) according to the path, after the description information is analyzed by the mobile phone, a searched device list is listed on a mobile phone interface, when a user selects a certain device to project, the mobile phone communicates with the selected television (or the set top box) in an HTTP protocol, the link of the video to be projected is pushed to the television (or the set top box), and the television (or the set top box) starts video playing after acquiring the video, at this moment, the screen projection function of the video application software is preliminarily realized, and then the mobile phone can send a control instruction to a projected television (or a set top box) or monitor the state of the projected television (or the set top box).

At present, most of smart phones and smart televisions (or set top boxes) in the DLNA standard are supported, but a general large enterprise or a star hotel, in consideration of network security, isolates a mobile phone network and a smart television (or set top box) network, divides the mobile phone network and the smart television (or set top box) network into different local area networks or different VLANs, and the two networks are not communicated with each other.

Disclosure of Invention

The invention aims to solve the technical problem of the prior art, and aims to provide a screen projection method for projecting a mobile phone video application to a smart television or a set top box in a different local area network from a mobile phone.

The invention also aims to provide a screen projection system for realizing screen projection of a mobile phone video application to an intelligent television or a set top box in a different local area network with a mobile phone.

The invention aims to provide a screen projection intelligent device for realizing screen projection of a mobile phone video application to an intelligent television or a set top box in a different local area network with a mobile phone.

In order to achieve the first purpose, the invention provides a screen projection method under different local area networks, wherein a screen projection gateway which is connected with a mobile terminal local area network main switch and a television equipment local area network main switch through a network is arranged, and the mobile terminal completes the screen projection function to the television equipment through the mobile terminal local area network main switch, the screen projection gateway and the television equipment local area network main switch in sequence.

As a further improvement, the screen-casting gateway includes a mobile terminal gateway module for connecting at least one mobile terminal lan main switch, a television equipment gateway module for connecting at least one television equipment lan main switch, an M-SEARCH forwarding module working according to HTTPMU and HTTPU protocols, and an HTTP forwarding module working according to HTTP protocols, and the screen-casting process is as follows:

s1, the M-SEARCH forwarding module monitors a mobile terminal network port module, receives an M-SEARCH message sent to the mobile terminal network port module by a mobile terminal requesting screen projection, and forwards the M-SEARCH message to a television equipment local area network by sending the M-SEARCH message to the television equipment network port module;

s2, the M-SEARCH forwarding module waits for receiving an M-SEARCH response message replied by the television equipment capable of screen casting, and sends the updated Location field content in the M-SEARCH response message to the mobile terminal requesting screen casting;

s3, after the HTTP forwarding module waits for receiving an HTTP request message sent by a mobile terminal requesting screen projection, updating an HOST field in the HTTP request message, establishing TCP network connection with television equipment capable of screen projection, and sending the HTTP request message to the television equipment capable of screen projection;

and S4, the HTTP forwarding module waits for receiving an HTTP reply message replied by the television equipment capable of screen casting and sends the HTTP reply message to the mobile terminal requesting screen casting, so that the mobile terminal can control the television equipment to perform screen casting display and can acquire state information of the television equipment.

Further, in step S1, if the M-SEARCH message comes from a new mobile terminal, the M-SEARCH forwarding module will newly create an M-SEARCH forwarding thread corresponding to the new mobile terminal, and the new M-SEARCH forwarding thread forwards the M-SEARCH message to the local area network of the television apparatus.

Further, in step S2, the new M-SEARCH forwarding thread waits for receiving an M-SEARCH response message returned by the screen-throwable television device, and sends the updated Location field content in the M-SEARCH response message to the mobile terminal requesting screen throwing.

Further, in step S2, after receiving the M-SEARCH response message, the new M-SEARCH forwarding thread controls the HTTP forwarding module to newly create an HTTP forwarding thread corresponding to the new mobile terminal.

Further, in step S3, the new HTTP forwarding thread waits for receiving the HTTP request packet, updates the HOST field in the HTTP request packet, establishes a TCP network connection with the television apparatus capable of screen projection, and sends the HTTP request packet to the television apparatus capable of screen projection.

Further, in step S4, the new HTTP forwarding thread waits for receiving the HTTP reply packet, and sends the HTTP reply packet to the mobile terminal requesting screen projection.

In order to achieve the second purpose, the invention provides a screen projection system under different local area networks, which comprises a mobile terminal, a mobile terminal local area network main switch, television equipment, a television equipment local area network main switch and a screen projection gateway, wherein the mobile terminal completes the screen projection function to the television equipment by the method through the mobile terminal local area network main switch, the screen projection gateway and the television equipment local area network main switch in sequence.

As a further improvement, the screen-casting gateway comprises a mobile terminal port module for connecting at least one mobile terminal local area network main switch, a television equipment port module for connecting at least one television equipment local area network main switch, an M-SEARCH forwarding module working according to HTTPMU and HTTPU protocols, and an HTTP forwarding module working according to HTTP protocols; the M-SEARCH forwarding module is used for receiving the M-SEARCH message sent by the mobile terminal and forwarding the M-SEARCH message to a local area network of television equipment, and is used for receiving the M-SEARCH response message replied by the television equipment and sending the updated Location field content to the mobile terminal; the HTTP forwarding module is used for receiving an HTTP request message sent by the mobile terminal, updating an HOST field in the HTTP request message, establishing TCP network connection with the television equipment, sending the HTTP request message to the television equipment, receiving an HTTP reply message replied by the television equipment, sending the HTTP reply message to the mobile terminal, and enabling the mobile terminal to control the television equipment to perform screen projection display and acquire state information of the television equipment.

In order to achieve the third purpose, the invention provides a screen-casting intelligent device under different local area networks, which comprises a mobile terminal network port module, a television equipment network port module, an M-SEARCH forwarding module and an HTTP forwarding module, wherein the mobile terminal network port module is used for connecting at least one mobile terminal local area network main switch; the M-SEARCH forwarding module is used for receiving an M-SEARCH message sent by the mobile terminal and forwarding the M-SEARCH message to the local area network of the television equipment, and is used for receiving an M-SEARCH response message replied by the television equipment and sending the M-SEARCH response message to the mobile terminal; the HTTP forwarding module is used for receiving an HTTP request message sent by the mobile terminal, updating an HOST field in the HTTP request message, establishing TCP network connection with the television equipment, sending the HTTP request message to the television equipment, receiving an HTTP reply message replied by the television equipment and sending the HTTP reply message to the mobile terminal, so that the mobile terminal can control the television equipment to perform screen projection display and acquire state information of the television equipment by using the method.

Advantageous effects

Compared with the prior art, the invention has the advantages that: the invention can realize the screen projection function across network segments by arranging the screen projection gateway which is connected with the main switch of the local area network of the mobile terminal and the main switch of the local area network of the television equipment through the network, has simple network structure, can expand according to the actual network planning condition without being limited to a single network, and has flexible expansibility.

Drawings

FIG. 1 is a diagram of a UPnP component;

FIG. 2 is a diagram of a UPnP protocol stack;

FIG. 3 is a flow chart of the UPnP operation;

FIG. 4 is a schematic structural view of the present invention;

FIG. 5 is a schematic diagram of a mobile terminal network divided into a plurality of VLANs according to the present invention;

FIG. 6 is a schematic diagram of the M-SEARCH forwarding module according to the present invention;

FIG. 7 is a schematic diagram of the operation of the HTTP forwarding module of the present invention;

FIG. 8 is a flowchart illustrating the operation of the M-SEARCH forwarding thread in the present invention;

FIG. 9 is a flowchart illustrating the operation of the new M-SEARCH forwarding thread in the present invention;

FIG. 10 is a flowchart of the operation of the HTTP forwarding thread of the present invention;

FIG. 11 is a path information diagram of a device description;

fig. 12 is a diagram illustrating modification of path information in the device description.

Wherein: the system comprises an A-mobile terminal local area network main switch, a B-television equipment local area network main switch, a C-screen projection gateway, a D-mobile terminal and an E-television equipment.

Detailed Description

The invention will be further described with reference to specific embodiments shown in the drawings.

Referring to fig. 4-12, a screen projection method under different lans is provided, in which a screen projection gateway C is set to connect a mobile terminal lan master switch a and a television device lan master switch B via a network, and a mobile terminal D completes a screen projection function to a television device E via the mobile terminal lan master switch a, the screen projection gateway C, and the television device lan master switch B in sequence.

The screen-casting gateway C comprises a mobile terminal network port module used for being connected with at least one mobile terminal local area network main switch A, a television equipment network port module used for being connected with at least one television equipment local area network main switch B, an M-SEARCH forwarding module working according to HTTPMU and HTTPU protocols, and an HTTP forwarding module working according to HTTP protocols, wherein the screen-casting process comprises the following steps:

s1, monitoring a mobile terminal network port module by an M-SEARCH forwarding module, receiving an M-SEARCH message sent to the mobile terminal network port module by a mobile terminal D requesting screen projection, and forwarding the M-SEARCH to a television equipment local area network by sending the M-SEARCH to the television equipment network port module;

s2, the M-SEARCH forwarding module waits for receiving an M-SEARCH response message replied by the television equipment E capable of screen casting, and sends the updated Location field content in the M-SEARCH response message to the mobile terminal D requesting screen casting;

s3, after the HTTP forwarding module waits for receiving an HTTP request message sent by the mobile terminal D requesting screen projection, the HOST field in the HTTP request message is updated, TCP network connection is established with the television equipment E capable of screen projection, and the HTTP request message is sent to the television equipment E capable of screen projection;

and S4, the HTTP forwarding module waits for receiving an HTTP reply message replied by the television equipment E capable of screen casting and sends the HTTP reply message to the mobile terminal D requesting screen casting, so that the mobile terminal D can control the television equipment E to perform screen casting display and can acquire state information of the television equipment E.

The steps S1 and S2 are used for the mobile terminal D to find the television device E, and the steps S3 and S4 are used for the mobile terminal D to project a screen to the television device E, where the mobile terminal D may be a mobile phone, a tablet computer, or other movable video playing device, and the television device E is a television or a set-top box. The mobile terminal network port module is provided with a network port for connecting a main switch A of a local area network of the mobile terminal, and the television equipment network port module is provided with a network port for connecting a main switch B of the local area network of the television equipment. And the screen projecting gateway C is also provided with a management network port for dispatching. And a CPU is arranged in the screen-casting gateway C and runs a Linux operating system, and the CPU controls the work of the mobile terminal network port module, the television equipment network port module, the M-SEARCH forwarding module, the HTTP forwarding module and the management network port.

In an actual network environment, the situation that a plurality of local area networks of the mobile terminal exist exists, and network port expansion can be performed according to the actual situation. For the case that the mobile terminal network is divided into a plurality of VLANs, as shown in fig. 5, a Trunk port needs to be configured on the core switch where the mobile terminal network is located, and data of each VLAN of the mobile terminal network is allowed to pass through, a Trunk port needs to be simulated on the corresponding port on the screen-casting gateway, and the Linux operating system has a tool for configuring the port as the Trunk port, so that multicast messages of each VLAN of the mobile terminal network can be received.

As shown in fig. 8 and 9, in step S1, the M-SEARCH forwarding module monitors the portal module of the mobile terminal, and if the received data is an M-SEARCH message of the http mu protocol, determines whether the M-SEARCH message is from the new mobile terminal D, i.e., whether the M-SEARCH message is from the new IP. If the M-SEARCH message comes from a new mobile terminal D, the M-SEARCH forwarding module creates an M-SEARCH forwarding thread corresponding to the new mobile terminal D, and the new M-SEARCH forwarding thread sends the M-SEARCH message to a local area network of the television equipment; otherwise, a new M-SEARCH forwarding thread is not created.

In step S2, the new M-SEARCH forwarding thread waits for receiving the M-SEARCH response message returned by the screen-projectable television apparatus E, and sends the M-SEARCH response message to the mobile terminal D requesting screen projection, where the M-SEARCH response message includes the path information responding to the apparatus description, i.e., the information included in the Location field, as shown in fig. 11. The IP and port number in the path information are the ports of the IP and HTTP services of the television apparatus E, and before returning the received M-SEARCH response message to the mobile terminal D, it is necessary to modify the IP in Location to the IP address of the mobile terminal D, where it is assumed that the IP address of the internet access is 192.168.1.110, and an unused port number is allocated, and the updated data is as shown in fig. 12.

In step S2, the new M-SEARCH forwarding thread receives the M-SEARCH response message and controls the HTTP forwarding module to newly create an HTTP forwarding thread corresponding to the new mobile terminal D.

As shown in fig. 10, in step S3, the new HTTP forwarding thread waits for receiving the HTTP request message, updates the HOST field in the HTTP request message, modifies the IP address in the HOST field in the HTTP request message to the IP address of the television apparatus E capable of screen projection, establishes a TCP network connection with the television apparatus capable of screen projection, and sends the HTTP request message to the television apparatus E capable of screen projection.

In step S4, the new HTTP forwarding thread waits for receiving the HTTP reply message, and sends the HTTP reply message to the mobile terminal D requesting screen projection, so that the cross-segment forwarding of the device description is completed, and the mobile terminal D can control the television device E to perform screen projection display and obtain the state information thereof.

The invention can realize the screen projection function across network segments by arranging the screen projection gateway which is connected with the main switch of the local area network of the mobile terminal and the main switch of the local area network of the television equipment through the network, has simple network structure, can expand according to the actual network planning condition without being limited to a single network, and has flexible expansibility.

A screen projection system under different local area networks comprises a mobile terminal D, a mobile terminal local area network main switch A, a television device E, a television device local area network main switch B and a screen projection gateway C, wherein the mobile terminal D completes the screen projection function of the television device E through the mobile terminal local area network main switch A, the screen projection gateway C and the television device local area network main switch B in sequence by using the method.

The screen-casting gateway C comprises a mobile terminal network port module used for being connected with at least one mobile terminal local area network main switch A, a television equipment network port module used for being connected with at least one television equipment local area network main switch B, an M-SEARCH forwarding module working according to HTTPMU and HTTPU protocols, and an HTTP forwarding module working according to HTTP protocols; the M-SEARCH forwarding module is used for receiving the M-SEARCH message sent by the mobile terminal D and forwarding the M-SEARCH message to the local area network of the television equipment, and is used for receiving the M-SEARCH response message sent by the television equipment E and updating the Location field content in the M-SEARCH response message and sending the updated Location field content to the mobile terminal D; the HTTP forwarding module is used for receiving an HTTP request message sent by the mobile terminal D, establishing TCP network connection with the television equipment E, sending the HTTP request message to the television equipment E, receiving an HTTP reply message replied by the television equipment E and sending the HTTP reply message to the mobile terminal D, so that the mobile terminal D can control the television equipment E to perform screen projection display and acquire state information of the television equipment E.

An intelligent screen projection device under different local area networks comprises a mobile terminal network port module, a television equipment network port module, an M-SEARCH forwarding module and an HTTP forwarding module, wherein the mobile terminal network port module is used for being connected with at least one mobile terminal local area network main switch A, the television equipment network port module is used for being connected with at least one television equipment local area network main switch B, the M-SEARCH forwarding module works according to HTTPMU and HTTPU protocols, and the HTTP forwarding module works according to HTTP protocols. The M-SEARCH forwarding module is used for receiving an M-SEARCH message sent by a mobile terminal D through a main switch A of a mobile terminal LAN, forwarding the M-SEARCH to a television equipment LAN through a television equipment network port module, and searching available television equipment E for the mobile terminal D. After receiving the M-SEARCH message, the available television equipment E replies an M-SEARCH response message to the television equipment network port module, and the M-SEARCH forwarding module receives the M-SEARCH response message and updates the Location field content therein, and then sends the M-SEARCH response message to the mobile terminal D through the mobile terminal network port module to complete the equipment discovery process. The HTTP forwarding module is used for receiving an HTTP request message sent by the mobile terminal D, updating an HOST field in the HTTP request message, establishing TCP network connection with the television equipment E and sending the HTTP request message to the television equipment E, and is used for receiving an HTTP reply message replied by the television equipment E and sending the HTTP reply message to the mobile terminal D, so that the mobile terminal D can control the television equipment E to perform screen projection display and acquire state information of the television equipment E by using the method.

The above is only a preferred embodiment of the present invention, and it should be noted that it is obvious to those skilled in the art that several variations and modifications can be made without departing from the structure of the present invention, which will not affect the effect of the implementation of the present invention and the utility of the patent.