System for efficiently covering a sectorized cell utilizing beam forming and sweeping

A system that effectively provides segmented cell coverage in shared and dedicated channels using beamforming and frequency sweeping

Technical field

The present invention relates to a system for effectively providing segmented cell coverage in shared and dedicated channels using beamforming and frequency sweeping.

Background technique

Segmentation is a known technology to provide a clear coverage area in an individual cell site and can be achieved with "smart antenna" technology. The smart antenna method dynamically changes the radiation pattern of an antenna to form a "beam", which can specifically concentrate the energy transmitted and received by the antenna and provide coverage for a desired terrain. Beamforming is an enhancement in segmentation, because the segment can be adjusted in its direction and width. Both technologies are used: 1) reduce the interference between the cell and the wireless transmit/receive units (WTRUs) deployed between the cells; 2) increase the permission between a receiver and a transmitter Range; 3) Locating the geographic location of a wireless transmit/receive unit (WTRU). These technologies are usually used in dedicated frequency channels of wireless transmit/receive units (WTRUs), once their general location is known.

Before knowing the location of a wireless transmit/receive unit (WTRU), the shared channel broadcasts information that all wireless transmit/receive units (WTRUs) may receive. When this information may be sent to a static section, it will not be sent in a changing beam. There is an inherent inefficiency in this method, because additional steps are required to determine the appropriate beam to use for dedicated data exchange. In addition, beams must generally be large enough to provide a wide coverage area, which in turn means that their power is lower due to the distance from the transmitter. In such cases, it must use higher power, longer symbol times, and/or a more robust coding architecture to cover the same range.

Figure 1 shows the conventional shared channel coverage, with four partially overlapping wide beams. When a cell site is given a degree of reuse, it will provide a full range of coverage. By having a unique identifier for each segment transmission, it also provides a rough command to the wireless transmission/receiving unit (WTRUs) that detects one of the transmissions.

Please refer to FIG. 2, which shows a dedicated downlink beam between a primary station (P) and several wireless transmit/receive units (WTRU3, WTRU4). Assuming that the same power and all other attributes of the master station P in Fig. 1 and Fig. 2 are equal, the wireless transmission/reception units (WTRU3, WTRU4) shown in Fig. 2 are better than those shown in Fig. 1 /The receiving unit (WTRU1, WTRU2) may be farther away from the master station P. Optionally, this coverage can be achieved by reducing the symbol rate or increasing the error correction coding to be almost the same. Any of these methods can reduce the data transmission rate. This can also be applied to the receiver uplink beam pattern of the master station P, and the same annotations and requests regarding coverage are sent from the wireless transmission/receiving units (WTRUs) to the master station P Get data options.

In the prior art, a master station P or a wireless transmit/receive unit (WTRU) usually uses higher power, lower symbol rate, error correction coding and diversity in time, frequency or space ( diversity) to increase its range. However, the result of these methods is the lack of optimized operation. Furthermore, there is no coordination between the shared and dedicated communication channels in the coverage adjustment.

The downlink dedicated channel can be transmitted via a smart antenna in a beam with a narrow width. The narrow beam is treated as a narrower area. The advantage of narrowing the beam is to reduce the impact on other areas of the cell. This cell has a positive effect on the efficiency of the system. However, dedicated channels are still susceptible to interference caused by shared channels, and shared channels must be available to all moving parts in the entire coverage area. Figure 3 shows the currently deployed radiation pattern of a cell system. This cell system uses a small coverage area 10 covered by a dedicated channel transmitted by a smart antenna system and has a narrow-width beam and an omni-directional antenna. An omnidirectional pattern of transmission throughout a wide coverage area covered by a shared channel. Because the shared channel is transmitted at a high output power to ensure complete cell coverage, the reception of a wireless transmit/receive unit (WTRU) of the dedicated channel can be closer to the high-powered one due to the wireless transmit/receive unit (WTRU). Interference by sharing the channel transmitter.

Therefore, it is urgent to provide a method for providing fair coverage of shared and dedicated channels in wireless communication systems without the lack of conventional technology.

Summary of the invention

A communication system is used to transmit and receive shared and dedicated channel communication between at least one primary station and at least one secondary station, using at least one beam including an antenna. This system includes a device for generating and shaping the beam and a device for sweeping and shaping the beam. The frequency sweeping device selectively directs the shaped beams in a plurality of directions.

Description of the drawings

Figure 1 shows a conventional shared channel coverage architecture between a master station and several wireless transmit/receive units (WTRUs) with four partially overlapping wide beams.

Figure 2 shows a conventional downlink dedicated beam architecture between a master station and several wireless transmit/receive units (WTRUs) that use dedicated beams.

Fig. 3 is a conventional radiation pattern of a cell system. The cell system uses a dedicated channel to cover a narrow-width beam covering a small coverage area and a shared channel to cover an omnidirectional pattern covering a wide coverage area.

Figure 4 shows a rotating shared channel beam transmitted from a master station.

Figure 4A shows a flow chart of a common beacon channel (common beacon channel) sweeping.

Figure 5 shows the known irregularly distributed beam patterns of wireless transmit/receive units (WTRUs).

Fig. 6 shows a beam shape with a beam width adjusted to a flow pattern.

Figure 7 shows a beam pattern with equal coverage areas of dedicated and shared channels.

Figure 8 shows a beam pattern with equal coverage areas of dedicated and shared channels.

Figure 9 is a flowchart of an embodiment in which the shared channel beacon channel is swept.

FIG. 10 is a flowchart of an embodiment in which a unique shared beacon channel is transmitted to different locations of a cell.

detailed description

The present invention will be explained with reference to icons, in which the same numbers represent the same components throughout. The foregoing description of beamforming can be applied to signal transmission and reception. For example, a narrower transmit beam causes less interference to devices outside the beam. The above description of the present invention can be applied to the reception and transmission of signals, and the content of the special part of this description will be clearly referred to for reception or transmission when it is not an example of the present invention.

The present invention is broadly concerned with considering coverage in a wireless communication system that uses smart antennas to transmit shared and dedicated channels, and provides coverage similar to shared and dedicated channels. This shared channel, as its name implies, is used via all devices. The system and method of the present invention arranges these shared channels in a way that provides useful information to the system and wireless transmit/receive unit (WTRU) to finally establish a dedicated channel.

Please refer to FIG. 4, the dashes refer to the possible positions of P1-Pn representing a shared channel beam B transmitted from a master station PS. During the execution of a specific time, the beam B only exists in one of the positions P1, as shown by the solid line. The arrow shows the time sequence of beam B. In this illustration, the beam B continuously moves clockwise from one position P1 to the other P2-Pn, although the clockwise rotation is not necessary.

This system is provided to identify the beam B at each P1-Pn position. FIG. 4A is a flowchart of the method 40 in the embodiment of the present invention shown in FIG. 4, and the identified beam B includes a unique identifier. When the beam B is in each P1-Pn position, it is swept in the vicinity of the cell (step 41). For example, in a first position P1, a first identification character I1 will be transmitted, and in a second position P2, a second identification character I2 will be generated, and so on for each P1-Pn position. If the beam B is continuously scanned, at each level, (or the current digital level), a different identification word I1-In will be sequentially generated.

When a wireless transmit/receive unit (WTRU) successfully obtains the beacon shared channel (step 42), it will report the identification number of the shared channel to the PS (step 44). This information is used by the system to determine wireless transmission/reception The location of the units (WTRUs) (step 48). Because the shared channel has only a short time in a section, all the interference caused by the shared channel to the dedicated channel is therefore reduced. A minor deficiency may be an extended acquisition time, but this deficiency can be alleviated by increasing the data rate of the shared channel.

A second embodiment is used to identify the P1-Pn position of beam B using a time stamp as a type of identification character, which is the wireless transmit/receive unit (WTRU) returning to the PS, and this time stamp or identification character Returning to PS is to inform PS that beam B has been detected by the wireless transmit/receive unit (WTRU). During the execution of that time, the PS now knows the P1-Pn positions of beam B that can be communicated with the wireless transmit/receive unit (WTRU). However, it should be noted that the direction of the wireless transmit/receive unit (WTRU) from the PS is not necessary due to possible reflections.

A third embodiment is used to identify the P1-Pn position of beam B using time-synchronization. Beam B is positioned and correlated with a known time stamp. One way to achieve this is to make the wireless transmitting/receiving unit (WTRUs) and PS both access the same time reference, such as Global Positioning System (GPS), National Institute of Standards and Technology (National Institute of Standards and Technology) Internet time or Radio Time Broadcast (WWV) or meet Maintain synchronized local timers.

A fourth embodiment is used to identify the P1-Pn positions of beam B, which are the markers transmitted from the public construction by synchronizing both the wireless transmission/receiving unit (WTRUs) and the PS. The wireless transmit/receive units (WTRUs) can detect and recognize PS beam transmission, but the P1-Pn positions of individual beam B are not necessary. When it detects this beam B, it reports the time factor to the PS via the wireless transmit/receive unit (WTRU), and this PS can determine which beam B the wireless transmit/receive unit (WTRU) refers to. The advantage of this embodiment is that the shared channel transmission does not require additional data to identify the P1-Pn positions of beam B.

A fifth embodiment used to identify the P1-Pn position of beam B is to incorporate a global positioning system (GPS) into the wireless transmit/receive unit (WTRU), and then the wireless transmit/receive unit (WTRU) is connected to Longitude and report this information to PS to determine its geographic location. Then, the PS can use this information to accurately generate beam B, beam width, and power. Another advantage of this embodiment is that the precise location obtained by the wireless transmit/receive unit (WTRU) will allow the user to determine the location of the wireless transmit/receive unit (WTRU) if needed.

Please refer to Figure 5, the beam pattern can be customized upon request of the system administrator. In this way, the PS can set the beam B in a pattern consistent with the desired density of the wireless transmit/receive unit (WTRU) in a specific area. For example, a wide beam W1, W2, W3 can be compared with a few Wireless transmit/receive units (WTRUs) are projected to P1, P2, and P3, respectively, while narrower beams N1, N5, N6 and most wireless transmit/receive units (WTRUs) are projected to P4, P5, respectively , P6 position. This promotes the generation of narrow dedicated beams B in denser areas, and at the same time increases the processing capacity used for the uplink and downlink of the shared channel to establish the initial communication.

The operation of the beam width is preferably performed in real time. However, the communication status and the nature of the application determine the suitability of the number of beam positions P1-Pn and the associated beam width type. The beam pattern formed should have sufficient width so that the number of wireless transmit/receive units (WTRUs) entering and leaving the beam can be controlled without excessive handoff to other beams. A static device can be served by a narrow beam. For example, a fast-moving car cannot be efficiently served by a narrow beam orthogonal to traffic, but can be served by a narrow beam parallel to the conduction direction. . A narrow orthogonal beam can only be used for short message services, and cannot be used for voice services, such as telephones.

The other advantage of using different beam widths is the nature of the movement of wireless transmit/receive units (WTRUs) within an area. Please refer to FIG. 6, which shows a building BL (representing an area with initially slower moving walking speed devices WTRUs) and a high-speed information path (highway) H (representing an area with initially faster moving devices WTRUs). The slower device WTRUs can be served by narrow beams N1-N3, which are likely to be traversed during a communication execution. Or, faster mobile WTRUs need wider beams W1-W3 to support a communication.

Beamwidth shaping also reduces the handover frequency of wireless transmit/receive units (WTRUs) from one beam B to other beams, and the handover requires more system information than a typical communication, because when When this handover occurs, two independent communication links are maintained. Because voice communication is less tolerable during latency execution, which is often associated with handover, beam handover should also be avoided.

Data services are related to packet size and volume. Although some small packets can be transmitted without problems, large packets that require a significant number of handovers can use excessive bandwidth. When the link is handed over, the bandwidth is too large. This will happen when trying to be re-established, and when multiple identical data is sent to try to perform a reliable transmission, the bandwidth will also be exhausted. Downlink shared channel communication usually follows the uplink transmission. By knowing the PS transmission type, the wireless transmit/receive unit (WTRU) can determine the appropriate time to send its uplink transmission. To perform the necessary timing, a known fixed or broadcast time relationship is used. In an example of a fixed relationship, the wireless transmit/receive unit (WTRU) uses a common timing clock, and the wireless transmit/receive unit (WTRU) waits until a certain time, where the PS has been formed throughout the wireless transmission before the transmission /A beam of the receiving unit (WTRU) section. In this example, a broadcast time relationship, the PS informs the wireless transmit/receive unit (WTRU) when to send its uplink signal, the uplink and downlink beamforming may or may not partially overlap to avoid partial overlap It is usually an advantage, therefore, a device will respond to a transmission in less time than when the same propagation period of the entire antenna beamforming timing cycle occurs.

It should be noted that CMD and other radio frequency (RF) protocols use a form of time division. When responding to these types of temporary public works, both the beam section and timing of the protocol will be very important. Other time-independent RF protocols, for example, slotted Aloha (slotted Aloha) only involve sections.

The above-described embodiments are directed to beam B that is "sweeped" in a continuous manner near the PS. In many cases, it will typically be the most convenient way to accomplish the present invention. However, there are other ways to assume different locations, for example, it is desirable to have more instances in a particular area. This can be accomplished by generating beams at a series of timed-positions. For example, if there are 7 positions (numbered from 1 to 70), a series of (1, 2, 3, 4, 2, 5, 6, 2 , 7, 1) can be used, this always has the area covered by beam position number 2 longer than other positions, but has the same stop time. A longer stop time in an area is also promising. For example, this order (1, 2, 3, 4, 4, 5, 6, 7, 1) beam position number 4 remains unchanged for the two time execution periods, any suitable order can be used and modified The analysis is guaranteed by the situation.

Similarly, there is no need to limit the beam position to a rotating pattern, and the beam position can be generated in any order to provide the operation of the communication system. For example, spreading beam B throughout time, such that each quadrant is covered by at least one beam B, may be useful for wireless transmit/receive units (WTRUs) that are close to the PS and may be covered by more than one beam position.

It should be noted that similar to all RF transmissions, if there is a Faraday type obstruction (ie, a basic metal top), an RF signal only stops at a physical point. Usually the signal disappears one after another, and the boundary is some clear decay value from the transmitted peak. In order to provide sufficient coverage in the application of the present invention, it is preferable that the adjacent beam positions partially overlap to some extent, and this partial overlap tends to be closer to the transmitting and receiving antennas. Close to a public building antenna site, any wireless transmit/receive unit (WTRU) is likely to be able to communicate via beam B in a number of different locations. Devices that can communicate via several beam positions can, if necessary, use these multiple positions to achieve higher data rates. However, when the device is farther away, it is more likely to be able to communicate via only one immediate beaming, and obtaining a higher data rate requires additional techniques, such as a longer stop time.

Please refer to FIG. 7, which shows an embodiment in which the shared beacon channel is swept through the cells denoted by P1 to Pn at positions P divided into n numbers. Each position P represents a different shared channel beam B, a wireless transmit/receive unit (WTRU) is located in the beam position P3 and a PS is located in the center of the cell.

Please refer to FIG. 9 which shows the procedure of FIG. 7 according to an embodiment of the present invention. Procedure 81 starts when the shared beacon channel is swept near the cell via positions P1 to Pn (step 91). Each position P represents an identifier of the energy gathered by the antenna and its unique shared beacon channel signal. ). A wireless transmit/receive unit (WTRU) is located in the cell coverage area where a unique shared beacon channel is obtained (step 92), and then the wireless transmit/receive unit (WTRU) reports the obtained beacon identifier to the PS (Step 94), the PS receives the identifier from the wireless transmit/receive unit (WTRU) and determines the location of the wireless transmit/receive unit (WTRUs) (step 96), so the wireless transmit/receive unit (WTRU) designates a dedicated The direction of the channel to the wireless transmit/receive unit (WTRU) (step 98).

Another embodiment of the present invention is shown in FIG. 8, which includes a shared channel beam in each sector, without having to scan the coverage area of the cell. Although such a choice slightly increases the interference in the cell, it provides the same coverage as the shared channel. As shown, the PS has eight positions P1 to Pn, each representing a different unswept unique shared beacon channel signal, and a wireless transmit/receive unit (WTRU) is located at position P4.

Please refer to FIG. 10 which shows an alternative program 100 of FIG. 8 according to an embodiment of the present invention. Eight unique shared beacon channel signals are transmitted to positions P1 to P8 in the cell (step 101). Each position P represents the physical location of the energy gathered by the antenna and an identifier of its unique shared beacon channel signal ( identifier). A wireless transmit/receive unit (WTRU) located in the cell coverage area obtains one of the eight unique shared beacon channel signals (step 102) and reports which beam the beam identifier is obtained (step 104) to the PS . The PS receives the identifier from the wireless transmission/reception unit (WTRU) and determines the location of the wireless transmission/reception unit (WTRU) (step 106). Then, the PS assigns a dedicated channel to the direction of the wireless transmit/receive unit (WTRU) (step 108).

In this example, a wireless transmit/receive unit (WTRU) is placed at or near the boundary of two or more sectors, and the wireless transmit/receive unit (WTRU) may have difficulty identifying which sector is associated with . When the wireless transmit/receive unit (WTRU) obtains a section, the system will deploy hysteresis in the rule system of its instructions to ensure that the wireless transmit/receive unit (WTRU) a certain limited time before expecting another section Have an acceptable signal quality.

Those familiar with this technology in the related field should understand that the number of beams or the beam positions spread in a cell as described above have been used in the example. More or less number of beams, or beam positions, can be changed or replaced by those familiar with the technology, but they are all within the scope defined by the appended claims.