Method and system for improving the spectral efficiency of a data communication link

(54) Title: METHOD AND SYSTEM TO IMPROVE (57) Summary: SPECTRAL EFFICIENCY OF A DATA COMMUNICATION CONNECTION (30) Unionist Priority: 27/03/2007 us 60 / 908,289 (73) Owner (s): Telcom Ventures LLC (72) Inventor (s): George Ron Olexa, Rajendra Singh (74) Attorney (s): Dannemann, Siemsen, Bigler & Ipanema Moreira (86) International Request: pct us2008054985 of 26/02/2008 (87) International Publication : wo 2008 / H8593from 10/02/2008

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Invention Patent Descriptive Report for METHOD AND SYSTEM TO IMPROVE THE SPECTRAL EFFICIENCY OF A DATA COMMUNICATION CONNECTION.

CROSS REFERENCE TO RELATED ORDERS

This application is based on and derives benefits from the filing date of Provisional Patent Application No. 60/908289, filed on March 27, 2007, the contents of which are incorporated into this by reference.

Field of invention

Methods and apparatus consistent with the present invention refer to communications by a mobile device with a plurality of transceivers, and more particularly, to reuse channels to improve spectral efficiency.

Brief Description of Drawings

Detailed modalities of the present invention will be described with reference to the accompanying drawings, in which:

Figure 1 illustrates a mobile satellite communication system according to an embodiment of the present invention;

Figure 2A illustrates a distribution of channels in a beam of light points;

Figure 2B illustrates a distribution of channels in a beam of light points with the addition of a plurality of out-of-band channels, according to an embodiment of the present invention;

Figure 2C illustrates a distribution of channels in a beam of light points with the addition of out-of-range spectrum in an MSS / ATC system, according to another embodiment of the present invention;

Figure 3 illustrates delivery or transfer limits (hand-off ') between the Mobile Satellite System (MSS) mode, Terrestrial ATC Mode (TMA) and Enhanced Terrestrial Mode (TME) according to an embodiment of the present invention; and

Figure 4 illustrates a flowchart describing a method for communicating between a mobile device with plural transceivers in accordance with an embodiment of the present invention.

Detailed Description of Various Modalities

Modalities of the present invention will be described in detail with reference to the accompanying drawings.

Throughout the description, various acronyms and shorthand annotations are used to help understand certain concepts pertaining to the system and associated services. These acronyms and shorthand annotations are intended only for the purpose of providing an easy methodology to communicate the ideas expressed in this and are in no way to limit the scope of the present invention.

The present invention can be embodied in many different forms and should not be construed as being limited to the modalities set forth herein, and are defined by the appended claims. Like reference numbers refer to like elements throughout the specification.

Figure 1 illustrates a mobile satellite communication system 100 with multiple communication devices interacting with one another in accordance with an embodiment of the present invention.

As shown in Figure 1, a satellite transceiver 102 can communicate bidirectionally with multiple mobile devices 106. Likewise, a terrestrial base station 104 can communicate bidirectionally with multiple mobile devices 106. In this embodiment, a mobile device 106 can include a mobile cell phone, a personal digital assistant (PDA), or any mobile device that is capable of communicating data to other objects.

Satellite transceiver 102 can include any object that is capable of orbiting another object and capable of communicating data bidirectionally with other objects.

A base station 104 can include any station with a radio transceiver that maintains communications with a mobile radio device within a given range.

According to an embodiment of the present invention, there are four different communication connections to be discussed.

In the satellite-to-ground communication connection 108, a satellite transceiver 102 can transmit data to a mobile device 106. Here, satellite-to-ground communication can be a part of the standard Mobile Satellite System (MSS) communication. In one embodiment, satellite transceiver 102 can transmit and receive data to and from an area illuminated by a beam of light dots 116 surrounding a mobile device 106. In a ground-to-satellite communication connection 112, a mobile device 106 can transmit data to a satellite transceiver 102. In a base station to mobile device communication connection 114, a base station 104 can transmit data to a device mobile 106. In a mobile device communication connection to base station 110, a mobile device 106 can transmit data to a base station 104.

Satellite transceiver 102 can transmit data over multiple channels. Each channel can have an assigned frequency. According to an embodiment of the present invention, a satellite transceiver 102 can transmit through any of the four channels labeled Ai, Bi, Ci, Di, respectively, as shown in figure 2A. Of course, any number of channels can be provided. Mobile device 106 can transmit to satellite transceiver 102 over multiple channels. Each channel can have an assigned frequency. According to an embodiment of the present invention, the mobile device 106 can transmit through any of the four channels labeled A, B, C, D, respectively, corresponding to the channels Ai, B- |, Ci, D- |, respectively.

In one embodiment, communication from satellite transceiver 102 will be through one of those channels, for example, channel A- | The mobile device 106 will transmit through the corresponding channel A. Within the beam of light points 116 of the satellite transceiver 102, base stations 104 will also be communicating with mobile devices 106. Typically, the frequencies used to communicate between base stations 104 and mobile devices 106 are different from the frequencies used to communicate between satellite transceiver 102 and mobile devices

106. Alternatively, the conventional MSS / ATC standard provides that channels reserved for satellite communications, but not used by satellite transceiver 102, can be used for mobile base station communications within beam beam 116 of satellite transceiver 102 . In this way, the other channels, in this example, Bi, Ci and Di channels can be used for mobile base station communications, for example, as Auxiliary Terrestrial Component (ATC) channels. According to the MSS standard, figure 2A provides a plurality of channels used in these data transmissions. The satellite-to-ground communication connection will be referred to as an MSS communication downlink and the earth-to-satellite communication connection will be referred to as an MSS communication downlink.

In the transmission of uplink data, in the illustrated mode, there are four possible channels labeled A, B, C and D, respectively, as shown in figure 2A. The uplink channel A is associated with the downlink channel Ai mentioned above. That is, channels A and Ai form a channel pair. In other words, the downlink channel Ai refers to half the channel used to send data from a satellite to a terrestrial device on Earth. Uplink channel A, on the other hand, refers to the other half of the channel to send data from a terrestrial device to satellite 102. Similarly, this is the case for the remaining channel pairs B / Bi, C / Ci, and D / Di, where B, C and D correspond to the uplink channels and B- |, Ci and Di correspond to the downlink channels.

In the example shown in Figure 2A, the frequency spectrum from 2000 to 2020 MHz can be used for conventional MSS communication uplinks 202 and the frequency spectrum from 2180 to 2200 MHz can be used for MSS communication downlink 204. In this example, four channels of 5MHz width are used as uplink and downlink communication channels.

Figure 2B illustrates an allocation of channels in a beam of bright spots with the addition of a plurality of channels out of range, according to an embodiment of the present invention. As shown in figure 2B, there are a plurality of dual downlink T / S channels 250 used for satellite communication to mobile device (downlink S channels) and base station to mobile device (downlink T channels). The notation T and S is generally used to indicate ground-based communication (T), as a communication between the base station and the mobile device and a satellite-based communication (S), as a communication between the mobile device and the satellite. For example, in one embodiment, the one or more terrestrial (T) channels can be ATC channels and one or more satellite (S) channels can be MSS channels, although this system can be used separately from an MSS / ATC. The dual T / S downlink channels 250 allow both satellite transceiver 102 and base stations 104 to communicate with mobile device 106 on each of the plurality of channels 250. The satellite transmission will not interfere with the transmission of the base station on the same frequency because the signal from the base station is an order of magnitude stronger than the satellite signal in the coverage area of ​​the light beam transmission of the transceiver. satellite 102 The downlink channels S on the dual downlink channels T / S 250 (that is, downlink channels from satellite to mobile device) are paired with the uplink channels S 252 (i.e., uplink channels from mobile to satellite).

The uplink channels (i.e., mobile device channels to base station) corresponding to the downlink T channels (i.e., base station channels to mobile device) on the dual T / S downlink channels 250 are manipulated differently. As shown in figure 2B, a plurality of terrestrial channels out of the uplink band (T OOB) 254 are added to the uplink channels S (i.e., uplink channels from mobile to satellite). T OOB channels 254 allow a mobile device 106 to communicate with a base station 104 without interfering with reception by satellite transceiver 102. Each out-of-band terrestrial channel (T OOB channel) in the plurality of uplink channels T OOB 254 together with each of the plurality of downlink channels T in the plurality of downlink channels of the T / S 250 form a channel pair terrestrial allowing communications between a base station and a mobile device. In the embodiment illustrated in figure 2B, the OOB spectrum portion is comprised of four OOB uplink channels and each of the four OOB uplink channels is paired with a respective channel on the four downlink T channels. , it should be appreciated that any number of channels can be implemented, as desired.

Each T OOB uplink channel on T OOB channels 254 can be used together with a corresponding T downlink channel in the plurality of dual T / S downlink channels 250 for terrestrial transmission within a coverage area of ​​a bundle of points from a satellite transceiver. The T OOB uplink spectrum can include any spectrum with propagation characteristics suitable for mobile or portable use.

The interference is mitigated because the T OOB uplink link is not seen by satellite transceiver 102. The U OOB 254 uplink channels are outside the pass range of the satellite transceiver.

Matching the UOB U-link spectrum (mobile base station device) with terrestrial U-link spectrum T in the dual T / S downlink spectrum (at the satellite downlink frequency) in the manner described above, does not exist substantially no uplink interference quoted for any operational satellite transceiver in the normal satellite uplink range. The satellite transceiver sees only energy associated with the desired uplink for land-to-space communications. Any energy associated with the uplink to terrestrial base stations is removed to another frequency range outside the satellite uplink spectrum that does not substantially cause any interference to the satellite transceiver.

In areas where the satellite is the sole service provider, the uplink from the mobile device to the satellite transceiver and the downlink from the satellite transceiver to the mobile device operates on a designated satellite band. In areas where terrestrial base stations operate, either some or all of the satellite downlink spectrum is used by terrestrial base stations to provide downlink (that is, downlink from the base station to the mobile device). terrestrial signals are of a higher order of magnitude in the coverage area, stronger terrestrial signals will cancel out satellite downlink signals. In the uplink direction, the OOB spectrum is used on the terrestrial uplink (ie uplink from the mobile device to the base station) with substantially no effect on satellite operation since the OOB uplink spectrum is outside of the normal satellite uplink spectrum.

Figure 2C illustrates an allocation of channels in a beam of bright spots with the addition of an out-of-range channel in an MSS / ATC system, according to another embodiment of the present invention. As shown in figure 2B, there are a plurality of data transmission uplink channels 208. According to the MSS / ATC standard, one or more channels can be used as either a satellite channel (eg, MSS) or a terrestrial channel (for example, ATC). For example, in one embodiment, an uplink channel 210 may be used as an MSS uplink channel (i.e., mobile to satellite communication channels). The remaining channels 212 can be used as terrestrial uplink channels (i.e., communication channels from mobile device to base station), for example, in ATC channels.

In addition, figure 2C shows modified data transmission connections 216 according to the out-of-range channel and channel reuse techniques described in this. Modified data transmission downlink 216 may include an MSS / ATC dual downlink channel 218 in addition to the normal downlink terrestrial channels 219 (i.e., base station communication channels for mobile device) that are made pairs with terrestrial uplink channels 212 (ie, communication channels from mobile device to base station). The dual downlink channel of MSS / ATC 218 allows both satellite transceiver 102 and base stations 104 to communicate with mobile devices 106 on the same channel. Similar to the modality described above with respect to figure 2B, the satellite transmission will not interfere with the transmission of the base station on the same frequency because the signal from the base station is orders of magnitude stronger than the satellite signal.

The uplink channel corresponding to the downlink channel of the base station for mobile device on the dual downlink channel 218 is handled differently. As shown in figure 2C, an out-of-band uplink terrestrial channel (OOB) 214 is added to data transmission uplink channels 208. For example, an ATC OOB 214 uplink channel is added to the transmission connections of data 208. This terrestrial uplink channel (e.g., ATC OOB uplink channel) 214 allows a mobile device 106 to communicate with a base station 104 without interfering with reception by satellite transceiver 102. The outbound uplink terrestrial channel (eg ATC OOB uplink channel) 214 together with the downlink terrestrial channel (eg ATC downlink channel) 218 ​​forms a terrestrial channel pair (eg example, an ATC channel pair) allowing communications between the base station and mobile device.

The OOB spectrum is a piece of spectrum that can be equal to the spectrum allocation of any channel transmitted on the data transmission connection. The same OOB spectrum can be used for any beam of light from a satellite transceiver using any channel. Preferably, the OOB spectrum can include any spectrum with propagation characteristics suitable for mobile or portable use.

Interference is mitigated because the OOB channel is not seen by the satellite transceiver. That is, the OOB channel is outside the satellite transceiver's pass range.

The schemes described above improve spectral efficiency. For example, referring to the modality illustrated in figure 2C, with MSS / ATC convention communications a beam of light points would normally allow three of the four channels, for example, to be used for terrestrial data communications. Thus, a quarter of the channels would not be available for terrestrial communications. The additional use of an MSS downlink channel for satellite transmissions to mobile device coupled with a mobile device uplink to base station in additional OOB spectrum outside the pre-assigned spectrum portion for satellite communications enables an increase in spectral efficiency. That is, another channel pair is now available for terrestrial data transmission.

For example, referring to the modality illustrated in figure 2C, if each of the uplink channels and downlink channels of MSS or ATC occupies 20 MHz of bandwidth and the terrestrial OOB uplink channel (ATC OOB) it occupies a 5 MHz part of terrestrial spectrum not paired, the efficiency of an MSS / ATC system can be increased by 12%. In other words, 45 MHz of allocated spectrum causes 50 MHz of effective spectrum.

Similarly, referring to the modality illustrated in figure 2B, in the downlink direction, each of the four downlink channels is used both in mobile satellite communications (downlink S channels) and from the base station to device mobile (downlink channels T). In the uplink direction, each of the four uplink channels is used for communication between the mobile device and the satellite. Uplink communication between the mobile device and the base station is handled using the four OOB uplink channels to prevent interference with the satellite uplink channels. So, there are a total of 8 uplink channels. Normally, in the downlink direction there would also be 8 counterpart downlink channels, that is, 4 downlink channels for communication between the satellite and the mobile device (downlink S channels) and 4 downlink channels for communication between the base station and the mobile device (downlink channels T) causing a total of 16 satellite and terrestrial channels. However, because the base station signal is orders of magnitude stronger than the satellite signal, the terrestrial signal would override the satellite signal. Then, the 4 downlink channels for communication between the satellite and the mobile device (downlink channels S) and the 4 downlink channels for communication between the base station and the mobile device (downlink channels T) can be combined or fused in such a way that each downlink channel S and a corresponding downlink channel T use the same frequency range. As a result, in the downlink direction, only 4 downlink channels are used instead of the normal 8 channels in this example.

Therefore, if each of the uplink and downlink channels and each of the OOB uplink channels occupies the same bandwidth, for example, 5 MHz of bandwidth, the efficiency of a terrestrial satellite system can be increased by 25% (ie 4 channels divided by a total of 16 channels).

The application of OOB spectrum can be applied to a terrestrial implementation of coverage base station locations and auxiliary base station locations. Coverage base station locations can include any location used for wide coverage, for example, a location located at a higher elevation. Auxiliary base station locations can include any locations used to fill coverage and capacity at least partially within the coverage of the coverage location, for example, locations located at a lower elevation than the coverage location. The application of OOB spectrum may allow the use of co-channel of the same downlink channel for both auxiliary base station communications connection to mobile device and for coverage base station communications connection to mobile device. Interference on the uplink side is avoided by using the OOB spectrum for uplink communication from the mobile device to auxiliary ground base station

This implementation can avoid regulatory difficulties associated with ATC as the terrestrial implementation will have no negative effect on satellite operations. In addition, this implementation may also offer an alternative method of implementing a terrestrial component in a satellite-based communication system.

Figure 3 illustrates hand off limits between Mobile Satellite System (MSS) mode, Terrestrial ATC Mode (TMA) mode and Enhanced Terrestrial Mode (TME) mode, according to one embodiment of the present invention.

As shown in Figure 3, a beam of light points 116 illuminates an area surrounding a mobile device 106. Within this area, there are three modes of communication in which satellite transceiver 102 can communicate bidirectionally with mobile devices 106. Similarly , in some of this area, base stations 104 can communicate bi-directionally with mobile devices 106.

The MSS mode region 302 is the region where mobile devices 106 can communicate bidirectionally with satellite transceiver 102. In the MSS mode region 302, mobile devices 106 are out of range of base stations 104. The TMA mode region 306 and TME mode region 304 are regions where mobile devices 106 can communicate with one or other base stations 104 or satellite transceivers 102. Additionally, figure 3 shows the various limits at which mobile devices 106 are delivered or transferred handed off between modes.

The MSS mode refers to the way in which a mobile device 106 is communicating via a satellite transceiver 102 on a portion of the radio spectrum assigned to communications by satellite transceiver 102 (ie, downlink and upstream MSS communication link) according to the conventional MSS standard. The MSS mode can be used where terrestrial communications with a base station 104 are not possible. The channels employed for adjacent satellite light beam beams 116 are governed by conventional rules to avoid interference from adjacent light beam beams.

The TMA mode refers to the way in which a mobile device 106 is communicating via a terrestrial base station 104 within a beam of light points 116 from a satellite transceiver 102. The spectrum is assigned to both communication connections from satellite stations. terrestrial bases for mobile device and how much mobile device communication connections to terrestrial base stations employing conventional MSS / ATC standards. For example, one channel is assigned for satellite communications and the remaining channels can be used for terrestrial communications, as shown in figure 2A.

TME mode refers to the way in which a mobile device 106 is communicating via a terrestrial base station 104 using the assigned spectrum using conventional MSS / ATC standards, the spectrum assigned to the MSS communication connection for an additional terrestrial base station communication connection to mobile device and the out-of-range spectrum that is not part of the spectrum portion assigned to the MSS communication connection for a additional mobile device communication to base station.

TMA 306 mode regions between TME 304 mode regions and MSS 302 mode regions cause mobile devices 106 which may have been receiving communications from base station 104 using a shared channel with a downlink from the satellite transceiver in the regions TME 304 mode regions to switch to an unused channel for satellite communications in accordance with the MSS / ATC standard before mobile devices 106 enter the MSS 302 mode regions. Here, it is assumed that the TMA mode coverage is greater than the TME mode coverage. That is, the TME mode allows the use of more channels. In this case, the TMA mode covers any given geographical area that is covered by the TME mode.

Interference mitigation in TME mode can be achieved using different multiplexing schemes for the base station connection to the mobile device and the satellite connection to the mobile device sharing the same channel. For example, a broadband code division (CDMA) multiple access signal can be used in communication connections from base stations to mobile devices. The satellite communication connection to a mobile device may employ orthogonal frequency division (OFDM) multiplexing. Of course, many other variations are possible. If a channel is subdivided into multiple parts, the broadband CDMA signal will appear as a narrow band signal with weak signal strength and will be rejected by the CDMA system's gain discriminator. As a result, any degradation in the communication connection is minimal.

In general, in areas of transition between ground operations and satellite operations, several methods can be used to achieve a free interference situation or to minimize interference in a hand over between the terrestrial and satellite systems. For example, if the individual channel bandwidths in satellite systems and ground systems are similar, a portion of the satellite downlink spectrum can be eliminated from use in the outer coverage areas of the terrestrial system in order to provide a channel free of interference so-called cocanal for delivery or transfer between the satellite and terrestrial systems in those transition areas where the terrestrial service ends and the satellite-only service begins.

However, the bandwidth of the individual channels used on the satellite can also be narrower than the bandwidth of a channel used on a terrestrial network. For example, this may be the case when the MSS system uses a modified Global System for Mobile communication channels (GSM) and the terrestrial network uses Universal Mobile Telecommunications System (UMTS) or World Interoperability for Microwave Access (WiMax) ), or other 3G or 4G broadband transmission technologies. If the bandwidth of the individual channels used on the satellite is narrower than a channel bandwidth in the terrestrial chain, the difference in energy density per Hz between wide terrestrial channels and narrow satellite channels can be explored as a protection from interference between ground operations and satellite operations. Indeed, at a land cover edge, terrestrial signals may have less energy than near the base station. Additionally, the bandwidth of terrestrial channels being wider than the bandwidth of the satellite system, the result is that the energy density per Hz for the terrestrial system is less than the energy density per Hz for the system of satellite. Consequently, in the transition area, the mobile device would see the satellite transmission system and release the terrestrial transmission system since the energy density of the terrestrial transmission system is less than the energy density in the satellite transmission system. This minimizes or substantially eliminates interference between satellite and terrestrial transmission systems in the transition areas.

Figure 4 illustrates a flowchart 400 describing a method for communicating between a mobile device 106 with plural transceivers in accordance with an embodiment of the present invention. A second transceiver may be positioned in an area covered by a first transceiver. In addition, in this embodiment, a first signal is received by the mobile device of the first transceiver which has a lower energy than a second signal received by the mobile device of the second transceiver.

The first transceiver transmits to the mobile device on any one of a plurality of channels (S402). Next, a second transceiver transmits to the mobile device 106 on any one of the plurality of channels (S404). In turn, the mobile device 106 transmits to the first transceiver on the channel (channel one) in which the first transceiver is transmitting to the mobile device 106 (S406). Finally, mobile device 106 transmits to the second transceiver on either the plurality of channels other than channel one or on a channel separate from the plurality of channels (S408).

The first transceiver may be a satellite transceiver 102. 5 In addition, the second transceiver may be a base station 104. In one embodiment, any of the plurality of channels other than channel one may be an Auxiliary Ground Component (ATC) channel having a spectrum equal to the spectrum allocation of any one of the plurality of channels other than channel one. In another embodiment, none of the plurality of channels used in a transmission of the first transceiver or the second transceiver can be configured to be either a Mobile Satellite System (MSS) channel or an Auxiliary Terrestrial Component (ATC) channel.

It will be understood by those skilled in the art that various substitutions, modifications and changes can be made in the form and details without departing from the spirit and scope of the present invention as defined by the following claims. Therefore, it is to be appreciated that the modalities described above are for the purpose of illustration only and are not to be interpreted as limitations of the invention.