CONFIGURING A DEVICE FOR OFDM COMMUNICATION

The present invention relate to configuring a device for wireless communications. One embodiment of the invention relates to configuring a device for OFDM communication

In an OFDM system, it is often advantageous to multiplex users in frequency domain to increase the system's multiplexing capability and to take advantage of frequency domain

One technique of multiplexing a user' s signal in frequency domain is frequency diversity transmission where the signal of one user is distributed across the- bandwidth. Typically, a plurality of earner frequencies (where each, "carrier frequency" is typically & respective narrow band of frequencies) are allocated in a comb fas hion or according to a frequency hopping pattern so that the user's signal is spread across the &equetwiy doms-k. Tbis teclmique can have fbe advanfag© of sigαifieaatly reducing the probabili^ ώ(# a user's signal

Aaother techaiqtiβ is frequeacy selectivity transmission wtoe carrier frequencies (where eaeϊi ^H camβr feeq\jeacy ⁴ ' is typie-ally a respective fiauo^ Isaftά of fequemies) are alioc^eά to the ttaijsmissioα of a user si^aal in a duster fasMoa so that Jftere ^s a good prdbability that at least some of ϋm user signal is defectively transmitted ≠ firequenckss wliere the channel oOBClition k favoυrøble. This tβάmiquc isas tfas -\dτa∑3tag-& that freqwtsfiey domain scheάuliύg galii caα he realized.

It is sa aid of the piesøϊtt iavβation to provide a technique for coαfigtsπug a device for a wireless communication wfc.ere%y eoutlics with one of mote dihm -wireless ttaasmissi«s{s) k the same area caα be avoided svea wbθ?e the one or nsore other wireless fcransfisissioBS are aJiocatecf combinafioβs of resources tα a coaffictiag way, sucli as caα. be tfι« c^.se, for example, wherø some wireless commutucsflons are βeqveacy diversity ttaasmission and other wireless commwύmύom are fequaacy selectivity transmissions.

According to a first aspect of the present invention, there is provided a method of configuring a device for a wireless communication, the method comprising the steps of: selecting a first combination of resources in relation to a first wireless communication in a first area involving a first device, and selecting one or more other combination(s) of resources in relation to one or more other wireless communication(s) in said first area that take priority over said first wireless communication; providing via a wireless interface said first device with information identifying said first combination of resources and said one or more other combination(s) of resources; and configuring the first device for said first wireless communication on the basis of said information identifying said first combination of resources and said one or more other combination(s) of resources.

According to another aspect of the present invention, there is provided a device for configuring a transmitter and/or receiver for a wireless communication, wherein the device is arranged to: (a) receive information identifying a first combination of resources selected in relation to a first wireless communication in a first area and information identifying one or more other combination^) of resources selected in relation to one or more other wireless communication(s) in said first area that take priority over said first wireless communication; and (b) configure a transmitter and/or receiver for said first wireless communication on the basis of said information identifying said first combination of resources and said one or more other combination(s) of resources

According to another aspect of the present invention, there is provided a wireless communications network, including: (i) a device for participating in a first wireless communication in a first area; (ii) a controller for selecting a first combination of resources in relation to said first wireless communication involving a first device, and selecting one or more other combination(s) of resources in relation to one or more other wireless communication(s) in said first area that take priority over said first wireless communication; and (iii) a transmitter for transmitting to said device information identifying said first combination of resources and said one or more other combination(s) of resources; and wherein said device is arranged to configure itself for said first wireless communication on the basis of said information identifying said first combination of resources and said one or more other combination(s) of resources.

According to another aspect of the present invention, there is provided a computer program product comprising program code means which when loaded into a computer controls the computer to configure a device for a first wireless communication in a first area on the basis of information identifying a first combination of resources selected in relation to said first wireless communication, and information identifying one or more other combination(s) of resources selected in relation to one or more other wireless communication(s) in said first area.

According to another aspect of the present invention, there is provided a controller for controlling the configuration of a device for a wireless communication, wherein the controller is arranged to: (a) select a first combination of resources in relation to a first wireless communication within a first area and involving a first device, and select one or more other combination(s) of resources in relation to one or more other wireless communication(s) within the same area and taking priority over the first wireless communication; and (b) to arrange transmission to the first device of information identifying both the first combination of resources and the one or more other combination(s) of resources.

According to another aspect of the present invention, a method of controlling the configuration of a device for a wireless communication, including the steps of: (a) selecting a first combination of resources in relation to a first wireless communication within a first area and involving a first device, and selecting one or more other combination(s) of resources in relation to one or more other wireless communication(s) within the same area and taking priority over the first wireless communication, and (b) arranging transmission to the first device of information identifying both the first combination of resources and the one or more other combination(s) of resources.

According to another aspect of the present invention, a computer program product comprising program code means which when loaded into a computer controls the computer to perform a method including the steps of: (a) selecting a first combination of resources in relation to a first wireless communication within a first area and involving a first device, and selecting one or more other combination(s) of resources in relation to one or more other wireless communication(s) within the same area and taking priority over the first wireless communication, and (b) arranging transmission to the first device of information identifying both the first combination of resources and the one or more other combination(s) of resources..

In one embodiment, the step of configuring the first device for said first wireless communication using selected resources from said first combination of resources so as to avoid any conflict between said first wireless communication and said one or more other wireless communication(s).

In one embodiment, said one or more other combination(s) of resources are selected from predetermined combinations of resources.

hi one embodiment, said one or more other combination(s) of resources are selected from said predetermined combinations of resources according to a predetermined selection rule, and said step of providing said first device with information for identifying said first combination of resources and said one or more other combination^) of resources involves specifying the final one of the one or more other predetermined combination(s) of resources selected in relation to said one or more other wireless communications), and wherein the first device determines the identity of the remaining one or more other predetermined combination(s) of resources selected in relation to said one or more other wireless communication(s) by reference to said predetermined selection rule.

In one embodiment, the first combination of resources is a first type of combination of resources, and the one or more other combinations) of resources are each a different, second type of combination of resources.

In one embodiment, said first combination of resources includes a first combination of carrier frequencies, and said one or more other combination(s) of resources includes one or more other combination(s) of carrier frequencies, and including the step of determining at the first device whether or not the first combination of carrier frequencies and the one or more other combination(s) of carrier frequencies share any individual carrier frequencies.

In one embodiment, said first wireless communication is either one of a frequency diversity transmission or a frequency selectivity transmission, and said one or more other wireless communication(s) are each the other of a frequency diversity transmission and a frequency selectivity transmission.

In one embodiment, said first combination of carrier frequencies includes a plurality of predetermined groups of carrier frequencies selected according to a predetermined selection rule, and the first device determines the identity of the plurality of predetermined groups of carrier frequencies selected in relation to the first wireless transmission partly by reference to said predetermined rule of selecting said predetermined groups.

In one embodiment, said one or more other combinations(s) of carrier frequencies also include a plurality of predetermined groups of carrier frequencies selected according to a predetermined selection rule, and the first device determines the identity of the plurality of predetermined groups of carrier frequencies selected in relation to the one or more other wireless transmission(s) by reference to said predetermined rule for selecting said predetermined groups.

In one embodiment, the device for configuring a transmitter and/or receiver for a wireless communication is part of a handset.

In one embodiment, additional signalling and control information is used to multiplex the frequency diversity transmissions and the frequency selectivity transmissions in the same OFDM symbol.

One embodiment uses efficient control channel messages to enable frequency domain multiplexing of frequency diversity transmissions and frequency selectivity transmissions. The total resources consumed by one type of transmissions are broadcast to all the users in the system. In addition, the information about the resource allocation, as if there is no resource allocated to the other type of transmissions, is also transmitted to the intended user. Based on these two sets of information, each user can calculate the exact resource to be used for the communication in which it is involved.

An embodiment of the present invention is described hereunder, by way of example only, with reference to the accompanying drawings, in which:

Figure 1 is a schematic illustration of two user handsets in position for wireless communication with a common base station;

Figure 2 is a schematic illustration of a handset according to an embodiment of a claimed invention;

Figure 3 illustrates an example of grouping individual carrier frequencies for frequency diversity interlaces and frequency selectivity sub-bands in an OFDM symbol; Figure 4 illustrates a method according to an embodiment of the claimed invention; and Figure 5 also illustrates a method according to an embodiment of the claimed invention.

The embodiment of the invention is described, by way of example only, in the context of a 20MHz OFDM system. The embodiment may also be applied to other type of systems and systems with different bandwidth.

Assuming 2048-point FFT (Fast Fourier Transform) is used, there are totally 2048 sub- carriers available. A set of sub-carriers is denoted as ω = {fo, fi, /j, ...,/2047}- For frequency diversity multiplexing, the available bandwidth is divided between 16 interlaces, with each interlace /„ = {f _n , f _n +j6, fn+32, — _> fn+2032}, n = 0, 1, ..., 15. Some of the interlaces may be allocated to pilot channel and control channels. One or more several interlaces may be allocated to one user. For frequency selectivity multiplexing, the available bandwidth is divided between 16 sub-bands, with each sub-band B _m = {fnsm, fmm+i, fmm+2, ■•• _> fi28m ₊ i2 ₇ }, m = O ₃ 1, ..., 15. One or several of these sub-bands may also be allocated to one user. These two frequency domain allocation schemes are shown in Figure 3.

A frequency diversity transmission is allocated a set of frequency interlaces /„ with n e G _r

For example, G,- = {2, 10} means h and Ijo are allocated to packet /. Denote the set of all sub- carrier allocated to packet i by

Suppose there are N _d frequency diversity transmissions. The set of all sub-carriers allocated to frequency diversity transmissions is

where

is the set of all frequency interlaces allocated to frequency diversity transmissions.

Likewise, a frequency selectivity transmission is allocated a set of frequency sub-bands B _m with m e Hj . For example, H _j = {0, 1} means Bo and B1 are allocated to packetj. Denote the set of all sub-carriers allocated to packetj by

Suppose there are N _s frequency selectivity transmissions. The set of all sub-carriers allocated to frequency selectivity transmissions is

where

is the set of all frequency sub-bands allocated to frequency selectivity transmissions.

When there are both frequency diversity transmission and frequency selectivity transmission in the same OFDM symbol, there will typically be intersection between any interlace with any sub-band, i.e., I _n D B _n ≠ 0, for any n and m. For example, suppose a frequency diversity transmission is allocated a set of interlaces G ₁ = {2, 10} , i. e. , D ₁ = B(G ₁ ) = I ₂ U I _So • Suppose a frequency selectivity transmission is allocated a set of sub-bands H ₂ =[O, 1} , i.e., S ₂ = S(H2) = B ₀ U)B ₁ . In this case, the intersection D ₁ H-S ₂ =If ₂ f ₁₀ ... f ₂₅₀ } belongs to both the set D ₁ and the set S ₂ .

In order to enable the intended user to reliably detect and decode the packet, the resource allocation information is communicated to the intended user. For frequency diversity transmission of packet /, the information about set G ₁ is communicated to the intended user(s).

For frequency selectivity transmission of packet j, the information about set H _j is communicated to the intended user(s). In addition, a rule is specified to resolve the conflict between frequency diversity transmissions and frequency selectivity transmissions.

The following technique is used to communicate G,. and H _j efficiently and resolve the conflict between G,- , z = 1 ..., N _d snά H _j , j = \ ..., N _s .

Frequency interlaces are allocated in a specified order. For example, frequency interlaces can be allocated with a bit-reversed-order (BRO) fashion, i.e., the frequency interlaces are allocated in the order of 0, 8, 4, 12, 2, 10, 6, 14, 1, 9, 5, 13, 3, 11, 7, 15. Only continuous allocation with the order specified is allowed. For example, an allocation of G ₁ ={2, 10, 6, 14} is allowed, but an allocation of G,- = {8, 4, 6, 14} is not allowed.

If a packet is allocated G ₁ = {2, 10, 6, 14} , it is only necessary to communicate the indices of the first and last interlaces. In this example, it is only necessary to tell the intended user that the index of the first interlace is 2, and the index of the last interlace is 14. Alternatively, G ₁ - can be sufficiently accumulated by communicating only the index of the first interlace, and the cardinality of G,. . Li this example, it is only necessary to tell the intended user that the index of the first interlace is 2, and there are 4 interlaces assigned to his packet.

To efficiently communicate H ₁ , frequency sub-bands are allocated in a specified order. For example, the frequency sub-bands may be allocated in the order of 0, 1, 2, 3, 4, 5, 6, 7, 8, 9,

10, 11, 12, 13, 14, and 15. Only continuous allocation with the order specified is allowed. For example, an allocation of H ₁ = {0, 1, 2, 3} is allowed, but an allocation of

H ₁ ={0, 1, 5, 6} is not allowed. If a packet is allocated H ^" , = {0, 1, 2, 3} , it is only necessary to communicate the indices of the first and last sub-bands. In this example, it is only necessary to tell the intended user that the index of the first sub-band is 0, and the index of the last sub-band is 3. Alternatively, H ₁ can be sufficiently communicated by communicating only the index of the first sub-band, and the cardinality of H ₁ . In this example, it is only necessary to tell the intended user that the index of the first sub-band is 0, and there are 4 sub-bands assigned to his packet.

In addition, there is specified a rule to resolve conflict of resource allocation between frequency diversity transmissions and frequency selectivity transmissions.

In one example, frequency diversity transmissions are given higher priority than frequency selectivity transmissions. In other words, whenever there is conflict between frequency diversity allocation G ₁ and frequency selectivity allocation H _j , the intersection

D(Gi) Pi S(H _j ) = D ₁ C] SJ is always assigned to the frequency diversity transmission. The actual frequency selectivity allocation is then SJ X (D ₁ C]SJ) . In order to enable an intended user of a frequency selectivity transmission to determine its actual resource allocation, information about the set F is also communicated to the intended user. Because frequency interlaces are allocated in order, . it is only necessary to communicate the cardinality of T, which is denoted by Frequency Diversity Multiplexing Bandwidth (FDMB). For example, if FDMB = 8, the set of interlaces used for frequency diversity transmission is F = (O, 8, 4, 12, 2, 10, 6, 14} . Frequency interlaces I ₀ , I ₈ , U, In, h, ho, U, and I ₁₄ are allocated to frequency diversity transmissions. With that information, a frequency selectivity transmission with resource assignment H _j will be actually allocated sub-carriers

S(H _j ) \ (S(HJ) n D(T)) = S _j X (SJ n D) .

In another example, frequency selectivity transmissions are given higher priority than frequency diversity transmissions in terms of frequency allocation. In other words, whenever there is conflict between frequency diversity allocation G ₁ and frequency selectivity allocation H _j , the intersection D(G _I ) C] S(HJ) = D ₁ C] SJ is always assigned to the frequency selectivity transmission. The actual frequency diversity allocation is then D _t X (D _t fl S _j ) . In order to enable an intended user of frequency diversity transmission to identify its actual resource allocation, we propose to also communicate the information about the set λ . Because frequency sub-bands are allocated in order, we only need to communicate the cardinality of λ , which is denoted by Frequency Selectivity Multiplexing Bandwidth (FSMB). For example, if FSMB = 8, then λ = {0, 1, 2, 3, 4, 5, 6, 7} . Frequency sub-bands Bo, Bj, B2, B3, B4, B5, Be, and Bγ are allocated to frequency selectivity transmissions. With that information, a frequency diversity transmission with resource assignment G ₁ will be actually allocated sub-carriers D(G ₁ ) X (D(Gi) fl S(A)) = Di X(Di C)S) .

The above-described embodiment enables frequency domain multiplexing of frequency diversity transmissions and frequency selectivity transmissions with relatively little overhead.

With reference to Figures 1 and 2, in one example, packet i is to be transmitted between a base station 12 (which functions as a BTS/Node B) and a first user handset 14, and packet j is to be transmitted in the same OFDM symbol between the same base station 12 and a different, second user handset 16 within the area 18 covered by the base station 12. A BSC/RNC 13 is connected by a land line 15 to the base station 12, and controls and manages the base station

12 as well as other base stations (not shown). A scheduler collated with the BSC/RNC 13 allocates a frequency diversity set G ₁ to packet i, and allocates a frequency selectivity set H _j to packet/. In this example, frequency diversity transmissions are given higher priority than frequency selectivity transmissions. Accordingly, if there is conflict between frequency diversity allocation G _; and frequency selectivity allocation H _j , the intersection is assigned to the frequency diversity transmission G ₁ . The actual frequency selectivity allocation for packet j is then all of set H _j other than the carrier frequencies also belonging to set G ₁ . The BSC/RNC 13 instructs the base station 12 to communicate information identifying the set G ₁ to the first user handset 14, and to communicate information identifying both the set H _j and the set G ₁ to the second user handset 16. The communication of such information can be done efficiently using the techniques described above. A microprocessor 22 located within second user handset 16 receives this information from the transmitter/receiver 24 of the second user handset 16 and determines on the basis of such information which carrier frequencies are to be used for the transmission of packet j. The microprocessor 22 then configures the transmitter/receiver 24 accordingly so as to reliably detect and decode packet j.

Figure 4 illustrates the method steps carried out by the BSC/RNC 13, and Figure 5 illustrates the method steps carried out in turn by the BSC/RNC 13, base station 12 and handset 16.

Alternatively, the allocation of frequency diversity set G ₁ to packet i, and frequency selectivity set H _j to packet/ could be carried out by a scheduler collated with the base station

12.

Appropriately adapted computer program code product may be used for implementing the functions of the controller associated with the base station and/or the microprocessor of the

second user hand set. The program code product for providing the operation may be stored on and provided by means of _. a carrier medium such as a carrier disc, card or tape. A possibility is to download the program code product via a data network. Implementation may be provided with appropriate software in a server.

The concept can be implemented in ways other than those described in detail above without deviating from the scope of the invention. Examples of variations include, but are not limited to, the following:

A. The order of frequency interlaces can be configured, using signalling messages or other means.

B. The order of frequency sub-bands can be configured, using signalling messages or other means.

C. Some of the frequency interlaces may be reserved or used in other ways, either by other control channels, or by other data channels. For example, some interlaces or sub-bands may be allocated for pilot tones, or control information for forward link or reverse link. Some interlaces or sub-bands may be reserved for dedicated-channel type of communication. The reservation may also be changed by signalling messages or other means.

D. There may be multiple OFDM symbols in a slot. The frequency multiplexing and frequency allocation of these OFDM symbols may or may not be the same.

E. Only the frequency interlaces for frequency diversity transmissions are allocated in order whereas frequency sub-bands for frequency selectivity transmissions are allocated freely.

F. Only frequency sub-bands for frequency selectivity transmissions are allocated in order, whereas frequency interlaces for frequency diversity transmissions are allocated freely.

G. The information of either the total number of frequency interlaces, or the total number of frequency sub-bands is transmitted, or both.

AU these different ways of operation can, for example, be configured through signalling messages.

The applicant draws attention to the fact that the present invention may include any feature or combination of features disclosed herein either implicitly or explicitly or any generalisation thereof, without limitation to the scope of any definitions set out above. In view of the

foregoing description it will be evident to a person skilled in the art that various modifications may be made within the scope of the invention.