IPC분류정보
| 국가/구분 |
United States(US) Patent
등록
|
| 국제특허분류(IPC7판) |
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| 출원번호 |
US-0323291
(2008-11-25)
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| 등록번호 |
US-8290070
(2012-10-16)
|
| 우선권정보 |
IT-TO2007A0850 (2007-11-26) |
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발명자
/ 주소 |
- Guerrieri, Lorenzo
- Guerrini, Eleonora
- Veronesi, Daniele
- Bisaglia, Paola
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| 출원인 / 주소 |
|
| 대리인 / 주소 |
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| 인용정보 |
피인용 횟수 :
1 인용 특허 :
37 |
초록
▼
A method for loading bits over a set of subcarriers of a multiple-carrier communications system comprises the operation of associating with the subcarriers respective numbers of bits chosen from among a plurality of available constellations. The method envisages definition of a performance target fo
A method for loading bits over a set of subcarriers of a multiple-carrier communications system comprises the operation of associating with the subcarriers respective numbers of bits chosen from among a plurality of available constellations. The method envisages definition of a performance target for the system and execution of bit loading, guaranteeing the aforesaid target on a plurality of subcarriers. The performance target can be a target error rate, such as a bit-error rate (BER), or else be transferred into a constraint, such as, for example, a threshold, in a metric of log-likelihood ratios (LLRs). In this case, there is preferably envisaged application to the signals received within the multiple-carrier system a function that estimates a signal to noise ratio on each sub-carrier. The aforesaid metric of log-likelihood ratios (LLRs) is hence defined as a function of said signal to noise ratios.
대표청구항
▼
1. A method, comprising: defining a performance target for a multiple-carrier communications system;configuring said multiple-carrier communications system for transmitting packet data with a coded-data packet length;loading bits over a set Ω of subcarriers of said multiple-carrier communications sy
1. A method, comprising: defining a performance target for a multiple-carrier communications system;configuring said multiple-carrier communications system for transmitting packet data with a coded-data packet length;loading bits over a set Ω of subcarriers of said multiple-carrier communications system, the loading including associating with said subcarriers respective numbers of bits chosen from amongst a plurality of available constellations, and guaranteeing said performance target on a plurality of said subcarriers; andchoosing a cardinality of said set Ω of subcarriers as a function of said coded-data packet length. 2. The method according to claim 1, wherein: defining said performance target includes defining said performance target as target error rate for said multiple-carrier communications system; andguaranteeing said performance target includes guaranteeing said target error rate on the plurality of said subcarriers. 3. The method according to claim 2, wherein said target error rate is a bit-error rate. 4. The method according to claim 1, wherein said set Ω of subcarriers is a subset of carriers available in said multiple-carrier communications system. 5. The method according to claim 4, including: transferring said performance target into a constraint in a metric of log-likelihood ratios, wherein transferring said performance target includes defining said performance target as a threshold in said metric of log-likelihood ratios;estimating, on signals received in said multiple-carrier communications system, a signal to noise ratio on each subcarrier of said subcarriers; anddetermining said metric of log-likelihood ratios as a function of said signal to noise ratios. 6. The method according to claim 1, including configuring said multiple-carrier communications system for transmitting data coded with a turbo code. 7. A method, comprising: defining a performance target for a multiple-carrier communications system;loading bits over a set Ω of subcarriers of said multiple-carrier communications system, the loading including associating with said subcarriers respective numbers of bits chosen from amongst a plurality of available constellations, and guaranteeing said performance target on a plurality of said subcarriers;transferring said performance target into a constraint in a metric of log-likelihood ratios, wherein the associating, with each subcarrier identified by a symbol k within said set Ω, comprises:determining for said subcarriers a first bit allocation {mk }, with k εΩ;determining for said subcarriers a second bit allocation {mk′} , with k εΩ; corresponding to a bit allocation immediately higher than said first bit allocation;calculating for said subcarriers a cost wk, ∀kεΩ, associated with shifting from said first bit allocation to said second bit allocation, said shifting involving shifting to a higher-order constellation;ordering said costs {wχ1, wχ2, . . . , wχ|Ω|} according to an order χ that determines subcarriers with greater probability of being subject to a constellation shift;seeking, following said order, subcarriers that can be loaded with a higher-order constellation, whilst satisfying said constraint in the metric of log-likelihood ratios; andincreasing to said second bit allocation, mk′, the number of bits loaded on said subcarriers that can be loaded with a higher-order constellation, identified with said seeking. 8. The method according to claim 7, wherein said set Ω of subcarriers is a subset of carriers available in said multiple-carrier communications system, the method including: configuring said multiple-carrier communications system for transmitting packet data with a coded-data packet length; andchoosing a cardinality of said set Ω of subcarriers as a function of said coded-data packet length. 9. A method, comprising: defining a performance target for a multiple-carrier communications system;loading bits over a set Ω of subcarriers of said multiple-carrier communications system, the loading including associating with said subcarriers respective numbers of bits chosen from amongst a plurality of available constellations, and guaranteeing said performance target on a plurality of said subcarriers;transferring said performance target into a constraint in a metric of log-likelihood ratios, wherein the associating, with each subcarrier identified by a symbol k within said set Ω, comprisesdetermining for said subcarriers a first bit allocation {mk}, with kεΩ;determining for said subcarriers a set Bk′={mk′εC:0
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