Performance evaluation of multicarrier channels with forward error correction and automatic retransmission request

• US 7,103,096 B2
• Filed: 12/20/2000
• Issued: 09/05/2006
• Est. Priority Date: 10/12/2000
• Status: Expired due to Fees

• Current Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Original Assignee: 3Com Corporation (HP Inc.)
• Inventors: Williams, Richard G. C., Mitlin, Vlad
• Primary Examiner(s): Bayard, Emmanuel
• Application Number:
  US09/741,639
• Publication Number:
  US 20020108081A1
• Time in Patent Office: 2,085 Days
• Field of Search: 375/219, 375/220, 375/221, 375/222, 375/240.22, 375/259, 375/265, 375/295, 375/209, 375/225, 375/138, 375/132, 375/139, 375/224, 375/227, 380/241, 380/248, 380/249, 380/251, 380/252, 370/248, 370/249, 370/241, 370/251, 370/441, 370/335, 311/227, 714/774, 714/751
• US Class Current: 714/748
• CPC Class Codes: H04L 1/0009 by adapting the channel coding H04L1/1812 takes precedence
• CPC Class Codes: H04L 1/1825 Adaptation of specific ARQ protocol parameters according to transmission conditions
• CPC Class Codes: H04L 5/0044 allocation of payload

Abstract

In one embodiment, a method and apparatus increases a bit load of a multicarrier system comprising a channel having a plurality of subchannels. A bit load is determined for at least one subchannel based on a target symbol error rate ε_S a maximum number of symbol errors that can be corrected t, a number of symbols in an information field K, and a maximum number of transmissions k, and a number of bits per subchannel. The maximum number of symbol errors t, the number of symbols in the information field K and the maximum number of transmissions k, is selected such that a net coding gain is increased. In another embodiment, a method determines data flow for a channel having a plurality of subchannels in a multi-carrier system.

Claims

1. A method of determining data flow for a channel having a plurality of subchannels in a multi-carrier system, comprising:

determining data flow for the channel in terms of an input intensity λ

_in, and a probability of having a frame having no or a correctable number of errors ρ

; and

adjusting channel performance in accordance with the data flow.

2. The method of claim 1 wherein said data flow is determined in accordance with the following relationships:

3. The method of claim 2 wherein the data flow is determined by applying said relationships to data flow in a downstream direction, and applying said relationships to data flow in an upstream direction.

4. A method of determining data flow for a channel having a plurality of subchannels in a multi-earner system, comprising:

determining an upstream data flow;

determining a downstream data flow; and

superimposing the upstream data flow and the downstream data flow to determine a channel data flow.

5. The method of claim 4 wherein the channel uses forward error correction.

6. A method of determining throughput in a multicarrier transmission system having a channel, comprising:

generating a representation of the throughput of the channel in a first direction with respect to the throughput of the channel in a second direction; and

determining the throughput of the channel in a first direction with respect to the throughput of the channel in a second direction using the representation;

wherein the representation is generated in accordance with the following relationships;

7. A method of increasing a bit load of a multicarrier system comprising a channel having a plurality of subchannels, comprising:

determining a bit load for at least one subchannel based on a target symbol error rate ε

_S, a maximum number of symbol errors that can be corrected t, a number of symbols in an information field K, and a maximum number of transmissions k, and a number of bits per subchannel; and

selecting the maximum number of symbol errors t, the number of symbols in the information field K and the maximum number of transmissions k, such that a coding gain is increased.

8. The method of claim 7 wherein the coding gain is a function of an average number of transmissions for a frame.

9. The method of claim 7 wherein the bit load is determined in accordance with the following relationships:

10. The method of claim 9 wherein ω

(b_i) is approximated in accordance with the following relationship;

11. The method of claim 9 wherein ε

_S is determined in accordance with the following relationship;

12. The method of claim 9 wherein ω

(b_l) is determined in accordance with the following relationship;

13. The method of claim 7 further comprising:

determining a total increase in the number of bits to be sent in a DMT symbol (G_i(t,K,k)) in accordance with the following relationship;

G_d(t,K,k)=B_DMT(t,K,k)−

B_DMT(0,K1).

14. A method of determining an uncoded bit error rate ρ

_b based on a target symbol error rate ε

_S and a maximum number of transmissions k, comprising;

determining the uncoded bit error rate ρ

_b based on a weighted series expansion of the target bit error rate ε

_S, comprising weights W that are a function of a maximum number of symbol errors that can be corrected t and a number of symbols in an information field K; and

selecting the maximum number of symbol errors t, the number of symbols in the information field K and the maximum number of transmissions k, such that the uncoded bit error rate ρ

_b that produces a symbol error rate that is less than or equal to the target symbol error rate ε

_S is largest.

15. The method of claim 14 wherein said weighted series expansion to determine said uncoded bit error rate ρ

_b comprises the following relationship;

16. A method of selecting transmission parameters a multicarrier system having a channel comprising a plurality of subchannels, comprising:

selecting a number (s) of discrete multi-tone symbols in a forward-error-correction frame, a number (z) of forward-error-correction control symbols in a discrete multitone symbol, and a maximum number of transmissions (k), based on a signal-to-noise ratio and a number of subchannels associated with the signal-to-noise ratio; and

transmitting information in accordance with the selected number (s) of discrete multi-tone symbols, the number (z) of forward-error-correction control symbols in the discrete multitone symbol and the maximum number of transmissions (k).

17. The method of claim 16 wherein said selecting comprises selecting an adjustment value per subchannel based on the signal-to-noise ratio and the number of subchannels associated with the signal-to-noise ratio;

and

adjusting a number of bits per subchannel for at least one subchannel in accordance with the adjustment value.

18. The method of claim 16 wherein the signal-to-noise ratio is an average signal-to-noise ratio of the associated number of subchannels.

19. The method of claim 16 further comprising:

storing, in a table, the number (s) of discrete multi-tone symbols in the forward-error-correction frame, the number (z) of forward-error-correction control symbols in the discrete multitone symbol associated with the signal-to-noise ratio, the maximum number of transmissions (k) and the number of subchannels associated with the signal-to-noise ratio, for different values of s, z, signal-to-noise ratios and numbers of subchannels.

20. The method of claim 19 wherein for each value of signal-to-noise ratio and number of bits per subchannel of the table, the associated values of s, z and k are also associated with an adjustment value that provides a maximal net coding gain g_n, such that the associated values of s, z and k is selected from a subset of associated s, z and k values.

21. A method of determining an optimum bit load b per subchannel in a multicarrier system with forward error correction, comprising:

computing one or more values of a maximum number of symbol errors that can be corrected t, a number of symbols in the information field K and a maximum number of transmissions k to determine the optimum bit load per subchannel in accordance with the following relationship;

b=[γ

+Φ

(γ

,t,K,k,ε

)]/10 log 2

wherein

22. An apparatus for determining throughput in a multicarrier transmission system having a channel, comprising:

means for generating a representation of the throughput of the channel in a first direction with respect to the throughput of the channel in a second direction; and

means for determining the throughput of the channel in a first direction with respect to the throughput of the channel in a second direction using the representation;

wherein the representation is generated in accordance with the following relationships;

23. An apparatus for increasing a bit load of a multicarrier system comprising a channel having a plurality of subchannels, comprising:

means for determining a bit load for at least one subchannel based on a target symbol error rate ε

_S, a maximum number of symbol errors that can be corrected t, a number of symbols in an information field K, and a maximum number of transmissions k, and a number of bits per subchannel; and

means for selecting the maximum number of symbol errors t, the number of symbols in the information field K and the maximum number of transmissions K such that a coding gain is increased.

24. The apparatus of claim 23 wherein the coding gain is a function of an average number of transmissions for a frame.

25. The apparatus of claim 23 wherein the bit load is determined in accordance with the following relationships:

26. The apparatus of claim 25 wherein ω

(b_i is approximated in accordance with the following relationship;

27. The apparatus of claim 25 wherein ε

_S is determined in accordance with the following relationship;

28. The apparatus of claim 25 wherein ω

(b_i) is determined in accordance with the following relationship;

29. The apparatus of claim 23 further comprising:

means for determining a total increase in the number of bits to be sent in a DMT symbol (G_l(t,K,k)) in accordance with the following relationship;

G_d(t,K,k)=B_DMT(t,K,k)−

B_DMT(0,K1).

30. An apparatus for determining an uncoded bit error rate ρ

_b based on a target symbol error rate ε

_S and a maximum number of transmissions k, comprising;

means for determining the uncoded bit error rate ρ

_b based on a weighted series expansion of the target bit error rate ε

_S, comprising weights W that are a function of a maximum number of symbol errors that can be corrected t and a number of symbols in an information field K; and

means for selecting the maximum number of symbol errors t, the number of symbols in the information field K and the maximum number of transmissions k, such that the uncoded bit error rate ρ

_b that produces a symbol error rate that is less than or equal to the target symbol error rate ε

_S is largest.

31. The apparatus of claim 30 wherein said weighted series expansion to determine said uncoded bit error rate ρ

_b comprises the following relationship;

32. An apparatus for selecting transmission parameters a multicarrier system having a channel comprising a plurality of subchannels, comprising:

means for selecting a number (s) of discrete multi-tone symbols in a forward-error-correction frame, a number (z) of forward-error-correction control symbols in a discrete multitone symbol, and a maximum number of transmissions (k), based on a signal-to-noise ratio and a number of subchannels associated with the signal-to-noise ratio; and

means for transmitting information in accordance with the selected number (s) of discrete multi-tone symbols, the number (z) of forward-error-correction control symbols in the discrete multitone symbol and the maximum number of transmissions (k).

33. The apparatus of claim 32 wherein said means for selecting comprises selecting an adjustment value per subchannel based on the signal-to-noise ratio and the number of subchannels associated with the signal-to-noise ratio;

and

means for adjusting a number of bits per subchannel for at least one subchannel in accordance with the adjustment value.

34. The apparatus of claim 32 wherein the signal-to-noise ratio is an average signal-to-noise ratio of the associated number of subchannels.

35. The apparatus of claim 32 further comprising:

means for storing, in a table, the number (s) of discrete multi-tone symbols in the forward-error-correction frame, the number (z) of forward-error-correction control symbols in the discrete multitone symbol associated with the signal-to-noise ratio, the maximum number of transmissions (k) and the number of subchannels associated with the signal-to-noise ratio, for different values of s, z, signal-to-noise ratios and numbers of subchannels.

36. The apparatus of claim 35 wherein for each value of signal-to-noise ratio and number of bits per subchannel of the table, the associated values of s, z and k are also associated with an adjustment value that provides a maximal net coding gain g_n, such that the associated values of s, z and k is selected from a subset of associated s, z and k values.

37. An apparatus for determining an optimum bit load b per subchannel in a multicarrier system with forward error correction, comprising:

means for computing one or more values of a maximum number of symbol errors that can be corrected t, a number of symbols in the information field K and a maximum number of transmissions k to determine the optimum bit load per subchannel in accordance with the following relationship;

b=[γ

+Φ

(γ

t,K,k,ε

)]10 log 2

wherein