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

US 20020108081A1
Filed: 12/20/2000
Published: 08/08/2002
Est. Priority Date: 10/12/2000
Status: Active Grant

First Claim

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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 C and a probability of having a frame having no or a correctable number of errors p; and

adjusting channel performance in accordance with the data flow.

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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. Data flow for the channel is determined in terms of an input intensity λ_in, and a probability of having a frame having no or a correctable number of errors p. The channel performance is adjusted in accordance with the data flow.

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55 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 C and a probability of having a frame having no or a correctable number of errors p; and
  
  adjusting channel performance in accordance with the data flow.
- View Dependent Claims (2, 3)
- - 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-carrier 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.
- View Dependent Claims (5, 6, 7)
- - 5. The method of claim 4 wherein the channel uses forward error correction.
  - 6. The method of claim 4 wherein the upstream data flow comprises retransmitting data.
  - 7. The method of claim 4 wherein the downstream data flow comprises retransmitting data.

8. 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.
- View Dependent Claims (9)
- - 9. The method of claim 8 wherein the representation is generated in accordance with the following relationships:

10. A method of determining throughput in a multicarrier transmission system, comprising:
- determining the throughput of a channel in an upstream and downstream direction in accordance with the following relationships;
  
  $H_{u} = \max Λ_{u} = \min {\begin{matrix} V_{u} / [\frac{N_{d}}{K_{d}} 1 - \frac{{(1 - p_{d})}^{k_{d}}}{p_{d}} + \frac{M_{u}}{K_{u}} \frac{V_{u}}{V_{d}} (\frac{1}{m_{u}} + \frac{1 - p_{u}}{p_{u}}) (1 - {(1 - p_{u})}^{k_{u}})], \\ V_{u} / [\frac{M_{d}}{K_{d}} \frac{V_{d}}{V_{u}} (\frac{1}{m_{d}} + \frac{1 - p_{d}}{p_{d}}) (1 - {(1 - p_{d})}^{k_{d}}) + \frac{N_{u}}{K_{u}} 1 - \frac{{(1 - p_{u})}^{k_{u}}}{p_{u}}] \end{matrix}}, and$ $H_{d} = \max Λ_{d} = \min {\begin{matrix} V_{d} / [\frac{N_{d}}{K_{d}} 1 - \frac{{(1 - p_{d})}^{k_{d}}}{p_{d}} + \frac{M_{u}}{K_{u}} \frac{V_{u}}{V_{d}} (\frac{1}{m_{u}} + \frac{1 - p_{u}}{p_{u}}) (1 - {(1 - p_{u})}^{k_{u}})], \\ V_{d} / [\frac{M_{d}}{K_{d}} \frac{V_{d}}{V_{u}} (\frac{1}{m_{d}} + \frac{1 - p_{d}}{p_{d}}) (1 - {(1 - p_{d})}^{k_{d}}) + \frac{N_{u}}{K_{u}} 1 - \frac{{(1 - p_{u})}^{k_{u}}}{p_{u}}] \end{matrix}},$ wherein M_drepresents a length of an acknowledgment frame in a downstream direction, K_drepresents the length of an information field in the downstream direction, M_drepresents a number of information frames between positive acknowledgment frames in the downstream direction, p_drepresents a probability of an information frame being accepted in the downstream direction, k_drepresents a maximum number of transmissions in the downstream direction, Λ
  
  _drepresents a number of information bits per unit time in the downstream direction, N_drepresents a total frame length in the downstream direction, M_urepresents a length of an acknowledgment frame in an upstream direction, N_urepresents a total frame length in the upstream direction, K_urepresents the length of an information field in the upstream direction, m_urepresents a number of information frames between positive acknowledgment frames in the upstream direction, p_urepresents a probability of an information frame being accepted in the upstream direction, k_urepresents a maximum number of transmissions in the upstream direction, Λ
  
  _urepresents a number of information bits per unit time in the upstream direction, V_urepresents a data rate in the upstream direction, and V_drepresents a data rate in the downstream direction.

11. 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.
- View Dependent Claims (12, 13, 14, 15, 16, 17, 19)
- - 12. The method of claim 11 wherein the coding gain is a function of an average number of transmissions for a frame.
  - 13. The method of claim 11 wherein the bit load is determined in accordance with the following relationships:
  - 14. The method of claim 13 wherein ω
    - (b_i) is approximated in accordance with the following relationship;
  - 15. The method of claim 13 wherein ε
    - _Sis determined in accordance with the following relationship;
  - 16. The method of claim 13 wherein ω
    - (b_i) is determined in accordance with the following relationship;
  - 17. The method of claim 11 further comprising:
    - 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,K,1).
  - 19. The method of claim 18 wherein said weighted series expansion to determine said uncoded bit error rate p_bcomprises the following relationship:

18. A method of determining an uncoded bit error rate p_bbased on a target symbol error rate ε
- _Sand a maximum number of transmissions k, comprising;
  
  determining the uncoded bit error rate p_bbased 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 p_bthat produces a symbol error rate that is less than or equal to the target symbol error rate ε
  
  _Sis largest.

20. 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). 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
  
  )]/10log2
  
  wherein $Φ (γ, t, K, k, ɛ) = 10 \log {10^{- γ / 10} + \frac{3 \log e}{2 \log [\frac{α 〈 ω (b) 〉 \sqrt{8 / π}}{W (t, K, k) {(αɛ / β)}^{\frac{1}{(t + 1) k}}}] - \log \log [\frac{α 〈 ω (b) 〉 \sqrt{8 / π}}{W (t, K, k) {(αɛ / β)}^{\frac{1}{(t + 1) k}}}] + \log (\frac{\log e}{2})}}$ $W (t, K, k) = {{[(\begin{matrix} K + C + R - 1 \\ t \end{matrix})]}^{\frac{1}{(t + 1) k}} [(\begin{matrix} K + C + R \\ t + 1 \end{matrix})]}^{- \frac{k - 1}{(t + 1) k}}, 〈 ω (b) 〉 = \frac{1}{b_{\max}} \int_{1}^{b_{\max}} ω (b) (1 - 2^{- b / 2}) d b$ α
  
  represents a number of bits per symbol, γ
  
  represents a signal-to-noise ratio, ε
  
  represents a target symbol error rate, k represents a maximum number of transmissions, C+R represents a number of redundant symbols in an error correction field, b represents a number of bit positions of a quadrature-amplitude-modulation symbol, ω
  
  (b) represents an average fraction of erroneous bits in an erroneous b-sized quadrature-amplitude-modulation symbol, and b_maxis a maximum number of bit positions of the quadrature-amplitude-modulation symbol per subchannel; and
  
  selecting a bit load per subchannel in accordance with the maximum number of symbol errors that can be corrected t, a number of symbols in the information field K and the maximum number of transmissions k.
- View Dependent Claims (21, 22, 23, 24, 27, 28, 29, 30, 31)
- - 21. The method of claim 20 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.
  - 22. The method of claim 20 wherein the signal-to-noise ratio is an average signal-to-noise ratio of the associated number of subchannels.
  - 23. The method of claim 20 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.
  - 24. The method of claim 23 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.
  - 27. The method of claim 26 wherein the predetermined number of times is determined in accordance with a measured signal-to-noise ratio value representing at least a subset of the subchannels of the channel, and forward error correction parameters.
  - 28. The method of claim 26 wherein the multi-carrier system is a discrete multi-tone system.
  - 29. The method of claim 26 wherein the discrete multi-tone system comprises the G-lite standard.
  - 30. The method of claim 26 wherein the discrete multi-tone system comprises the G.dmt standard.
  - 31. The method of claim 26 wherein the forward error correction parameters are Reed-Solomon forward error correction parameters.

25. 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

26. A method for transmitting data in a multi-carrier system between a downstream station and an upstream station, coupled by a channel having a plurality of subchannels, comprising:
- transmitting an information frame from the upstream station;
  
  receiving the information frame at the downstream station;
  
  determining whether the information frame is non-correctable;
  
  transmitting a negative acknowledgement when the information frame is non-correctable; and
  
  transmitting the information frame if the information frame has not be to transmitted a predetermined number of times from the upstream station.

32. 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.
- View Dependent Claims (33, 36, 37, 38, 39, 40, 41)
- - 33. The apparatus of claim 32 wherein the representation is generated in accordance with the following relationships:
  - 36. The apparatus of claim 35 wherein the coding gain is a function of an average number of transmissions for a frame.
  - 37. The apparatus of claim 35 wherein the bit load is determined in accordance with the following relationships:
  - 38. The apparatus of claim 37 wherein ω
    - (b_i) is approximated in accordance with the following relationship;
  - 39. The apparatus of claim 37 wherein ε
    - _Sis determined in accordance with the following relationship;
  - 40. The apparatus of claim 37 wherein ω
    - (b_i) is determined in accordance with the following relationship;
  - 41. The apparatus of claim 35 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,K,1).

34. An apparatus for determining throughput in a multicarrier transmission system, comprising:
- means for determining the throughput of a channel in an upstream and downstream direction in accordance with the following relationships;
  
  $H_{u} = \max Λ_{u} = \min {\begin{matrix} V_{u} / [\frac{N_{d}}{K_{d}} \frac{1 - {(1 - p_{d})}^{k_{d}}}{p_{d}} + \frac{M_{u}}{K_{u}} \frac{V_{u}}{V_{d}} (\frac{1}{m_{u}} + \frac{1 - p_{u}}{p_{u}}) (1 - {(1 - p_{u})}^{k_{u}})], \\ V_{u} / [\frac{M_{d}}{K_{d}} \frac{V_{d}}{V_{u}} (\frac{1}{m_{u}} + \frac{1 - p_{u}}{p_{u}}) (1 - {(1 - p_{u})}^{k_{u}}) + \frac{N_{u}}{K_{u}} \frac{1 - {(1 - p_{d})}^{k_{d}}}{p_{d}}] \end{matrix}}, and$ $H_{d} = \max Λ_{d} = \min {\begin{matrix} V_{d} / [\frac{N_{d}}{K_{d}} \frac{1 - {(1 - p_{d})}^{k_{d}}}{p_{d}} + \frac{M_{u}}{K_{u}} \frac{V_{u}}{V_{d}} (\frac{1}{m_{u}} + \frac{1 - p_{u}}{p_{u}}) (1 - {(1 - p_{u})}^{k_{u}})], \\ V_{d} / [\frac{M_{d}}{K_{d}} \frac{V_{d}}{V_{u}} (\frac{1}{m_{d}} + \frac{1 - p_{d}}{p_{d}}) (1 - {(1 - p_{d})}^{k_{d}}) + \frac{N_{u}}{K_{u}} \frac{1 - {(1 - p_{u})}^{k_{u}}}{p_{u}}] \end{matrix}},$ wherein M_drepresents a length of an acknowledgment frame in a downstream direction, K_drepresents the length of an information field in the downstream direction, m_drepresents a number of information frames between positive acknowledgment frames in the downstream direction, p_drepresents a probability of an information frame being accepted in the downstream direction, k_drepresents a maximum number of transmissions in the downstream direction, Λ
  
  _drepresents a number of information bits per unit time in the downstream direction, N_drepresents a total frame length in the downstream direction, M_urepresents a length of an acknowledgment frame in an upstream direction, N_urepresents a total frame length in the upstream direction, K_urepresents the length of an information field in the upstream direction, m_urepresents a number of information frames between positive acknowledgment frames in the upstream direction, p_urepresents a probability of an information frame being accepted in the upstream direction, k_urepresents a maximum number of transmissions in the upstream direction, Λ
  
  _urepresents a number of information bits per unit time in the upstream direction, V_urepresents a data rate in the upstream direction, and V_drepresents a data rate in the downstream direction.

35. 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.

42. An apparatus for determining an uncoded bit error rate p_bbased on a target symbol error rate ε
- _Sand a maximum number of transmissions k, comprising;
  
  means for determining the uncoded bit error rate Pb 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 p_bthat produces a symbol error rate that is less than or equal to the target symbol error rate ε
  
  _Sis largest.
- View Dependent Claims (43)
- - 43. The apparatus of claim 42 wherein said weighted series expansion to determine said uncoded bit error rate p_bcomprises the following relationship:

44. 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).
- View Dependent Claims (45, 46, 47, 48)
- - 45. The apparatus of claim 44 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.
  - 46. The apparatus of claim 44 wherein the signal-to-noise ratio is an average signal-to-noise ratio of the associated number of subchannels.
  - 47. The apparatus of claim 44 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.
  - 48. The apparatus of claim 47 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.

49. 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
  
  )]/10log2 wherein $Φ (γ, t, K, k, ɛ) = 10 \log {10^{- γ / 10} + \frac{3 \log e}{2 \log [\frac{α 〈 ω (b) 〉 \sqrt{8 / π}}{W (t, K, k) (αɛ / β) \frac{1}{(t + 1) k}}] - \log \log [\frac{α 〈 ω (b) 〉 \sqrt{8 / π}}{W (t, K, k) (αɛ / β) \frac{1}{(t + 1) k}}] + \log (\frac{\log e}{2})}}$ $W (t, K, k) = {{[(\begin{matrix} K + C + R - 1 \\ t \end{matrix})]}^{\frac{1}{(t + 1) k}} [(\begin{matrix} K + C + R \\ t + 1 \end{matrix})]}^{\frac{k - 1}{(t + 1) k}} 〈 ω (b) 〉 = \frac{1}{b_{\max}} \int_{1}^{b_{\max}} ω (b) (1 - 2^{- b / 2}) \partial b$ α
  
  represents a number of bits per symbol, y represents a signal-to-noise ratio, ε
  
  represents a target symbol error rate, k represents a maximum number of transmissions, C+R represents a number of redundant symbols in an error correction field, b represents a number of bit positions of a quadrature-amplitude-modulation symbol, ω
  
  (b) represents an average fraction of erroneous bits in an erroneous b-sized quadrature-amplitude-modulation symbol, and b_maxis a maximum number of bit positions of the quadrature-amplitude-modulation symbol per subehannel; and
  
  means for selecting a bit load per subchannel in accordance with the maximum number of symbol errors that can be corrected t, a number of symbols in the information field K and the maximum number of transmissions k.

50. A method for transmitting data in a multi-carrier system between a downstream station and an upstream station, coupled by a channel having a plurality of subchannels, comprising:
- a transmitter to transmit an information frame from the upstream station;
  
  a receiver to receive the information frame at the downstream station, the receiver to determine whether the information frame is non-correctable, and transmit a negative acknowledgement when the information frame is non-correctable;
  
  wherein the transmitter, in response to the negative acknowledgment, transmits the information frame if the information frame has not be transmitted a predetermined number of times from the upstream station.
- View Dependent Claims (51, 52, 53, 54, 55)
- - 51. The apparatus of claim 50 wherein the predetermined number of times is determined in accordance with a measured signal-to-noise ratio value representing at least a subset of the subchannels of the channel, and forward error correction parameters.
  - 52. The apparatus of claim 50 wherein the multi-carrier system is a discrete multi-tone system.
  - 53. The apparatus of claim 50 wherein the discrete multi-tone system comprises the G-lite standard.
  - 54. The apparatus of claim 50 wherein the discrete multi-tone system comprises the G.dmt standard.
  - 55. The apparatus of claim 50 wherein the forward error correction parameters are Reed-Solomon forward error correction parameters.

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Current Assignee
Hewlett-Packard Development Company, L.P. (HP Inc.)
Original Assignee
3Com Corporation (HP Inc.)
Inventors
Mitlin, Vlad, Williams, Richard G.C.

Granted Patent

US 7,103,096 B2
Time in Patent Office

Days
Field of Search
US Class Current

714/746
CPC Class Codes

H04L 1/0009   by adapting the channel cod...

H04L 1/1825   Adaptation of specific ARQ ...

H04L 5/0044   allocation of payload

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

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

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