Method and apparatus for allocating bandwidth in a wireless communication system

• US 6,925,068 B1
• Filed: 05/21/1999
• Issued: 08/02/2005
• Est. Priority Date: 05/21/1999
• Status: Expired due to Term

• Current Assignee: Quarterhill Inc. (f/k/a Wi-LAN Inc.)
• Original Assignee: Quarterhill Inc. (f/k/a Wi-LAN Inc.)
• Inventors: Klein, Israel Jay, Stanwood, Kenneth L., Gilbert, Sheldon L., Mollenauer, James F.
• Primary Examiner(s): Pham, Chi
• Assistant Examiner(s): LY, ANH VU H
• Application Number:
  US09/316,518
• Time in Patent Office: 2,265 Days
• Field of Search: 370/280, 370/294, 370/314, 370/329, 370/345, 370/347, 370/437, 370/442, 370/458, 370/465, 370/468
• US Class Current: 370/329
• CPC Class Codes: H04L 2012/5607 Radio
• CPC Class Codes: H04L 2012/561 Star, e.g. cross-connect, concentrator, subscriber group equipment, remote electronics
• CPC Class Codes: H04L 5/0064 Rate requirement of the data, e.g. scalable bandwidth, data priority
• CPC Class Codes: H04L 5/0092 Indication of how the channel is divided
• CPC Class Codes: H04Q 11/0478 Provisions for broadband connections
• CPC Class Codes: H04W 28/0268 using specific QoS parameters for wireless networks, e.g. QoS class identifier [QCI] or guaranteed bit rate [GBR] negotiating SLA or negotiating QoS H04W28/24
• CPC Class Codes: H04W 28/06 Optimizing the usage of the radio link, e.g. header compression, information sizing , discarding information system modifying transmission characteristic according to link quality by modifying frame length H04L1/0007; dynamic adaptation of the packet size for flow control or congestion control H04L47/365
• CPC Class Codes: H04W 28/14 using intermediate storage
• CPC Class Codes: H04W 4/06 Selective distribution of broadcast services, e.g. multimedia broadcast multicast service [MBMS]; Services to user groups; One-way selective calling services
• CPC Class Codes: H04W 56/0005 synchronizing of arrival of multiple uplinks
• CPC Class Codes: H04W 60/00 Affiliation to network, e.g. registration; Terminating affiliation with the network, e.g. de-registration
• CPC Class Codes: H04W 72/044 based on the type of the allocated resource
• CPC Class Codes: H04W 72/0453 Resources in frequency domain, e.g. a carrier in FDMA
• CPC Class Codes: H04W 72/20 Control channels or signalling for resource management
• CPC Class Codes: H04W 72/21 in the uplink direction of a wireless link, i.e. towards the network
• CPC Class Codes: H04W 72/23 in the downlink direction of a wireless link, i.e. towards a terminal
• CPC Class Codes: H04W 72/30 Resource management for broadcast services
• CPC Class Codes: H04W 72/51 based on terminal or device properties
• CPC Class Codes: H04W 72/56 based on priority criteria
• CPC Class Codes: H04W 74/06 using polling
• CPC Class Codes: H04W 76/11 : Allocation or use of connection identifiers
• CPC Class Codes: H04W 8/24 : Transfer of terminal data

Abstract

An adaptive time division duplexing (ATDD) method and apparatus for duplexing transmissions on a communication link in wireless communication systems. Communication link efficiency is enhanced by dynamically adapting to the uplink and downlink bandwidth requirements of the communication channels. Time slots are flexibly and dynamically allocated for uplink or downlink transmissions depending upon the bandwidth needs of a channel. Communication link bandwidth requirements are continuously monitored using sets of pre-determined bandwidth requirement parameters. Communication channels are configured to have either symmetric or asymmetric uplink/downlink bandwidths depending upon the needs of the channel. Channel bandwidth asymmetry can be configured alternatively in favor of the uplink transmissions.(i.e., more time slots are allocated for uplink transmissions than for downlink transmissions) or in favor of the downlink transmissions (i.e., more time slots are allocated for downlink transmissions than for uplink transmissions). A myriad of time slot allocation schemes are possible. One simplified time slot allocation scheme uses a “frame-based” approach. A preferred channel bandwidth analysis technique is disclosed which monitors and updates bandwidth requirement parameters associated with communication sessions, base stations and cell cluster controllers. In accordance with this technique, a communication session is preferably assigned both an “initial” and an “actual” set of bandwidth parameters.

Claims

1. A method for adaptively duplexing transmissions in a communication link using a time division duplexing scheme wherein transmissions are communicated in an uplink direction during uplink time slots and wherein transmissions are communicated in a downlink direction during downlink time slots, comprising the steps of:

(a) monitoring bandwidth usage in the communication link over a period of time to determine uplink and downlink bandwidth utilization parameters;

(b) predicting an uplink bandwidth requirement and a downlink bandwidth requirement of the communication link, wherein the uplink and downlink bandwidth requirements are predicted using the uplink and downlink bandwidth utilization parameters;

(c) setting an uplink/downlink bandwidth requirement ratio based upon the uplink and downlink bandwidth requirements of the link;

(d) allocating uplink and downlink time slots in a frame with the set uplink/downlink ratio in response to bandwidth requests; and

(e) enabling uplink transmissions during the allocated uplink time slots and downlink transmissions during the allocated downlink time slots.

2. The method of claim 1, wherein the uplink and downlink bandwidth requirements are initially determined when the link is installed in the communication system.

3. The method of claim 1, wherein the uplink and downlink bandwidth requirements are determined by periodically monitoring the bandwidth utilization parameters for uplink and downlink transmissions in the communication link.

4. The method of claim 1, wherein the uplink and downlink bandwidth requirements are determined by periodically monitoring requests for uplink and downlink transmissions in the communication link.

5. The method of claim 1, wherein the bandwidth requirements are periodically determined and the associated uplink/downlink bandwidth requirement ratio for the link is periodically updated, and wherein the uplink and downlink time slot allocations are updated periodically in response to the updated uplink/downlink bandwidth ratio.

6. The method of claim 5, wherein the uplink and downlink bandwidth requirements are periodically determined by continuously monitoring the transmissions in the communication link.

7. The method of claim 1, wherein the uplink and downlink bandwidth requirements vary depending upon the type of service provided over the communication link.

8. The method of claim 1, wherein the uplink and downlink bandwidth requirements vary depending upon the type of user of the communication link.

9. The method of claim 1, wherein the communication link comprises a wireless communication link.

10. The method of claim 1, wherein the uplink and downlink time slots are dynamically allocated using a frame-based time slot allocation approach.

11. The method of claim 10, wherein a frame comprises N time slots, and wherein the frame-based time slot allocation approach comprises allocating a first number N₁ time slots (where N is greater than or equal to N₁) for downlink transmissions only, and allocating the remaining N₂ time slots for uplink transmissions only (where N₂ equals N−

N₁).

12. The method of claim 10, wherein a frame comprises N time slots, and wherein the frame-based time slot allocation approach comprises allocating a first number N₁ time slots (where N is greater than or equal to N₁) for downlink transmissions only, and allocating the remaining N₂ time slots for both uplink and downlink transmissions (where N₂ equals N−

N₁).

13. The method of claim 10, wherein a frame comprises N time slots, and wherein the frame-based time slot allocation approach comprises allocating a first number N₁ time slots (where N is greater than or equal to N) for uplink transmissions only, and allocating the remaining N₂ time slots for downlink transmissions only (where N₂ equals N−

N₁).

14. The method of claim 10, wherein a frame comprises N time slots, and wherein the frame-based time slot allocation approach comprises allocating a first number N₁ time slots (where N is greater than or equal to N₁) for uplink transmissions only, and allocating the remaining N₂ time slots for both uplink or downlink transmissions (where N₂ equals N−

N₁).

15. The method of claim 1, wherein the uplink and downlink bandwidth requirements are determined using a plurality of associated uplink and downlink statistical bandwidth parameters.

16. The method of claim 15, wherein the statistical bandwidth parameters comprise both an initial and actual set of statistical parameters reflective of the bandwidth requirements of the communication link.

17. The method of claim 16, wherein the initial set of statistical parameters are set when the communication link is installed, and wherein the actual set of statistical parameters are periodically updated as the uplink and downlink bandwidth utilization of the communication link varies.

18. The method of claim 17, wherein the initial set of statistical parameters are based upon an estimate of the number of users and the type of user of the communication link.

19. An apparatus for adaptively duplexing transmissions in a communication link of a wireless communication system using a time division duplexing scheme wherein transmissions are communicated in an uplink direction during uplink time slots and wherein transmissions are communicated in a downlink direction during downlink time slots, comprising:

(a) means for monitoring bandwidth utilization in the communication link over a period of time to determine uplink and downlink bandwidth utilization parameters;

(b) means for predicting an uplink bandwidth requirement and a downlink bandwidth requirement of the communication link, wherein the uplink and downlink bandwidth requirements are predicted using the uplink and downlink bandwidth utilization parameters;

(c) means, responsive to the predicting means, for setting an uplink/downlink bandwidth requirement ratio based upon the uplink and downlink bandwidth requirements of the link;

(d) means, responsive to the setting means, for allocating uplink and downlink time slots in a frame with the uplink/downlink bandwidth requirement ratio; and

(e) means for enabling uplink transmissions during the allocated uplink time slots and downlink transmissions during the allocated downlink time slots.

20. The apparatus of claim 19, wherein the uplink and downlink bandwidth requirements are determined by periodically monitoring the bandwidth utilization parameters for uplink and downlink transmissions in the communication link.

21. The apparatus of claim 19, wherein the uplink and downlink bandwidth requirements are determined by periodically monitoring requests for uplink and downlink transmissions in the communication link.

22. The apparatus of claim 19, wherein the predicting settings and allocating means comprise a computer program executing on a programmable processor.

23. The apparatus of claim 22, wherein the programmable processor is in a cluster controller, and wherein the cluster controller controls a plurality of base stations in the wireless communication system, and wherein one selected base station controls transmissions in the communication link.

24. The apparatus of claim 23, wherein the communication link comprises a wireless communication between the selected base station and a CPE.

25. A method for monitoring and updating uplink and downlink bandwidth requirements in a wireless communication system including a base station and at least one CPE, the method comprising:

initializing the base station with an initial set of bandwidth utilization parameters, including a first estimate of the uplink and downlink bandwidth requirements of at least one CPE in a frame;

setting the uplink/downlink ratio of the frame based upon the initial set of bandwidth utilization parameters;

monitoring bandwidth use by the at least one CPE and the base station over a period of time;

updating the initial set of bandwidth utilization parameters with an actual set of bandwidth utilization parameters based on the monitoring; and

setting the uplink/downlink ratio of a subsequent frame based upon the updated bandwidth utilization parameters.

26. The method of claim 25, wherein updating the initial set of bandwidth utilization parameters includes determining a second estimate of the uplink and downlink bandwidth requirements of the at least one CPE.

27. A method for monitoring and updating uplink and downlink bandwidth requirements for a communication link using a time division duplexing scheme wherein transmissions are communicated in an uplink direction during uplink time slots and wherein transmissions are communicated in a downlink direction during downlink time slots, comprising:

(a) determining an initial set of bandwidth utilization parameters, wherein the initial bandwidth utilization parameters comprise an estimate of the uplink and downlink bandwidth requirements; and

(b) updating the initial set of bandwidth utilization parameters with an actual set of bandwidth utilization parameters reflective of an actual bandwidth utilization of the uplink and downlink time slots, wherein the actual set of bandwidth parameters are calculated as follows;

$\begin{array}{c}\left(\begin{array}{c}{U}_{n+1}^{\left(M\right)}\\ D_{n+1}^{\left(M\right)}\end{array}\right)=<br><br>{\mathrm{\alpha <br><br>}}_M<br><br>\left(\begin{array}{c}{U}_n^{\left(M\right)}\\ D_n^{\left(M\right)}\end{array}\right)+\left(1-{\mathrm{\alpha <br><br>}}_M\right)<br><br>\left(\begin{array}{c}{\left(U_n-U_n^{\left(1\right)}\right)}^M\\ {\left(D_n-D_n^{\left(1\right)}\right)}^M\end{array}\right)<br><br>\text{\hspace{1em}<br><br>}<br><br>\mathrm{wherein}<br><br>\text{\hspace{1em}<br><br>}<br><br>{\mathrm{\alpha <br><br>}}_M<<br><br>1,\\ <br><br>M><br><br>1\\ \left(\begin{array}{c}{U}_{n+1}^{\left(1\right)}\\ D_{n+1}^{\left(1\right)}\end{array}\right)=<br><br>{\mathrm{\alpha <br><br>}}_1<br><br>\left(\begin{array}{c}{U}_n^{\left(1\right)}\\ D_n^{\left(1\right)}\end{array}\right)+\left(1-{\mathrm{\alpha <br><br>}}_1\right)<br><br>\left(\begin{array}{c}{U}_n\\ D_n\end{array}\right)<br><br>\text{\hspace{1em}<br><br>}<br><br>\mathrm{and}<br><br>\text{\hspace{1em}<br><br>}<br><br>\mathrm{wherein}<br><br>\text{\hspace{1em}<br><br>}<br><br>{\mathrm{\alpha <br><br>}}_1<<br><br>1,M=1;<br><br>\end{array}$

and wherein U^(M)_n, D^(M)_n comprise uplink and downlink filtered moments, respectively, of order M at an instant n, and wherein U_n, D_n respectively comprise an uplink and downlink accumulated bandwidth requirement influenced by the actual bandwidth utilization.

28. The method of claim 27, wherein the initial set of bandwidth utilization parameters is periodically updated with the actual set of bandwidth parameters calculated in step (b).

29. The method of claim 27, further comprising monitoring rejected transmissions, wherein the following parameters are updated when transmissions are rejected:

$\left(\begin{array}{c}{U}_{n+1}^{\mathrm{\prime <br><br>}}\\ \text{\hspace{1em}<br><br>}\\ D_{n+1}^{\mathrm{\prime <br><br>}}\end{array}\right)={\mathrm{\gamma <br><br>}}_1<br><br>\left(\begin{array}{c}\begin{array}{c}{U}_n^{\mathrm{\prime <br><br>}}\\ \text{\hspace{1em}<br><br>}\end{array}\\ D_n^{\mathrm{\prime <br><br>}}\end{array}\right)+\left(1-{\mathrm{\gamma <br><br>}}_1\right)<br><br>\left(\begin{array}{c}\mathrm{\delta <br><br>}<br><br>\text{\hspace{1em}<br><br>}<br><br>U\\ \text{\hspace{1em}<br><br>}\\ \mathrm{\delta <br><br>}<br><br>\text{\hspace{1em}<br><br>}<br><br>D\end{array}\right)<br><br>\text{\hspace{1em}<br><br>}<br><br>\mathrm{wherein}<br><br>\text{\hspace{1em}<br><br>}<br><br>{\mathrm{\gamma <br><br>}}_1<<br><br>1;<br><br>$

and wherein U′

_n, D′

_n comprise a moving average of the uplink and downlink bandwidth requirements of rejected sessions.

30. The method of claim 27, further comprising monitoring rejected transmissions, wherein the following parameters are updated when transmissions are not rejected:

$\left(\begin{array}{c}{U}_{n+1}^{\mathrm{\prime <br><br>}}\\ D_{n+1}^{\mathrm{\prime <br><br>}}\end{array}\right)={\mathrm{\gamma <br><br>}}_2<br><br>\left(\begin{array}{c}{U}_n^{\mathrm{\prime <br><br>}}\\ D_n^{\mathrm{\prime <br><br>}}\end{array}\right)<br><br>\text{\hspace{1em}<br><br>}<br><br>{\mathrm{\gamma <br><br>}}_2<<br><br>1;<br><br>$

and wherein U′

_n, D′

_n comprise a moving average of the uplink and downlink bandwidth requirements of rejected sessions.

31. A method for monitoring and updating uplink and downlink bandwidth requirements for transmissions across a communication link in a wireless communication system, wherein the transmissions occur during frames comprising N time slots wherein N₁, N₂, . . . N_M are positive integers, and wherein $\sum _{}^{}$

k=1M⁢

 

⁢

Nk=N,

comprising;

(a) summing all of the uplink bandwidth requirements as follows;

for each integer value of k between 1 and M, $S_u^{\left(k\right)}=\sum <br><br>\text{\hspace{1em}<br><br>}<br><br>\sqrt[k]{U^{\left(k\right)}};<br><br>$

(b) summing all of the downlink bandwidth requirements as follows;

for each integer value of k between 1 and M, $S_d^{\left(k\right)}=\sum <br><br>\text{\hspace{1em}<br><br>}<br><br>\sqrt[k]{D^{\left(k\right)}};<br><br>$

(c) calculating an estimated bandwidth allocation scheme as follows;

${\hat{N}}_d=\mathrm{INT}<br><br>\left[\underset{k=1}{\overset{M}{\sum <br><br>}}<br><br>\text{\hspace{1em}<br><br>}<br><br>\frac{N_k<br><br>S_d^{\left(k\right)}}{S_d^{\left(k\right)}+S_u^{\left(k\right)}}\right],\text{\hspace{1em}<br><br>}<br><br>{\hat{N}}_u=N-{\hat{N}}_d;<br><br>$

(d) comparing the estimated bandwidth allocation scheme calculated in step (c) with the allocation scheme currently used, wherein the allocation scheme currently used is defined as N_d, N_u; and

(e) replacing N_d and N_u with the estimated bandwidth allocation scheme calculated in step (c) if |N_d−

{circumflex over (N)}_d|≧

μ

, wherein μ

comprises a pre-determined threshold.

32. The method of claim 31, further comprising monitoring rejected transmissions.

33. The method of claim 32, wherein monitoring transmissions comprises:

summing all of the rejected uplink bandwidth requirements as follows;

S′

_u=Σ

U′

;

summing all of the rejected downlink bandwidth requirements as follows;

S_d′

=Σ

D′

; and

calculating an expected allocation scheme as follows;

$\left(\begin{array}{c}{\tilde{N}}_u\\ \text{\hspace{1em}<br><br>}\\ {\tilde{N}}_d\end{array}\right)=\frac{1}{S_d^{\mathrm{\prime <br><br>}}+S_n^{\mathrm{\prime <br><br>}}}<br><br>\left(\begin{array}{c}{S}_u^{\mathrm{\prime <br><br>}}\\ \text{\hspace{1em}<br><br>}\\ S_d^{\mathrm{\prime <br><br>}}\end{array}\right).$

34. The method of claim 33, further comprising updating the bandwidth allocation scheme when the number of rejected transmissions exceeds a predetermined threshold.

35. The method of claim 34, wherein the bandwidth allocation scheme is updated in accordance with the following:

(a) determining if Max(S_u′

,S_d′

)>

S_o, wherein S_o is a constant, if so then proceeding to step (b);

(b) determining if |N_d−

Ñ

_d|>

μ

, wherein μ

is a constant, if so then proceeding to step (c);

(c) determining if Ñ

_d>

N_d and N_d<

N−

δ

, wherein δ

is a constant, if so then updating the downlink allocation N_d as follows;

N_d←

N_d+δ

;

(d) determining if Ñ

_d<

N_d and N_d>

δ

, if so then updating the downlink allocation N_d as follows;

N_d←

N_d−

δ

;

(e) updating the uplink allocation N_u whenever the downlink allocation is updated in either steps (c) or (d) as follows;

N_u←

N−

N_u; and

(f) updating the bandwidth allocation parameters whenever the-values of N_d and N_u are updated.

36. The method of claim 35, further comprising alerting the wireless communication system if Max(S_u′

,S_d′

)>

T, wherein T is a predetermined threshold value.