Source: http://www.google.com/patents/US7907574?dq=7,172,682
Timestamp: 2017-10-24 04:36:54
Document Index: 502749729

Matched Legal Cases: ['art 90', 'art 120', 'arts 90', 'art 120', 'art 200', 'art 200', 'art 200']

Patent US7907574 - Channel scheduling - Google Patents
A method for transmitting data in a code division multiple access (CDMA) communication network, consisting of allocating a common Walsh code to a group of transceivers, and allocating a respective, different long code to each transceiver in the group. The method further includes time-multiplexing transmission...http://www.google.com/patents/US7907574?utm_source=gb-gplus-sharePatent US7907574 - Channel scheduling
Publication number US7907574 B2
Application number US 10/768,845
Also published as CA2554601A1, CN1938976A, EP1714413A1, EP1830504A2, EP1830504A3, US20050180350, WO2005074179A1
Publication number 10768845, 768845, US 7907574 B2, US 7907574B2, US-B2-7907574, US7907574 B2, US7907574B2
Inventors Sergio Kolor, Gilad Bornstein
Patent Citations (27), Non-Patent Citations (1), Classifications (11), Legal Events (3)
US 7907574 B2
A method for transmitting data in a code division multiple access (CDMA) communication network, consisting of allocating a common Walsh code to a group of transceivers, and allocating a respective, different long code to each transceiver in the group. The method further includes time-multiplexing transmission of the data to the transceivers in the group by applying the common Walsh code and the respective long code of each transceiver to data packets directed to the transceivers so as to form multiplexed data packets. The multiplexed data packets are transmitted in sequence over the network to the group of transceivers.
38. The computer readable medium according to claim 36, further comprising instructions that, when read and executed, cause the computer to re-allocate a specific transceiver comprised in a first group comprised in the two or more groups to a second group comprised in the two or more groups in response to radio conditions at the specific transceiver.
The present invention relates generally to cellular telephone communications, and specifically to allocation of channels during such communication.
As demand for bandwidth increases for cellular communications, in particular for data packet transfers, allocation of resources within the limited bandwidth available becomes more difficult. In order to be useful, the allocation needs to satisfy a number of often conflicting, and not necessarily well defined, criteria. Such criteria include a concept of fairness, where all users requiring a data packet transfer service are allocated the limited packet resources on a generally “equal” basis. In such a fair distribution of resources no specific user is allocated substantially more or less resources than an “average” allocation, in any time frame where the allocation is performed. The concept of fairness may be applied to users having very different transmission and reception conditions, for example by allocating more resources to a user with poor reception conditions. Application of a particular fairness concept to a group of users may have to take into account, inter alia, different levels of service to which users in the group are entitled, for example, by some of the users in the group having subscribed to a premium service.
It is an object of some aspects of the present invention to provide a method and apparatus for allocating data channels in a code division multiple access (CDMA) cellular network.
FIG. 1 is a schematic illustration of a cellular network system, according to an embodiment of the present invention;
Reference is now made to FIG. 1, which is a schematic illustration of a network system 10, according to an embodiment of the present invention. System 10 operates according to a code division multiple access (CDMA) protocol, typically an industry-standard CDMA protocol such as a CDMA2000 protocol provided by the Telecommunications Industry Association of Arlington, Va. System 10 typically comprises a cellular communication network. It will be appreciated, however, that system 10 may comprise other types of communication network operating according to a CDMA protocol. Such types include, but are not limited to, wireless networks comprising mobile transceivers and/or networks comprising transceivers physically coupled, by communication cables such as conductive cable and/or optical fibres, to a central radio transmitter of the network. Hereinbelow, by way of example, system 10 is assumed to comprise a wireless cellular network comprising mobile transceivers.
The allocation of a channel comprises allocation of a Walsh code and of a “long” code, the two codes together forming a unique set. Although in theory there is no limit to the length of the Walsh code, longer codes consume more BSC resources. In practice, the length of each code is defined by the protocol; the Walsh code is set according to the data rate, and the long code mask generating the long code, to 42 bits, although any other suitable lengths may be used. The codes are applied to a packet—either data or voice—at the transmitter. The receiver to which the packet is directed, i.e., the receiver using the common Walsh code and long code, decodes the coded packet using the unique set of codes, and is therefore able to use the packet. A receiver using the common Walsh code but a different long code decodes the packet; however, because it has a different long code, such a receiver is unable to use the packet, and so effectively rejects the decoded packet.
r=N·R (1)
where r is the data transfer rate at which the data is transmitted,
N is a number, and
R is a fundamental rate at which data is transmitted.
Hereinbelow, by way of example, N is assumed to be chosen from {1, 2, 4, 8, 16, 32} and R is assumed to be approximately equal to 9.6 Kb/s. It will be understood, however, that N may take other values including fractional values, and that R may comprise any other suitable fundamental rate of data transmission.
FSP=MAX — SP−USP (2)
It will be understood that flowchart 90 increases the number of channels, and that flowchart 120 decreases the number. Implementation of flowcharts 90, 120, and flowcharts similar to flowchart 120 as described above, enables manager 58 to allocate supplemental channels substantially evenly over the different rates of the channels, by apportioning Walsh codes between the different rates. Implementation of the flowcharts also limits the total number of supplemental channels according to the resources—including power, Walsh codes, and CSM resources—available after fundamental channels have been allocated.
Carrier Interference
value CIk, an identity Ak of the channel assigned to call k, an average data throughput rate Tk for the call, a data throughput rate Sk for a current time slot, and a required rate RRk—chosen from rates defined by equation (1)—for the call.
for a call, and corresponding required rates RR at which the supplemental channel allocated to the call is required to transmit. The ranges of values of
are typically pre-set by the operator of system 10 at startup of the system.
Call setup procedure 150 allocates a new entry k in call table 140. The procedure is activated when scheduler 64 receives an “allocate call” message from core manager 60. Manager 60 sends the allocate call message to scheduler 64 when a data call setup from the mobile 16 implementing the call is complete. The allocate call message includes a call identity and a power level, PILOT_STRENGTH, of the reference pilot of the call at call setup.
Carrier Interference ,
CIk, for call k. Alternatively or additionally, procedure 150 estimates a value of CIk by another method, such as by a direct determination of the
value. The value of CIk is also measured during progress of a call, as described below with reference to pilot measurement procedure 156. Procedure 150 uses the value of CIk to find a channel rate and an assigned channel for call k, according to channel determination process 158.
value in time slot n. Scheduler process 162 applies the steps of flowchart 200 to each supplemental channel in channel allocation table 142.
C I k [ n ] T k [ n ]
for each call found in step 202. For the call with the highest value of
C I k [ n ] T k [ n ] ,
scheduler process 162 sets Sk[n]=RRk, and for the other calls found in step 202, Sk[n]=0.
T k [ n + 1 ] = ( 1 - 1 t c ) · T k [ n ] + ( 1 t c ) · S k [ n ] ( 3 )
It will be apparent from consideration of flowchart 200 that step 204 chooses the call within the specific channel being processed that is to be transmitted in time slot n, i.e., the call with the highest value of
C I k [ n ] T k [ n ] .
This call typically has a minimum value of Tk[n] for all calls allocated to the channel, since the allocation ensures that all calls have approximately equal values of CIk[n].
By applying flowchart 200 a new user of a channel typically receives data packet service at the expense of existing users, since the new user has an initial low value of Tk. This is advantageous on a short term basis, since the new user receives an “initial burst” of data without significantly affecting previous users. However, if the new user continues to receive data, the previous users may be adversely affected. Some embodiments of the present invention limit the initial burst by assigning an initial value of
CI k [ n ] T k [ n ]
to a new user. Typically, the initial value of
is set to be a multiple of an average value of the existing
values. Preferably, the multiple is set to be between approximately 1 and approximately 2.
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U.S. Classification 370/335, 455/452.1
International Classification H04J11/00, H04B7/216, H04W72/00
Cooperative Classification H04J13/0048, H04L12/40013, H04J13/18
European Classification H04J13/18, H04L12/40A1, H04J13/00B7B
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