HK1065902B - The method and device for minimizing the amount of data necessary to signal code and timeslot assignments - Google Patents

Description

Method and apparatus for minimizing the amount of data required for signaling code and time slot assignments

Technical Field

The present invention relates to wireless hybrid Time Division Multiple Access (TDMA)/Code Division Multiple Access (CDMA) communication systems. More particularly, the invention relates to configuring physical channels in such systems.

Background

Wireless communication systems are evolving from carrying basic voice and paging information to portable voice, paging, and other data information such as internet data. The bandwidth required for all of these data types of information has varied dramatically. Some of the data requires a wider bandwidth than traditional voice and paging information.

In a CDMA communication system, multiple communications are transmitted in a shared frequency spectrum, the communications being distinguished by their channelization codes. To make more efficient use of the shared spectrum, hybrid TDMA/CDMA communication systems time-divide the shared bandwidth into repeating frames having a particular number of timeslots. Communications are transmitted in the system using one or more time slots and one or more codes. One such system is a Universal Mobile Telecommunications System (UMTS) Time Division Duplex (TDD) communication system that uses CDMA for 15 time slots. In TDD, the time slots of a particular cell are only used for uplink or downlink communication.

To deal with the problem that different communications require different bandwidths, adaptive modulation and coding (AM & C) is used. In AM & C, a modulation and coding scheme for transmitting data is changed to more efficiently use radio resources. For example, the modulation used for the data may be varied, for example using Binary Phase Shift Keying (BPSK), Quadrature Phase Shift Keying (QPSK), or M-ary (M-ary) quadrature amplitude modulation, etc. Further, data may be allocated in a single code in a time slot, in multiple codes in a time slot, in a single code in multiple time slots, or in multiple codes in multiple time slots.

Because data transmitted to or from a particular User Equipment (UE) may be transmitted using a variety of modulations, time slots, and coding schemes, the modulation/time slot/coding information must be communicated to the UE. This type of information is typically signaled or broadcast to the UE and is typically performed using a low-speed control channel. Signaling the information uses useful overhead and air resources. Because AM & C is not typically applied to control channels, any information transmitted over the control channel uses more air resources than would be required if the information were transmitted over the channel to which AM & C was applied. However, whether AM & C is used or not, it is desirable to reduce signaling overhead.

Therefore, it is desirable to transmit as much modulation/slot/coding information as possible through channels to which AM & C is applied. In addition, it is desirable to reduce the time slot and code allocation signaling.

Disclosure of Invention

A sequential code is provided for potential allocation to users in a wireless hybrid TDMA/CDMA communication system. At least one (1) time slot is selected to support the communication. For each selected slot, at least one (1) code is selected. If more than one code is selected, the codes are consecutively selected, and for at least one (1) of the selected time slots, the identifiers of the first and last of the selected consecutive codes are signaled. The user receives the signaled identifier and supports communication as identified using the selected continuity code.

Drawings

Fig. 1 is a simplified illustration of a wireless physical channel configuration signaling system for downlink.

Fig. 2 is a simplified depiction of such a system as an uplink.

Fig. 3 is a flow chart of signaling using continuity coding.

Fig. 4 is an explanatory table of allocation using continuity coding.

Fig. 5 is a flow chart for encoding a signal using common continuity.

FIG. 6 is a table illustrating assignments using common continuity codes.

Fig. 7 is a flow diagram of signaling using common continuity coding located in a continuity slot.

Fig. 8 is an illustrative table of assignments for using common continuity coded signals located in consecutive time slots.

Fig. 9 is a flow chart of signaling using a full slot allocation.

Fig. 10 is an explanatory table of the full slot allocation.

Fig. 11 is a flow chart of signaling using consecutive full slots.

Fig. 12 is an explanatory table of the continuity full slot allocation.

Fig. 13 is a table summarizing the bits required to signal the code/slot assignments for a sixteen code and twelve available slot system.

Fig. 14 is a flow chart of a method of calculating all the continuity codes in all the slots.

Fig. 15 is a table illustrating continuity code allocation.

Detailed Description

The present invention will be described with reference to the drawing figures, in which numerals and the like represent elements throughout.

A method 53 for allocating codes to time slots according to the present invention uses continuous coding and will be described with reference to the flow chart of figure 3, a brief description of the allocation of codes to UEs a, B and C being shown in figure 4. In fig. 4, twelve (12) potential slots and sixteen (16) potential codes are presented, but the invention is not limited to a particular number of slots and/or codes.

Each time slot is potentially assigned a predetermined number of codes, for example sixteen codes. The predetermined number of codes is assigned an order or sequence, e.g., from 0 to 15, (step 54). For a particular UE, only consecutive codes are assigned to the UE in a given time slot (step 56). To illustrate, referring to FIG. 4, UE A is assigned codes 4-8 in slot 2. Codes 1, 3 and 4 are not allowed to be allocated to UE a unless code 2 is also allocated to UE a, which has likewise been allocated codes 6-9 in slot 6; codes 9-12 that UE B has been allocated in slot 2 and codes 0-13 that have been allocated in slot 9; and UE C has been allocated codes 1-5 in slot 11.

Referring back to fig. 3, to signal this allocation scheme to the UE, for each allocated slot, an indication of the first and last codes of the consecutive codes is required, (step 58), for sixteen (16) potential coding orders, eight (8) bits are required. Four (4) bits indicate the starting code, (codes 0 to 15), and four (4) bits indicate the number of last codes or consecutive codes, (codes 0 to 15) or consecutive codes (1 to 16). for a twelve (12) slot system, 96 bits are required, (eight (8) bits per slot times twelve (12) slots).

One method for reducing the number of bits in the downlink transmission in the control channel is to signal only a small portion of the allocation information (hereinafter referred to as "pre-signaled information") over the control channel, while the remainder of the allocation information is transmitted with the downlink data (hereinafter referred to as "post-signaled information"), the post-signaled information transmitted with the downlink data will undergo the same AM & C processing as the data, thus significantly reducing the air resources required to convey the allocation information over the control channel.

In a typical system, it takes two (2) time slots to recover the data, as the control information must be received and then processed in preparation for receiving the actual data. The pre-signaled information, which must therefore relay only the allocation information for the first two (2) slots for transmitting downlink data, contains a four (4) bit indicator for the first used slot; a four (4) bit indicator for the next slot; with an indicator of the first and last code for each of the used slots, (every two (2) bits). Thus, only a maximum of sixteen (16) bits are used to signal the information signaled first, and the remaining allocation information is transmitted as the information signaled later together with the downlink data. As a result, for a sixteen (16) coded and twelve (12) slot system, only sixteen (16) bits are the information signaled first, and the remaining post-signaling information is transmitted along with the downlink data.

One advantage of this approach is that it allows the use of any number of codes in any time slot, however. This approach requires signaling for the typical allocation of at least two time slots, and possibly all time slots. While this limits the choice of coding for continuity coding, and the use of code reallocation, this limitation is not significant. If the optimal reallocation requires non-consecutive codes, the use of the slotted UE codes can be repackaged to allow allocation of only consecutive codes to all UEs.

A second method 80 for allocating codes and time slots uses common consecutive codes and is described with reference to the flow chart of fig. 5 and in fig. 6 for a brief description of the allocation of UE a, UE B and UE C codes. Each time slot is potentially assigned a predetermined number of codes, for example sixteen (16) codes. The predetermined number of codes is assigned an order or sequence, e.g., from 0 to 15, (step 82). The same set of consecutive codes assigned to one slot must be assigned to all slots for a particular UE, (step 84). To illustrate using fig. 6, UE a is assigned time slots 2, 3 and 11 and is assigned codes 2-4 in each time slot. However, because UE A has been allocated codes 2-4 in slot 2, it cannot be allocated only codes 2 or codes 2-5 in other slots. Similarly, UE B is assigned codes 0-13 in time slots 8 and 9; and UE C is allocated code 11 in time slots 11 and 12.

In order to signal this allocated scheme to the UE, an indication of the first and last codes of the contiguous set and an indicator of the timeslot in use are required (step 86). For the system of fig. 6, eight (8) bits are required for consecutive codes, (four (4) bits for the first code and four (4) bits for the last code or number of codes), and twelve (12) bits for identifying the time slot used. Each bit corresponds to a time slot. In one (1) embodiment, a one (1) bit value indicates that the slot is used and a zero (0) bit value indicates that it is not used, thus requiring a total of twenty (20) bits.

The use of the pre-signaling information and the post-signaling information with method 80, which must indicate the first used time slot and the next time slot, as well as the first and last codes in common order, reduces the number of pre-signaling bits. For the system of fig. 6, eight (8) bits indicate the first two (2) slots of the twelve (12) slots, (four (4) bits indicate each slot) and eight (8) bits are used for the number of start and end codes or codes. Therefore, a total of sixteen (16) bits of information are required to be signaled first.

To further reduce the bits of the previously signaled information, five (6) bits can be used for the first two (2) slots, four (4) bits indicating the first used slot and the fifteen bits indicating whether the next slot is used, with the result that sixteen (16) or thirteen (13) bits are the previously signaled information, along with up to ten (10) bits of the subsequently signaled information.

An advantage of the second approach is that it reduces the number of messages that are signaled first, and a disadvantage is that it reduces the flexibility of code and slot allocation, so that each slot used by a particular UE must be allocated the same code.

A third method 90 for code and time slot allocation uses common consecutive codes in consecutive time slots and is described with reference to the flow chart of figure 7 and a brief description of such code allocation for UE a, UE B and UE C in figure 8. Each time slot is potentially assigned a predetermined number of codes, such as sixteen (16) codes. This predetermined number of codes is assigned an order or sequence, e.g., from 0 to 15, (step 92). In this method, not only the same code is assigned to each used time slot, but also only consecutive time slots can be assigned (step 94). To illustrate using fig. 8, UE a is assigned codes 2-4 in time slots 5-7. However, UE a cannot be allocated codes 2-4 in time slots 5, 6, and 8 unless time slot 7 is also allocated. Similarly, UE B is assigned codes 0-13 in time slots 8 and 9. UE B cannot be allocated a lesser or greater number of codes in any other time slot, nor codes 0-13 in time slots 11 or 12 unless time slot 10 is allocated. UE C is assigned code 11 in slot 11.

To signal this allocation scheme to a UE, an indication of the first and last allocation codes (or numbers) of the allocation codes and an indication of the first and last allocation codes (or numbers) of the allocation slots in each slot are signaled (step 96). For the system of fig. 8, eight (8) bits are required for allocation of codes and eight (8) bits for allocation of time slots, (four (4) for the first time slot and four (4) for the last time slot, or number of time slots), for a total of sixteen (16) bits.

The use of this method 90 reduces the number of bits that are signaled first and then. In this method 90, thirteen (13) bits must be signaled first before the data, (eight (8) codes for use in the time slot, four (4) codes for the first used time slot, and one (1) bit to indicate whether the other time slots are used or not). Four (4) bits indicating the last slot, or number of slots, are transmitted with the data as information to be later signaled, provided that other slots are used.

This third approach limits the amount of signaling, but at the cost of flexibility in the allocation of codes/time slots.

The fourth method 100 for allocating codes and time slots allocates all codes in a time slot to a UE and is described with reference to the flowchart of fig. 9 and a brief description of such allocation for UE a, UE B and UE C in fig. 10. In this method the UE a is allocated all the codes of time slots 2 and 5, the UE b is allocated all the codes of time slots 8 and 9, and the UE C is allocated all the codes of time slot 11.

To signal this allocation scheme to a UE, an indicator of the allocated time slot is needed (step 104). For the system of fig. 10, the indicator is a twelve (12) bit field with each bit indicating whether a particular slot is used. Typically, the UE knows the maximum number of codes in a slot. However, if the maximum number of codes is not known, an indicator of the number of codes is sent, (also part of step 104), e.g., four (4) bits indicate that the maximum number of codes ranges from 0 to 16.

The use of this method 100 reduces the number of bits previously signaled. In this method 100, indicators of the first two used time slots are signaled. For the system of fig. 10, the two slot indicators are eight (8) bits. Indicators of the remaining allocated time slots are signaled as information to be later signaled together with the information in the first time slot. Alternatively, to further reduce the number of transmitted bits, five (5) bits of the information that is signaled first may be used. The four (4) bits indicate the first slot and the fifth bit indicates whether the next slot is used.

The fifth method 110 uses a complete contiguous time slot for code and time slot allocation and is described with reference to the flowchart of fig. 11 and a brief description of such allocation for this UE a, UE B and UE C in fig. 12. In this method, the UE is allocated all codes in consecutive time slots (step 112). To explain using fig. 12, UE a is all codes that are assigned to time slots 2-4. In the case where time slot 4 is not allocated to UE a, UE a cannot be allocated all the codes of time slots 2, 3, and 5. Similarly, UE B is assigned all the codes of slots 8 and 9; and UE C is assigned all the codes of slot 11.

To signal this allocation scheme to the UE, the indicators (or numbers) of the first and last time slots of the used time slots are signaled (step 114). For the system of fig. 11, eight (8) bits are required, (four (4) for the first used slot and four (4) for the last slot or number of slots).

The use of this method 110 reduces the number of bits previously signaled. In this method 110, only five (5) bits are transmitted as the information that was signaled first. The four (4) bits indicate the first usage code and the fifth bit indicates whether the next slot is used (step 74). If the following slot is used, four (4) bits are signaled as post-signaled information along with the transmitted downlink data to indicate the last slot or number of slots.

A sixth method 120 calculates all the continuity codes in all the time slots and is described with reference to the flowchart of fig. 14, and a simplified illustration of such code allocation for UE a, UE B and UE C in fig. 15. In this method 120, all codes in all time slots are continuously computed (step 122), and then the UE is assigned the required number of codes (step 124). To illustrate using FIG. 15, UE A is assigned codes 69-99, UE B is assigned codes 129-142 and UE C is assigned codes 162-181.

To signal this allocation structure to the UE, an indication of the first and last codes is required (step 126), which for the system of fig. 15 is sixteen (16) bits, (eight (8) bits for the first code and eight (8) bits for the last code). Alternatively, the indicator of the first code may be signaled with the number of codes; especially when the number of codes is small.

The use of the information signaled first and later and the method 120 reduces the number of bits signaled first, in which method 120 thirteen (13) bits must be signaled as information signaled first, (eight (8) codes for the first code and five (5) bits for the first two (2) slots). If more codes are used, the count of codes can be replaced in later signaled information.

The bits required to signal the code/slot assignments for the six (6) schemes of the sixteen (16) code and twelve (12) available slot system are summarized in the table of fig. 13.

Although the present invention may be implemented by many physical systems, a system for implementing the present invention will be described with reference to fig. 1, which illustrates a simple wireless hybrid TDMA/CDMA communication system for physical channel configuration signaling. The preferred embodiment is used for data transmitted in the downlink, e.g. the high speed downlink channel, but the physical channel configuration signalling can also be used in other embodiments, e.g. the uplink.

Downlink data communicated to a particular UE 24 is allocated at least one code and at least one time slot by the resource management device 28. The resource management means 28 may be in a Radio Network Controller (RNC) or in a node-B20. The resource management device 28 allocates codes and time slots as will be described in more detail below. The allocation code and time slot are sent to a signaling transmitter 30 and an AM & C controller 32 in the base station 22. The signaling transmitter 30 arranges for transmission of code and time slot information as will also be described in detail below.

The data modulation and propagation means 34 modulates, propagates and time-division multiplexes the downlink data in the time slots and the codes assigned by the resource management means 28. The modulated data and signaled information is broadcast by an antenna 36 or array of antennas via the wireless radio channel 26.

In a particular UE 24, the transmitted downlink data and signaled information is received by an antenna 38. The signaling receiver 40 recovers the signaled information and relays it to the AM & C controller 42. The AM & C controller 42 decides the modulation to be used and indicates the code and time slot for the downlink data to the data detection means 44. One potential data detection device 44 is a link detection device that uses a channel estimation device, but other data detection devices may be used. The data detection means 44 uses the time slot and code information from the AM & C controller 42 to recover the downlink data.

Fig. 2 illustrates a simple system for uplink physical channel configuration signaling. The resource management means 28 allocates a code/time slot for uplink data for a particular UE. The allocation code/time slot is sent to a signaling transmitter 30 in the base station 22. The signal transmitter 30 arranges the transmitted codes and slot information as will also be described in detail below. The signaled information is passed through a converter 48 or splitter and is propagated through the wireless radio channel 26 by the antenna 36 or array of antennas.

The particular UE 24 receives the signaled information. The received information is passed to the signaling receiver 40 through the switch 50 or splitter. The signaled information is recovered by the signaling receiver 40 and relayed to the AM & C controller 42. The AM & C controller 42 relays the uplink code and time slot assignments to the data modulation and propagation device 52. The data modulation and propagation means 52 propagates and time-division multiplexes the uplink data as directed by the AM & C controller 42 in time slots and together with the code signaled by the base station 22, the modulated data being passed by the UE antenna 38 via the wireless radio channel 26 through a switch 50 or splitter.

The transmitted data is received by a base station antenna 36 or antenna array. The received data is passed to the data detection device 46 via a switch 48 or splitter. One possible data detection device 34 is a link detection device that uses a channel estimation device, but other detection devices may be used. A base station AM & C controller 32 receives the code and slot assignments from the resource management device 28. The data detection means 46 uses the assigned code and time slot to be directed by the AM & C controller 32 to recover uplink data from the received uplink signal.

While this invention has been described in terms of preferred embodiments, other variations within the scope of the invention will be apparent to those skilled in the art.

Claims (19)

1. A method for minimizing the amount of data required to signal code and time slot assignments to support communication for users in a wireless hybrid Time Division Multiple Access (TDMA)/Code Division Multiple Access (CDMA) communication system, the TDMA/CDMA communication system including at least one transmitter and at least one receiver, whereby the system supports Radio Frequency (RF) communication using at least one time slot from a predetermined sequence of time slots and a predetermined sequence of codes, the method comprising:

at the transmitter:

selecting at least one time slot from the time slots in the preset sequence;

for at least one selected time slot, selecting successive codes from the predetermined sequence of codes; and is

Signaling an identifier of a first and a last code of the at least one selected slot and the selected consecutive codes through a control channel, and signaling allocation information of codes between the first and the last codes together with downlink data; and is

Wherein the at least one selected time slot and the selected consecutive code are used to support the communication.

2. The method of claim 1, wherein the last code is identified by the number of consecutive codes.

3. The method of claim 1, wherein each selected time slot is potentially assigned a different set of consecutive codes, and the signaled identifier comprises an identifier of the first and last codes of each selected time slot.

4. The method of claim 1, further comprising selecting a plurality of time slots, wherein each selected time slot is assigned the same consecutive code.

5. The method of claim 4, further comprising signaling a slot identifier for each selected slot.

6. The method of claim 5, wherein the slot identifier is a set of bits, each bit associated with a slot.

7. The method of claim 1, wherein the method further comprises selecting a plurality of time slots; whereby the plurality of selected time slots are consecutive and the same code is assigned to each selected time slot; and

the identifiers of the first and last codes of each selected slot are signaled.

8. The method of claim 1, wherein the communication is a downlink communication.

9. The method of claim 1, wherein the hybrid TDMA/CDMA communication system is a hybrid time division duplex communication system using CDMA.

10. The method of claim 1, further comprising signaling a number of codes for each selected time slot.

11. A method for minimizing the amount of data required to signal a code/time slot assignment to support communication for users in a wireless hybrid Time Division Multiple Access (TDMA)/Code Division Multiple Access (CDMA) communication system, the method comprising:

selecting at least one time slot;

for the at least one selected time slot, selecting consecutive codes of the selected time slot;

signaling an identifier of a first and a last code of the selected consecutive codes and the at least one selected slot through a control channel, and signaling allocation information of codes between the first and the last codes together with downlink data; and

using the at least one selected time slot and the selected consecutive code to support the communication.

12. The method of claim 11, wherein the identifier is one bit per slot.

13. The method of claim 11, further comprising:

providing a predetermined sequence of time slots; whereby the selected time slots are consecutive and at least one selected time slot identifier comprises identifiers of the first and last time slots of the consecutive time slots.

14. The method of claim 13, wherein the last slot identifier is an identifier associated with the last slot.

15. The method of claim 13, wherein the last slot identifier is an identifier associated with a number of slots of the consecutive slots.

16. A method for minimizing the amount of data required to signal code and time slot assignments to support communication for users in a wireless hybrid Time Division Multiple Access (TDMA)/Code Division Multiple Access (CDMA) communication system, the TDMA/CDMA communication system including at least one transmitter and at least one receiver, whereby the system supports Radio Frequency (RF) communication using at least one time slot from a plurality of time slots and a plurality of codes, the method comprising:

at the transmitter:

selecting at least one time slot from the plurality of time slots;

for the at least one selected time slot, selecting a consecutive code from the plurality of codes;

signaling a first identifier of the at least one selected time slot; and

signalling the second identifier of the first and last code of the selected consecutive code via a control channel, signalling the allocation information of the codes between the first and the last code together with downlink data, and

wherein at least a selected time slot and a selected consecutive code associated with the first and second identifiers are used to support the communication.

17. The method of claim 16, wherein the first and second identifiers are combined into a single identifier.

18. A method for minimizing the amount of data required to signal code and time slot assignments to support communication for users in a wireless hybrid Time Division Multiple Access (TDMA)/Code Division Multiple Access (CDMA) communication system that utilizes a plurality of time slots, each time slot having a plurality of codes, the method comprising:

continuously encoding codes of the plurality of time slots;

selecting a consecutive code from the plurality of codes to support the communication;

signalling the identifiers of the first and last codes of the selected consecutive codes over a control channel, while signalling the allocation information of the codes between the first and the last codes together with downlink data; and

the time slot associated with the identifier and the selected consecutive code are used to support the communication.

19. A wireless hybrid Time Division Multiple Access (TDMA)/Code Division Multiple Access (CDMA) transmitter for minimizing the amount of data required to signal codes and time slot assignments to support communication for users, wherein Radio Frequency (RF) communication utilizes at least one time slot from a predetermined sequence of time slots and a predetermined sequence of codes is utilized, the transmitter comprising:

means for selecting at least one time slot from said predetermined sequence of time slots;

means for selecting successive codes from the predetermined sequence of codes for at least one selected time slot;

means for signaling an identifier of a first and a last code of the at least one selected time slot and the selected consecutive codes over a control channel, while signaling allocation information of codes between the first and the last codes together with downlink data; and is

Wherein the at least one selected time slot and the selected consecutive code are used to support the communication.