Cell switching and packet combining in a wireless communication system
View Patent ↗A method is provided to allow a mobile station to communicate with two different cells during a handoff between the cells. During the handoff, the mobile station may controllably combine information received from both of the cells with which it is communicating.
1. A method of communicating with at least a first and a second cell during a handoff from the first cell to the second cell, the method comprising:
transmitting, from a mobile unit, first information encoded with a first code such that the first cell can decode the first information;
transmitting, from the mobile unit, second information encoded with a second code, different than the first code, such that the second cell can decode the second information;
receiving, at the mobile unit, information from both the first and second cells for a time interval during which the first and second cells are able to concurrently decode the first and second information, respectively, wherein the time interval begins when the second cell has successfully decoded a first number of transmissions of said second information and ends after the mobile unit stops transmitting said first information.
2. A method, as set forth in claim 1 , wherein transmitting the first and second information comprises delivering a first and second signal indicative of a quality of a communications channel between the mobile unit and the first and second cell.
3. A method, as set forth in claim 2 , further comprising reducing power used to deliver the first and second signals in response to receiving a request from both the first and second cell.
4. A method, as set forth in claim 2 , further comprising:
discontinuing transmission of said first information from the mobile unit to the first cell in response to successfully receiving information transmitted in a selected number of transmission time intervals from the second cell, and wherein the time interval ends when the first cell has failed to receive a second number of transmissions of said first information in response to the mobile unit to discontinuing transmission of said first information.
5. A method, as set forth in claim 2 , wherein delivering the first and second signals indicative of a quality of a communications channel with the first cell and with the second cell further comprises encoding the first and second signals using first and second orthogonal code sequences.
6. A method, as set forth in claim 1 , further comprising combining the information received from the first and second cells during the preselected period in which the first and second cells are able to concurrently decode the first and second information, respectively.
7. A method, as set forth in claim 6 , wherein combining the information received from the first and second cells during the switching further comprises combining a first and second sub-block of information respectively received from the first and second cells provided that the first and second sub-blocks are from a common block of information.
8. A method, as set forth in claim 6 , wherein combining the information received from the first and second cells during the switching further comprises combining a first and second sub-block of information respectively received from the first and second cells using Chase combining.
9. A method, as set forth in claim 6 , wherein combining the information received from the first and second cells during the switching further comprises combining a first and second sub-block of information respectively received from the first and second cells using Chase combining provided that the first and second sub-blocks have a common redundancy version.
10. A method, as set forth in claim 6 , wherein combining the information received from the first and second cells during the switching further comprises combining a first and second sub-block of information respectively received from the first and second cells using incremental redundancy combining.
11. A method of communicating with at least a first and a second cell during a handoff from the first cell to the second cell, the method comprising:
receiving, at a mobile unit, information only from the first cell in response to transmitting, from the mobile unit, first information encoded with a first code such that the first cell can decode the first information;
switching from communicating with the first cell to communicating with the second cell;
receiving information from both the first and second cells for a time interval during the switching in response to transmitting, from the mobile unit, the first information encoded with the first code concurrently with transmitting, from the mobile unit, second information encoded with a second code, different than the first code, such that the second cell can decode the second information, wherein the time interval begins when the second cell has successfully decoded a first number of transmissions of said second information and ends after the mobile unit discontinues transmitting said first information; and
receiving information only from the second cell after the switching in response to discontinuing transmission of the first information encoded with the first code.
12. A method, as set forth in claim 11 , further comprising:
delivering a first signal indicative of a quality of a communications channel with the first cell prior to the switching;
delivering a second signal indicative of a quality of a communications channel with the second cell after the switching; and
delivering the first and second signals indicative of a quality of a communications channel with the first cell and with the second cell during the switching.
13. A method, as set forth in claim 12 , further comprising discontinuing delivery of the first signal in response to receiving information from the second cell for a preselected period.
14. A method of communicating with a mobile station through at least a first and a second cell during a handoff from the first cell to the second cell, comprising:
switching from communicating with the mobile station via the first cell to communicating with the mobile station via the second cell;
transmitting information through both the first and second cells to the mobile station for a time interval during the switching the time interval corresponding to a period when the mobile station is concurrently transmitting first information encoded with a first code such that the first cell can decode the first information and second information encoded with a second code, different than the first code, such that the second cell can decode the second information, wherein the time interval begins when the second cell has successfully decoded a first number of transmissions of said second information and ends after the mobile unit stops transmitting said first information.
15. A method, as set forth in claim 14 , further comprising receiving a first and second signal indicative of a quality of a communications channel between the mobile station and the first cell and the second cell during the switching.
16. A method, as set forth in claim 15 , further comprising discontinuing delivery of the information from the first cell in response to failing to receive the first signal for a preselected period.
17. A method, as set forth in claim 15 , wherein delivery of the information from the second cell is initiated in response to receiving the second signal for a preselected period.
18. A method, as set forth in claim 15 , wherein receiving the first and second signals indicative of the quality of the communications channel with the first cell and with the second cell during the switching further comprises decoding the first and second signals wherein the first signal may be decoded by the first cell and the second signal may be decoded by the second cell.