Abstract:
An Enhanced Reverse Link Encapsulation packet for a MDDI system combines and improves upon the functionality of the Round Trip Delay Measurement packet and Reverse Encapsulation packet. The combination of these packets allows for reduced MDDI link overhead when providing client reverse link transmission. This packet allows for dynamic reverse link bandwidth allocation and therefore improved MDDI link utilization.

Description:
CLAIM OF PRIORITY UNDER 35 U.S.C. §119 
       [0001]    The present application for patent claims priority to Provisional Application No. 61/002,982 entitled “High Data Rate Interface Apparatus &amp; Method” filed Nov. 13, 2007, and Provisional Application No. 61,004,374 entitled “High Data Rate Interface Apparatus &amp; Method” filed Nov. 27, 2007, both applications are assigned to the assignee hereof and are hereby expressly incorporated herein by reference. 
       CLAIM OF PRIORITY UNDER 35 U.S.C. §120 
       [0002]    The present application for patent is a Continuation-in-Part and claims priority to patent application Ser. No. 12/116,018 entitled “A Packet Structure for a Mobile Display Digital Interface” filed May 6, 2008, and is assigned to the assignee hereof and is hereby expressly incorporated herein by reference. 
     
    
     BACKGROUND 
       [0003]    1. Field 
         [0004]    The present invention relates generally to communication links and more particularly to a method, system, and computer program product for providing an improved packet structure for Mobile Display Digital Interface (MDDI) links. 
         [0005]    2. Background 
         [0006]    In the field of interconnect technologies, demand for ever increasing data rates, especially as related to video presentations, continues to grow. 
         [0007]    The Mobile Display Digital Interface (MDDI) is a cost-effective, low power consumption, transfer mechanism that enables very-high-speed data transfer over a short-range communication link between a host and a client. MDDI requires a minimum of just four wires plus power for bidirectional data transfer that delivers a maximum bandwidth of up to 8 Gbits per second. 
         [0008]    In one application, MDDI increases reliability and decreases power consumption in clamshell phones by significantly reducing the number of wires that run across a handset&#39;s hinge to interconnect the digital baseband controller with an LCD display and/or a camera. This reduction of wires also allows handset manufacturers to lower development costs by simplifying clamshell or sliding handset designs. Further, differential signaling employed with MDDI reduces electromagnetic interference that can occur over traditional parallel connections. 
         [0009]    There are some improvements needed to the current MDDI systems. Existing systems first transmit a round trip delay measurement packet and then transmit a separate reverse encapsulation packet in order for the host to receive data from the client. Further, the existing systems provide a maximum reverse byte indicator from the client to the host in the reverse encapsulation packet. The presently claimed invention does not have this indicator and instead defines the maximum length in the packet length field, so the client can send up to the identified maximum length, and sends a “0” in the packet length field to indicate that the data transmission has been completed. The presently claimed invention is a significant improvement over the present systems by removing the redundant field transmissions. 
       SUMMARY 
       [0010]    Aspects of the claimed invention, disclosed herein, address the above stated needs by providing a method, system, and computer program product that provides an enhanced reverse link encapsulation packet. The enhanced reverse link encapsulation packet combines the features of a round trip delay packet with a reverse encapsulation packet in a single packet. The first part of the reverse transmission is a preamble that allows the host to sync up to the reverse link data so that it can accurately sample the reverse data. 
         [0011]    Further aspects, features, and advantages of the claimed present invention, as well as the structure and operation of the various aspects of the claimed present invention, are described in detail below with reference to the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]      FIG. 1  is a block diagram that illustrates an example environment using a MDDI interface; 
           [0013]      FIG. 2A  shows a typical MDDI packet structure; 
           [0014]      FIG. 2B  depicts a typical forward link structure; 
           [0015]      FIG. 3  shows the prior art enhanced reverse link encapsulation packet; and 
           [0016]      FIG. 4  shows the new enhanced reverse encapsulation packet. 
       
    
    
     DETAILED DESCRIPTION 
       [0017]    The word “exemplary” is used herein to mean “serving as an example, instance, or illustration.” Any aspects described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other aspects. 
         [0018]    The aspects described, and references in the specification to “one aspect”, “an aspect”, “an example aspect”, etc., indicate that the aspects described may include a particular feature, structure, or characteristic, but every aspect may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same aspect. Further, when a particular feature, structure, or characteristic is described in connection with an aspect, it is submitted that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other aspects, whether or not explicitly described. 
         [0019]    The Mobile Display Digital Interface (MDDI) is a cost-effective, low power consumption, transfer mechanism that enables very-high-speed serial data transfer over a short-range communication link between a host and a client. In order to fully appreciate the new features introduced herein, a brief discussion of the MDDI system is provided. 
         [0020]    In the following, examples of MDDI will be presented with respect to a camera module contained in an upper clamshell of a mobile phone. However, it would be apparent to persons skilled in the relevant art(s) that any module having functionally equivalent features to the camera module could be readily substituted and used in aspects of this invention. 
         [0021]    Further, according to aspects of the invention, a MDDI host may comprise one of several types of devices that can benefit from using the claimed present invention. For example, the host could be a portable computer in the form of a handheld, laptop, or similar mobile computing device. It could also be a Personal Data Assistant (PDA), a paging device, or one of many wireless telephones or modems. 
         [0022]    Alternatively, the host could be a portable entertainment or presentation device such as a portable DVD or CD player, or a game playing device. Furthermore, the host can reside as a host device or control element in a variety of other widely used or planned commercial products for which a high speed communication link is desired with a client. For example, a host could be used to transfer data at high rates from a video recording device to a storage based client for improved response, or to a high resolution larger screen for presentations. An appliance, such as a refrigerator, that incorporates an onboard inventory or computing system and/or Bluetooth connections to other household devices, can have improved display capabilities when operating in an internet or Bluetooth connected mode, or have reduced wiring needs for in-the-door displays (a client) and keypads or scanners (client) while the electronic computer or control systems (host) reside elsewhere in the cabinet. In general, those skilled in the art will appreciate the wide variety of modern electronic devices and appliances that may benefit from the use of this interface, as well as the ability to retrofit older devices with higher data rate transport of information utilizing limited numbers of conductors available in either newly added or existing connectors or cables. At the same time, a MDDI client may comprise a variety of devices useful for presenting information to an end user, or presenting information from a user to the host. For example, a micro-display incorporated in goggles or glasses, a projection device built into a hat or helmet, a small screen or even holographic element built into a vehicle, such as in a window or windshield, or various speaker, headphone, or sound systems for presenting high quality sound or music. Other presentation devices include projectors or projection devices used to present information for meetings, or for movies and television images. Another example would be the use of touch pads or sensitive devices, voice recognition input devices, security scanners, and so forth that may be called upon to transfer a significant amount of information from a device or system user with little actual “input” other than touch or sound from the user. In addition, docking stations for computers, car kits or desk-top kits, and holders for wireless telephones may act as interface devices to end users or to other devices and equipment, and employ either clients (output or input devices such as mice) or hosts to assist in the transfer of data, especially where high speed networks are involved. However, those skilled in the art will readily recognize that the claimed present invention is not limited to these devices, there being many other devices on the market, and proposed for use, that are intended to provide end users with high quality images and sound, either in terms of storage and transport or in terms of presentation at playback. The claimed present invention is useful in increasing the data throughput between various elements or devices to accommodate the high data rates needed for realizing the desired user experience. 
         [0023]      FIG. 1  is a block diagram that illustrates an example environment using a MDDI interface. In the example of  FIG. 1 , MDDI is used to interconnect modules across the hinge of a clamshell phone  100 . It must be noted here that while certain aspects of the presently claimed invention will be described in the context of specific examples, such as MDDI interconnections in a clamshell phone, this is done for illustration purposes only and should not be used to limit the present invention to such aspects. As will be understood by a person skilled in the relevant art(s) based on the teachings herein, aspects of the presently claimed invention may be used in other devices including any that may benefit from having MDDI interconnections. 
         [0024]    Referring to  FIG. 1 , a lower clamshell section  104  of clamshell phone  100  includes a mobile station modem (MSM) baseband chip  102 . MSM  102  is a digital baseband controller. An upper clamshell section  114  of clamshell phone  100  includes a liquid crystal display (LCD) module  116  and a camera module  118 . 
         [0025]    Still referring to  FIG. 1 , a MDDI link  110  connects camera module  118  to MSM  102 . Typically, a MDDI link controller is integrated into each of camera module  118  and MSM  102 . In the example of  FIG. 1 , a MDDI host  122  is integrated into camera module  118 , while a MDDI client  106  resides on the MSM side of MDDI link  110 . Typically, the MDDI host is the master controller of the MDDI link. In the example of  FIG. 1 , pixel data from camera module  118  are received and formatted into MDDI packets by MDDI host  122  before being transmitted onto MDDI link  110 . MDDI client  106  receives the MDDI packets and re-converts them into pixel data of the same format as generated by camera module  118 . The pixel data are then sent to an appropriate block in MSM  102  for processing. 
         [0026]    Still referring to  FIG. 1 , a MDDI link  112  connects LCD module  116  to MSM  102 . In the example of  FIG. 1 , MDDI link  112  interconnects a MDDI host  108 , integrated into MSM  102 , and a MDDI client  120  integrated into LCD module  116 . In the example of  FIG. 1 , display data generated by a graphics controller of MSM  102  are received and formatted into MDDI packets by MDDI host  108  before being transmitted onto MDDI link  112 . MDDI client  120  receives the MDDI packets and re-converts them into display data for use by LCD module  116 . 
       Frame Structure 
       [0027]    The original frame structure is described in U.S. Pat. No. 6,760,772 B2, entitled “Generating and Implementing a Communication Protocol and Interface for High Speed Data Transfer”, issued Jul. 6, 2004, (&#39;772 patent), and the description is hereby incorporated by reference. This original packet structure  200  is shown in  FIG. 2A . The fields depicted in  FIG. 2A  include, packet length  202 , which is typically a 16-bit value that specifies the total number of bytes in the packet, not including packet length field  202 , packet type  204 , which is a 16-bit unsigned integer that specifies the type of information contained in packet  200 , data bytes  206 , which is the data sent between the host and client, and CRC  208 , which is a 16-bit cyclic redundancy check calculated over data bytes  206 , packet type  204 , and packet length fields  202 . 
         [0028]    As shown in  FIG. 2B , information transmitted over the MDDI link is grouped into packets. Multiple packets are grouped into a sub-frame  210 , and multiple sub-frames make up a media frame  212 . Every sub-frame  210  begins with a sub-frame header packet  214 . 
       Enhanced Reverse Encapsulation Packet 
       [0029]    The previously described enhanced reverse link encapsulation packet is disclosed in co-pending patent application Ser. No. 12/116,018, and is shown in  FIG. 3 . This packet combines the functionality of the round trip delay measurement packet to help align the host to the incoming data stream with the reverse link encapsulation packet used to transfer data from the client to the host. This packet uses a synchronization pattern to find the alignment of the incoming byte data. Once the synchronization pattern is found in the incoming data stream, the host can reliably sample the remaining reverse link data bits to put together a reverse link data and packet stream. 
         [0030]    This prior art enhanced reverse link encapsulation packet  300  contained a maximum reverse bytes field  316  to indicate how many reverse bytes can by transmitted from the client back to the host. The remaining numbered elements in  FIG. 3  are similar ( 302  through  314  and  318  through  328 ) and function similarly to the elements described below in  FIG. 4  for the new enhanced reverse link encapsulation packet ( 402  through  414  and  418  through  428 ). The max reverse bytes field  316  of  FIG. 3  is removed for the presently claimed invention and the functionality of this feature is included data rate divisor  410  as described below. The detail of the maximum number of bytes that can be transmitted from the client to the host can be derived from packet length field  402  of the enhanced reverse encapsulation packet  400  as well as data rate divisor  410  that is to be used for reverse transmission. 
         [0031]    The packet contents for the new enhanced reverse link encapsulation packet  400 , as shown in  FIG. 4 , are as follows: 
         [0032]    Packet length  402  comprises 2 bytes that contain a 16-bit unsigned integer that specifies the total number of bytes in the packet not including packet length  402  field. 
         [0033]    Packet length field  402  defines the maximum packet length. In the presently claimed invention, the packet data length  402  sent from the host to the client must be non-zero. It is the client that can send packet lengths of zero back to the host to terminate transmission 
         [0034]    Packet type  404  comprises 2 bytes that contain a 16-bit unsigned integer. In this example, a packet type  404  of 84 identifies the packet as an enhanced reverse link encapsulation packet  400 . 
         [0035]    The next field is hClient ID  406  comprising 2 bytes that contain a 16-bit unsigned integer reserved for the client ID. 
         [0036]    Reverse link flags  408  comprise 1 byte that contains an 8-bit unsigned integer that contains a set of flags to request information from the client and specify the reverse link interface type. In this example, if a bit is set to one, then the host requests the specified information from the client. If the bit is zero then the host does not need the information from the client. For example, Bit  0  could indicate that the host needs a client capability packet. It shall be sent by the client to the host in reverse data packets  424  field. Bit  1  could indicate that the host needs the client request and status packet. It shall be sent by the client to the host in reverse data packets  424  field. Bit  2  could indicate that the host needs the client to transmit a synchronization byte before transmitting the first data byte of a reverse link packet  424 . 
         [0037]    Reverse rate divisor  410  comprises 1 byte that contains two 4-bit unsigned integers with valid values of 0, 1, 2, 4 or 8 that specify the number of MDDI_Stb cycles that occur per reverse link data clock, except for the value of 0. The first divisor indicates the divisor to be used for the sync pattern, and the second value indicates the divisor to be used for packet data. The reverse link data clock is equal to the forward link data clock divided by the quantity: two times reverse rate divisor  410 , except when the quantity in this field is 0, and in that case the reverse link clock is equal to the forward link clock. The reverse link data rate is related to the reverse link data clock, and the interface type on the reverse link in the following examples: 
         [0038]    Interface Type 1 indicating the reverse data rate equals the reverse link data clock; 
         [0039]    Interface Type 2 indicating the reverse data rate equals two times reverse link data clock; 
         [0040]    Interface Type 3 indicating that the reverse data rate equals four times reverse link data clock; and 
         [0041]    Interface Type 4 indicating that the reverse data rate equals eight times reverse link data clock. 
         [0042]    Turn-around  1  length  412  comprises 1 byte that contains an 8-bit unsigned integer that specifies the total number of bytes that are allocated for turn-around  1 . The recommended length of turn-around  1  is the number of bytes required for the MDDI_Data drivers in the host to disable their outputs. This is based on the output disable time, the forward link data rate, and the forward link interface type selection being used. Turn-around  2  length  414  comprises 1 byte that contains an 8-bit unsigned integer that specifies the total number of bytes that are allocated for turn-around  2 . The recommended length of turn-around  2  is the number of bytes required for the round-trip delay plus the time required for the host to enable its MDDI_Data drivers. Turn-around  2  length  414  may be also be any value larger than the minimum required value calculated to allow sufficient time to process reverse link packets in the host. Parameter CRC  418  comprises 2 bytes that contain a 16-bit CRC of all bytes from packet length  402  to turn-around  2  length  414 . If this CRC fails to check, then the entire packet should be discarded. All zero  1   420  comprises 8 bytes that each contain an 8-bit unsigned integer equal to zero. This field ensures that all MDDI_Data signals are at a logic-zero level for a sufficient time to allow the client to begin recovering clock using only MDDI_Stb prior to disabling the host&#39;s line drivers during turn-around  1   422  field. Turn-around  1   422  comprises a first turn-around period. The number of bytes specified by turn-around  1  length  412  parameter is allocated to allow the MDDI_Data line drivers in the client to enable before the line drivers in the host are disabled. The client shall enable its MDDI_Data line drivers during bit  0  of turn-around  1   422  and the host shall disable its outputs and be completely disabled prior to the last bit of turn-around  1   422 . The MDDI_Stb signal behaves as though MDDI_Data 0  were at a logic-zero level during the entire turn-around  1   422  period. 
         [0043]    Reverse synchronization and data packets  424  are shown as a single field in  FIG. 4 . The first byte in this field should be the synchronization pattern (0x053F) if requested by bit two being set to logic one in reverse link flags  408  field. This field should be followed by the packet length field of the first reverse link packet. More than one packet can be transmitted in the reverse data period if there is enough room. The client may send filler packets or drive the MDDI_Data lines to a logic-zero level when it has no data to send to the host for a period of two reverse link byte times. If the MDDI_Data lines are driven to zero for this period, the host will interpret this as a packet with a zero length (not a valid length) and both the host and the client will move from the reverse encapsulation field to the Turn-around  2  field  400  after this period. Turn-around  2   426  comprises the second turn-around period. The number of bytes is specified by the turn-around  2  length  414  parameter. The host shall enable its MDDI_Data line drivers and be completely enabled prior to the last bit of turn-around  2   426  and the client shall disable its outputs and be completely disabled prior to the last bit of turn-around  2   426 . The purpose of turn-around  2   426  is to allow the remaining amount of data from reverse data packets  424  field to be transmitted from the client. Due to variations in different systems and the amount of safety margin allocated it is possible that neither the host nor client will be driving the MDDI_Data signals to a logic-zero level during some parts of the turn-around  2   426  field as seen by the line receivers at the host. The MDDI_Stb signal behaves as though MDDI_Data 0  were at a logic-zero level during the entire turn-around  2   426  period. All zero  2   428  comprises 8 bytes that each contain an 8-bit unsigned integer equal to zero. This field ensures that all MDDI_Data signals are at a logic-zero level for a sufficient time to allow the client to begin recovering clock using both MDDI_Data 0  and MDDI_Stb after enabling the host&#39;s line drivers following the turn-around  2   426  field. 
         [0044]    This specification discloses one or more aspects that incorporate the features of the claimed invention. The disclosed aspects merely exemplify the claimed invention. 
         [0045]    The scope of the claimed invention is not limited to the disclosed aspects. The invention is defined by the claims appended hereto. 
         [0046]    Those of skill in the art would understand that information and signals may be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referenced throughout the above description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles or any combination thereof. 
         [0047]    Those of skill would further appreciate that the various illustrative logical blocks, modules, circuits, and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software or combinations of both. To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention. 
         [0048]    The various illustrative logical blocks, modules, and circuits described in connection with the embodiments disclosed herein may be implemented or performed with a general purpose processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration. 
         [0049]    The steps of a method or algorithm described in connection with the embodiments disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. A software module may reside in Random Access Memory (RAM), flash memory, Read Only Memory (ROM), Electrically Programmable ROM (EPROM), Electrically Erasable Programmable ROM (EEPROM), registers, hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. An exemplary storage medium is coupled to the processor such that the processor can read information from, and write information to, the storage medium. In the alternative, the storage medium may be integral to the processor. The processor and the storage medium may reside in an ASIC. The ASIC may reside in a user terminal. In the alternative, the processor and the storage medium may reside as discrete components in a user terminal. 
         [0050]    The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.